Pesq. Vet. Bras. 32(8) The study aimed to determine the antimicrobial resistance patterns and to identify molecular resistance markers in Staphylococcus spp. (n=210) isolated from small ruminant mastitis in Brazil. The antimicrobial resistance patterns were evaluated by the disk diffusion test and by detection of the presence of mecA, blaZ, ermA, ermB, ermC and msrA genes by PCR. The efϐlux pump test was performed using ethidium bromide and bioϐilm production was determined by Congo red agar test along with PCR for detection of the icaD gene. The isolates were most resistant to amoxicillin (50.0%), streptomycin (42.8%), tetracycline (40.4%), lincomycin (39.0%) and erythromycin (33.8%). Pan-susceptibility to all tested drugs was observed in 71 (33.8%) isolates and 41 Staphylococcus isolates were positive for the efϐlux pump. Although phenotypic resistance to oxacillin was observed in 12.8% of the isolates, none harbored the mecA gene. However, 45.7% of the isolates harbored blaZ indicating that beta-lactamase production was the main mechanism associated with staphylococci resistance to beta-lactams in the present study. The other determinants of resistance to antimicrobial agents ermA, ermB, ermC, and msrA were observed in 1.4%, 10.4%, 16.2%, and 0.9% of the isolates, respectively. In addition, the icaD gen was detected in 32.9% of the isolates. Seventy three isolates (54 from goats and 19 from sheep) were negative for all resistance genes tested and 69 isolates presented two or more resistance genes. Association among blaZ, ermA, ermB, ermC and efϐlux pump were observed in 17 isolates, 14 of which originated from goats and three from sheep. The data obtained in this study show the resistance of the isolates to beta-lactamics, which may be associated with the use of antimicrobial drugs without veterinary control.
Abstract. Persistent buffalo mastitis caused by Staphylococcus spp. gives rise to economic losses and may be resistant to antimicrobial therapy. The aim of the present study was to determine resistance patterns and the presence of mecA, blaZ, and efflux pump in Staphylococcus spp. isolated from cases of mastitis in Brazilian buffalo herds. Susceptibility to antimicrobials was determined by the disk diffusion test and detection of the mecA and blaZ genes by polymerase chain reaction. The efflux pump screening test was performed by growing samples in Muller-Hinton agar containing ethidium bromide. The percentages for resistance to the drugs tested were: 71.8% to penicillin, 49.2% to amoxicillin, 65.8% to oxacillin, 62.3% to cefquinome, 44.7% to cephalonium, 45.2% to ciprofloxacin, 32.6% to enrofloxacin, 58.7% to erythromycin, 42.7% to florfenicol, 34.6% to gentamicin, 35.1% to trimethoprim-sulfamethoxazole, 8.5% to tetracycline + neomycin + bacitracin, 43.2% to cephalothin, 38.1% to streptomycin, 58.7% to tetracycline, 31.6% to norfloxacin, 45.2% to ceftriaxone, 43.2% to nitrofurantoin, 57.7% to doxycycline, and 53.7% to cephalexin. Simultaneous resistance to 4 or more antimicrobial drug groups was observed in 112 isolates, using the mecA (11) and blaZ (79) genes, and efflux pump (47). It is concluded that Staphylococcus spp. isolates from cases of mastitis in Brazilian buffalo show varying levels of resistance to antibiotics, and caution should be exercised in choosing therapeutics in order to minimize the risk to public health.
