Susceptibilities of bovine summer mastitis bacteria to antimicrobial agents

Abstract

The susceptibility to 9 antimicrobial agents of 32 aerobic bacterial isolates and to 10 antimicrobial agents of 37 anaerobic bacterial isolates from 23 cases of bovine summer mastitis (16 Actinomyces pyogenes isolates, 8 Streptococcus dysgalactiae isolates, 3 S. uberis isolates, 3 S. acidominimus isolates, 2 Streptococcus spp., 15 Peptostreptococcus indolicus isolates, 10 Fusobacterium necrophorum isolates, and 12 isolates of anaerobic gram-negative rods) was determined by the agar dilution method. All isolates except one Bacteroides fragilis isolate (beta-lactamase producer) were susceptible to penicillin G, amoxicillin, amoxicillin-clavulanate, cefoxitin, clindamycin, and chloramphenicol (the B. fragilis strain was susceptible to the last four), which had MICs at which 90% of isolates were inhibited (MIC90s) of < or = 0.06, < or = 0.06, < or = 0.06 0.25, < or = 0.06, and 4.0 micrograms/ml, respectively. Spiramycin was active against the gram-positive aerobes (MIC90, 1.0 microgram/ml) but not against the anaerobes (MIC90, 16.0 micrograms/ml). Similar trends were noted for susceptibilities of aerobic and anaerobic bacteria to ofloxacin (MIC90s, 2.0 and 8 micrograms/ml, respectively). Occasional strains of aerobic streptococci were resistant to oxytetracycline, but all anaerobes were susceptible. Tinidazole was active against all anaerobes (MIC90, 2.0 micrograms/ml). beta-Lactamase was produced only by the B. fragilis isolate.

Antimicrobial Susceptibility ofArcanobacterium pyogenesIsolated from Cattle and Pigs

“…The MIC 90 of oxytetracycline, reported by Cohen et al . (1995) in Israel was >100 μg/ml for isolates from the uterus of cows, whereas it was 0.5 μg/ml according to Jousimies‐Somer et al . (1996) in Finland who examined 16 isolates from bovine udder secretions.…”

“…None of the isolates from cattle and pigs were resistant to these penicillins and cephems, as stated by Guérin‐Faublée et al . (1993) and Jousimies‐Somer et al . (1996).…”

Anti‐microbial Susceptibility of Streptococcus spp. Isolated from Bovine Mastitis in Argentina

“…Several reports have been published regarding anti‐microbial susceptibility of streptococci isolated from bovine mastitis (Berghash et al., 1983; Roberts and Brown, 1994; Watts et al., 1995; Jousimies‐Somer et al., 1996; Owens et al., 1997; Thornsberry et al., 1997; Myllys et al., 1998; Salmon et al., 1998; Erskine et al., 2002; Guérin‐Faublée et al., 2002; Rossitto et al., 2002). In this study we identified the susceptibility of streptococci to anti‐microbials frequently used in our country as a therapy for bovine mastitis.…”

Use of Antimicrobials in the Treatment of Reproductive Diseases in Cattle and Horses

“…In principle, T. pyogenes and most anaerobic species are susceptible to benzylpenicillin and ampicillin in vitro (Jousimies‐Somer et al. ; VMD ). In the UK, nearly half of the T. pyogenes isolates from bovine mastitis were resistant to OTC (VMD ), whereas in Finland, no resistance was detected (Jousimies‐Somer et al.…”

“…In the UK, nearly half of the T. pyogenes isolates from bovine mastitis were resistant to OTC (VMD ), whereas in Finland, no resistance was detected (Jousimies‐Somer et al. ).…”