Methicillin-resistant Staphylococcus spp. investigation in hospitalized horses and contacting personnel in a teaching veterinary hospital.

Staphylococci are well-known opportunistic pathogens associated with suppurative diseases in humans and animals. Antimicrobial resistance is an emergent threat to humans and animals worldwide. This study investigated the prevalence of methicillin-resistant Staphylococcus spp. (MRS) in hospitalized horses and contacting personnel (veterinarians and staff), and assessed possible interspecies transmission in a teaching veterinary hospital. Nasal swabs from horses (n = 131) and humans (n = 35) were collected. The microorganisms were identified by traditional biochemical tests and genotypic methods, i.e., PCR, internal transcript spacer PCR (ITS-PCR), and gene sequencing. Staphylococcal species were isolated in 18% (23/131) of the horses, of which 8% (11/131) were S. hyicus, 4 % (5/131) were S. aureus, 4% (5/131) were S. pseudintermedius, and 2% (2/131) were S. schleiferi subsp. coagulans. The mecA gene was detected in an S. pseudintermedius isolate. Staphylococcus spp. was isolated in 40% (14/35) of the human samples, all of which were S. aureus. In four samples of S. aureus, the clonal profile ST398 was identified; among them, a clonal similarity of 98.1% was observed between a horse and a contacting human. This finding supports the need for biosecurity measures to avoid the spread of multidrug-resistant staphylococci in humans and horses.

Staphylococcus spp. Isolated from Bovine Subclinical Mastitis in Different Regions of Brazil: Molecular Typing and Biofilm Gene Expression Analysis by RT-qPCR.

Bovine mastitis is mainly caused by bacteria of the genus Staphylococcus spp., which possess different virulence factors, including the capacity for biofilm formation that provides enhanced protection against the action of immune system components and serves as a barrier against the penetration of antimicrobial agents. This study aimed to characterize 181 Staphylococcus spp. Strains-including Staphylococcusaureus and coagulase-negative staphylococci (CoNS) isolated from bovine subclinical mastitis in six Brazilian states-by molecular methods. RT-qPCR was used to verify the expression of genes of the ica operon-mainly responsible for biofilm formation-as well as bap and bhp. Chromosome similarity among the isolates was investigated by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). The icaA gene was detected in 79 (43.6%) isolates, icaB in 24 (13.2%), icaC in 57 (31.4%), and icaD in 127 (70.1%). The bap gene was identified in 66 (36.4%) isolates, while the bhp gene was found in nine (4.9%). RT-qPCR confirmed the expression of the icaA gene in 60 (75.9%) isolates, of icaB in six (25%), of icaC in 26 (45.6%), and of icaD in 80 (63%). Clonal typing of the isolates by PFGE permitted the identification of eight Staphylococcusaureus clusters that simultaneously included ≥3 strains, with a similarity of ≥80%. Regarding the other species studied, three clusters were observed for Staphylococcuschromogenes and four clusters for Staphylococcusepidermidis. Only one cluster each was identified for Staphylococcussaprophyticus and Staphylococcussimulans, while the other species did not form any cluster. With respect to MLST, ST126 and ST1 were the prevalent sequence types in S. aureus, while in S.epidermidis all sequence types were different. These results reveal strains with the same evolutionary origin as other isolates, which might cause infections in humans and animals, suggesting their ability to spread between these species.

Expression of genes encoding resistance in Staphylococcus spp. isolated from bovine subclinical mastitis in Brazil.

