chlortetracycline and Escherichia-coli-Infections

Topics: Animals; Cecum; Chlortetracycline; Clostridium Infections; Coccidiosis; Diet; Enteritis; Escherichia coli Infections; Female; Male; Rabbits; Sulfaquinoxaline

Topics: Acute Radiation Syndrome; Anti-Bacterial Agents; Chloramphenicol; Chlortetracycline; Diphtheria; Enterobacter aerogenes; Escherichia coli Infections; Oxytetracycline; Penicillin G; Penicillins; Pharmacology; Proteus Infections; Pseudomonas Infections; Radiation Injuries, Experimental; Rats; Research; Staphylococcal Infections; Streptococcal Infections; Streptomycin

Antibiotic use in beef cattle is a risk factor for the expansion of antimicrobial-resistant Salmonella populations. However, actual changes in the quantity of Salmonella in cattle feces following antibiotic use have not been investigated. Previously, we observed an overall reduction in Salmonella prevalence in cattle feces associated with both ceftiofur crystalline-free acid (CCFA) and chlortetracycline (CTC) use; however, during the same time frame the prevalence of multidrug-resistant Salmonella increased. The purpose of this analysis was to quantify the dynamics of Salmonella using colony counting (via a spiral-plating method) and hydrolysis probe-based qPCR (TaqMan® qPCR). Additionally, we quantified antibiotic-resistant Salmonella by plating to agar containing antibiotics at Clinical & Laboratory Standards Institute breakpoint concentrations. Cattle were randomly assigned to 4 treatment groups across 16 pens in 2 replicates consisting of 88 cattle each. Fecal samples from Days 0, 4, 8, 14, 20, and 26 were subjected to quantification assays. Duplicate qPCR assays targeting the Salmonella invA gene were performed on total community DNA for 1,040 samples. Diluted fecal samples were spiral plated on plain Brilliant Green Agar (BGA) and BGA with ceftriaxone (4 μg/ml) or tetracycline (16 μg/ml). For comparison purposes, indicator non-type-specific (NTS) E. coli were also quantified by direct spiral plating. Quantity of NTS E. coli and Salmonella significantly decreased immediately following CCFA treatment. CTC treatment further decreased the quantity of Salmonella but not NTS E. coli. Effects of antibiotics on the imputed log10 quantity of Salmonella were analyzed via a multi-level mixed linear regression model. The invA gene copies decreased with CCFA treatment by approximately 2 log10 gene copies/g feces and remained low following additional CTC treatment. The quantities of tetracycline or ceftriaxone-resistant Salmonella were approximately 4 log10 CFU/g feces; however, most of the samples were under the quantification limit. The results of this study demonstrate that antibiotic use decreases the overall quantity of Salmonella in cattle feces in the short term; however, the overall quantities of antimicrobial-resistant NTS E. coli and Salmonella tend to remain at a constant level throughout.

Topics: Animals; Anti-Bacterial Agents; Bacterial Proteins; Cattle; Cephalosporins; Chlortetracycline; Colony Count, Microbial; DNA, Bacterial; Drug Resistance, Multiple, Bacterial; Escherichia coli; Escherichia coli Infections; Feces; Foodborne Diseases; Longitudinal Studies; Male; Microbial Sensitivity Tests; Prevalence; Red Meat; Salmonella; Salmonella Infections, Animal