RESUMOObjetivou-se neste estudo identificar os fatores de risco associados à mastite infecciosa caprina no sertão do Estado da Bahia. Foram visitadas 13 propriedades, totalizando 320 cabras em lactação e 640 metades mamárias. Amostras de leite foram coletadas após prévia antissepsia do teto e processadas utilizando-se as técnicas convencionais para o isolamento e identificação dos micro-organismos. Para o estudo dos fatores de risco foram aplicados questionários com perguntas referentes ao manejo sanitário dos rebanhos. A análise de fatores de risco foi efetuada em duas etapas: análise univariada e multivariada. A frequência de animais positivos para o exame microbiológico do leite foi de 29,06% (93/320), sendo que o percentual de amostras positivas foi de 18,44% (118/640). Foram isolados 118 micro-organismos, sendo o gênero Staphylococcus o mais frequente. Na análise univariada para fator de risco, quanto à variável assistência veterinária, os caprinos de propriedades sem assistência veterinária apresentaram maiores frequências de positividade para a mastite. Para a variável local de ordenha, observou-se que a positividade para a mastite foi menor quando se realizava a ordenha em plataforma. Na análise multivariada, observou-se que a predominância de animais mestiços constitui fator de risco para mastite (OR = 1,907; p = 0,010). Faz-se necessária a difusão de tecnologias direcionadas para melhoria das condições de higiene da ordenha, ambiente e do próprio ordenhador, objetivando a redução dos índices da mastite infecciosa nos rebanhos e consequentemente a garantia da qualidade sanitária dos produtos obtidos a partir do leite de cabra produzido em pequenas propriedades rurais. PALAVRAS-CHAVE: Epidemiologia, mastite, pequenos ruminantes. ABSTRACT RISK FACTORS FOR INFECTIOUS MASTITIS IN DAIRY GOATS RAISED IN BAHIA STATE,BRAZIL. The present study was aimed to identify risk factors associated to infectious mastitis in goats in a semiarid region of Bahia State, Brazil. Milk samples were taken from a total of 320 animals and 640 teats on 13 dairy goat farms. The samples were collected after teat disinfection, and were submitted to standard culture and identification of microorganisms. To evaluate the sanitary management an epidemiological questionnaire was used. The risk-factor analysis was performed in two steps: univariate and multivariate. The frequency of animals and mammary glands positive for the microbiologic exam was 29.06% (93/320) and 18.44% (118/640), respectively. One hundred eighteen bacteria were isolated, Staphylococcus spp. being the most prevalent. In the univariate risk-factor analysis, in regard to veterinary support, goats from farms without technical support presented higher frequencies to mastitis. In regard to the place of milking, a lower frequency of mastitis was detected where milking platforms were used. In the multivariate analysis, the predominance of mixed breeds was observed as an important risk factor for mastitis (OR = 1.907; p = 0.010). The spread of technology is necessary for better...
ResumoO presente trabalho teve como objetivos determinar o perfil de sensibilidade aos antimicrobianos e avaliar a presença de mecanismos de resistência antimicrobiana em Staphylococcus spp. (n=36) isolados de mastite em ovelhas do município de Chapecó-SC. O potencial para produção de biofilme foi determinado pelos testes fenotípicos de Agar Vermelho Congo, DAPI e Violeta de Genciana e por teste molecular pela técnica de PCR para a detecção do gene icaD. Para determinar o perfil de resistência aos antimicrobianos, foi realizado o teste de difusão em disco e detecção dos genes de resistência blaZ, mecA, erm (A, B e C) e msrA. O teste da bomba de efuxo foi realizado através do crescimento das culturas em Agar Muller Hinton contendo brometo de etídio. Os resultados mostraram que 1 (2,78%), 36 (100%) e 10 (27,78%) isolados foram considerados produtores de biofilme pelos testes de Agar Vermelho Congo, DAPI e Violeta de Genciana, respectivamente, enquanto que o gene icaD foi observado em apenas 2 (5,55%) isolados. O menor percentual de sensibilidade foi observado para ampicilina (58,33%) e penicilina (58,33%). Os isolados avaliados foram positivos para os genes de resistência blaZ (58,33%) e msrA (11,11%). Nenhum isolado apresentou os genes de resistência erm (A, B, C) e apenas uma amostra foi positiva para o teste da bomba de efluxo. Palavras-chave: Mastite, ovinos, genes de resistência, bomba de efluxo, biofilme, PCR AbstractThis study aimed to determine the antimicrobial susceptibility profile and to assess the presence of mechanisms of antimicrobial resistance in Staphylococcus spp. (n=36) isolated from mastitis in sheep's Chapecó-SC. The potential for biofilm production was determined by phenotypic tests of Congo Red Agar, DAPI and Gentian Violet and by PCR for the detection of icaD gene. To evaluate the antimicrobial resistance testing was performed disk diffusion and detection of resistance genes blaZ, mecA, ermA, ermB and ermC and msrA also performed by PCR.The pump test was conducted by efuxo crop growth Muller Hinton agar containing ethidium bromide. The results showed that 1 (2,78%), 36 (100%) and
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