tetracycline and Mastitis--Bovine

Streptococcus uberis is one of the most common pathogens associated with bovine mastitis, commonly treated with antimicrobials (AM), favoring the appearance of antimicrobial resistance (AMR). The objective of this work was to determine the proportion of phenotypic AMR among S. uberis isolated worldwide from bovine intramammary infections between the years 1983-2022, and to assess the variables associated by means of a systematic review and metanalysis. Sixty articles were eligible for quantitative review. Ninety-four independent studies were obtained. The antimicrobials evaluated in more S. uberis strains were penicillin (21,987 strains), oxacillin (21,727 strains), erythromycin (20,013 strains), and ampicillin (19,354 strains). Most of the studies included in this meta-analysis were from Europe (44), followed by America (25), Africa (10), Asia (10), and Oceania (5). Among the included articles, 22 were published from 1983 to 2006, 23 from 2007 to 2012, 25 from 2013 to 2015, and the remaining 24 after 2016. Penicillin, erythromycin, and tetracycline were the antimicrobials with >25 studies. Therefore, the following analyses were performed only for these antimicrobials, presenting a high heterogeneity index (I

Topics: Animals; Anti-Bacterial Agents; Anti-Infective Agents; Cattle; Cattle Diseases; Drug Resistance, Bacterial; Erythromycin; Female; Mastitis, Bovine; Microbial Sensitivity Tests; Penicillins; Streptococcal Infections; Tetracycline

This study investigated the antimicrobial susceptibility of methicillin-resistant Staphylococcus aureus (MRSA) isolated from cases of subclinical bovine mastitis in China, as well as resistance mechanisms and virulence genes encoding adhesins and toxins. We determined antimicrobial susceptibility using the disk diffusion method, and analyzed resistance, adhesin, and toxin genes using PCR. We confirmed MRSA in 73 of 498 (14.7%) Staph. aureus isolates recovered from subclinical mastitic milk samples. All isolates were positive for mecA. The MRSA isolates showed high resistance to penicillin (100.0%), gentamicin (100.0%), and tetracycline (98.6%). All MRSA isolates harbored resistance genes blaZ (penicillin), aacA/aphD (gentamicin), and tetM (alone or in combination with tetK, tetracycline). Moreover, all isolates carried the adhesin genes fnbpA, clfA, clfB, cna, sdrE, and map/eap, and most carried sdrC (98.6%), sdrD (95.9%), bbp (94.5%), and ebpS (80.8%). The toxin genes seh, hla, and hld were present in all isolates, and most isolates carried sea (71.2%), seg (84.9%), sei (82.2%), lukE-lukD (97.3%), and hlg (72.6%). These findings of high-level resistance to antimicrobials commonly used in dairy cattle should lead to calls for antibiogram analysis before antimicrobial therapy. The high frequency of adhesin and toxin genes in MRSA indicates their potential virulence in bovine mastitis in China.

Topics: Adhesins, Bacterial; Animals; Anti-Bacterial Agents; Cattle; China; Female; Gentamicins; Mastitis, Bovine; Methicillin-Resistant Staphylococcus aureus; Microbial Sensitivity Tests; Polymerase Chain Reaction; Staphylococcal Infections; Tetracycline; Virulence

The purpose of this study was to determine tetracycline and other antimicrobial residues in milk from dairy cows treated for clinical mastitis. Data on cow health and drugs used were obtained from the farm veterinarians. A milk sample from each affected udder quarter of each cow was taken for bacterial identification before treatment. All 35 cows in the study were treated with an intramammary product containing tetracycline, neomycin, bacitracin, and prednisolone (tetracycline injector) and also simultaneously with other drugs via the intramammary or parenteral route. The withhold period of the 'tetracycline product' was eight milkings but, in all cases, longer withhold periods were prescribed due to off-label application of additional combinations of drugs. Milk samples from treated udder quarters, taken two milkings before and two after the prescribed withhold period, were analysed for antimicrobial residues. Additionally, milk samples were taken from untreated healthy udder quarters to check if any crossover of drugs had occurred. Three screening tests were used for antimicrobial detection. In 15 (42·9%) cows the milk samples from the treated infected quarters contained tetracycline residues above the maximum residue limit (MRL) after the prescribed withhold period and, in two cases (5·7%) the same was true for neomycin and cefquinome residues. Cephalexin above the MRL was detected in only one case (2·9%). Beta-lactams did not exceed the MRL after the prescribed withhold period. Antimicrobial residues were not detected in milk samples from untreated quarters. Cow condition including parity, decreased milk production and severity of mastitis significantly influenced the excretion of antimicrobials in milk (P ≤ 0·05). No significant differences were found between the tetracycline positive and tetracycline negative cows regarding the bacteria involved, combination antimicrobial therapy, or treatment interval and duration.