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

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

The goals of this study were to evaluate factors affecting recovery and antimicrobial resistance (AMR) in intrauterine E. coli in post-partum dairy cows with and without metritis from commercial California dairy farms. Using a cross-sectional study design, a total of 307 cows were sampled from 25 farms throughout California, from which a total of 162 intrauterine E. coli isolates were recovered. During farm visits, cows within 21 days post-partum were categorized in one of three clinical presentation groups before enrollment: metritis (MET, n = 86), defined as a cow with watery, red or brown colored, and fetid vaginal discharge; cows with purulent discharge (PUS, n = 106), defined as a non-fetid purulent or mucopurulent vaginal discharge; and control cows, (CTL, n = 115) defined as cows with either no vaginal discharge or a clear, non-purulent mucus vaginal discharge. Cows diagnosed as MET had significantly higher odds for recovery of E. coli compared to cows diagnosed as CTL (OR = 2.16, 95% CI: 1.17-3.96), with no significant difference observed between PUS and CTL, and PUS and MET. An increase in days in milk (DIM) at the time of sampling was significantly associated with a decrease in the odds ratio for E. coli recovery from intrauterine swabs (OR = 0.94, 95% CI: 0.89-0.98). All intrauterine E. coli were resistant to ampicillin (AMP), with an AMR prevalence of 30.2% and 33.9% observed for chlortetracycline and oxytetracycline, respectively. Only 8.6% of isolates were resistant to ceftiofur (CEFT), one of the most common drugs used to treat cows on farms sampled. No significant difference in the prevalence of AMR was observed among clinical groups at the individual cow level. At the farm level, a significantly higher odds for isolating intrauterine E. coli resistant to chlortetracycline (OR: 2.6; 95% CI: 3.7-58.0) or oxytetracycline (OR: 1.9; 95% CI: 1.4-33.8) was observed at farms that used an intrauterine infusion of oxytetracycline as a treatment for metritis when compared to those farms that did not use this practice. Findings from this study indicate the need for further research supporting a broader understanding of farm practices driving AMR in cows with metritis, as well as data to increase the accuracy of breakpoints for AMR classification of intrauterine E. coli from cattle.

Topics: Animals; Anti-Bacterial Agents; Cattle; Cattle Diseases; Chlortetracycline; Cross-Sectional Studies; Drug Resistance, Bacterial; Endometritis; Escherichia coli; Escherichia coli Infections; Farms; Female; Humans; Oxytetracycline; Pelvic Inflammatory Disease; Risk Factors

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

This study was conducted to investigate how chitosan (COS) affects intestinal mucosal barrier function and to further explain mechanisms of COS on growth performance. Thirty piglets, weaned at 21 days of age, were challenged with enterotoxigenic Escherichia coli during preliminary trial period. Three groups of Piglets in individual pens were fed a corn-soybean meal diet containing no addition, 50 mg/kg chlortetracycline, or 300 mg/kg COS for 21 days. Jejunal morphology and histology were analyzed under light microscope. The concentrations of occludin proteins were determined by western blot. Immunohistochemistry assays were used to determine secretory immunoglobulin (sIgA) level. Real-time PCR was used to detect Toll-like receptor 4 (TLR4) and Claudin-1 in jejunal mucosa. Feeding COS or chlortetracycline reduced (P<0.05) feed conversion ratio. Villus length, villus length/crypt depth, and goblet cells, were increased (P<0.05), but villus width and crypt depth were decreased (P<0.05) in both COS and chlortetracycline groups. Intraepithelial lymphocytes were higher (P<0.05) in the COS group than both chlortetracycline and control groups. Occludin protein expression was increased (P<0.01) in the COS group, but was decreased (P<0.05) in the chlortetracycline group. Expression of sIgA protein was higher (P<0.05) in the COS group than both control and chlortetracycline groups, however TLR4 mRNA expression was decreased (P<0.05) in both COS and chlortetracycline groups. There was no difference in expression of claudin-1 among the three groups. In conclusion, chitosan and the antibiotic have similar effects in promoting piglet growth and reducing intestinal inflammation, but different effects on intestinal mucosal barrier function. This indicates that chitosan can replace chlortetracycline as a feed additive for piglets.