INTRODUCTION: Staphylococci are the most important agents associated with bovine mastitis. This study aimed at characterizing resistance factors to antimicrobials in Staphylococcus spp. isolated from the milk of cows with subclinical mastitis. METHODOLOGY: In vitro resistance of 243 Staphylococcus spp. isolates to antimicrobials commonly used in clinical practice was evaluated. The detection and expression of genes encoding resistance mecA (gene encoding penicillin binding protein 2a) mecALGA251 (mecA homologue), blaZ (gene encoding penicillin resistance), femA and femB (genes encoding essential factors - A and B - for the expression of methicillin resistance) and aacA-aphD (gene encoding for a bifunctional enzyme that confers resistance to gentamicin) using PCR and RT-PCR was investigated. RESULTS: One or more genes encoding resistance to different antimicrobials were detected in 184 Staphylococcus spp. SAMPLES: The femA and femB genes were the most frequent. Regarding the variables' detection (N = number of strains) and expression (% of strains), the following results were obtained: blaZ (N = 40 - 82.5%), femA (N = 147 - 47.6%), aacAaphD (N = 30 - 43.3%), femB (N = 138 - 29.7%), mecA (N = 33 - 27.3%), mecALGA251 (N = 01 - 0.0%). There was a higher occurrence of phenotypic resistant strains for amoxicillin, ampicillin and penicillin in isolates positive for detection and/or expression of blaZ gene when compared with the other genes. CONCLUSIONS: The present study provides new information on genotypic traits of Staphylococcus isolates from bovine subclinical mastitis especially regarding the evaluation of expression of genes associated with antimicrobial resistance in Staphylococcus spp. using molecular tools.

Detection of Enterotoxigenic Potential and Determination of Clonal Profile in Staphylococcus aureus and Coagulase-Negative Staphylococci Isolated from Bovine Subclinical Mastitis in Different Brazilian States.

Epidemiological studies have identified Staphylococcus aureus as the most common agent involved in food poisoning. However, current research highlights the importance of toxigenic coagulase-negative staphylococci (CoNS) isolated from food. The aim of this study was to characterize Staphylococcus spp. isolated from cows with bovine subclinical mastitis regarding the presence of genes responsible for the production of staphylococcal enterotoxins and of the tst-1 gene encoding toxic shock syndrome toxin 1, and to determine the clonal profile of the isolates carrying any of the genes studied. A total of 181 strains isolated in different Brazilian states, including the South, Southeast, and Northeast regions, were analyzed. The sea gene was the most frequent, which was detected in 18.2% of the isolates, followed by seb in 7.7%, sec in 14.9%, sed in 0.5%, see in 8.2%, seg in 1.6%, seh in 25.4%, sei in 6.6%, and ser in 1.6%. The sej, ses, set, and tst-1 genes were not detected in any of the isolates. The typing of the isolates by pulsed-field gel electrophoresis revealed important S. aureus and S. epidermidis clusters in different areas and the presence of enterotoxin genes in lineages isolated from animals that belong to herds located geographically close to each other.

Influência da contagem de células somáticas nos constituintes do leite da região sudoeste do Paraná, Brasil / Influence of somatic cells levels on milk componentes in southwest Paraná, Brazil

Este estudo tem como objetivo verificar a características físico-químicas do leite da região sudoestedo Paraná. Para tanto, 293 propriedades foram classificadas segundo o número de animais. Posteriormente foiefetuado o sorteio simples de cada classe, perfazendo uma média de nove animais e diferentes característicasquanto à raça, tipo de ordenha e estagio de lactação. Foi realizado o CMT e colheitas de amostras (de julho aoutubro de 2010) para CCS em frascos contendo conservante bromopol e enviados ao Laboratório do Programade Análise de Rebanhos Leiteiros da Associação Paranaense de Criadores de Bovinos da Raça Holandesa(APCBRH) em equipamento de citometria de fluxo. As frequências de todos os constituintes foram submetidasao teste de Tukey. Os resultados demonstraram que animais com CMT positivo me pelo menos um dos quartosmamários médias e desvio padrão de gordura (%), proteína (%), lactose (%), sólidos totais (%) e CCS (CCS x1000/mL) de 2,41 ± 1,22, 3,302 ± 0,46, 4,44 ± 0,45, 10,99 ± 1,32 e 443,80 ± 688,90, respectivamente.Destacando que as frequências de gordura e sólidos totais estão fora dos parâmetros estabelecidos pela IN 62.Pode-se verificar que as vacas em lactação região sudoeste do estado do Paraná apresentam índices de taxas degordura e sólidos totais abaixo do estabelecido pela IN 62, necessitando de medidas sanitárias para reduzir oíndice de mastite o que pode estar interferindo diretamente na qualidade do leite produzido

