Surto de mastite bovina causada por Arcanobacterium pyogenes / Outbreak of bovine mastitis caused by Arcanobacterium pyogenes

An uncommon outbreak of mastitis caused by Arcanobacterium pyogenes in 26 cows is reported. The epidemiological findings, clinical signs, microbiological exams, somatic cell count, in vitro susceptibility profile of strains, efficacy of intramammary treatment and control measures were discussed. Florfenicol (96.2%), cefoperazona (92.3%), cefaloxin (84.6%) and ceftiofur (84.6%) were the most effective antimicrobials, and neomicin (27.0%) and enrofloxacin (17.4%) the least effective antimicrobials.(AU)

ETIOLOGIA E SENSIBILIDADE BACTERIANA DA MASTITE SUBCLÍNICA EM OVELHAS DA RAÇA SANTA INÊS.

Milk samples from 242 Santa Inês breed ewes tested for subclinical mastitis using California Mastitis Test (CMT) score 1+, 2+ and 3+ were cultured. The bacteriological tests were run in 5% sheep blood agar and MacConkey agar and the microorganism observed were identified using the gram method and taxonomy proves. Then the microorganisms were submitted to in vitro antibacterial susceptibility test. A total of 94 microorganisms were isolate in pure and in association culture distributed as followed: Staphylococcus sp(n=50; 53,1%), Streptococcus sp (n=18; 19,1%), Corynebacterium sp (n=11; 11,7%), Staphylococcus aureus(n=9; 9,6%), Proteus sp (n=3; 3,2%), Micrococcus sp (n=1; 1,1%), Acinetobacter calcoaceticus (n=1; 1,1%) and Bacillus sp (n=1; 1,1%). The antibacterial susceptibility test showed among the agents isolated in highest frequency that florfenicol, gentamicin and cefalexin were the drugs of better effectiveness. KEY-WORDS: Ewe. Mastitis. Microorganisms. Antibiotics.

Examinaram-se 242 amostras de leite de ovelhas da raça Santa Inês com mastite subclínica, diagnosticada pelo teste California Mastitis Test (CMT), escore 1+, 2+ e 3+. Realizaram-se cultivos microbiológicos em meios de ágar-sangue ovino 5% e MacConkey, sendo que os microrganismos isolados foram identificados por esfregaços corados pelo método de Gram e provas taxonômicas. Em seguida, submetidos ao teste de sensibilidade bacteriana in vitro. Isolou-se um total de 94 microrganismos em cultura pura e em associação, distribuídos da seguinte maneira: Staphylococcus sp (n=50; 53,1%), Streptococcus sp (n=18; 19,1%), Corynebacterium sp (n=11; 11,7%), Staphylococcus aureus (n=9; 9,6%), Proteus sp (n=3; 3,2%), Micrococcus sp(n= 1; 1,1%), Acinetobacter calcoaceticus (n=1; 1,1%) e Bacillus sp (n=1; 1,1%). No teste de sensibilidade in vitro aos antimicrobianos observou-se que Staphylococcus sp, Corynebacterium sp e Streptococcus sp foram os microrganismos isolados com maior freqüência, sendo o florfenicol, a gentamicina e a cefalexina as drogas de melhor eficácia.PALAVRAS-CHAVE: Ovelha. Mastite. Microrganismos. Antibióticos.