Topics: Animals; Anti-Bacterial Agents; Cattle; Cephalexin; Drug Residues; Drug Therapy, Combination; Female; Mastitis, Bovine; Milk; Tetracycline; Veterinary Drugs

This Regional Research Communication describes the characterisation of ampicillin, penicillin and tetracycline resistance in Staphylococcus aureus isolated from bovine subclinical mastitis in Minas Gerais State, Brazil. Ninety S. aureus isolates from bovine mastitis exhibiting phenotypic resistance to ampicillin, penicillin and/or tetracycline were selected for this study. The minimum inhibitory concentration (MIC) of each antibiotic was determined using the E-Test® and the production of beta-lactamase was determined by cefinase disks. The resistance genes blaZ, tet(K), tet(L), tet(M), and tet(O) were investigated by PCR in all of the isolates. The MIC results classified 77, 83 and 71% of the isolates as resistant to ampicillin, penicillin and tetracycline, respectively. The MIC50 and MIC90 were, respectively, 1 and 2 µg/ml for ampicillin, 0·5 and 1 µg/ml for penicillin and 32 and 64 µg/ml for tetracycline. Eighty-six per cent of beta-lactamase producing isolates were detected. Of the 90 isolates investigated, 97% amplified blaZ, 84% amplified tet(K), 9% amplified tet(L), 2% amplified tet(M) and 1% amplified tet(O). Seventy-nine isolates (88%) showed blaZ together with at least one tet gene. S. aureus isolates showed high MIC50 and MIC90 values for the three antimicrobials. The blaZ and tet(K) genes were widespread in the herds studied, and most of the isolates harboured blaZ and tet(K) concomitantly.

Topics: Ampicillin; Animals; beta-Lactamases; Brazil; Cattle; Female; Mastitis, Bovine; Microbial Sensitivity Tests; Milk; Penicillin Resistance; Penicillins; Polymerase Chain Reaction; Staphylococcus aureus; Tetracycline; Tetracycline Resistance

A total of 112 Staphylococcus aureus isolates obtained from subclinical bovine mastitis cases were examined for antibiotic susceptibility and biofilm-forming ability as well as genes responsible for antibiotic resistance, biofilm-forming ability, and adhesin. Antimicrobial susceptibility of the isolates were determined by disk diffusion method. Biofilm forming ability of the isolates were investigated by Congo red agar method, standard tube method, and microplate method. The genes responsible for antibiotic resistance, biofilm-forming ability, and adhesion were examined by PCR. Five isolates (4.5%) were identified as methicillin-resistant Staph. aureus by antibiotic susceptibility testing and confirmed by mecA detection. The resistance rates to penicillin, ampicillin, tetracycline, erythromycin, trimethoprim-sulfamethoxazole, enrofloxacin, and amoxicillin-clavulanic acid were 45.5, 39.3, 33, 26.8, 5.4, 0.9, and 0.9%, respectively. All isolates were susceptible against vancomycin and gentamicin. The blaZ (100%), tetK (67.6%), and ermA (70%) genes were the most common antibiotic-resistance genes. Using Congo red agar, microplate, and standard tube methods, 70.5, 67, and 62.5% of the isolates were found to be biofilm producers, respectively. The percentage rate of icaA, icaD, and bap genes in Staph. aureus isolates were 86.6, 86.6, and 13.4%, respectively. The adhesion molecules fnbA, can, and clfA were detected in 87 (77.7%), 98 (87.5%), and 75 (70%) isolates, respectively. The results indicated that Staph. aureus from sublinical bovine mastitis cases were mainly resistant to β-lactams and, to a lesser extent, to tetracycline and erythromycin. Also, biofilm- and adhesion-related genes, which are increasingly accepted as an important virulence factor in the pathogenesis of Staph. aureus infections, were detected at a high rate.

