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.

Short communication: ß-Lactam resistance and vancomycin heteroresistance in Staphylococcus spp. isolated from bovine subclinical mastitis.

The use of antimicrobial agents has led to the emergence of resistant bacterial strains over a relatively short period. Furthermore, Staphylococcus spp. can produce ß-lactamase, which explains the survival of these strains in a focus of infection despite the use of a ß-lactam antibiotic. The aim of this study was to evaluate the resistance of Staphylococcus spp. isolated from bovine subclinical mastitis to oxacillin and vancomycin (by minimum inhibitory concentration) and to detect vancomycin heteroresistance by a screening method. We also evaluated ß-lactamase production and resistance due to hyperproduction of this enzyme and investigated the mecA and mecC genes and performed staphylococcal cassette chromosome mec typing. For this purpose, 181 Staphylococcus spp. isolated from mastitis subclinical bovine were analyzed. Using the phenotypic method, 33 (18.2%) of Staphylococcus spp. were resistant to oxacillin. In contrast, all isolates were susceptible to vancomycin, and heteroresistance was detected by the screening method in 13 isolates. Production of ß-lactamase was observed in 174 (96%) of the Staphylococcus spp. isolates. The mecA gene was detected in 8 isolates, all of them belonging to the species Staphylococcus epidermidis, and staphylococcal cassette chromosome mec typing revealed the presence of type I and type IV isolates.

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.

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.