This study aims to determine the physical and chemical characteristics of milk fromsouthwestern Paraná region. To this end, 293 properties were classified according to the number of animals, waslater made simple drawing of each class, making an average of nine animals and different characteristicsregarding race, milking type and stage of lactation. CMT and sampling (July-October 2010) to CCS in vialscontaining preservative Bromopol and sent to the Laboratory of Analysis Program dairy herd of ParanáAssociation of Cattle Breeders of Holstein (APCBRH) was performed on equipment flow cytometry. Thefrequencies of all constituents were subjected to Tukey's test. The results demonstrated that animals with CMTplus me at least one of mammary glands and average standard deviation of fat (%) Protein (%) Lactose (%) totalsolids (%) and CCS (CCS x 1000 / ml) 2.41 ± 1.22, 3.302 ± 0.46, 4.44 ± 0.45, 10.99 ± 1.32 and 443.80 ± 688.90,respectively. Noting that the frequencies of fat and solids are outside the parameters of IN 62 (referrals). One cancheck that lactating cows southwest region of the state of Paraná present rate indices of fat and total solids belowestablished by IN 62, requiring health measures to reduce the incidence of mastitis which may be interferingdirectly in the quality of milk produced

Influência da contagem de células somáticas nos constituintes do leite da região sudoeste do Paraná, Brasil / Influence of somatic cells levels on milk componentes in southwest Paraná, Brazil

Este estudo tem como objetivo verificar a características físico-químicas do leite da região sudoestedo Paraná. Para tanto, 293 propriedades foram classificadas segundo o número de animais. Posteriormente foiefetuado o sorteio simples de cada classe, perfazendo uma média de nove animais e diferentes característicasquanto à raça, tipo de ordenha e estagio de lactação. Foi realizado o CMT e colheitas de amostras (de julho aoutubro de 2010) para CCS em frascos contendo conservante bromopol e enviados ao Laboratório do Programade Análise de Rebanhos Leiteiros da Associação Paranaense de Criadores de Bovinos da Raça Holandesa(APCBRH) em equipamento de citometria de fluxo. As frequências de todos os constituintes foram submetidasao teste de Tukey. Os resultados demonstraram que animais com CMT positivo me pelo menos um dos quartosmamários médias e desvio padrão de gordura (%), proteína (%), lactose (%), sólidos totais (%) e CCS (CCS x1000/mL) de 2,41 ± 1,22, 3,302 ± 0,46, 4,44 ± 0,45, 10,99 ± 1,32 e 443,80 ± 688,90, respectivamente.Destacando que as frequências de gordura e sólidos totais estão fora dos parâmetros estabelecidos pela IN 62.Pode-se verificar que as vacas em lactação região sudoeste do estado do Paraná apresentam índices de taxas degordura e sólidos totais abaixo do estabelecido pela IN 62, necessitando de medidas sanitárias para reduzir oíndice de mastite o que pode estar interferindo diretamente na qualidade do leite produzido(AU)

This study aims to determine the physical and chemical characteristics of milk fromsouthwestern Paraná region. To this end, 293 properties were classified according to the number of animals, waslater made simple drawing of each class, making an average of nine animals and different characteristicsregarding race, milking type and stage of lactation. CMT and sampling (July-October 2010) to CCS in vialscontaining preservative Bromopol and sent to the Laboratory of Analysis Program dairy herd of ParanáAssociation of Cattle Breeders of Holstein (APCBRH) was performed on equipment flow cytometry. Thefrequencies of all constituents were subjected to Tukey's test. The results demonstrated that animals with CMTplus me at least one of mammary glands and average standard deviation of fat (%) Protein (%) Lactose (%) totalsolids (%) and CCS (CCS x 1000 / ml) 2.41 ± 1.22, 3.302 ± 0.46, 4.44 ± 0.45, 10.99 ± 1.32 and 443.80 ± 688.90,respectively. Noting that the frequencies of fat and solids are outside the parameters of IN 62 (referrals). One cancheck that lactating cows southwest region of the state of Paraná present rate indices of fat and total solids belowestablished by IN 62, requiring health measures to reduce the incidence of mastitis which may be interferingdirectly in the quality of milk produced(AU)