Topics: Adhesins, Bacterial; Animals; Anti-Bacterial Agents; Bacterial Proteins; beta-Lactams; Biofilms; Cattle; Coagulase; DNA, Bacterial; Drug Resistance, Multiple, Bacterial; Erythromycin; Female; Mastitis, Bovine; Methicillin-Resistant Staphylococcus aureus; Methyltransferases; Microbial Sensitivity Tests; Staphylococcal Infections; Tetracycline

The aim of this study was to characterise the phenotypic and genotypic antibiotic resistance patterns of Streptococcus agalactiae isolated from cows with mastitis in China. Antibiotic resistance was based on minimum inhibitory concentrations and detection of resistance genes by PCR. S. agalactiae isolates most frequently exhibited phenotypic resistance to tetracycline, while the resistance genes most frequently detected were ermB, tetL and tetM. Resistance genes were detected in some susceptible isolates, whereas no resistance genes could be detected in some resistant isolates, indicating that the resistance genotype does not accurately predict phenotypic resistance.

Topics: Amikacin; Animals; Anti-Bacterial Agents; Bacterial Proteins; Cattle; China; Drug Resistance, Bacterial; Erythromycin; Female; Genotype; Gentamicins; Mastitis, Bovine; Microbial Sensitivity Tests; Penicillin G; Phenotype; Streptococcus agalactiae; Tetracycline

The susceptibility of mastitis-causing Escherichia coli and Staphylococcus aureus to two commonly used antibiotics, tetracycline and penicillin G, was tested in raw milk and in Muller-Hinton (MH) broth by introducing a pH indicator, bromocresol purple, which was shown to be a simple, sensitive, and rapid method. The minimum inhibitory concentration (MIC) of penicillin G in milk was the same as those in MH broth, whereas the MIC of tetracycline in milk was 4 to 32 times that in MH. An irreversible binding between tetracycline and large molecules of milk, which might be due to a hydrophobic interaction, was demonstrated by a dialysis test, suggesting the observed impairing effect was due to the action of milk on the tetracycline being tested. Further investigation revealed that much of the reduction of tetracycline's activity in milk was attributable to the milk protein casein, while other heat-sensitive components in milk also play some roles.

Topics: Animals; Anti-Bacterial Agents; Cattle; Escherichia coli; Escherichia coli Infections; Female; Mastitis, Bovine; Milk; Protein Binding; Staphylococcal Infections; Staphylococcus aureus; Tetracycline

The aim of this study was to determine the antimicrobial resistance of streptococci isolated from mastitic bovine milk samples. A total of 178 isolates belonging to 6 different Streptococcus species were examined: S. uberis (n = 99), S. bovis (n = 30), S. oralis (n = 24), S. salivarius (n = 13), S. intermedius (n = 7), and S. agalactiae (n = 5). Only 8.9% (16/178) of the isolates were susceptible to all antimicrobial agents tested in this study, and S. agalactiae and S. intermedius isolates were all resistant to at least 1 antimicrobial agent tested. Overall, the most frequently observed resistance was to tetracycline (61.2%), followed by lincomycin (43.2%), gentamycin (35.3%), oxacillin (34.3%), and erythromycin (28.6%). Cephalothin and penicillin were the only antimicrobial agents to which most of the streptococci (>or=92%) were susceptible. Wide differences in the prevalence of resistance are apparent among the individual species: S. salivarius displayed exceptionally high resistance to cephalothin (23.0%) and oxacillin (76.9%) and S. agalactiae (20%) and S. intermedius (14.2%) to penicillin. Streptococcus salivarius and S. agalactiae were all susceptible to erythromycin, but others showed various rates of resistance ranging from 12.5% to 42.8%. Resistance to 3 or more of 7 antimicrobial agents was observed in all species (37.6%, 67/178).

