rifampin and Mastitis--Bovine

One hundred and fifty-nine cases of clinical Staphylococcus aureus mastitis were analyzed to detect factors associated with bacteriological cure after therapy. On 100 Dutch dairy farms, data were collected from four clinical trials with five intramammary treatment regimes designed to treat beta-lactamase-positive pathogens. Infected quarters were treated three times, with a 12-h interval between treatments. Treatment was extended for 2 d if results of the trial treatment were, according to the owner, not satisfactory. The overall bacteriological cure rate was 52%. The bacteriological cure rate of clinical beta-lactamase-negative S. aureus mastitis was significantly higher than that of clinical beta-lactamase-positive S. aureus mastitis. Bacteriological cure was also significantly higher if somatic cell count of the cow was low at the milk recording prior to the onset of the clinical mastitis. The bacteriological cure rate of clinical beta-lactamase-negative S. aureus mastitis was also significantly higher after an extended treatment compared with no extended treatment. The seriousness of the various clinical symptoms and the bacteriological cure rate of clinical S. aureus mastitis were not associated.

Topics: Ampicillin; Animals; Antibiotics, Antitubercular; beta-Lactam Resistance; Cattle; Cefazolin; Cephalosporins; Cloxacillin; Colistin; Double-Blind Method; Female; Mastitis, Bovine; Milk; Penicillins; Rifampin; Staphylococcal Infections; Staphylococcus aureus; Trimethoprim

One hundred and fifty-nine cases of clinical Staphylococcus aureus mastitis were analyzed to detect factors associated with bacteriological cure after therapy. On 100 Dutch dairy farms, data were collected from four clinical trials with five intramammary treatment regimes designed to treat beta-lactamase-positive pathogens. Infected quarters were treated three times, with a 12-h interval between treatments. Treatment was extended for 2 d if results of the trial treatment were, according to the owner, not satisfactory. The overall bacteriological cure rate was 52%. The bacteriological cure rate of clinical beta-lactamase-negative S. aureus mastitis was significantly higher than that of clinical beta-lactamase-positive S. aureus mastitis. Bacteriological cure was also significantly higher if somatic cell count of the cow was low at the milk recording prior to the onset of the clinical mastitis. The bacteriological cure rate of clinical beta-lactamase-negative S. aureus mastitis was also significantly higher after an extended treatment compared with no extended treatment. The seriousness of the various clinical symptoms and the bacteriological cure rate of clinical S. aureus mastitis were not associated.

Topics: Ampicillin; Animals; Antibiotics, Antitubercular; beta-Lactam Resistance; Cattle; Cefazolin; Cephalosporins; Cloxacillin; Colistin; Double-Blind Method; Female; Mastitis, Bovine; Milk; Penicillins; Rifampin; Staphylococcal Infections; Staphylococcus aureus; Trimethoprim

In order to counter the antibiotic resistance phenomenon, a prudent and rational use of antimicrobials should be driven by an accurate clinical diagnosis and, when possible, by the isolation of the etiological agent followed by susceptibility testing, with the aim to select the most suitable molecule for therapy. Cow mastitis is considered the main cause of antibiotic use in the cattle breeding sector. The purpose of this study was to compare the broth microdilution (BMD) method performed with Sensititre Custom Plates and the agar disk diffusion (ADD) method in determining antimicrobial susceptibility of 215 isolates from bovine mastitis, including contagious pathogens (Staphylococcus aureus, Streptococcus agalactiae) and environmental (Streptococcus uberis, Streptococcus dysgalactiae, Enterococcus spp., Escherichia coli, Serratia marcescens, Klebsiella pneumoniae). We compared results of the following antimicrobials: amoxicillin/clavulanic acid, ampicillin, cefazolin, ceftiofur, enrofloxacin, erythromycin, kanamycin, oxacillin, penicillin, pirlimycin, rifampicin and trimethoprim/sulphonamides. We applied MIC breakpoints and zone diameter breakpoints as recommended by CLSI and EUCAST. MIC and disk diffusion diameters were compared for 1839 microorganism/antimicrobial combination and discrepancies between the two methods were classified as very major discrepancy (VMD), major discrepancy (MD) and minor discrepancy (MiD). The overall agreement between the two methods was found to be 80.7% with a Cohen's kappa coefficient of 0.397, thus indicating a fair concordance. BMD method and ADD method demonstrated a satisfactory agreement (89 to 100%) for S. aureus and S. marcescens and all antimicrobial agents tested. Low agreement was observed for S. uberis and rifampicin (20%), enrofloxacin (49%), penicillin (51%) and pirlimycin (52%), E. coli and ampicillin (20%), S. dysgalactiae and enrofloxacin (44%), S. agalactiae and rifampicin (25%). A possible explanation for the discrepancies detected could be found in the breakpoints used which, sometimes, are not specific for the tissue-matrix of isolation/animal species/pathogen agent. The majority of the discrepancies found were MiD and MD, revealing a higher restrictiveness of the BMD method, while VMD represented only 0.2% of the total observations, a comforting fact since this type of error may result in treatment failure.

Topics: Agar; Ampicillin; Animals; Anti-Bacterial Agents; Anti-Infective Agents; Cattle; Enrofloxacin; Escherichia coli; Female; Mastitis, Bovine; Microbial Sensitivity Tests; Penicillins; Rifampin; Staphylococcus aureus

The polymorphic mutation frequencies for 154 Staphylococcus aureus isolates from Chinese bovine clinical mastitis cases were investigated. We found that nearly 29% of the isolates presented as weak mutators, while only two (1.3%) strong mutators were detected. Of the 15 weak mutators that exhibited ciprofloxacin resistance phenotypes, only one isolate was found to be mutS deficient. All of the ciprofloxacin-resistant isolates had the classic ciprofloxacin resistance mutations at codon 80 within the ParC subunit of topoisomerase IV and codon 84/88 within the GyrA subunit of DNA gyrase. The proportion of ciprofloxacin-resistant isolates among the weak mutators (34.1%) was significantly higher than that found in the normomutators (11.4%) and hypomutators (0%) (P < 0.001, Fisher's exact test), suggesting a positive correlation between weak mutators and ciprofloxacin resistance.