Prevalence and etiology of bovine mastitis in the Nova Tebas, Parana / Prevalência e etiologia da mastite bovina na região de Nova Tebas, Paraná

Mastitis is an infection which often commits animals assigned for milk production. It has been the major price raise factor for dairy cattle breeding. Economical losses impact on professional fees, drugs, death and early discard of the animal as well as dairy companies as a result of the downturn in product end-quality, decrease of industrial procedure regarding dairy product manufacturing and changes in mastitic milk composition. Considering the relevance of such disease, this study verifies mastitis prevalence and etiology in the region of Nova Tebas, PR by analyzing 336 lactating dairy cows from 17 farms, totalizing 1324 mammary quarters through CMT, SCS and bacterial isolation. Negative (1120 mammary quarters 84.6%) and positive (204 mammary quarters 15.4%) results for CMT were verified. Among the positive quarters, 155 (75.9%) presented bacterial growth higher prevalence of coagulase-negative Staphylococcus SCN 51 (32.9%), Streptococcus sp. 49 (31.6%); Corynebacterium bovis 19 (12.3%), coagulase-positive Staphylococcus SCP 19 (12.3%), Gram-negative bacilli (BGN) 12 (7.7%), Corynebacterium sp. 3 (1.9%), and Candida sp. 2 (1.2%). Results show that mastitis in the region of Nova Tebas is compatible to those found all over Brazil together with the highest prevalent etiological agents. Such profile of animals with mastitis can be noticed from screening tests used for mastitis such as CMT and SCS.(AU)

A mastite é a infecção mais frequente dos animais destinados à produção de leite e que mais onera a pecuária leiteira. As perdas econômicas são causadas tanto pelos honorários profissionais, medicamentos, morte ou descarte precoce de animais, bem como em laticínios, pela queda na qualidade do produto final e diminuição no rendimento industrial para a fabricação dos seus derivados e pelas alterações na composição do leite mastítico. Considerando a relevância desta enfermidade, este estudo teve como objetivo verificar a prevalência e etiologia de mastite na região de Nova Tebas PR, analisando 336 vacas em lactação de 17 propriedades, totalizando 1324 quartos mamários através do CMT, CCS e isolamento bacteriano. Verificou-se 1120 quartos mamários (84,6%) negativos no teste de CMT e 204 (15,4%) positivos. Dentre os quartos positivos, 155 (75,9%) apresentaram crescimento bacteriano, verificando a maior prevalência Staphylococcus coagulase negativa - SCN 51 (32,9%), Streptococcus sp. 49 (31,6%), Corynebacterium bovis 19 (12,3%), Staphylococcus coagulase positiva - SCP 19 (12,3%), bacilo Gram negativo (BGN) 12 (7,7%), Corynebacterium sp. 3 (1,9%), e Candida sp. 2 (1,2%). Os resultados encontrados neste trabalho mostram que a prevalência de mastite na região de Nova Tebas é compatível aos encontrados nas demais regiões do Brasil, bem como os agentes etiológicos mais frequentes.(AU)

Prevalence and etiology of bovine mastitis in the Nova Tebas, Parana / Prevalência e etiologia da mastite bovina na região de Nova Tebas, Paraná

Mastitis is an infection which often commits animals assigned for milk production. It has been the major price raise factor for dairy cattle breeding. Economical losses impact on professional fees, drugs, death and early discard of the animal as well as dairy companies as a result of the downturn in product end-quality, decrease of industrial procedure regarding dairy product manufacturing and changes in mastitic milk composition. Considering the relevance of such disease, this study verifies mastitis prevalence and etiology in the region of Nova Tebas, PR by analyzing 336 lactating dairy cows from 17 farms, totalizing 1324 mammary quarters through CMT, SCS and bacterial isolation. Negative (1120 mammary quarters 84.6%) and positive (204 mammary quarters 15.4%) results for CMT were verified. Among the positive quarters, 155 (75.9%) presented bacterial growth higher prevalence of coagulase-negative Staphylococcus SCN 51 (32.9%), Streptococcus sp. 49 (31.6%); Corynebacterium bovis 19 (12.3%), coagulase-positive Staphylococcus SCP 19 (12.3%), Gram-negative bacilli (BGN) 12 (7.7%), Corynebacterium sp. 3 (1.9%), and Candida sp. 2 (1.2%). Results show that mastitis in the region of Nova Tebas is compatible to those found all over Brazil together with the highest prevalent etiological agents. Such profile of animals with mastitis can be noticed from screening tests used for mastitis such as CMT and SCS.