Topics: Animals; Anti-Bacterial Agents; Cattle; Drug Resistance, Bacterial; Erythromycin; Female; Gentamicins; Korea; Lactation; Mastitis, Bovine; Milk; Oxacillin; Streptococcus; Tetracycline

In the present report we describe the characteristics of 189 antimicrobial-resistant Streptococcus agalactiae isolates from bovine (38 isolates) and human (151 isolates) sources. All the strains were resistant to tetracycline (TET), and 16 (8.5%) were also resistant to erythromycin, corresponding to 23.7% of the TET-resistant bovine isolates and 4.6% of the TET-resistant human isolates. The tet(O), erm(B), and mreA resistance-related genes, as well as the bca and scpB virulence-related genes, were the most frequent among the bovine isolates, while the tet(M), erm(A), mreA, bca, lmb, and scpB genes were the most prevalent among the isolates from humans. Although a few major clusters were observed, pulsed-field gel electrophoresis results revealed a variety of profiles, reflecting the substantial genetic diversity among strains of this species isolated from either humans or bovines.

Topics: Animals; Bacterial Proteins; Brazil; Cattle; Cattle Diseases; Drug Resistance, Bacterial; Electrophoresis, Gel, Pulsed-Field; Erythromycin; Female; Humans; Mastitis, Bovine; Microbial Sensitivity Tests; Streptococcal Infections; Streptococcus agalactiae; Tetracycline; Virulence

To determine the prevalence and molecular characteristics of Shiga toxin-producing Escherichia coli (STEC) isolates from bovine mastitic milk in Brazil.. A total of 2144 milk samples from dairy cattle showing mastitis were screened for the presence of E. coli. A total of 182 E. coli isolates were selected and examined. All were subjected to dot blot analysis using the CVD419 probe for the detection of the enterohaemolysin (hly) gene, and to a multiplex PCR for the detection of stx1, stx2 and eaeA genes. STEC were isolated from 22 (12.08%) milk samples. All the STEC isolates were tested for sensibility to 10 antimicrobials; the resistances most commonly observed were to cephalothin (86.3%), tetracycline (63.6%) and doxycycline (63.6%).. STEC isolates were found in bovine mastitic milk in Brazil.. STEC isolates from mastitic milk were potentially pathogenic for human in that they belonged to serogroups associated with diarrhoea and haemolytic-uraemic syndrome, some of them were stx2, eaeA and hly positive.

Topics: Adhesins, Bacterial; Animals; Anti-Bacterial Agents; Brazil; Cattle; Cephalothin; Doxycycline; Drug Resistance, Microbial; Escherichia coli O157; Escherichia coli Proteins; Female; Genes, Bacterial; Hemolysin Proteins; Mastitis, Bovine; Milk; Prevalence; Shiga Toxin 1; Shiga Toxin 2; Shiga Toxins; Tetracycline

In the present study 79 streptococcal cultures isolated from subclinical mastitis of 54 cows from seven dairy farms (A-G) in Hesse, Germany, were comparatively investigated using conventional and molecular methods. The isolates could be identified as Streptococcus agalactiae, belonging to Lancefield's serological group B by determination of cultural, biochemical and serological properties and by polymerase chain reaction (PCR)-mediated amplification of species-specific parts of the 16S ribosomal DNA, the 16S-23S rDNA intergenic spacer region and the CAMP factor gene cfb. The investigated group B streptococci were further characterized serologically for specific polysaccharide and protein antigens. Serotyping the isolates revealed a predominance of surface protein antigen X, either alone or in combination with polysaccharide antigen Ia. This could be observed for 39 isolates of farms A, B and C. Six group B streptococci from farm E displayed the serotype pattern III/Rib, two isolates from farm G showed the serotype pattern Ib/calpha. The remaining cultures from farms D and F (n=32) were non-typable. The occurrence of protein Rib could be confirmed by PCR amplification of the gene rib. The two isolates with serotype pattern Ib/calpha also reacted positively for the cbeta-encoding gene bag. Additional properties which allowed a phenotypic characterization of the S. agalactiae were the degree of pigmentation, growth properties in fluid media and soft agar, the surface hydrophobicity, the ability to hemagglutinate rabbit erythrocytes and their resistance reactions to tetracycline and minocycline. The isolates of the seven farms showed identical or almost identical characteristics. The 79 group B streptococci were additionally investigated by macrorestriction analysis of their chromosomal DNA using the restriction endonucleases SmaI, ApaI and SalI. The restriction patterns obtained by pulsed-field gel electrophoresis displayed identical or closely related patterns for the cultures of the various farms. The pheno- and genotypic characteristics of the 79 group B streptococci of the present study revealed that a single S. agalactiae strain or at least closely related subtypes of this strain were responsible for the mastitis situation of the seven farms.

