chlortetracycline and Swine-Diseases

Feed-grade chlortetracycline (CTC) and copper are both widely utilized in U.S. pig production. Cluster randomized experiment was conducted to evaluate the effects of CTC and copper supplementation in weaned pigs on antimicrobial resistance (AMR) among fecal Escherichia coli. Four treatment groups: control, copper, CTC, or copper plus CTC were randomly allocated to 32 pens with five pigs per pen. Fecal samples were collected weekly from three pigs per pen for six weeks. Two E. coli isolates per fecal sample were tested for phenotypic and genotypic resistance against antibiotics and copper. Data were analyzed with multilevel mixed effects logistic regression, multivariate probit analysis and discrete time survival analysis. CTC-supplementation was significantly (99% [95% CI=98-100%]) associated with increased tetracycline resistance compared to the control group (95% [95% CI=94-97%]). Copper supplementation was associated with decreased resistance to most of the antibiotics tested, including cephalosporins, over the treatment period. Overall, 91% of the E. coli isolates were multidrug resistant (MDR) (resistant to ≥3 antimicrobial classes). tetA and blaCMY-2 genes were positively associated (P<0.05) with MDR categorization, while tetB and pcoD were negatively associated with MDR. tetA and blaCMY-2 were positively associated with each other and in turn, these were negatively associated with both tetB and pcoD genes; which were also positively associated with one another. Copper minimum inhibitory concentration was not affected by copper supplementation or by pcoD gene carriage. CTC supplementation was significantly associated with increased susceptibilities of E. coli to copper (HR=7 [95% CI=2.5-19.5]) during treatment period. In conclusion, E. coli isolates from the nursery pigs exhibited high levels of antibiotic resistance, with diverse multi-resistant phenotypic profiles. The roles of copper supplementation in pig production, and pco-mediated copper resistance among E. coli in particular, need to be further explored since a strong negative association of pco with both tetA and blaCMY-2 points to opportunities for selecting a more innocuous resistance profile.

Topics: Animals; Anti-Bacterial Agents; Chlortetracycline; Copper; Dietary Supplements; Drug Resistance, Multiple, Bacterial; Drug Therapy, Combination; Escherichia coli; Escherichia coli Infections; Feces; Swine; Swine Diseases

Shoulder ulcers can have a significant impact on the welfare of sows. In Denmark, rubber mats are used for treatment of shoulder ulcers. The objective of the study was to compare a treatment consisting of a combination of rubber mats and zinc ointment with the effect of local antibiotic spray (chlortetracycline) on shoulder ulcers.. A total of 304 sows with shoulder ulcers were observed shortly after farrowing (day 1) and on days 14 and 21 after the first observation. The sows were paired according to the grade of the shoulder ulcer using the official Danish scoring system. From each pair of sows, one sow was allocated to mat group (M) and the other to an antibiotic group (A) in a random way. In the M group, rubber mats were placed on the floor, and the ulcers were treated with zinc ointment once a day. In the A group, sows were treated with antibiotic spray daily. The size of the shoulder ulcer was measured manually on a continuous scale on days 1, 14 and 21. The data were analysed by use of two multivariable models where the response was the area of the shoulder ulcer on day 14 and day 21, respectively. Explanatory variables were treatment, herd, parity, body condition and size of ulcer on day 1. If a sow had an ulcer on both shoulders, the shoulder with the largest ulcer was selected.. The treatment consisting of mats and zinc ointment had a statistical significant effect on the size of the shoulder ulcer on day 14 and day 21 compared to daily treatment with antibiotic spray. For lean sows that were kept on rubber mats and zinc ointment, the average shoulder ulcer was significantly smaller on day 14 (3.8 cm(2) versus 9.5 cm(2) when antibiotic spray was used) and day 21 (3.4 cm(2) versus 6.6 cm(2)) compared to lean sows that were only treated with antibiotic spray. For fat sows this was also the case when using the lesion on day 21 as the response (2.0 cm(2) versus 5.7 cm(2)) but not on day 14. Moreover, the size of the lesion on day 1 was statistically associated with the size of the lesion on day 14 and on day 21. The treatment was equally effective in the three herds.. Rubber mats and daily smearing with zinc ointment slow progression and contribute to the healing of shoulder ulcers compared with housing on slats and daily spraying with antibiotics. It is recommended to place a rubber mat in the farrowing crate at the first sign of shoulder ulcers.

Topics: Animals; Anti-Bacterial Agents; Chlortetracycline; Floors and Floorcoverings; Forelimb; Housing, Animal; Ointments; Skin Ulcer; Swine; Swine Diseases; Zinc

To evaluate effects of quaternary benzo(c)phenanthridine alkaloids (QBAs) against Salmonella spp and determine effects on growth performance, organism shedding, and gastrointestinal tract integrity in pigs inoculated with Salmonella enterica serovar Typhimurium.. 36 Salmonella isolates and twenty 5-week-old pigs.. Minimum inhibitory concentration of QBAs against the Salmonella isolates was determined. Pigs were allocated to 4 groups and inoculated with Salmonella organisms. Pigs received diets supplemented with 1.5 g of QBAs/1,000 kg of feed, 0.75 g of QBAs/1,000 kg of feed, or 59.4 g of chlortetracycline/1,000 kg of feed or a nonsupplemented (control) diet. Pigs were weighed on day 0 and then weekly for 40 days. Fecal samples were collected to quantify Salmonella organisms. Gastrointestinal tract integrity was evaluated by measuring transepithelial resistance.. In vitro, 9 of 36 (25%) Salmonella isolates were inhibited at 90 μg of QBAs/mL; all 36 were inhibited at 179 μg of QBAs/mL. Diets containing QBAs significantly decreased Salmonella spp shedding; shedding was lower 40 days after inoculation for pigs fed diets containing QBAs or chlortetracycline than for pigs fed the control diet. Growth performance was similar for pigs fed diets containing QBA or chlortetracycline. Gastrointestinal tract integrity was improved in pigs fed the diet containing 1.5 g of QBAs/1,000 kg of feed.. QBAs and chlortetracycline decreased Salmonella spp shedding but did not differ with regard to growth performance. Gastrointestinal tract integrity was better, albeit not significantly, in pigs fed diets containing QBAs. Further investigation into the role of QBAs and their mechanism as an immunomodulator is necessary.

Topics: Animals; Bacterial Shedding; Benzophenanthridines; Chlortetracycline; Drug Resistance, Multiple; Feces; Gastrointestinal Tract; Growth and Development; Microbial Sensitivity Tests; Salmonella Infections, Animal; Swine; Swine Diseases

Previously we have shown that experimentally infected swine, fed an antibiotic-free diet, can become colonized and shed Escherichia coli O157:H7 for at least 2 months. However, in epidemiological studies this organism is only rarely recovered from domestic swine and the basis for this discrepancy is not clear. In this report we demonstrate that significantly fewer pigs fed diets containing subtherapeutic levels of either tylosin or chlorotetracycline shed E. coli O157:H7 for longer than 2 weeks compared to those fed an antibiotic-free diet. In contrast to tylosin and chlorotetracycline, the addition of bacitracin methylene disalicylate to the diet did not influence the recovery of E. coli O157:H7. These results suggest that some antibiotics may alter the gastrointestinal tract flora in ways that create a less favorable environment for E. coli O157:H7 in swine.