A mastite é a infecção mais frequente dos animais destinados à produção de leite e que mais onera a pecuária leiteira. As perdas econômicas são causadas tanto pelos honorários profissionais, medicamentos, morte ou descarte precoce de animais, bem como em laticínios, pela queda na qualidade do produto final e diminuição no rendimento industrial para a fabricação dos seus derivados e pelas alterações na composição do leite mastítico. Considerando a relevância desta enfermidade, este estudo teve como objetivo verificar a prevalência e etiologia de mastite na região de Nova Tebas PR, analisando 336 vacas em lactação de 17 propriedades, totalizando 1324 quartos mamários através do CMT, CCS e isolamento bacteriano. Verificou-se 1120 quartos mamários (84,6%) negativos no teste de CMT e 204 (15,4%) positivos. Dentre os quartos positivos, 155 (75,9%) apresentaram crescimento bacteriano, verificando a maior prevalência Staphylococcus coagulase negativa - SCN 51 (32,9%), Streptococcus sp. 49 (31,6%), Corynebacterium bovis 19 (12,3%), Staphylococcus coagulase positiva - SCP 19 (12,3%), bacilo Gram negativo (BGN) 12 (7,7%), Corynebacterium sp. 3 (1,9%), e Candida sp. 2 (1,2%). Os resultados encontrados neste trabalho mostram que a prevalência de mastite na região de Nova Tebas é compatível aos encontrados nas demais regiões do Brasil, bem como os agentes etiológicos mais frequentes.

Importância do mapeamento e monitoramento do perfil de resistência e detecção dos genes de resistência de Staphylococcus sp. relacionados à mastite bovina / Importance of mapping and monitoring the resistence profile and resistance gene detection of Staphylococcus sp. related to mastitis bovine / Importancia del mapeo y monitore del perfil de resistencia y detección de los genes de resistencia de Staphylococcus sp. relacionados a la mastitis bovina

A mastite é a doença mais importante do gado leiteiro, pois acarreta grandes prejuízos devido a perda da produção, gastos com serviços veterinários e medicamentos. Sua etiologia é diversificada, porém as bactérias são as maiores causadoras da doença, principalmente o Staphylococcus aureus, caracterizando uma mastite contagiosa. A doença causa problemas a saúde pública devido aos resíduos de antibióticos, bactérias e suas toxinas que podem ser eliminadas no leite, além dos prejuízos para a indústria de laticíneos. Para diminuir taxas de infecção e prevenir novas infecções são utilizados antibióticos, tanto no período de lactação, quando necessário, ou no período seco, onde acabam sendo utilizados sem prévia cultura microbiológica e antibiograma. Atualmente são detectados estirpes de Staphylococcus aureus multirresistentes, tanto em ambiente hospitalar (HA-MRSA) como na comunidade (CA-MRSA). A resistência aos antibióticos é expressa devido a mutações de seus genes ou por meio da aquisição de genes de resistência de outras bactérias, da mesma espécie ou não. Inúmeros trabalhos vêm sendo desenvolvidos para caracterizar os fatores de patogenicidade destes dois tipos de estirpes, no intuito de mapear e rastrear as infecções em humanos e animais. Em humanos, a pesquisa do gene mecA e o estudo do perfil de resistência aos antimicrobianos em cepas de S. aureus vêm sendo amplamente utilizados para estudos epidemiológicos d casos de infecção. Com a epidemiologia molecular dos genes de resistência é possível distinguir a transferência horizontal da disseminação clonal de resistência bacteriana. Dessa forma, uma abordagem voltada a saúde pública, faz-se necessária e oportuna.