Topics: Animals; Antigens, Bacterial; Bacterial Proteins; Bacterial Typing Techniques; Cattle; Chromosomes, Bacterial; Culture Media; DNA, Bacterial; Electrophoresis, Gel, Pulsed-Field; Germany; Hemagglutination; Mastitis, Bovine; Microbial Sensitivity Tests; Minocycline; Molecular Epidemiology; Polymerase Chain Reaction; Polymorphism, Restriction Fragment Length; Serotyping; Streptococcal Infections; Streptococcus agalactiae; Tetracycline

Minimal inhibition concentration (MIC) values of 100 Finnish and 100 Israeli Escherichia coli isolated from clinical bovine mastitis were determined for ampicillin, cephalexin, ceftazidime, dihydrostreptomycin, gentamicin, tetracycline, trimethoprim-sulfadiazine, and ciprofloxacin by an agar dilution method. The in vitro antimicrobial susceptibility of the E. coli isolates was high; only 27% showed resistance to one or more tested antimicrobial agents. Fifteen percent of the Israeli isolates and 14% of the Finnish isolates were resistant to tetracycline, 3 and 16% to cephalexin, 10 and 7% to ampicillin, 13 and 9% to dihydrostreptomycin, and 4 and 2% to trimethoprim-sulfadiazine. No gentamicin-, ceftazidime-, or ciprofloxacin-resistant isolates were detected. Eleven percent of all the isolates were resistant to two or more antimicrobial agents. Tetracycline was most often associated with multiresistant patterns. Most of the multiresistant isolates had very high MIC values, whereas most of those that were resistant to only one tested antibiotic had MIC values close to the susceptibility breakpoint. Antimicrobial resistance appeared to pose no problem in E. coli isolated from mastitic milk of both countries. This is probably due to the controlled use of antimicrobial agents in the treatment of dairy herds. Some differences were present in the resistance patterns, which may reflect the different use of antimicrobial agents in these two countries.

Topics: Ampicillin; Animals; Anti-Bacterial Agents; Cattle; Ceftazidime; Cephalexin; Ciprofloxacin; Dihydrostreptomycin Sulfate; Drug Combinations; Drug Resistance, Microbial; Escherichia coli; Female; Finland; Gentamicins; Israel; Mastitis, Bovine; Microbial Sensitivity Tests; Sulfadiazine; Tetracycline; Trimethoprim

A total of 169 Escherichia coli strains were isolated from cows with cases of clinical mastitis. beta-Glucuronidase production, serum sensitivity, and susceptibility to selected antibacterials were analyzed using the fluorometric beta-glucuronidase assay. About 89% (150 of 169) of the isolates tested positive for beta-glucuronidase. Of these isolates producing beta-glucuronidase, 102 (68%) were resistant or moderately resistant to bovine serum. The antibacterial susceptibility of 96 isolates was tested in broth and milk. There was a significant shift from lower fluorometric minimum inhibitory concentration for tetracycline, sulfadoxin-trimethoprim, enrofloxacin, and gentamicin in broth to higher fluorometric minimum inhibitory concentration in milk. Serum sensitivity and susceptibility to tested antibacterials in broth or in milk were not related. Gentamicin and sulfadoxin-trimethoprim seemed to be more potent in mastitic milk than in normal milk, suggesting a possible synergistic effect between these exogenous antibacterials and the indigenous antibacterial agents in mastitic milk.

Topics: Ampicillin; Animals; Anti-Bacterial Agents; Anti-Infective Agents; Blood Bactericidal Activity; Cattle; Enrofloxacin; Escherichia coli; Escherichia coli Infections; Female; Fluoroquinolones; Gentamicins; Glucuronidase; Mastitis, Bovine; Microbial Sensitivity Tests; Milk; Quinolones; Sulfadoxine; Tetracycline; Trimethoprim

DNA-DNA hybridisation was used to compare the genetic relation of human and bovine strains of Streptococcus agalactiae. All strains showed significant homology under very stringent hybridisation conditions. The extent of relatedness did not correlate with the serological type. It was demonstrated that the S faecalis transposon Tn916 could be inserted randomly into the S agalactiae chromosome when introduced by conjugation. The ability of Tn916 insertion to cause genetic changes in S agalactiae was confirmed by identification of a mutation in lactose and trehalose fermentation associated with acquisition of the transposon. This system should be useful in genetic analysis of the pathogenicity of S agalactiae.