Topics: Animal Feed; Animals; Anti-Bacterial Agents; Chlortetracycline; Diet; Escherichia coli Infections; Escherichia coli O157; Feces; Intestines; Palatine Tonsil; Swine; Swine Diseases; Time Factors; Tylosin

A disease challenge experiment was conducted to determine if including 10% dried distillers grains with solubles (DDGS) in the diet, with or without antimicrobial supplementation, reduces the incidence or severity, or both, of intestinal lesions in growing pigs after an Lawsonia intracellularis challenge. One hundred 17-d-old weaned pigs were blocked by sex, ancestry, and BW and randomly allotted to 1 of 5 treatment groups: negative control, unchallenged, corn-soy diet; positive control, challenged, corn-soy diet; 10% DDGS diet, challenged; positive control with antimicrobial regimen, challenged; and 10% DDGS diet with antimicrobial regimen, challenged. For antimicrobial-supplemented treatments, diets contained 33 ppm bacitracin methylene disalicylate throughout the experiment, with chlortetracycline (Aureomycin) pulsed at 550 ppm from d 3 prechallenge to d 11 postchallenge. Challenged pigs were orally inoculated with 8.0 x 10(8) L. intracellularis organisms after a 4-wk prechallenge period. On d 21 postchallenge, pigs were euthanized, lesions of intestinal mucosa were evaluated, and ileal tissue samples were analyzed by immunohistochemistry to determine the presence and proliferation rate of L. intracellularis. Compared with other dietary treatments, feeding a diet containing 10% DDGS reduced ileum and colon lesion length and prevalence (P < 0.05) and reduced severity of lesions in the ileum (P < 0.05) and colon (P < 0.10) in challenged pigs. Compared with other challenged pigs, those fed the diet containing the antimicrobial regimen had a lower prevalence and severity of lesions in the jejunum (P < 0.05) and tended to have reduced total tract lesion length (P = 0.11). Compared with other challenged pigs, pigs on the 10% DDGS diet with antimicrobial regimen exhibited no differences in length, severity, or prevalence of lesions (P > 0.15), but fecal shedding of L. intracellularis was reduced on d 14 postchallenge (P < 0.05). No dietary effects on fecal shedding were observed by d 20 postchallenge (P > 0.10). The proportion of cells infected with L. intracellularis was reduced when DDGS (P = 0.05) or antimicrobial (P = 0.10) diets were fed. Under the conditions of this experiment, dietary inclusion of 10% DDGS appears to provide some benefit to growing pigs subjected to a moderate L. intracellularis challenge, similar to those of a currently approved antimicrobial regimen.

Topics: Animal Feed; Animal Nutritional Physiological Phenomena; Animals; Anti-Bacterial Agents; Bacitracin; Chlortetracycline; Desulfovibrionaceae Infections; Diet; Disease Susceptibility; Edible Grain; Female; Gastrointestinal Tract; Ileitis; Lawsonia Bacteria; Male; Solubility; Swine; Swine Diseases

The purpose of this study was to compare the efficacy of Mycoplasma hyopneumoniae vaccination with pulse medication in a pig herd chronically infected with Mycoplasma hyopneumoniae. Control groups of pigs were compared to vaccinated or treated groups. Medication and vaccination induced a significant reduction of pneumonia score (46.37% and 29.8% respectively, compared to 53.85% for control groups, p < 0.05). The treatment did not induce a significant reduction of the mean range of lung lesions (3.75) compared to the control groups (4.25). The mean range of lung lesions was significantly reduced by vaccine (3.06, p < 0.005) but not by treatment. Neither the medication nor the vaccination were able to clear M hyopneumoniae or Pasteurella multocida from lung tissue. In this herd, the vaccination had a beneficial effect on daily weight gain of pigs (695.9 g/day compared to 683.1 g/day for the control groups). The improvement of the age at slaughtering was 1.3 days for treated groups and 2.4 days for vaccinated groups compared to control groups. The vaccination induced a significant improvement in muscle rate (57.05%) compared to control groups (56.41%, p < 0.05) and to treated groups (56.21%, p < 0.001). In this herd infected with M hyopneumoniae, after allowing for treatment cost, manpower excepted, the increase in value was from -3 FF to -11 FF for the antibiotic treatment and +10.4 FF for the vaccination. From economical and medical points of view, the vaccination was preferable to the treatment under the conditions described in this study.

Topics: Animals; Anti-Bacterial Agents; Bacterial Vaccines; Chlortetracycline; Diterpenes; Lung; Mycoplasma; Mycoplasma Infections; Pasteurella Infections; Pasteurella multocida; Swine; Swine Diseases; Vaccination

The objective was to study the effects of microencapsulated organic acids (OA) and essential oils (EO) on growth performance, immune system, gut barrier function, nutrient digestion and absorption, and abundance of enterotoxigenic Escherichia coli F4 (ETEC F4) in the weaned piglets challenged with ETEC F4. Twenty-four ETEC F4 susceptible weaned piglets were randomly distributed to 4 treatments including (1) sham-challenged control (SSC; piglets fed a control diet and challenged with phosphate-buffered saline (PBS)); (2) challenged control (CC; piglets fed a control diet and challenged with ETEC F4); (3) antibiotic growth promoters (AGP; CC + 55 mg·kg-1 of Aureomycin); and (4) microencapsulated OA and EO [P(OA+EO); (CC + 2 g·kg-1 of microencapsulated OA and EO]. The ETEC F4 infection significantly induced diarrhea at 8, 28, 34, and 40 hr postinoculation (hpi) (P < 0.05) in the CC piglets. At 28 d postinoculation (dpi), piglets fed P(OA+EO) had a lower (P < 0.05) diarrhea score compared with those fed CC, but the P(OA+EO) piglets had a lower (P < 0.05) diarrhea score compared with those fed the AGP diets at 40 dpi. The ETEC F4 infection tended to increase in vivo gut permeability measured by the oral gavaging fluorescein isothiocyanate-dextran 70 kDa (FITC-D70) assay in the CC piglets compared with the SCC piglets (P = 0.09). The AGP piglets had higher FITC-D70 flux than P(OA+EO) piglets (P < 0.05). The ETEC F4 infection decreased mid-jejunal VH in the CC piglets compared with the SCC piglets (P < 0.05). The P(OA+EO) piglets had higher (P < 0.05) VH in the mid-jejunum than the CC piglets. The relative mRNA abundance of Na+-glucose cotransporter and B0AT1 was reduced (P < 0.05) by ETEC F4 inoculation when compared with the SCC piglets. The AGP piglets had a greater relative mRNA abundance of B0AT1 than the CC piglets (P < 0.05). The ETEC F4 inoculation increased the protein abundance of OCLN (P < 0.05), and the AGP piglets had the lowest relative protein abundance of OCLN among the challenged groups (P < 0.05). The supplementation of microencapsulated OA and EO enhanced intestinal morphology and showed anti-diarrhea effects in weaned piglets challenged with ETEC F4. Even if more future studies can be required for further validation, this study brings evidence that microencapsulated OA and EO combination can be useful within the tools to be implemented in strategies for alternatives to antibiotics in swine production.

Topics: Animals; Anti-Bacterial Agents; Carboxylic Acids; Chlortetracycline; Diarrhea; Diet; Drug Compounding; Enterotoxigenic Escherichia coli; Escherichia coli Infections; Female; Gastrointestinal Microbiome; Immunity; Jejunum; Male; Nutrients; Oils, Volatile; Random Allocation; Swine; Swine Diseases; Weaning

To investigate the mechanisms leading to an increase in the prevalence of blaCMY -2 conferring resistance to ceftiofur in pigs receiving a feed medicated with chlortetracycline and penicillin, and to examine the effect of supplementation with a clay mineral on this phenomenon.. In 138 blaCMY -2 -positive Escherichia coli isolates from faeces of pigs receiving feed supplemented or not with 2% clinoptilolite, from day 2 to day 28 after weaning, isolates from the two groups differed significantly with respect to their phylogenetic group: phylotype A predominated in the supplemented group, whereas phylotypes B1 and D predominated in the control group, as determined by PCR. In 36 representative isolates, pulsed-field gel electrophoresis and antimicrobial susceptibility testing revealed that the blaCMY -2 -positive E. coli isolates were polyclonal with diverse antimicrobial resistance patterns and blaCMY -2 -carrying plasmids of incompatibility (Inc) groups, A/C, I1 and ColE were observed in transformants as detected by PCR. Enterobacter cloacae possessing blaCMY -2 -carrying IncA/C plasmids were found in the pens before introduction of this batch of pigs. The blaCMY -2 -positive E. coli isolates were more clonally diverse in the control group than the supplemented group.. The blaCMY -2 gene appears to have spread both horizontally and clonally in this batch of pigs and may have spread from previous batches of pigs via plasmids carried by Ent. cloacae and expanded in animals of the present batch in the presence of the selection pressure due to administration of chlortetracycline and penicillin in the feed. Feed supplementation may have an effect on clonal diversity of blaCMY -2 -positive isolates.. Implementation of improved hygiene measures, decreased administration of certain antimicrobials on farm and feed supplementation with certain ingredients may limit antimicrobial resistance spread between and within batches of animals.

