Staphylococcus aureus is one of the major casual agents of intra-mammary infections (IMI) in dairy cow and it is characterized by wide variability of pathogenic and contagious properties of different genotypes [1]. The aim of this study was to subtype S. aureus isolates from European and American countries according to the frequency of genotypes and their different profiles, in order to compare them with their specific molecular characteristic. A total of 66 S. aureus isolates from 57 farms situated in Italy, Germany, New York State and Brazil, was collected from clinical mastitis quarter samples. These isolates, all nuc positives, were genotyped by RS-PCR [2][3]; this method, based on the amplification of the 16S-23S rRNA intergenic spacer region, is accurate, rapid and inexpensive [4]. Then, they were analyzed for genes encoding superantigens (from sea to sel and tsst), but also for mecA gene. At first, the RS-PCR analysis revealed 28 different profiles and, within these, 7 new variants of existing genotypes; in particular, they included GTBN_I, GTBN_II, GTBY_I, GTAQ_I (Brazil), GTR_XIII (Italy), GTC_V,GTI_V (New York State). Major genotypes with their variants were combined into genotypic clusters (CL) [5]; for each country, a specific genotypic pattern was found. In fact, in Italy and Germany, the most prevalent ones were CLB (29,4%) and CLR (64,7%), respectively; CLC, situated in Europe, was also widespread in New York State (70,6%), while CLBY was the most prominent in Brazil (40%). Additionally, all isolates were analyzed to investigate the diffusion of virulence factors, related to S. aureus pathogenicity; especially enterotoxins were identified in the majority of them. Among the 66 isolates, only 12 were non enterotoxigenic, whereas the remaining 54 isolates had at least 1 of the genes coding for A, C, D, G, H, I and J enterotoxins. In agreement with a previous study [2] showing that GTB was characterized by the presence of sea, sed and sej, our results showed that also Italian isolates were positive for these SEs. Moreover, this Swiss study revealed that GTC was positive for sec, seg and tsst; the same results were found for GTC German isolates. Furthermore, 2 different Italian isolates harboured tsst and mecA, while 4 German ones were positive for tsst and another 1 for mecA; interestingly, GTS was found only in the Italian and German isolates positive for mecA, in accordance with previous results [4]. On the contrast, the American ones harboured at least one of sea, sed, seg, seh, sei. In conclusion, this study confirms the wide variety of S. aureus genotypes, related to geographical origin of the isolates and to their virulence factors.
Comparision among Staphyloccocus aureus isolates from European and American countries: genotyping, detection of genes encoding superantigens and methicillin resistance (mecA).
Paola Cremonesi;Bianca Castiglioni;
2018
Abstract
Staphylococcus aureus is one of the major casual agents of intra-mammary infections (IMI) in dairy cow and it is characterized by wide variability of pathogenic and contagious properties of different genotypes [1]. The aim of this study was to subtype S. aureus isolates from European and American countries according to the frequency of genotypes and their different profiles, in order to compare them with their specific molecular characteristic. A total of 66 S. aureus isolates from 57 farms situated in Italy, Germany, New York State and Brazil, was collected from clinical mastitis quarter samples. These isolates, all nuc positives, were genotyped by RS-PCR [2][3]; this method, based on the amplification of the 16S-23S rRNA intergenic spacer region, is accurate, rapid and inexpensive [4]. Then, they were analyzed for genes encoding superantigens (from sea to sel and tsst), but also for mecA gene. At first, the RS-PCR analysis revealed 28 different profiles and, within these, 7 new variants of existing genotypes; in particular, they included GTBN_I, GTBN_II, GTBY_I, GTAQ_I (Brazil), GTR_XIII (Italy), GTC_V,GTI_V (New York State). Major genotypes with their variants were combined into genotypic clusters (CL) [5]; for each country, a specific genotypic pattern was found. In fact, in Italy and Germany, the most prevalent ones were CLB (29,4%) and CLR (64,7%), respectively; CLC, situated in Europe, was also widespread in New York State (70,6%), while CLBY was the most prominent in Brazil (40%). Additionally, all isolates were analyzed to investigate the diffusion of virulence factors, related to S. aureus pathogenicity; especially enterotoxins were identified in the majority of them. Among the 66 isolates, only 12 were non enterotoxigenic, whereas the remaining 54 isolates had at least 1 of the genes coding for A, C, D, G, H, I and J enterotoxins. In agreement with a previous study [2] showing that GTB was characterized by the presence of sea, sed and sej, our results showed that also Italian isolates were positive for these SEs. Moreover, this Swiss study revealed that GTC was positive for sec, seg and tsst; the same results were found for GTC German isolates. Furthermore, 2 different Italian isolates harboured tsst and mecA, while 4 German ones were positive for tsst and another 1 for mecA; interestingly, GTS was found only in the Italian and German isolates positive for mecA, in accordance with previous results [4]. On the contrast, the American ones harboured at least one of sea, sed, seg, seh, sei. In conclusion, this study confirms the wide variety of S. aureus genotypes, related to geographical origin of the isolates and to their virulence factors.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