Topics: Animal Feed; Animals; Anti-Bacterial Agents; Chitosan; Chlortetracycline; Claudin-1; Diet; Enterotoxigenic Escherichia coli; Escherichia coli Infections; Food Additives; Immunoglobulin A; Intestinal Mucosa; Jejunum; Occludin; RNA, Messenger; Swine; Toll-Like Receptor 4

A randomized controlled field trial was conducted to evaluate the effects of two sets of treatment strategies on ceftiofur and tetracycline resistance in feedlot cattle. The strategies consisted of ceftiofur crystalline-free acid (CCFA) administered to either one or all of the steers within a pen, followed by feeding or not feeding a therapeutic dose of chlortetracycline (CTC). Eighty-eight steers were randomly allocated to eight pens of 11 steers each. Both treatment regimens were randomly assigned to the pens in a two-way full factorial design. Non-type-specific (NTS) E. coli (n = 1,050) were isolated from fecal samples gathered on Days 0, 4, 12, and 26. Antimicrobial susceptibility profiles were determined using a microbroth dilution technique. PCR was used to detect tet(A), tet(B), and bla CMY-2 genes within each isolate. Chlortetracycline administration greatly exacerbated the already increased levels of both phenotypic and genotypic ceftiofur resistance conferred by prior CCFA treatment (P<0.05). The four treatment regimens also influenced the phenotypic multidrug resistance count of NTS E. coli populations. Chlortetracycline treatment alone was associated with an increased probability of selecting isolates that harbored tet(B) versus tet(A) (P<0.05); meanwhile, there was an inverse association between finding tet(A) versus tet(B) genes for any given regimen (P<0.05). The presence of a tet(A) gene was associated with an isolate exhibiting reduced phenotypic susceptibility to a higher median number of antimicrobials (n = 289, median = 6; 95% CI = 4-8) compared with the tet(B) gene (n = 208, median = 3; 95% CI = 3-4). Results indicate that CTC can exacerbate ceftiofur resistance following CCFA therapy and therefore should be avoided, especially when considering their use in sequence. Further studies are required to establish the animal-level effects of co-housing antimicrobial-treated and non-treated animals together.

Topics: Animals; Anti-Bacterial Agents; Antiporters; Bacterial Proteins; beta-Lactamases; Cattle; Cattle Diseases; Cephalosporins; Chlortetracycline; Drug Resistance, Multiple, Bacterial; Escherichia coli; Escherichia coli Infections; Feces; Microbial Sensitivity Tests

Topics: Animals; Anti-Bacterial Agents; beta-Lactamases; Cattle; Cattle Diseases; Cephalosporins; Chlortetracycline; Drug Resistance, Multiple, Bacterial; Escherichia coli; Escherichia coli Infections; Feces; Plasmids; United States

To characterize class 1 integrons and resistance genes in tetracycline-resistant Escherichia coli originating from beef cattle subtherapeutically administered chlortetracycline (A44), chlortetracycline and sulfamethazine (AS700), or no antimicrobials (control).. Tetracycline-resistant E. coli (control, n = 111; AS700, n = 53; A44, n = 40) were studied. Class 1 integrons, inserted gene cassettes and the presence of other antimicrobial resistance genes, as well as phylogenetic analysis, were performed by PCR, restriction enzyme analysis and sequencing. Susceptibilities to 11 antimicrobials were conducted on all isolates. Prevalence of class 1 integrase was higher (P < 0·001) in isolates from AS700 (33%) and A44 (28%) steers as compared to control (7%). Most integron gene cassettes belonged to the aad or dfr families. Correlations were found between the tet(A) gene and the genetic elements sul1 (r = 0·44), aadA1 (r = 0·61), cat (r = 0·58) and intI1(r = 0·37). Both closely and distantly related isolates harboured integrons with identical gene cassette arrays.. Subtherapeutic administration of chlorotetracycline alone or in combination with sulfamethazine may select for class 1 integrons in bovine tetracycline-resistant E. coli isolates. Vertical spread and horizontal transfer are responsible for the dissemination of a particular type of class 1 integron, but this study could not differentiate if this phenomenon occurred within or outside of the feedlot. Tetracycline-resistant E. coli strains with sul1 and tet(A) genes were more likely to harbour class 1 integrons.. Subtherapeutic use of chlortetracycline and sulfamethazine may promote the presence of class 1 integrons in tetracycline-resistant E. coli isolated from feedlot cattle.