Topics: Aluminum Silicates; Animal Feed; Animals; Anti-Bacterial Agents; beta-Lactamases; Cephalosporins; Chlortetracycline; Clay; Dietary Supplements; Drug Resistance, Bacterial; Electrophoresis, Gel, Pulsed-Field; Escherichia coli; Escherichia coli Infections; Escherichia coli Proteins; Farms; Feces; Phylogeny; Plasmids; Swine; Swine Diseases; Weaning

Statistical analysis of antimicrobial resistance data largely focuses on individual antimicrobial's binary outcome (susceptible or resistant). However, bacteria are becoming increasingly multidrug resistant (MDR). Statistical analysis of MDR data is mostly descriptive often with tabular or graphical presentations. Here we report the applicability of generalized ordinal logistic regression model for the analysis of MDR data. A total of 1,152 Escherichia coli, isolated from the feces of weaned pigs experimentally supplemented with chlortetracycline (CTC) and copper, were tested for susceptibilities against 15 antimicrobials and were binary classified into resistant or susceptible. The 15 antimicrobial agents tested were grouped into eight different antimicrobial classes. We defined MDR as the number of antimicrobial classes to which E. coli isolates were resistant ranging from 0 to 8. Proportionality of the odds assumption of the ordinal logistic regression model was violated only for the effect of treatment period (pre-treatment, during-treatment and post-treatment); but not for the effect of CTC or copper supplementation. Subsequently, a partially constrained generalized ordinal logistic model was built that allows for the effect of treatment period to vary while constraining the effects of treatment (CTC and copper supplementation) to be constant across the levels of MDR classes. Copper (Proportional Odds Ratio [Prop OR]=1.03; 95% CI=0.73-1.47) and CTC (Prop OR=1.1; 95% CI=0.78-1.56) supplementation were not significantly associated with the level of MDR adjusted for the effect of treatment period. MDR generally declined over the trial period. In conclusion, generalized ordered logistic regression can be used for the analysis of ordinal data such as MDR data when the proportionality assumptions for ordered logistic regression are violated.

Topics: Animals; Anti-Bacterial Agents; Chlortetracycline; Copper; Drug Resistance, Multiple, Bacterial; Escherichia coli; Escherichia coli Infections; Feces; Logistic Models; Swine; Swine Diseases

When considering the development of antimicrobial resistance in food animals, comparing gross use estimates of different antimicrobials is of little value due to differences in potencies, duration of activity, relative effect on target and commensal bacteria, and mechanisms of resistance. However, it may be valuable to understand quantities of different antimicrobials used in different ages of swine and for what applications. Therefore, the objective of this project was to construct an estimate of antimicrobial use through the feed in swine production in the United States. Estimates were based on data from the National Animal Health Monitoring System (NAHMS) Swine 2006 Study and from a 2009 survey of swine-exclusive practitioners. Inputs consisted of number of pigs in a production phase, feed intake per day, dose of the antimicrobial in the feed, and duration of administration. Calculations were performed for a total of 102 combinations of antimicrobials (n=17), production phases (n=2), and reasons for use (n=3). Calculations were first conducted on farm-level data, and then extrapolated to the U.S. swine population. Among the nursery phase estimates, chlortetracycline had the largest estimate of use, followed by oxytetracycline and tilmicosin. In the grower/finisher phase, chlortetracycline also had the largest use estimate, followed by tylosin and oxytetracycline. As an annual industry estimate for all phases, chlortetracycline had the highest estimated use at 533,973 kg. The second and third highest estimates were tylosin and oxytetracycline with estimated annual uses of 165,803 kg and 154,956 kg, respectively. The estimates presented here were constructed to accurately reflect available data related to production practices, and to provide an example of a scientific approach to estimating use of compounds in production animals.

Topics: Animal Feed; Animal Husbandry; Animals; Anti-Infective Agents; Chlortetracycline; Foodborne Diseases; Models, Statistical; Oxytetracycline; Practice Patterns, Physicians'; Surveys and Questionnaires; Sus scrofa; Swine; Swine Diseases; Time Factors; Tylosin; United States; Veterinarians; Veterinary Drugs

A sudden onset of extreme dysgalactia in gilts and sows in a 1,000-head farrow-to-wean herd was observed in December 2009. Signs of dysgalactia were identified in sows beginning 1 day after parturition and lasted 4 to 6 days. This resulted in a mean piglet preweaning mortality rate of 18% because of starvation.. Sows were neither off feed nor febrile. Udders were not inflamed or congested. Feed sample analysis did not find ergotamine, mycotoxin contamination, or ration formulation errors. Management practices were acceptable. Piglets attempted to stimulate milk production but none was elicited. Oxytocin (20 U) caused milk ejection but the effect was short-lived. Blood samples from sows with affected litters were positive for Mycoplasma suis (formerly Eperythrozoon suis) by PCR assay, and blood samples from sows with unaffected litters were negative.. Chlortetracycline fed to the entire sow herd at 22 mg/kg/d (10 mg/lb/d) for 2 weeks resulted in a near complete absence of dysgalactia in sows farrowing within 5 weeks after the start of treatment. Dysgalactia did occur in sows that received chlortetracycline > 5 weeks prior to farrowing. Currently, gestating sows and gilts receive chlortetracycline in feed at a dosage of 22 mg/kg/d for 2 weeks beginning 3 weeks prior to farrowing.. M suis is spread primarily by blood contact from animal to animal, and diagnosis of infection with this organism can be easily missed by means of standard diagnostic protocols unless PCR assays or specific stains are used. Therefore, its current prevalence and impact are likely to be greatly underestimated.

Topics: Animal Feed; Animals; Anti-Bacterial Agents; Chlortetracycline; Female; Lactation; Mycoplasma; Mycoplasma Infections; Pregnancy; Swine; Swine Diseases

A particularly virulent O149:H10 enterotoxigenic Escherichia coli clone harbours a newly characterized plasmid pTENT2 carrying the tetracycline-resistance tetA and the virulence genes estA, paa, and sepA that were not present in less virulent clones. The objectives of this study were to assess whether the additional genes on pTENT2 played a role in the increased severity of post-weaning diarrhoea and if they provided any potential advantage for the emergence of the highly virulent clone. Groups of pigs were dosed orally with isogenic pTENT2-positive and pTENT2-negative ETEC strains, and the clinical and pathological changes were compared between the groups. Two additional groups were given the pTENT2-positive strains and maintained on feed with or without chlortetracycline to assess the effect of subtherapeutic levels of tetracycline on the short-term persistence of the ETEC O149:H10 clone. The severity of diarrhoea within the first few hours post-inoculation was significantly increased (p=0.0408) in animals receiving pTENT2-positive strains as compared to animals receiving pTENT2-negative strains. There were no consistent or significant histopathological differences between any of the groups and no significant difference in the persistence of ETEC between groups.