Mastitis is the most important diseasesin milk cattle because it causes great disadvantages due to the production loss, expenses with medical service and remedy. Its etiology is diversified, but bacteria are the most common cause of the disease, especially Staphylococcus aureus, characterizing contagious mastitis. The disease causes problems to Public Health bacauseof the residual part of antibiotics, bacteria and toxins that can be eliminated in the milk, besides the loss caused to dairy industries. To reduce infection ratios and prevent new infection, antibiotics are used in the lactation period, whenever they are necessary, or in the dry period, when they are utilized without previous microbiological culture or antibiogram. Currently, there are detected bloodlines of Staphylococcus aureus that are multiresistant in hospital environment (HA-MRSA) as well as in the community (CA-MRSA). The resistance to antibiotics happen because of genic mutations or the acquisition of resistant genes from other bacteria, from the same species or not. Countless papers are being developed to characterize the pathogenic factors of these two kinds of bloodlines,aiming to map and keep track of the infections in humans and animals. For humans, the genic research of mecA and the profile studies of the resistance to the antimicrobiotics on S. aureus strains are being largely used to epidemiological studies in case of infection. With molecular epidemiology of resistant gens, it is possible to distinguish the horizontal transference of the clonal dissemination of the bacterial resistance. Therefore, an approach towards public health shows itself is necessary and favorable.

La mastitis es la enfermedad más importante del ganado lechero, causa daños importantes debido a la pérdida de producción, costos con servicios veterinarios y medicamentos. Su etiología es variada, pero las bacterias son las mayores causadoras de la enfermedad, especialmente Staphylococcus aureus, caracterizando mastitis contagiosa. La enfermedad causa problemas de salud pública debido a los residuos de antibióticos, las bacterias y sus toxinas pueden ser eliminadas en la leche, además del daño para la industria de lácteos. Para reducir las tasas de infección y prevenir nuevas infecciones son utilizados antibióticos, tanto en el período de lactancia, cuando sea necesario, o en la estación seca, que terminan siendo utilizados sin previa cultura microbiológica y antibiograma. Actualmente se detectan cepas multirresistentes de Staphylococcus saureus, tanto en ambiente hospitalario (HA-MRSA) como en la comunidad (CA-MRSA). La resistencia a los antibióticos se expresa debido a mutaciones de sus genes o mediante la adquisición de genes de resistencia de otras bacterias, de la misma especie o no. Innúmeros trabajos se han realizado para caracterizar los factores de patogenicidad de estos dos tipos de cepas, con el fin de mapear y rastrear las infecciones en humanos y animales. En humanos, la investigación del gene meca y el estudio del perfil de resistencia antimicrobiana en cepas de S. aureus han sido ampliamente utilizados para estudios epidemiológicos de casos de infección. Con la epidemiología molecular de los genes de resistencia es posible distinguir la transferencia horizontal de propagación clonal de resistencia bacteriana. Así, un enfoque centrado en la salud pública se hace necesario y oportuno.

Importância do mapeamento e monitoramento do perfil de resistência e detecção dos genes de resistência de Staphylococcus sp. relacionados à mastite bovina / Importance of mapping and monitoring the resistence profile and resistance gene detection of Staphylococcus sp. related to mastitis bovine / Importancia del mapeo y monitore del perfil de resistencia y detección de los genes de resistencia de Staphylococcus sp. relacionados a la mastitis bovina