Topics: Animals; Anti-Bacterial Agents; Cattle; Chlortetracycline; DNA, Bacterial; Escherichia coli; Escherichia coli Infections; Escherichia coli Proteins; Integrases; Integrons; Male; Phylogeny; Polymerase Chain Reaction; Sulfamethazine; Tetracycline Resistance

To evaluate administration of chlortetracycline in feed of cattle as a method to select for tetracycline resistance among enteric bacteria in feedlot settings.. 20 steers.. Steers were randomly assigned to an exposed cohort (n = 10) or an unexposed cohort (control cohort; 10). Chlortetracycline (22 mg/kg) in cottonseed meal was administered to the exposed cohort on days 0 through 4, 6 through 10, and 12 through 16. The control cohort was administered only cottonseed meal. Fecal samples were collected from 16 steers on days -7, 0, 2, 6, 8, 12, 14, 19, 22, 26, and 33, and Escherichia coli and Enterococcus spp were isolated. Minimum inhibitory concentration (MIC) of selected antimicrobials was estimated.. Overall, 56.0% and 31.4% of E coli and Enterococcus isolates, respectively, were resistant to tetracycline. Exposure to chlortetracycline was associated with a significant temporary increase in log(2) MIC for both genera but returned to preexposure values by day 33. Averaged across time, the proportion of tetracycline-resistant E coli and Enterococcus isolates was significantly greater in exposed than in unexposed steers. Although all ceftiofur-resistant E coli isolates were coresistant to tetracycline, exposure to chlortetracycline led to a significant decrease in the proportion of E coli resistant to ceftiofur during exposure.. Exposure to chlortetracycline was associated with a temporary increase in the likelihood of recovering resistant bacteria. Exposure to chlortetracycline decreased the likelihood of recovering ceftiofur-resistant E coli isolates, even though isolates were coresistant to tetracycline. These findings warrant further investigation.

Topics: Animal Feed; Animals; Cattle; Cattle Diseases; Chlortetracycline; Drug Resistance, Bacterial; Enterobacteriaceae; Enterobacteriaceae Infections; Environmental Exposure; Escherichia coli; Escherichia coli Infections; Male; Microbial Sensitivity Tests

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

Using a self-paired observational study, the association between therapeutic oxytetracycline use and the prevalence of virulence genes in commensal Escherichia coli (E. coli) from cattle was examined. Faeces were collected from 39 yearling bulls prior to and after treatment with oxytetracycline and from 44 untreated animals. Between samplings all animals received in-feed chlortetracycline for 16 days. Five E. coli were isolated from each sample and tested by a polymerase chain reaction (PCR) capable of detecting all verotoxin (vt) genes. Positive isolates were further tested with a multiplex PCR to detect vt1, vt2, eaeA and hlyA. For vt, 23 animals were positive at both samplings, 26 negative at both samplings, 22 negative animals became positive and 12 positive animals became negative. Sixty-eight per cent of the discordant pairs changed from vt-negative to vt-positive (95% CI 48-80) suggesting pressure toward becoming vt-positive perhaps due to the transfer of genes due to mixing of cattle in the months between samplings or an effect of chlortetracycline.

Topics: Administration, Oral; Animal Feed; Animals; Anti-Bacterial Agents; Cattle; Cattle Diseases; Chlortetracycline; DNA, Bacterial; Drug Administration Schedule; Drug Evaluation, Preclinical; Escherichia coli; Escherichia coli Infections; Feces; Injections, Subcutaneous; Oxytetracycline; Polymerase Chain Reaction; Population Surveillance; Prevalence; Seasons; Serotyping; Shiga Toxins; Time Factors

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

Using different variations of challenge, three trials were conducted to evaluate the efficacy of chlortetracycline in the control of chronic respiratory disease (CRD) caused by Escherichia coli and Mycoplasma gallisepticum. Experimentally infected birds were offered either food containing chlortetracycline at 300 ppm or water containing the drug at 120 mg litre-1. In each trial, medicated food and water were effective in the control of CRD as assessed by reduction in clinical signs, lower mortality and reduced severity of air sacculitis and other post mortem lesions. Weight gain was also improved by both forms of medication. M gallisepticum antibodies were demonstrated in surviving birds.