Topics: Animals; Anti-Bacterial Agents; Chlortetracycline; Diarrhea; Enterotoxigenic Escherichia coli; Escherichia coli Infections; Plasmids; Swine; Swine Diseases; Time Factors; Weaning

The objective of this research was to determine the effect of stocking density and inclusion of subtherapeutic chlortetracycline in the diet on Salmonella fecal prevalence and antimicrobial resistance in growing swine. A 2 x 2 factorial design was employed on a privately owned commercial swine farm. Four finisher rooms were included in the study. Two of the rooms received 50 g/tonnes of chlortetracycline in the ration, two rooms received no antimicrobials in the feed. In each room, alternate pens were assigned to either high stocking density (0.60 m2/pig) or low stocking density (0.74 m2/pig). Pigs were placed in the finisher rooms at 10 weeks of age and followed for 6 weeks. Individual fecal samples were collected from the floors of each pen and cultured once weekly. Antimicrobial resistance phenotypes were determined. Data were analyzed using multilevel, multivariable logistic regression. Pigs fed chlortetracycline were at increased odds (OR 6.88, 95% CI 2.77-17.12) to shed Salmonellae. No other associations between treatments (CTC and stocking density) and Salmonella prevalence or reduced susceptibility to antimicrobials were identified. Variance in the odds of a fecal sample to be positive was distributed mostly at the lowest level, the individual fecal sample. The increased risk of shedding associated with inclusion of subtherapeutic chlortetracycline in swine diets is discordant with previous results by our group, suggesting farm or strain specific factors may impact this association. Understanding this risk may provide a potential intervention for controlling Salmonella pre-harvest.

Topics: Animal Feed; Animal Husbandry; Animals; Anti-Bacterial Agents; Chlortetracycline; Colony Count, Microbial; Confidence Intervals; Drug Resistance, Bacterial; Feces; Female; Logistic Models; Microbial Sensitivity Tests; Multivariate Analysis; Odds Ratio; Population Density; Random Allocation; Salmonella enterica; Salmonella Infections, Animal; Swine; Swine Diseases

To investigate the effect of a therapeutic and sub-therapeutic chlortetracycline treatment on tetracycline-resistant Salmonella enterica serovar Typhimurium DT104 and on the commensal Escherichia coli in pig.. Salmonella Typhimurium DT104 was orally administered in all pigs prior to antibiotic treatment, and monitored with the native E. coli. Higher numbers of S. Typhimurium DT104 were shed from treated pigs than untreated pigs. This lasted up to 6 weeks post-treatment in the high-dose group. In this group, there was a 30% increase in E. coli with a chlortetracycline minimal inhibitory concentration (MIC) > 16 mg l-1 and a 10% increase in E. coli with an MIC > 50 mg l-1 during and 2 weeks post-treatment. This effect was less-pronounced in the low-dose group. PCR identified the predominant tetracycline resistance genes in the E. coli as tetA, tetB and tetC. The concentration of chlortetracycline in the pig faeces was measured by HPLC and levels reached 80 microg g-1 faeces during treatment.. Chlortetracycline treatment increases the proportion of resistant enteric bacteria beyond the current withdrawal time.. Treated pigs are more likely to enter abattoirs with higher levels of resistant bacteria than untreated pigs promoting the risk of these moving up the food chain and infecting man.

Topics: Animals; Anti-Bacterial Agents; Chlortetracycline; Digestive System; Drug Resistance, Multiple, Bacterial; Escherichia coli; Escherichia coli Infections; Feces; Genes, Bacterial; Salmonella Infections, Animal; Salmonella typhimurium; Swine; Swine Diseases; Tetracycline Resistance

Tetracyclines have been shown to have anti-inflammatory effects in addition to their antimicrobial action. We investigated the effects of in vivo administration of chlortetracycline (CTC) on ex vivo perfused pig livers. The retention and clearance of Salmonella choleraesuis, production of acute phase proteins C-reactive protein (CRP), and haptoglobin (HPG) by whole livers were studied. The in vitro modulation by CTC of TNF-alpha secretion by pig Kupffer cells (KC) was also studied. Pigs were dosed orally with CTC for three days, and given injections of Salmonella LPS 24 h before removal of the liver. Salmonella retention and clearance by livers of pigs given CTC was lower than by control livers (p < 0.01 and p < 0.05, respectively). We demonstrated an increase of CRP and HPG by livers from control pigs after a three-hour perfusion while pigs from CTC pretreated pigs varied in this response. Further, CTC decreased the secretion of TNF-alpha by cultured KC incubated in vitro with LPS. Modulation of TNF-alpha production by CTC suggests a potential for attenuating the inflammatory response. However, this possible beneficial action of CTC was accompanied by a significant decline in the antimicrobial effect of the liver.

Topics: Acute-Phase Reaction; Animals; Anti-Bacterial Agents; C-Reactive Protein; Chlortetracycline; Disease Models, Animal; Haptoglobins; Kupffer Cells; Liver; Perfusion; Salmonella; Salmonella Infections, Animal; Swine; Swine Diseases; Tumor Necrosis Factor-alpha

The authors have performed a comparative study of the efficacy of various in-feed medications for the treatment of 5- to 6-week-old specific pathogen-free (SPF) piglets experimentally infected on day 1 with Mycoplasma hyopneumoniae, on day 8 with Pasteurella multocida (serotype A), and on day 15 with Actinobacillus pleuropneumoniae (serotype 2). The treatment started on day 9 and continued for 12 consecutive days, then the piglets were euthanized for examination of macroscopic, histologic, and pathologic lesions and for the presence of mycoplasmas and bacteria in the lungs. Based on the results of clinical observations (respiratory signs, rectal temperature, body weight gain, and feed conversion efficiency), macroscopic and histologic lesions of the lungs, and microbiologic findings, the best results were obtained by treatment of pigs with Econor + chlortetracycline, followed by Tetramutin, Pulmotil, Cyfac, and lincomycin + chlortetracycline.

Topics: Actinobacillus Infections; Actinobacillus pleuropneumoniae; Animal Feed; Animals; Anti-Bacterial Agents; Chlortetracycline; Diterpenes; Drug Therapy, Combination; Mycoplasma; Mycoplasma Infections; Pasteurella Infections; Pasteurella multocida; Specific Pathogen-Free Organisms; Swine; Swine Diseases; Treatment Outcome; Weight Gain

Topics: Administration, Oral; Animals; Anti-Bacterial Agents; Chlortetracycline; Ileitis; Swine; Swine Diseases

To compare health and growth performance in barrows reared in all-in/all-out (AIAO) or continuous flow (CF) management systems.. 400 barrows.. Barrows (approx 2 months old) were allotted to 4 replications (100 barrows each); barrows were housed in AIAO or CF rooms (10 pens/room), and 50 pigs/replicate received chlortetracycline (CTC, 110 mg/kg of feed). Barrows from each pen were slaughtered at 3, 4, 5, and 6 months old.. Barrows in the AIAO room had greater total daily gain (TDG) and lean daily gain (LDG) than did barrows in the CF room. Addition of CTC did not improve TDG or LDG in either environment. Barrows in the AIAO room reached body weight of 104.5 kg in 169.7 days, compared with 177.3 days for barrows in the CF room. Feed-to-gain ratio was not affected by management or CTC. Lungs from barrows reared in AIAO facilities had a lower percentage of lesions than did lungs of barrows reared in CF facilities (1.74% vs 9.52%). Addition of CTC did not affect prevalence and extent of lung lesions. Extent of lung lesions was positively correlated with change in serum optical density (OD) to Mycoplasma hyopneumoniae (r = 0.35), but not with change in serum OD to Actinobacillus pleuropneumoniae. Lean growth and serum OD to M. hyopneumoniae and A. pleuropneumoniae were not correlated.. Health and growth performance were better for barrows in an AIAO facility, compared with a CF facility, but addition of CTC to feed failed to enhance health or performance of barrows in either facility.