Topics: Animals; Cattle; Conjugation, Genetic; DNA Transposable Elements; DNA, Bacterial; Drug Resistance, Microbial; Female; Humans; Mastitis, Bovine; Nucleic Acid Conformation; Nucleic Acid Hybridization; Streptococcal Infections; Streptococcus agalactiae; Tetracycline

Sixty-eight methicillin-resistant Staphylococcus aureus strains were isolated from mastitis milk samples originating from 20 Belgian dairyherds. All these strains appeared to be representatives of one single strain which was probably of human origin. Evidence is presented indicating a rapid in vivo evolutionary change in this strain. The following characteristics were found to be variable: the production of beta haemolysin inversely connected with fibrinolysin (staphylokinase) activity; the production of lipase, enterotoxin B and delta haemolysin; the resistance to neomycin, chloramphenicol, tetracyclines, methicillin and spectinomycin associated with constitutive or inducible macrolide resistance.

Topics: Animals; Belgium; Cattle; Chloramphenicol; Enterotoxins; Female; Fibrinolysin; Hemolysin Proteins; Lipase; Mastitis, Bovine; Methicillin; Milk; Neomycin; Penicillin Resistance; Staphylococcal Infections; Staphylococcus; Staphylococcus Phages; Tetracycline

Topics: Animals; Animals, Newborn; Anti-Bacterial Agents; Arthritis, Infectious; Cattle; Cattle Diseases; Cystitis; Diarrhea; Escherichia coli Infections; Female; Foot Diseases; Fusobacterium Infections; Liver Abscess; Mastitis, Bovine; Meningitis; Osteomyelitis; Pasteurella Infections; Pneumonia; Respiratory Tract Infections; Salmonella Infections, Animal; Sheep; Sheep Diseases; Streptococcal Infections; Sulfonamides; Tetracycline; Uterine Diseases

The results of sensitivity tests performed during the period from 1970 up to 1973 inclusive are compared with those obtained in pervious years. This showed that resistance to penicillin had increased in staphylococci causing bovine mastitis. During each single year, however, there was a decrease. S. typhimurium isolated from cattle showed increased resistance to chloramphenicol, neomycin and ampicillin; S. dublin showed an increase in resistance to chloramphenicol. E. coli isolated from calves with coli-bacillosis had become less sensitive to all the antibiotics studied. Pathogenic strains of E. coli isolated from swine also showed increased resistance, among others to tetracycline, neomycin and ampicillin. The danger constituted by this development and the factthat comparison with the results obtained by other presents difficulties in some cases are stressed.

Topics: Ampicillin; Animals; Anti-Bacterial Agents; Cattle; Chloramphenicol; Escherichia coli; Mastitis, Bovine; Microbial Sensitivity Tests; Neomycin; Penicillin Resistance; Penicillins; Salmonella; Salmonella typhimurium; Staphylococcus; Swine; Tetracycline

Topics: Ampicillin; Animals; Anti-Bacterial Agents; Biological Assay; Carbon Radioisotopes; Cattle; Dihydrostreptomycin Sulfate; Erythromycin; Female; Hydrogen-Ion Concentration; Injections; Lactation; Mammary Glands, Animal; Mastitis, Bovine; Milk; Penicillin G; Pregnancy; Streptococcal Infections; Tetracycline; Tritium

Dwarf-colony (D) variants of Staphylococcus aureus are relatively widespread etiological agents of bovine mastitis in Israel. D strains grow on ordinary solid nutrient media with pinpoint, transparent colonies. An epidemiological study indicated that these variants are more communicable than normal (N) S. aureus strains. Biochemically, several types of metabolic defects have been demonstrated among the D strains: strains from one herd were pantothenate-less, most of the other isolates were thiamine-less, and a few of them were both thiamine-and pantothenate-less. Among the thiamineauxotrophs were a few (from one herd) which were unable to concentrate thiamine-thiazole, whereas all of the other strains required thiamine-pyrimidine (HMP) in the form of pyrophosphate (HMP-PP). At least some of these D strains were defective in three functions: concentrative uptake of HMP, phosphorylation of HMP, and phosphorylation of HMP-monophosphate. Since mutants with normal growth occurred readily, we assumed that the information for these three functions exists on a polycistronic operon. Quantitative requirements for HMP-PP varied highly among the D strains, and other data also indicated that HMP-PP-requiring strains had not developed from a common source.