Topics: Air Sacs; Animals; Chickens; Chlortetracycline; Chronic Disease; Escherichia coli Infections; Mycoplasma Infections; Poultry Diseases; Respiratory Tract Infections; Specific Pathogen-Free Organisms; Weight Gain

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

Topics: Ampicillin; Animal Feed; Animals; Anti-Bacterial Agents; Chickens; Chloramphenicol; Chlortetracycline; Escherichia coli; Escherichia coli Infections; Feces; Food Additives; Lactobacillus; Penicillin Resistance; Poultry Diseases

Three replicate trials were conducted with broiler male chicks to test the therapeutic efficacy of doxycycline, chlortetracycline and lincomycin-spectinomycin in water against an artifically induced Escherichia coli infection. Mortality, lesion scores (heart, liver and air sac), and performance data were the criteria in evaluating therapeutic efficacy of these drugs. Results indicated the therapeutic efficacy of doxycycline was greater than chlortetracycline and lincomycin-spectinomycin.

Topics: Administration, Oral; Animals; Chickens; Chlortetracycline; Doxycycline; Escherichia coli Infections; Lincomycin; Male; Poultry Diseases; Spectinomycin; Water

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

Topics: Animals; Antigens, Bacterial; Chlortetracycline; Escherichia coli; Escherichia coli Infections; Intestinal Mucosa; Kidney; Lethal Dose 50; Liver; Lung; Macaca; Mice; Mice, Inbred A; Oxytetracycline; Rabbits; Rats; Shock, Septic; Tetracycline

Topics: Animals; Chlortetracycline; Escherichia coli; Escherichia coli Infections; In Vitro Techniques; Infections; Klebsiella; Klebsiella Infections; Listeria monocytogenes; Listeriosis; Mice; Microbial Sensitivity Tests; Pneumococcal Infections; Salmonella Infections, Animal; Salmonella typhimurium; Staphylococcal Infections; Staphylococcus; Streptococcus pneumoniae; Time Factors

Topics: Anti-Bacterial Agents; Chloramphenicol; Chlortetracycline; Depression, Chemical; Drug Resistance, Microbial; Enteritis; Escherichia coli; Escherichia coli Infections; Humans; Infant; Microbial Sensitivity Tests; Oxytetracycline; Streptomycin; USSR

Topics: Administration, Oral; Animals; Chlortetracycline; Depression, Chemical; Doxycycline; Drug Resistance, Microbial; Escherichia coli; Escherichia coli Infections; Humans; Kinetics; Methacycline; Oxytetracycline; Sepsis; Staphylococcal Infections; Staphylococcus; Tetracycline

Topics: Adult; Ampicillin; Anti-Bacterial Agents; Cephaloridine; Child; Chloramphenicol; Chlortetracycline; Colistin; Enteritis; Erythromycin Ethylsuccinate; Escherichia coli; Escherichia coli Infections; Humans; Kanamycin; Nalidixic Acid; Neomycin; Oleandomycin; Oxytetracycline; Penicillin Resistance; Polymyxins; Streptomycin; Tetracycline; Viomycin

Topics: Animals; Cattle; Cattle Diseases; Chlortetracycline; Drug Resistance, Microbial; Escherichia coli Infections; Salmonella Infections, Animal

Topics: Alanine; Amino Acids; Anti-Bacterial Agents; Arginine; Aspartic Acid; Child; Chloramphenicol; Chlortetracycline; Colistin; Drug Resistance, Microbial; Enteritis; Escherichia coli; Escherichia coli Infections; Glutamates; Glycine; Humans; In Vitro Techniques; Oxytetracycline; Proline; Serine; Streptomycin; Viomycin