Topics: Animal Feed; Animals; Anti-Bacterial Agents; Antibiotic Prophylaxis; Bacterial Infections; Chlortetracycline; Food Additives; Housing, Animal; Ivermectin; Liver; Lung; Male; Orchiectomy; Parasitic Diseases, Animal; Swine; Swine Diseases; Weight Gain

The present study was aimed at scrutinizing the efficacy of oral antimicrobial treatments at experimental challenge using a strain of Actinobacillus pleuropneumoniae serotype 2 known to cause severe disease. SPF pigs aged 10 weeks were infected intranasally and the antimicrobial treatments were initiated 5 h prior to that exposure. Several antimicrobial drugs, as well as the length of the treatment period, were elucidated. The outcome of the challenge was monitored by registration of clinical symptoms, weight gains and the development of serum antibodies to A. pleuropneumoniae. At necropsy, the magnitude of pathological lesions in the respiratory tract and the rate of reisolation of the infective strain were recorded. Animals that became diseased displayed a decreased growth rate caused, to a large extent, by a reduced feed intake. The performance with respect to daily weight gain and feed conversion corresponded well with the clinical signs developed and serologic reactions, as well as with the findings made at necropsy. The results obtained among pigs treated with enrofloxacin, but also with florfenicol or chlortetracycline, were superior to those of pigs treated with penicillin, tiamulin or tilmicosin. A positive effect was obtained using a strategic in-feed medication against infection with A. pleuropneumoniae. Provided that the drug used is effective against the target microbe, initiating treatment prior to infection appeared to be more important than the length of the treatment. It should, however, be remembered that A. pleuropneumoniae was reisolated from all but one medicated group following an experimental challenge given after initiating the medication. Consequently medical treatment as described did not eradicate the microbe.

Topics: Actinobacillus Infections; Actinobacillus pleuropneumoniae; Administration, Oral; Animals; Anti-Bacterial Agents; Anti-Infective Agents; Chlortetracycline; Diterpenes; Enrofloxacin; Fluoroquinolones; Macrolides; Penicillin V; Quinolones; Swine; Swine Diseases; Thiamphenicol; Tylosin

Due to the conditions of modern industrial pig fattening in intensive livestock farms, 24% to 69% of the animals become ill. The antibiotic metaphylaxis that is routinely administered leads to several problems in animals, human health, and the environment.. To investigate whether a homeopathic metaphylaxis is effective and potentially useful for replacing antibiotic metaphylaxis.. Animal subjects were divided into groups of 10 per pen, 2 pens sharing 1 trough. Twenty pigs were randomly assigned within a stall and were administered either antibiotics, homeopathy, or placebo.. A typical intensive livestock farm in Northern Germany.. 1440 piglets.. Homeopathic metaphylaxis is compared with placebo, the routine low-dose antibiotic metaphylaxis, and an antibiotic metaphylaxis in therapeutic dosage.. Incidence of diseases in general and of diseases of the respiratory tract.. Homeopathic metaphylaxis is significantly effective compared with placebo and routine low-dose antibiotic metaphylaxis for incidence of disease and rate of disease of the respiratory tract among the animals studied. Only by increasing the dosage of antibiotics to a therapeutic level does antibiotic metaphylaxis surpass homeopathic metaphylaxis.. An unacceptably high percentage of pigs in modern livestock management become ill, suffering mainly from diseases of the respiratory tract. The routine antibiotic dosage of metaphylaxis is too low to be effective. As a result, the problems of resistance and danger to human health and the environment are increasing. To confirm whether antibiotic metaphylaxis may be replaced by homeopathic metaphylaxis, this study should be repeated independently.

Topics: Animals; Anti-Infective Agents; Bacterial Infections; Chlortetracycline; Dimetridazole; Homeopathy; Random Allocation; Respiratory Tract Infections; Sulfamethazine; Swine; Swine Diseases

Eperythrozoon suis infection was identified in a pig herd during an investigation into anaemia and low viability in newborn piglets and severe regenerative macrocytic anaemia in older piglets. The organisms were identified in the erythrocytes of piglets a few days old. Extensive investigations failed to detect other causes of the anaemia and low viability. There was no response to parenteral iron administration alone but the piglets' viability and anaemia responded to the administration of tetracyclines. This is the first report of E suis infection in Northern Ireland.

Topics: Anemia; Animals; Animals, Newborn; Anti-Bacterial Agents; Chlortetracycline; Female; Mycoplasma; Mycoplasma Infections; Oxytetracycline; Swine; Swine Diseases

26 fattening pigs with spontaneous severe chronic bronchopneumonitis were orally treated with feed containing 800 ppm chlortetracycline (CTC) over 3 weeks. With the help of clinical investigation, transcutaneous measurement of the oxygen-saturation of the blood, X-ray of the thorax and bronchoalveolar lavage significant effects could be measured during and after finishing the treatment. In 19 spontaneous fallen ill untreated control animals recovery could not be detected by the used methods. After the end of the 3 weeks interval there were significant differences between treated and untreated animals detectable. By this investigations practical observations that oral treatment with 800 ppm in fattening pigs is effective was verified. But because of pharmacokinetic data higher concentrations would be recommendable. In the treated pigs a significant increase of the oxygen saturation of the blood occurred not before the 8th day of treatment. This underlines the importance of sufficient length of the treatment interval.

Topics: Administration, Oral; Animal Feed; Animals; Chlortetracycline; Chronic Disease; Pneumonia, Bacterial; Swine; Swine Diseases

Consumption of chlortetracycline (CTC) at concentration of 220 mg/kg of feed for 4 weeks in experiment 1 and at concentrations of 110 and 220 mg/kg for 3 weeks and 440 mg/kg for 2 weeks in experiment 2 failed to eliminate streptococci-induced lymphadenitis from swine referred to as principals. Abscesses, mostly in the head and neck, developed in at least a third of all swine in the various groups fed these CTC concentrations. Feeding of 220 mg of CTC/kg of feed in experiment 1 began 12 weeks after exposure of principals to an untypeable group E streptococci (GES; isolate 3X29A). In experiment 2, feeding of 110 and 220 mg of CTC/kg of feed began 5 weeks after exposure of principals to GES and feeding of 440 mg of CTC/kg of feed began 6 weeks after exposure. One or more cohabitating sentinel swine of experiment 1 and one or more sentinels in all groups of principals of experiment 2, except group 2, developed abscesses that were mostly in the head and neck. In experiment 2, correlation between serum GES antibody titer and development of one or more abscesses in the principals was highly significant (P < 0.01); however, correlation between antibody titer and abscesses in the sentinels only approached significance (P < 0.10).

Topics: Abscess; Administration, Oral; Animal Feed; Animals; Antibodies, Bacterial; Chlortetracycline; Dose-Response Relationship, Drug; Lymphadenitis; Prevalence; Streptococcal Infections; Swine; Swine Diseases

The antibiotic susceptibility of thirty-nine strains of Mycoplasma hyopneumoniae isolated from swine between 1970-1981 and 1989-1990 was investigated. From the present results, it is suggested that the susceptibility to chlortetracycline has been decreasing in Japan. On the other hand, all the strains were sensitive to lincomycin, thiamphenicol and macrolides. Newly developed macrolides such as tilmicosin, acetyl-isovaleryl-tylosin and mirosamycin had equal or higher activity than general macrolides.