Topics: Animals; Cattle; Ciprofloxacin; DNA Gyrase; DNA Mismatch Repair; DNA Topoisomerase IV; DNA, Bacterial; Drug Resistance, Bacterial; Female; Genes, Bacterial; Mastitis, Bovine; Microbial Sensitivity Tests; Mutation Rate; Rifampin; Staphylococcus aureus

Macrophages isolated from the involuted bovine mammary gland were cultured in vitro. Phagocytosis of opsonized Staphylococcus aureus occurred rapidly, but intracellular killing of bacteria was slow. Many intracellular staphylococci survived for up to 4 d exposure to extracellular cloxacillin and emerged from within the macrophages to multiply extracellularly when the antibiotic was inactivated. Rifampicin was significantly more efficient than cloxacillin in killing intracellular S. aureus after 18 h incubation, but it too failed to sterilize the cultures within 3 d. Staphylococci, which had remained viable within macrophages during 20 h incubation with extracellular cloxacillin, showed an increased sensitivity to dilute lysostaphin on subsequent exposure. A 3 d course of intramammary therapy with cloxacillin, commencing simultaneously with an infecting inoculum of approximately 10(8) colony forming units (c.f.u.) S. aureus, apparently eliminated the infection from one quarter of the udders of each of three lactating cows, but bacteria were re-isolated from two cows after a delay of several days. However, when other quarters of the same cows were infected with approximately 10(8) c.f.u. S. aureus which had been phagocytosed by autologous mammary macrophages, similar simultaneous antibiotic therapy failed to affect these infections. The in vitro and in vivo findings indicate the significance of intracellular survival of S. aureus as a factor contributing to failure of antibiotic therapy.

Topics: Animals; Cattle; Cells, Cultured; Cloxacillin; Female; Lysostaphin; Macrophages; Mammary Glands, Animal; Mastitis, Bovine; Penicillin Resistance; Phagocytosis; Rifampin; Staphylococcal Infections; Staphylococcus aureus

The activities of a range of antibiotics on Staphylococcus aureus organisms that survive within bovine neutrophils in vitro were studied in mice. Cloxacillin, floxacillin, and cephradine failed to kill intracellular staphylococci but increased the organisms' sensitivity to killing by lysostaphin after neutrophil disruption. Fusidate and clindamycin caused an apparent small reduction in viable intraleukocytic S aureus, whereas novobiocin did not demonstrate intracellular activity. Substantial intracellular bactericidal effects were shown in vitro by rifampin and rifamycin SV, even at concentrations in slight excess of the minimum inhibitory concentration. In a mouse model of chronic mastitis, intramammary therapy with rifampin was more effective in reducing viable S aureus in infected glands than was therapy with rifamycin SV.

Topics: Animals; Anti-Bacterial Agents; Cattle; Cloxacillin; Disease Models, Animal; Drug Therapy, Combination; Female; Leukocytes; Lysostaphin; Mastitis; Mastitis, Bovine; Mice; Neutrophils; Penicillin Resistance; Pregnancy; Rifampin; Rifamycins; Rodent Diseases; Staphylococcal Infections; Staphylococcus aureus

Investigations were carried out on the medicines mastiriphin--intramammary syringes, (Mf) in two variants "A" and "B", meant for the treatment of acute mastitis with cows and also mastiriphin depot--intramammary syringes (Mf-depot), as well as two variants with indications for subclinical mastitis cows, containing both medicines in 10 g with 80,000 VI rifampicin, SEC "Pharmachem". Experiments were carried out for determining the stability of the medicines at different pH. The investigations were carried out with 23 lactating and 22 non-lactating cows. Both the degree of retention and the velocity of elimination of rifampicin from the milk and the lactic secretion. It was proved in vitro that rifampicin is stable in a neutral milk milieu (pH 7) in the course of 24 hours, and while in acid or alkaline milieu it was quickly eliminated Mf "A" in the case of intramammary introduction created high bacteriostatic (therapeutic) concentrations in the milk of the lactating animals till the sixth (eighth hour, whereas Mf "B" and the imported analogue rifamasten, provided twice as high levels of antibiotic. Mf-depot "B" introduced in a intramammary way with non-lactating cows was retained in the lactic secretion between 15 and 20 days. The quarantine time limits for using the milk taken from cows, treated in an intramammary way, proved to be 72 hours.

Topics: Animals; Cattle; Chemical Phenomena; Chemistry, Physical; Delayed-Action Preparations; Drug Evaluation; Drug Evaluation, Preclinical; Drug Stability; Female; In Vitro Techniques; Lactation; Mammary Glands, Animal; Mastitis, Bovine; Pregnancy; Rifampin; Time Factors

Topics: Animals; Cattle; Cattle Diseases; Coloring Agents; Mastitis, Bovine; Milk; Rifampin

Topics: Animals; Cattle; Drug Resistance, Microbial; Female; Injections; Mammary Glands, Animal; Mastitis, Bovine; Milk; Rifampin; Staphylococcal Infections; Streptococcal Infections

Topics: Animals; Cattle; Drug Resistance, Microbial; Female; Mammary Glands, Animal; Mastitis, Bovine; Microbial Sensitivity Tests; Mutation; Rifampin; Staphylococcus

Topics: Animals; Cattle; Chloramphenicol; Female; Mastitis, Bovine; Rifampin