Topics: Anti-Bacterial Agents; Child, Preschool; Chloramphenicol; Chlortetracycline; Drug Resistance, Microbial; Enteritis; Erythromycin; Erythromycin Ethylsuccinate; Escherichia coli; Escherichia coli Infections; Humans; In Vitro Techniques; Neomycin; Oxytetracycline; Streptomycin; Tetracycline

Topics: Adult; Bacteria; Chloramphenicol; Chlortetracycline; Colistin; Erythromycin; Escherichia coli; Escherichia coli Infections; Female; Humans; In Vitro Techniques; Infections; Kanamycin; Male; Middle Aged; Penicillin G; Penicillin Resistance; Pseudomonas aeruginosa; Staphylococcal Infections; Staphylococcus; Streptococcus; Streptomycin; Surgical Wound Infection; Tetracycline

Topics: Ampicillin; Animals; Chlortetracycline; Escherichia coli Infections; Female; Klebsiella; Listeriosis; Male; Mice; Pasteurella Infections; Pseudomonas Infections; Salmonella Infections; Staphylococcal Infections; Streptococcal Infections; Streptococcus pneumoniae; Streptomycin; Sulfonamides

Topics: Animals; Chlortetracycline; Escherichia coli Infections; Klebsiella; Listeriosis; Mice; Pasteurella Infections; Pseudomonas Infections; Salmonella Infections; Staphylococcal Infections; Streptococcal Infections; Streptococcus pneumoniae

Topics: Bacteria; Chloramphenicol; Chlortetracycline; Escherichia coli Infections; Female; Humans; Infections; Influenza, Human; Intestinal Fistula; Intestinal Neoplasms; Lung Diseases; Male; Middle Aged; Orthomyxoviridae; Oxytetracycline; Penicillin Resistance; Penicillins; Peritonitis; Pleural Diseases; Postoperative Complications; Staphylococcal Infections; Streptomycin; Suppuration; Surgical Wound Infection; Urinary Tract Infections

Topics: Anti-Bacterial Agents; Chloramphenicol; Chlortetracycline; Drug Resistance; Drug Resistance, Microbial; Drug Therapy; Escherichia coli Infections; Humans; Proteus Infections; Pseudomonas Infections; Urinary Tract Infections; Urology

Topics: Animals; Chlortetracycline; Escherichia coli; Escherichia coli Infections; Lagomorpha; Oxytetracycline; Pharmacology; Pyelonephritis; Rabbits; Research

Topics: Anti-Bacterial Agents; Bacitracin; Child; Chloramphenicol; Chlortetracycline; Drainage; Empyema; Erythromycin; Escherichia coli Infections; Haemophilus influenzae; Humans; Infant; Infant, Newborn; Kanamycin; Novobiocin; Oleandomycin; Pediatrics; Penicillins; Pneumococcal Infections; Pneumothorax; Staphylococcal Infections; Streptococcal Infections; Sulfonamides; Surgical Procedures, Operative; Tetracycline; Vancomycin

Topics: Anthelmintics; Anti-Bacterial Agents; Antifungal Agents; Aqueous Humor; Chloramphenicol; Chlortetracycline; Conjunctivitis; Dihydrostreptomycin Sulfate; Drug Resistance; Drug Resistance, Microbial; Endophthalmitis; Escherichia coli Infections; Helminthiasis; Keratitis; Keratitis, Dendritic; Lens, Crystalline; Manometry; Mycoses; Oxytetracycline; Penicillins; Staphylococcal Infections; Tetracycline; Virus Diseases

Topics: Anti-Bacterial Agents; Chloramphenicol; Chlortetracycline; Drug Resistance, Microbial; Drug Therapy; Enterocolitis; Erythromycin; Escherichia coli Infections; Humans; Infant; Neomycin; Oxytetracycline; Penicillins; Polymyxins; Statistics as Topic; Streptomycin; Sulfanilamide; Sulfanilamides; Sulfonamides