Topics: Animals; Anti-Bacterial Agents; Chlortetracycline; Lincomycin; Macrolides; Microbial Sensitivity Tests; Mycoplasma; Mycoplasma Infections; Swine; Swine Diseases; Thiamphenicol

The minimal inhibitory concentrations (MIC) of five tetracyclines and ten other antimicrobial agents were determined for four porcine bacterial respiratory tract pathogens by the agar dilution method. For the following oxytetracycline-susceptible strains, the MIC50 ranges of the tetracyclines were: P. multocida (n = 17) 0.25-0.5 micrograms/ml; B. bronchiseptica (n = 20) 0.25-1.0 micrograms/ml; H. pleuropneumoniae (n = 20) 0.25-0.5 micrograms/ml; S. suis Type 2 (n = 20) 0.06-0.25 micrograms/ml. For 19 oxytetracycline-resistant P. multocida strains the MIC50 of the tetracyclines varied from 64 micrograms/ml for oxytetracycline to 0.5 micrograms/ml for minocycline. Strikingly, minocycline showed no cross-resistance with oxytetracycline, tetracycline, chlortetracycline and doxycycline in P. multocida and in H. pleuropneumoniae. Moreover, in susceptible strains minocycline showed the highest in vitro activity followed by doxycycline. Low MIC50 values were observed for chloramphenicol, ampicillin, flumequine, ofloxacin and ciprofloxacin against P. multocida and H. pleuropneumoniae. B. bronchiseptica was moderately susceptible or resistant to these compounds. As expected tiamulin, lincomycin, tylosin and spiramycin were not active against H. pleuropneumoniae. Except for flumequine, the MIC50 values of nine antimicrobial agents were low for S. suis Type 2. Six strains of this species showed resistance to the macrolides and lincomycin.

Topics: Animals; Anti-Bacterial Agents; Bacteria; Bordetella; Chlortetracycline; Doxycycline; Haemophilus; Microbial Sensitivity Tests; Minocycline; Oxytetracycline; Pasteurella; Respiratory Tract Infections; Streptococcus; Swine; Swine Diseases; Tetracycline; Tetracyclines

Clinical and pathologic variables of Salmonella typhisuis infections were studied in weanling pigs. The influence of daily feeding of low concentrations of chlortetracycline, penicillin, and sulfamethazine on S typhisuis infection also was determined. Ten pigs (group 1) given feed containing low concentrations of chlortetracycline, penicillin, and sulfamethazine when orally inoculated with S typhisuis became pyretic, developed a mild neutrophilia, and had increased serum agglutinating antibody titers, but were clinically normal. Lesions were not present, and S typhisuis was not isolated from 2 group-1 pigs that were killed and necropsied on postinoculation day 8. Then, the antimicrobial agents were withdrawn from the feed of the remaining 8 pigs for 6 days. The pigs were reinoculated with S typhisuis on postinoculation day 16 and developed mild clinical disease with sustained high rectal temperatures. Severe necrotizing typhlocolitis and ulcerative proctitis were found at necropsy in all 8 of the pigs. Similar findings were induced in 7 additional pigs (group 2) that were concurrently inoculated with S typhisuis, but that had no previous exposure to S typhisuis. Successful isolation of S typhisuis required special care and media.

Topics: Administration, Oral; Animals; Chlortetracycline; Female; Male; Penicillins; Salmonella Infections, Animal; Sulfamethazine; Swine; Swine Diseases

Oral prophylactic medication with either procaine penicillin G or a mixture of chlortetracycline, sulphadimidine and procaine penicillin G reduced the incidence of streptococcal meningitis in a herd of pigs with a high recorded prevalence of the disease, but to a significant extent (P less than 0.01) only in those pigs receiving procaine penicillin G. Subsequent studies showed that after oral administration of procaine penicillin G, benzylpenicillin was detectable in plasma only at very low concentration and similar results were obtained using the potassium salt of penicillin G. However, phenoxymethyl penicillin administered orally provided high plasma concentrations of this drug. A further investigation demonstrated that despite the low plasma concentrations of penicillin after oral administration of the procaine salt, gastrointestinal and urinary concentrations of the drug were relatively high for up to five hours.

Topics: Administration, Oral; Animal Feed; Animals; Chlortetracycline; Drug Combinations; Female; Meningitis, Pneumococcal; Penicillin G; Sulfamethazine; Swine; Swine Diseases

The antibacterial effects of a combination of tiamulin and chlortetracycline in vitro against a number of field isolates of Pasteurella multocida, Haemophilus pleuropneumoniae and Bordetella bronchiseptica were examined. There was a marked synergism between the two antibiotics against all eight isolates of P multocida, against seven of nine isolates of H pleuropneumoniae and against the single strain of B bronchiseptica tested. Two field trials were carried out on a herd with a history of complicated enzootic pneumonia where the presence of Mycoplasma hyopneumoniae and P multocida had been established and subsequently the presence of H pleuropneumoniae was discovered. Feed containing tiamulin at 100 ppm combined with chlortetracycline at 300 ppm was given for seven days to pigs affected with pneumonia, and the results were compared with untreated controls and pigs receiving chlortetracycline at 300 ppm. There was a follow-up observation period of three weeks when all groups received unmedicated feed. During the medication period the combination treated groups showed a statistically significant increase in average daily weight gain of 156 g (20.4 per cent) and in feed conversion efficiency of 0.576 (20.8 per cent) and a numerical improvement in average disease score in comparison with the untreated controls. These improvements were approximately double those observed in the groups treated with 300 ppm chlortetracycline which showed improvements of 93 g (12.2 per cent) in average daily gain and 0.301 (10.9 per cent) in feed conversion efficiency. During the following three weeks most of the initial gains were lost, probably owing to the reinfection of the treated groups by the untreated controls.

Topics: Animal Feed; Animals; Anti-Bacterial Agents; Bacterial Infections; Chlortetracycline; Diterpenes; Drug Synergism; Drug Therapy, Combination; Microbial Sensitivity Tests; Pneumonia; Pneumonia of Swine, Mycoplasmal; Swine; Swine Diseases

Three experiments were conducted to determine the effect of receiving diets containing alfalfa meal and certain feed additives on performance of comingled feeder pigs transported 900 to 1,100 km. In Exp. 1, the inclusion of 9.4% dehydrated alfalfa meal in receiving diets for 2 wk resulted in no difference (P greater than .1) in gain or feed conversion from purchase to market compared with pigs fed a basal corn-soybean meal (CS) diet or a diet containing 20% ground whole oats (O). In Exp. 2, pigs fed receiving diets containing 10% dehydrated alfalfa meal had no improvement (P greater than .1) in gain (.60 vs .61 kg/d) or conversion (3.25 vs 3.17) compared with CS-fed pigs. In Exp. 3, pigs fed a receiving diet for 2 wk containing 10% mid-bloom alfalfa ate more (P less than .002) feed daily for 2 wk (.82 vs .76 kg) and overall (P less than .04; 1.92 vs 1.85 kg) and had an improved (P less than .03) daily gain from purchase to market (.61 vs .59 kg) compared with CS-fed pigs. In Exp. 2, pigs fed diets containing 44 mg/kg tylosin (T) gained similar to pigs fed no additive (O) and slower (P less than .01) than pigs fed 110 mg/kg chlortetracycline (CTC; .59, .60 and .63 kg/d), with no significant differences in feed to gain conversion (3.12, 3.23 and 3.18).(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animal Feed; Animals; Bacitracin; Body Weight; Chlortetracycline; Diarrhea; Female; Food Additives; Leucomycins; Male; Medicago sativa; Salicylates; Swine; Swine Diseases; Transportation; Tylosin

Swine from two herds with different histories of antibiotic exposure were fed diets containing 0 or 55 mg of chlortetracycline (CTC)/kg. One of five pigs in each herd-diet treatment group was infected orally with Escherichia coli strain BEL15R that was resistant to nalidixic acid (NA), chloramphenicol (C), streptomycin (S), sulfamethizole (TH) and tetracycline (TE). Effects of CTC on the quantity and duration of fecal shedding of E. coli BEL15R and on the transmission of strain BEL15R and its R-100 plasmid from infected pigs to uninfected pigs and chicks were determined. Quantity and duration of shedding were greater in infected antibiotic-herd pigs than in infected nonantibiotic-herd pigs. Feeding on CTC increased the duration of shedding in infected pigs from both herds. Strain BEL15R colonized and was shed in one uninfected antibiotic pig in each treatment group, but it did not colonize in any of the uninfected nonantibiotic-herd pigs or in the uninfected chicks. In vivo transfer of resistance to C, S, TH and TE occurred in the infected antibiotic-herd pigs but not in the infected nonantibiotic-herd pigs. Transfer of the R-100 plasmid occurred from the infected to the uninfected antibiotic-herd pigs and to the uninfected chicks housed near the antibiotic-herd pigs fed CTC, but not to the chicks housed with the antibiotic-herd pigs fed the control diet. No transfer of resistance occurred from the infected nonantibiotic-herd pigs fed either CTC or control diet.