A mastite é a doença mais importante do gado leiteiro, pois acarreta grandes prejuízos devido a perda da produção, gastos com serviços veterinários e medicamentos. Sua etiologia é diversificada, porém as bactérias são as maiores causadoras da doença, principalmente o Staphylococcus aureus, caracterizando uma mastite contagiosa. A doença causa problemas a saúde pública devido aos resíduos de antibióticos, bactérias e suas toxinas que podem ser eliminadas no leite, além dos prejuízos para a indústria de laticíneos. Para diminuir taxas de infecção e prevenir novas infecções são utilizados antibióticos, tanto no período de lactação, quando necessário, ou no período seco, onde acabam sendo utilizados sem prévia cultura microbiológica e antibiograma. Atualmente são detectados estirpes de Staphylococcus aureus multirresistentes, tanto em ambiente hospitalar (HA-MRSA) como na comunidade (CA-MRSA). A resistência aos antibióticos é expressa devido a mutações de seus genes ou por meio da aquisição de genes de resistência de outras bactérias, da mesma espécie ou não. Inúmeros trabalhos vêm sendo desenvolvidos para caracterizar os fatores de patogenicidade destes dois tipos de estirpes, no intuito de mapear e rastrear as infecções em humanos e animais. Em humanos, a pesquisa do gene mecA e o estudo do perfil de resistência aos antimicrobianos em cepas de S. aureus vêm sendo amplamente utilizados para estudos epidemiológicos d casos de infecção. Com a epidemiologia molecular dos genes de resistência é possível distinguir a transferência horizontal da disseminação clonal de resistência bacteriana. Dessa forma, uma abordagem voltada a saúde pública, faz-se necessária e oportuna.(AU)

Mastitis is the most important diseasesin milk cattle because it causes great disadvantages due to the production loss, expenses with medical service and remedy. Its etiology is diversified, but bacteria are the most common cause of the disease, especially Staphylococcus aureus, characterizing contagious mastitis. The disease causes problems to Public Health bacauseof the residual part of antibiotics, bacteria and toxins that can be eliminated in the milk, besides the loss caused to dairy industries. To reduce infection ratios and prevent new infection, antibiotics are used in the lactation period, whenever they are necessary, or in the dry period, when they are utilized without previous microbiological culture or antibiogram. Currently, there are detected bloodlines of Staphylococcus aureus that are multiresistant in hospital environment (HA-MRSA) as well as in the community (CA-MRSA). The resistance to antibiotics happen because of genic mutations or the acquisition of resistant genes from other bacteria, from the same species or not. Countless papers are being developed to characterize the pathogenic factors of these two kinds of bloodlines,aiming to map and keep track of the infections in humans and animals. For humans, the genic research of mecA and the profile studies of the resistance to the antimicrobiotics on S. aureus strains are being largely used to epidemiological studies in case of infection. With molecular epidemiology of resistant gens, it is possible to distinguish the horizontal transference of the clonal dissemination of the bacterial resistance. Therefore, an approach towards public health shows itself is necessary and favorable.(AU)

La mastitis es la enfermedad más importante del ganado lechero, causa daños importantes debido a la pérdida de producción, costos con servicios veterinarios y medicamentos. Su etiología es variada, pero las bacterias son las mayores causadoras de la enfermedad, especialmente Staphylococcus aureus, caracterizando mastitis contagiosa. La enfermedad causa problemas de salud pública debido a los residuos de antibióticos, las bacterias y sus toxinas pueden ser eliminadas en la leche, además del daño para la industria de lácteos. Para reducir las tasas de infección y prevenir nuevas infecciones son utilizados antibióticos, tanto en el período de lactancia, cuando sea necesario, o en la estación seca, que terminan siendo utilizados sin previa cultura microbiológica y antibiograma. Actualmente se detectan cepas multirresistentes de Staphylococcus saureus, tanto en ambiente hospitalario (HA-MRSA) como en la comunidad (CA-MRSA). La resistencia a los antibióticos se expresa debido a mutaciones de sus genes o mediante la adquisición de genes de resistencia de otras bacterias, de la misma especie o no. Innúmeros trabajos se han realizado para caracterizar los factores de patogenicidad de estos dos tipos de cepas, con el fin de mapear y rastrear las infecciones en humanos y animales. En humanos, la investigación del gene meca y el estudio del perfil de resistencia antimicrobiana en cepas de S. aureus han sido ampliamente utilizados para estudios epidemiológicos de casos de infección. Con la epidemiología molecular de los genes de resistencia es posible distinguir la transferencia horizontal de propagación clonal de resistencia bacteriana. Así, un enfoque centrado en la salud pública se hace necesario y oportuno.(AU)