Topics: Animals; Bacteria; Chlortetracycline; Escherichia coli Infections; Oxytetracycline; Pharmacology; Pyelonephritis; Rabbits; Research

Topics: Anti-Bacterial Agents; Bronchial Fistula; Chloramphenicol; Chlortetracycline; Collapse Therapy; Drug Therapy; Empyema; Escherichia coli Infections; Humans; Klebsiella; Penicillins; Pneumonectomy; Polymyxins; Postoperative Complications; Staphylococcal Infections; Streptomycin; Tetracycline; Thoracic Surgery

Topics: Child; Chlortetracycline; Diethylstilbestrol; Erythromycin; Escherichia coli Infections; Female; Gentian Violet; Humans; Ointments; Oxytetracycline; Penicillins; Piperazines; Staphylococcal Infections; Streptococcal Infections; Trichomonas Vaginitis; Vulvovaginitis

Topics: Anti-Bacterial Agents; Chlortetracycline; Dogs; Enterobacter aerogenes; Escherichia coli Infections; Kanamycin; Neomycin; Oxytetracycline; Parotid Neoplasms; Penicillins; Peritonitis; Pharmacology; Proteus Infections; Rabbits; Rats; Staphylococcal Infections; Streptococcal Infections; Streptomycin; Sulfonamides

Topics: Abscess; Anti-Bacterial Agents; Chlortetracycline; Drug Resistance; Drug Resistance, Microbial; Erythromycin; Escherichia coli Infections; Female; Humans; Mastitis; Oxytetracycline; Penicillins; Pregnancy; Puerperal Infection; Punctures; Staphylococcal Infections

Topics: Burns; Candidiasis; Chloramphenicol; Chlortetracycline; Escherichia coli Infections; Humans; Influenza, Human; Klebsiella; Oximetry; Oxygen Inhalation Therapy; Oxytetracycline; Penicillins; Pneumococcal Infections; Pneumonia; Proteus Infections; Pseudomonas Infections; Staphylococcal Infections; Statistics as Topic; Streptococcal Infections; Streptomycin; Sulfanilamide; Sulfanilamides

Topics: Anti-Bacterial Agents; Bacillus; Biomedical Research; Brucellosis; Chloramphenicol; Chlortetracycline; Communicable Diseases; Cycloserine; Diphtheria; Dysentery; Dysentery, Bacillary; Erythromycin; Escherichia coli Infections; Humans; Influenza, Human; Liver Extracts; Methicillin; Penicillins; Pneumonia; Research; Staphylococcal Infections; Streptomycin; Syphilis; Tetracycline; Trachoma; Tuberculosis; USSR

Topics: Bacillus; Bile; Chloramphenicol; Chlortetracycline; Cholangitis; Cholecystitis; Dysentery; Dysentery, Bacillary; Escherichia coli Infections; Pharmacology; Proteus Infections; Staphylococcal Infections; Streptococcal Infections; Streptomycin

Topics: Biliary Tract; Chloramphenicol; Chlortetracycline; Cholangitis; Cholecystitis; Colistin; Drug Resistance; Drug Resistance, Microbial; Duodenum; Escherichia coli Infections; Oxytetracycline; Penicillins; Pneumococcal Infections; Staphylococcal Infections; Streptomycin

Topics: Animals; Chlortetracycline; Diphenhydramine; Escherichia coli; Escherichia coli Infections; Inflammation; Streptomycin; X-Rays

Topics: Child; Chloramphenicol; Chlortetracycline; Enteritis; Escherichia coli; Escherichia coli Infections; Gastroenteritis; Humans; Infant; Sulfadiazine

Topics: Bacteriology; Chlortetracycline; Enterococcus; Escherichia coli; Escherichia coli Infections; Pneumonia; Streptomycin

Topics: Anemia; Anemia, Pernicious; Chlortetracycline; Escherichia coli Infections; Humans; Vitamin B 12