Topics: Animals; Anti-Bacterial Agents; Chickens; Chlortetracycline; Escherichia coli; Escherichia coli Infections; Food Additives; Poultry Diseases; R Factors; Swine; Swine Diseases; Transformation, Bacterial

Swine from a herd routinely fed subtherapeutic levels of chlortetracycline (CTC) were fed a diet containing 55 mg of CTC/kg, a diet containing 55 mg of virginiamycin/kg, or a control diet. All animals were inoculated with Salmonella typhimurium that was susceptible to tetracycline. The quantity, duration and prevalence of shedding of S. typhimurium were determined. The infecting organism was first recovered from the animals fed CTC or the control diet on d 2, from animals fed virginiamycin on d 7 and from animals in a second control group on d 10. The infecting organism was recovered in fewer samples obtained during the initial 7 d postinfection than in those obtained during the last 24 d of the study. Little transfer of resistance to the infecting organism seemed to have occurred from the resident microflora because only two isolates (1%) had resistant patterns that differed from that of the infecting organism. Feeding CTC or virginiamycin to swine did not significantly increase or prolong shedding of an experimentally infected tetracycline-susceptible strain of S. typhimurium. Neither antibiotic affected the drug resistance of the infecting organism.

Topics: Animals; Chlortetracycline; Diet; Drug Resistance, Microbial; Food Additives; Salmonella Infections, Animal; Salmonella typhimurium; Swine; Swine Diseases; Virginiamycin

A swine dysentery (SD) model that produces consistent, homogeneous, and severe SD was used in 2 experiments to compare the prophylactic effectiveness of 5 commercially available swine feed additive products. Under the conditions of these studies, carbadox and carbadox + sulfamethazine proved to be the most effective agents in preventing SD during the infection + medication and postmedication periods. Olaquindox was effective in preventing SD in the infection + medication period; however, SD recurrence was high during the postmedication period. Nithiamide and chlortetracycline + sulfamethazine + penicillin were least effective in preventing SD during the infection + medication and postmedication periods.

Topics: Animals; Anti-Infective Agents; Carbadox; Chlortetracycline; Cyclic N-Oxides; Drug Evaluation; Dysentery; Penicillins; Quinoxalines; Sulfamethazine; Swine; Swine Diseases; Thiazoles

Topics: Amprolium; Animals; Chlortetracycline; Coccidiosis; Swine; Swine Diseases

Carbadox in combination with sulfamethazine did not interfere with the activity of sulfamethazine in clearing experimentally induced Bordetella bronchiseptica nasal infection. Evaluations in three field cases of infectious atrophic rhinitis indicated that carbadox in the feed was as effective as chlortetracycline + sulfamethazine + penicillin for improving growth rate and feed efficiency, as compared with nonmedicated controls, and in reducing the prevalence of lesions of infectious atrophic rhinitis.

Topics: Animal Feed; Animal Nutritional Physiological Phenomena; Animals; Bordetella; Bordetella Infections; Carbadox; Chlortetracycline; Drug Therapy, Combination; Penicillins; Quinoxalines; Rhinitis, Atrophic; Sulfamethazine; Swine; Swine Diseases; Turbinates

Topics: Animals; Cells, Cultured; Chlortetracycline; Drug Resistance, Microbial; Mycoplasma; Mycoplasma Infections; Swine; Swine Diseases

Swine were fed either a diet containing 110 mg of chlortetracycline (CTC) per kg (100 g/ton) or a control diet and were inoculated orally with Salmonella typhimurium that was either susceptible or resistant to CTC. The quantity, duration, and prevalence of fecal elimination of S. typhimurium, as well as the effect of CTC on the transmission of S. typhimurium from infected to uninfected swine, were determined. When animals were infected with CTC-resistant S. typhimurium, CTC increased the quantity (P < 0.05), duration (P < 0.05), and prevalence (P < 0.01) of fecal shedding, the transmission from infected to uninfected swine, and the recovery of the infecting organism at necropsy. When animals were infected with CTC-susceptible S. typhimurium, CTC reduced the quantity (between 7 and 10 days postinfection) (P < 0.01), duration (P < 0.05), and prevalence (P < 0.05) of fecal shedding, the transmission from infected to uninfected swine, and the recovery of the infecting organism at necropsy. Resistance to tetracycline was transferred in vivo to 4 and 6% of the susceptible infecting S. typhimurium recovered from the untreated and treated groups, respectively. The increased reservoir of S. typhimurium and the transfer of resistance to susceptible S. typhimurium have implications for both animal and public health.

Topics: Animal Feed; Animals; Chlortetracycline; Drug Resistance, Microbial; Feces; Lymph Nodes; Salmonella Infections; Salmonella Infections, Animal; Salmonella typhimurium; Swine; Swine Diseases

Topics: Animals; Chlortetracycline; Female; Gastrointestinal Hemorrhage; Intestinal Diseases; Male; Sulfamethazine; Swine; Swine Diseases

The purpose of these experiments was to determine the effects of prior exposure to antimicrobials on subsequent treatment of artificially induced colibacillosis in pigs. One- to two-week-old piglets were given 10(7) multiple antibiotic resistant Escherichia coli orally. Two groups of the piglets received priming doses at different levels of the antimicrobial preparation, ASP-250 before challenge. The remaining group received no antimicrobial. Piglets ill as a result of the challenge were treated with chloramphenicol of chlortetracycline, or received no treatment. Chloramphenicol was significantly more effective than chlortetracycline in terminating colibacillosis in the primed and unprimed groups. There were fewer deaths and relapse cases in those groups which received chloramphenicol treatment. Results in piglets treated with chlortetracycline were not significantly better than those which received no treatment.

Topics: Administration, Oral; Animal Feed; Animals; Chloramphenicol; Chlortetracycline; Escherichia coli Infections; Swine; Swine Diseases

The effect of chlortetracycline given at a concentration of 220.5 g/metric ton of feed and of a combination product which supplies chlortetracycline (110.2 g/metric ton), sulfamethazine (110.2 g/metric ton), and penicilin G (55.1 g/metric ton) on the occurrence and persistence of Salmonella typhimurium in experimentally infected swine was studied. Weanling pigs (av weight, 8.2 kg) were inoculated via the feed with 10(11) colony-forming units of S typhimurium 298-1NA. An equal number of nonexposed swine given identical treatment were used as controls. Infected pigs had increased temperatures (maximal av, 41 C) for the first 4 days after infection and severe diarrhea during the first 21 days. The use of chlortetracycline and a combination product at subtherapeutic concentrations in feed did not increase the Salmonella pool or prolong the carrier state in swine. A decrease in number of Salmonella shed from swine given chlortetracycline at the concentration of 220.5 g/metric ton was observed. Significant differences did not occur in Salmonella-related deaths or in emergence of multiple antibiotic-resistant Salmonella by antibiotic selection or R factor transfer. Zoonotic transmission of the infecting Salmonella to animal caretakers was not detected.

Topics: Administration, Oral; Animal Feed; Animals; Anti-Bacterial Agents; Chlortetracycline; Diarrhea; Feces; Female; Male; Penicillin G; Penicillin Resistance; Salmonella Infections, Animal; Salmonella typhimurium; Sulfamethazine; Swine; Swine Diseases

Weaned pigs were divided into nonmedicated control and medicated principal groups and 3 days later were exposed to infective oocysts comprised of mixed species of swine origin. In separate experiments, a chlortetracycline combination (plus sulfamethazine and penicilin), buquinolate, or lincomycin was administered prophylactically to the principals, starting 3 days before they were exposed to infection, and then was evaluated for efficacy against the experimental exposures. Comparisons between control and principal groups were made on the basis of fecal oocyst counts, fecal consistencies, and body weight gains. On the basis of oocyst counts, both chlortetracycline combination and buquinolate minimized the development of coccidial populations in groups given medicated feed; nonmedicated controls discharged substantial numbers of oocysts. Lincomycin medication was not effective in pigs given 111 mg/kg of feed; it was effective at dose levels of 330 mg/kg of feed and at 22 mg/kg body weight, intramuscularly. Medicated principals always gained more weight on the average than did their infected nonmedicated controls during the experiments. The data on oocyst production support the position that the 3 compounds can function as coccidiostats in swine.

