Molecular approaches for the identification of genetic subtypes of Staphylococcus aureus isolated from mammary infection
| Autor: | Cremonesi P., Capra E., Pozzi F., Tilola M., Drigo I., Graber H.U., Luini M., Vezzoli F., Piccinini R., Castiglioni B. |
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| Jazyk: | italština |
| Rok vydání: | 2013 |
| Předmět: | |
| Zdroj: | LXVII Convegno Nazionale S.I.S.Vet, Brescia, 17-19 Settembre 2013 info:cnr-pdr/source/autori:Cremonesi P., Capra E., Pozzi F., Tilola M., Drigo I., Graber H.U., Luini M., Vezzoli F., Piccinini R., Castiglioni B./congresso_nome:LXVII Convegno Nazionale S.I.S.Vet/congresso_luogo:Brescia/congresso_data:17-19 Settembre 2013/anno:2013/pagina_da:/pagina_a:/intervallo_pagine |
| Popis: | AIM: S. aureus is one of the most important causative agents of bovine mastitis and the clinical outcome can vary in relation to the strains involved in the mammary infection. The aim of this study, funded by Lombardy Region, was to develop a diagnostic protocol for the identification of genetic subtypes of S. aureus responsible for bovine mastitis, with particular virulence and diffusiveness. MATERIAL AND METHODS: S. aureus strains associated with intra-mammary infections were isolated from 8 "control" (< 4% of infected cows) and 8 "case" (> 28% of infected cows) herds for a total of 2015 cows included in the study. Milk samples were cultured with standard methods and the DNA was extracted from S. aureus strains using a protocol described in literature (Cremonesi et al., 2006). Twenty-four and 626 strains isolated from single quarters of "control" and "case" herds respectively, were analysed by both RS-PCR (Fournier et al., 2008) and multiplex PCR. The first method is based on the amplification of the 16S-23S rRNA intergenic spacer region, the multiplex PCR targets the genes encoding for enterotoxins and other virulence genes such as leukocidins and leukotoxins. A subset of 55 strains representative of "control" and "case" isolates was also analysed by ribotyping (automatic Riboprinter), by Identibac array tube system and by protein profiling using MALDI-TOF MS. RESULTS: The RS-PCR analysis of the 650 strains revealed 10 different profiles. In 5 out of 8 "case" herds this method identified the genotype GTB and GTB-variant indicated in literature (Graber et al., 2009) as characteristic of highly diffusive and pathogenic strains, while GTK, GTR_VI and a new genotype named GTbM circulated in the remaining 3 herds. Seven out of the 8 "control" herds, revealed only one S. aureus profile with a predominance of the GTS genotype. Except for 4 out of the 55 representative strains analysed, ribotyping gave a response similar to RS-PCR. Moreover, MALDI-TOF and Identibac analyses proved to be able to integrate the molecular profiling of S. aureus isolated in field. CONCLUSION: Our results confirmed that RS-PCR could be used as a rapid test for molecular typing of S. aureus strains isolated from bovine mastitis and could identify genetic subtypes with particular virulence. Ribotyping, MALDI-TOF and Identibac analyses showed their capability for molecular strains characterization, integrating RS-PCR data. Multivariate analysis by combining data from different techniques could be used to discover a simple panel of markers associated to S. aureus virulence and diffusiveness. BIBLIOGRAFY Cremonesi P., et al. (2006). J. Dairy Sci., 89:163-169; Fournier C., et al. (2008). Res. Vet. Sci., 85: 439-448; Graber HU., et al. (2009). J. Dairy Sci., 92(4) 1442-1451 |
| Databáze: | OpenAIRE |
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