Topics: Animals; Autoradiography; Carbon Radioisotopes; Cattle; Chloramphenicol; Diphosphates; Kinetics; Mastitis, Bovine; Microbial Sensitivity Tests; Milk; Oxidative Phosphorylation; Pantothenic Acid; Pyrimidines; Species Specificity; Staphylococcus; Staphylococcus Phages; Tetracycline; Thiamine; Thiazoles; Tritium

Immunity to reinfection with the homologous T-mycoplasma strain has been demonstrated in the bovine mammary gland. This immunity was generalized throughout the udder and was not confined to previously infected quarters. Two out of three cows which were immune to reinfection with the homologous strain were not immune to reinfection with a serologically distinct T-mycoplasma strain. Animals varied in their ability to resolve experimental mastitis with T-mycoplasmas: those which resolved the initial infection without antibiotic therapy were immune to challenge with the homologous strain, but those which needed to be given antibiotics to clear the first infection were not all immune to such challenge.

Topics: Animals; Antibodies; Antibody Formation; Cattle; Female; Mammary Glands, Animal; Mastitis, Bovine; Mycoplasma Infections; Species Specificity; Tetracycline

Topics: Animals; Cattle; Female; Fluoroscopy; Mastitis, Bovine; Methods; Milk; Staining and Labeling; Tetracycline

Topics: Ampicillin; Animals; Cattle; Chloramphenicol; Leucomycins; Mastitis, Bovine; Microbial Sensitivity Tests; Milk; Nitrofurantoin; Penicillin Resistance; Penicillins; Staphylococcal Infections; Staphylococcus; Streptomycin; Tetracycline

Topics: Animals; Anti-Bacterial Agents; Cattle; Culture Media; Drug Resistance, Microbial; Erythromycin; Leucomycins; Mastitis, Bovine; Microbial Sensitivity Tests; Mycoplasma; Tetracycline

Topics: Acetates; Animals; Anti-Bacterial Agents; Cattle; Erythromycin; In Vitro Techniques; Leucomycins; Mastitis, Bovine; Microbial Sensitivity Tests; Mycoplasma; Tetracycline

Topics: Animals; Candida; Candidiasis; Cattle; Germany, East; Mammary Glands, Animal; Mastitis, Bovine; Milk; Nystatin; Penicillins; Tetracycline; Yeasts

Topics: Animals; Anti-Bacterial Agents; Antibiotics, Antitubercular; Cattle; Female; Food Contamination; Food Preservation; Humans; Mastitis; Mastitis, Bovine; Tetracycline; Toxicology; Veterinary Medicine

Topics: Animals; Anti-Bacterial Agents; Cattle; Chloramphenicol; Female; Food Contamination; Humans; Mastitis; Mastitis, Bovine; Milk; Penicillins; Preventive Medicine; Staphylococcal Infections; Streptococcal Infections; Streptomycin; Tetracycline; Toxicology

Topics: Animals; Anti-Bacterial Agents; Cattle; Chick Embryo; Chloramphenicol; Coagulase; Drug Resistance, Microbial; Egg Yolk; Erythromycin; Female; Fermentation; Gelatin; Hemolysin Proteins; Humans; Hydrolases; Mammary Glands, Animal; Mannitol; Mastitis; Mastitis, Bovine; Mice; Neomycin; Oleandomycin; Penicillin Resistance; Pigmentation; Research; Staphylococcal Infections; Staphylococcus; Staphylococcus Phages; Tetracycline; Virulence

Topics: Animals; Anti-Bacterial Agents; Cattle; Female; Food Contamination; Injections, Intravenous; Mastitis; Mastitis, Bovine; Milk; Sulfanilamide; Sulfanilamides; Sulfonamides; Tetracycline