Topics: Animals; Chlortetracycline; Coccidiosis; Drug Therapy, Combination; Feces; Hydroxyquinolines; Lincomycin; Swine; Swine Diseases

The effect of chlortetracycline fed at concentrations of 10 or 20 grams per ton on the antibiotic resistance of fecal coliforms from weaned pigs from four different farms was studied. At admission to experimental quarters, coliforms resistant to at least one antibiotic predominated in all groups of animals. In pigs from three farms, chlortetracycline caused a reduction in the proportion of sensitive coliforms excreted, the extent of reduction depending on feeding practices on the farm of origin. In another experiment using pigs from a fourth farm, almost all coliforms isolated were resistant. Of all resistant strains isolated, those carrying resistance to a multiplicity of antibiotics predominated, and resistance to tracycline unaccompanied by that to other agents was relatively infrequent. Special studies of hemolytic coliforms from pigs from one farm identified two particular antibiotic sensitive types. No further isolations of these types were made once chlortetracycline administration began although 21 additional isolates were made from littermates receiving unsupplemented ration. These findings suggest that the elimination of sensitive strains resulting from chlortetracycline administration was due to a replacement of these strains by different resistant types rather than by acquisition of resistance by previously sensitive strains.

Topics: Administration, Oral; Animal Feed; Animals; Chlortetracycline; Drug Resistance, Microbial; Escherichia coli; Feces; Microbial Sensitivity Tests; Rectum; Salmonella Infections, Animal; Streptomycin; Swine; Swine Diseases; Tetracycline

Topics: Abscess; Animals; Arsenicals; Chlortetracycline; Female; Lymphadenitis; Palatine Tonsil; Penicillins; Pregnancy; Streptococcal Infections; Streptococcus; Sulfamethazine; Swine; Swine Diseases; Weaning

Topics: Abscess; Administration, Oral; Animal Feed; Animals; Anti-Bacterial Agents; Bacterial Vaccines; Chlortetracycline; Germ-Free Life; Lymphadenitis; Oxytetracycline; Penicillin G Benzathine; Streptococcal Infections; Streptococcus; Swine; Swine Diseases; Vaccination

Topics: Administration, Oral; Animal Feed; Animals; Antibodies, Bacterial; Antibody Formation; Chlortetracycline; Complement Fixation Tests; Disease Models, Animal; Hemagglutination Tests; Mycoplasma; Mycoplasma Infections; Pneumonia; Swine; Swine Diseases

Topics: Animals; Chlortetracycline; Dietary Carbohydrates; Female; Glucose; Heart Diseases; Hemorrhage; Male; Prothrombin Time; Rats; Salicylates; Sucrose; Swine; Swine Diseases; Syndrome; Vitamin K

Topics: Animals; Chlortetracycline; Mycoplasma Infections; Swine; Swine Diseases

Topics: Administration, Oral; Animals; Chlortetracycline; Drug Combinations; Salmonella Infections, Animal; Sulfamethazine; Swine; Swine Diseases; Water

The susceptibility of Mycoplasma hyopneumoniae to the action of three antibiotics and diethyl ether was determined. Infected swine were used in an in vivo sensitivity detection system. The parameter of susceptibility was lesion prophylaxis. In vivo, Mycoplasma hyopneumoniae appeared to be resistant to diethyl ether, tylosin tartrate, and erythromycin, but was susceptible to the action of chlortetracycline. Chlortetracycline was effective in preventing the development of lesions when given at levels which would be practical in commercial swine operations.

Topics: Animals; Anti-Bacterial Agents; Chlortetracycline; Erythromycin; Ethyl Ethers; Microbial Sensitivity Tests; Mycobacterium Infections; Mycoplasma; Mycoplasma Infections; Pneumonia; Swine; Swine Diseases; Tartrates

Pigs were found to be susceptible to Mycoplasma hyopneumoniae-induced swine enzootic pneumonia (SEP) when four hours old. Chlortetracycline was incapable of preventing transmission of SEP from infected pigs on the drug to susceptible, untreated pigs. When continuous medication was started at one or two weeks postinoculation, chlortetracycline partially or completely inhibited formation of SEP lesions but did not clear M. hyopneumoniae from inoculated pigs. Chlortetracycline administered orally was capable of completely suppressing the formation of SEP lesions in inoculated pigs if given prophylactically and if milk was withheld for several hours after each treatment; lesion suppression was incomplete if milk was given ad libitum. In either case treated animals remained infected with M. hyopneumoniae.

Topics: Administration, Oral; Age Factors; Animal Feed; Animals; Animals, Newborn; Chlortetracycline; Lung; Milk; Mycoplasma; Mycoplasma Infections; Pneumonia; Swine; Swine Diseases

Topics: Animals; Chlortetracycline; Paratyphoid Fever; Swine; Swine Diseases; Typhoid-Paratyphoid Vaccines

Topics: Animal Feed; Animals; Arsenic; Chickens; Chlortetracycline; Czechoslovakia; Drug Resistance, Microbial; Escherichia coli; Food Additives; Orthomyxoviridae Infections; Poultry Diseases; Research; Swine; Swine Diseases

Topics: Animals; Benzyl Compounds; Chlortetracycline; Drug Combinations; Ethylenediamines; Gastrointestinal Diseases; Swine; Swine Diseases

Topics: Analysis of Variance; Animal Feed; Animals; Body Weight; Carrier State; Chlortetracycline; Chronic Disease; Lung; Penicillins; Pneumonia; Sex Factors; Sulfamethazine; Swine; Swine Diseases

Topics: Animals; Chlortetracycline; Erysipelothrix Infections; Penicillin G Benzathine; Swine; Swine Diseases

Topics: Animals; Chlortetracycline; Lung; Pneumonia, Viral; Streptomycin; Swine; Swine Diseases; Tissue Extracts; Vitamin B Complex

Topics: Angiography; Animals; Chlortetracycline; Hepatic Artery; Liver Circulation; Liver Diseases; Necrosis; Postoperative Complications; Swine; Swine Diseases

Topics: Age Factors; Animal Diseases; Animals; Bronchopneumonia; Cattle; Chickens; Chlortetracycline; Delayed-Action Preparations; Ducks; Pasteurella Infections; Poultry Diseases; Rhinitis, Atrophic; Salmonella Infections, Animal; Swine; Swine Diseases; Tetracycline

Topics: Animals; Chlortetracycline; Furazolidone; Nitrofurans; Penicillins; Salmonella Infections, Animal; Sulfamethazine; Swine; Swine Diseases

Topics: Aerosols; Animals; Chlortetracycline; Methods; Pneumonia, Viral; Swine; Swine Diseases

Topics: Animals; Chlortetracycline; Rhinitis, Atrophic; Swine; Swine Diseases

Topics: Animals; Bronchopneumonia; Chlortetracycline; Swine; Swine Diseases

Topics: Animals; Anti-Bacterial Agents; Chlortetracycline; Drug Resistance, Microbial; Ethers; Pneumonia, Viral; Swine; Swine Diseases; Viruses, Unclassified

Topics: Abscess; Animals; Chlortetracycline; Lymphadenitis; Neck; Streptococcal Infections; Swine; Swine Diseases

Topics: Animals; Brucellosis; Chlortetracycline; Swine; Swine Diseases