RESUMO
Staphylococcus aureus (S. aureus) is an important causative agent of contagious intermammary infections in dairy cattle. S. aureus is also considered as an important foodborne pathogen and cause of food poisoning cases and outbreaks worldwide. In order to understand the molecular ecology of S. aureus, the present study compared phenotypic and genotypic characteristics of 70 S. aureus isolates from bovine mastitis milk samples collected during the period from August 2001 to March 2014 in different regions of Northern Germany. The S. aureus isolates were characterised phenotypically, as well as genotypically for their genetic diversity using multi-locus sequence typing (MLST), spa typing and the presence of virulence genes encoding 16 staphylococcal enterotoxins (sea-selu), toxic shock syndrome toxin (tst), thermonuclease (nuc), clumping factor (clfA and clfB), coagulase (coa) and the methicillin resistance gene mecA. A total of 16 sequence types were grouped into eight clonal complexes (CCs), and 17 spa types were identified. These included six novel sequence types and one novel spa type. The majority of bovine mastitis milk-associated sequence types belonged to the clonal complex CC5, CC97, CC133, and CC151 and showed closely related genotypes or lineages with sequence types of human origin. The genotype CC133 (ST133-t1403) was predominant, constituting 27.1% of the isolates. In addition, the S. aureus isolates displayed nine different enterotoxigenic profiles. All S. aureus were methicillin-susceptible (MSSA). The current study provides new information on phenotypic and genotypic traits of S. aureus isolates from bovine mastitis. The comparison of characteristics of isolates from the present study originating from mastitis milk showed similarities with human isolates. This might help to better understand the distribution of S. aureus in the one health context.
Assuntos
Mastite Bovina/microbiologia , Leite/microbiologia , Proteínas de Ligação às Penicilinas/deficiência , Staphylococcus aureus/isolamento & purificação , Animais , Proteínas de Bactérias , Bovinos , Farmacorresistência Bacteriana/genética , Enterotoxinas/genética , Feminino , Microbiologia de Alimentos , Genes Bacterianos/genética , Genótipo , Alemanha/epidemiologia , Humanos , Tipagem de Sequências Multilocus , Fenótipo , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/classificação , Staphylococcus aureus/genética , Fatores de Virulência/genéticaRESUMO
Staphylococcus (S.) aureus is one of the most important animal pathogens causing bovine mastitis. Also, it is a major human pathogen that may produce a variety of toxins which cause staphylococcal food poisoning. In the present study a LAMP assay based on gene nuc to identify S. aureus was developed and validated. The specificity of the LAMP assay was confirmed by using 70 S. aureus isolates and 21 non-S. aureus strains. The optimal temperature-time combination to amplify gene nuc successfully was 65 °C and 30 min. The analytical sensitivity of the developed LAMP assay was 0.26 pg of S. aureus DNA per reaction. The limit of detection evaluated with milk spiked with S. aureus was 9 × 102 CFU mL-1. The final results of this assay were available within less than 2 h. The present study showed that the LAMP assay based on gene nuc appeared to be rapid and simple, and could also be used to identify S. aureus isolates from mastitis milk of dairy cows.
