M Haveri1, A Roslöf, L Rantala, S Pyörälä. 1. Department of Clinical Veterinary Sciences, Faculty of Veterinary Medicine, University of Helsinki, Finland. maarit.haveri@helsinki.fi
Abstract
AIMS: To screen putative virulence genes in Staphylococcus aureus causing persistent and nonpersistent bovine intramammary infections (IMI) with different clinical characteristics. To examine, whether a possible relationship exists between genetic profile and infection persistence, clinical signs of infection, clonal type determined by pulsed-field gel electrophoresis (PFGE), and antimicrobial resistance. METHODS AND RESULTS: One-hundred and sixty-one S. aureus isolates derived from bovine IMI, consisting of 17 different PFGE types, were screened by conventional and multiplex-polymerase chain reaction (PCR) for 24 virulence genes for haemolysins (hla-hlg), leukocidins (lukED, lukM), exfoliative toxins (eta, etb), enterotoxins (sea-seo, seu), toxic-shock syndrome toxin (tst), and genes encoding penicillin (blaZ) and methicillin resistance (mecA). The majority of S. aureus isolated at the onset of mastitis carried haemolysin genes (76.7-97.4%), lukED (96.6%), and at least one gene for pyrogenic toxin superantigen (PTSAg) (69.0%). Strains carrying PTSAg-encoding genes were more common among predominant PFGE types and in persistent IMI. Strains concomitantly possessing sed, sej, and blaZ, putatively plasmid-encoded, were typically found in connection with persistent IMI. CONCLUSIONS: Our results suggest that certain genetic elements are over-representative in S. aureus isolates especially from persistent bovine mastitis. This phenomenon seems to be in connection with clonal type and is often concomitant with penicillin resistance. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first study to investigate associations between a large number of bacterial factors and outcome of S. aureus mastitis. The finding that widespread clonal types of S. aureus causing bovine mastitis of low treatment response may harbour characteristic genes could be improved for strain-specific diagnostic purposes.
AIMS: To screen putative virulence genes in Staphylococcus aureus causing persistent and nonpersistent bovine intramammary infections (IMI) with different clinical characteristics. To examine, whether a possible relationship exists between genetic profile and infection persistence, clinical signs of infection, clonal type determined by pulsed-field gel electrophoresis (PFGE), and antimicrobial resistance. METHODS AND RESULTS: One-hundred and sixty-one S. aureus isolates derived from bovine IMI, consisting of 17 different PFGE types, were screened by conventional and multiplex-polymerase chain reaction (PCR) for 24 virulence genes for haemolysins (hla-hlg), leukocidins (lukED, lukM), exfoliative toxins (eta, etb), enterotoxins (sea-seo, seu), toxic-shock syndrome toxin (tst), and genes encoding penicillin (blaZ) and methicillin resistance (mecA). The majority of S. aureus isolated at the onset of mastitis carried haemolysin genes (76.7-97.4%), lukED (96.6%), and at least one gene for pyrogenic toxin superantigen (PTSAg) (69.0%). Strains carrying PTSAg-encoding genes were more common among predominant PFGE types and in persistent IMI. Strains concomitantly possessing sed, sej, and blaZ, putatively plasmid-encoded, were typically found in connection with persistent IMI. CONCLUSIONS: Our results suggest that certain genetic elements are over-representative in S. aureus isolates especially from persistent bovinemastitis. This phenomenon seems to be in connection with clonal type and is often concomitant with penicillin resistance. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first study to investigate associations between a large number of bacterial factors and outcome of S. aureus mastitis. The finding that widespread clonal types of S. aureus causing bovinemastitis of low treatment response may harbour characteristic genes could be improved for strain-specific diagnostic purposes.
Authors: Caroline Le Maréchal; Nubia Seyffert; Julien Jardin; David Hernandez; Gwenaël Jan; Lucie Rault; Vasco Azevedo; Patrice François; Jacques Schrenzel; Maarten van de Guchte; Sergine Even; Nadia Berkova; Richard Thiéry; J Ross Fitzgerald; Eric Vautor; Yves Le Loir Journal: PLoS One Date: 2011-11-11 Impact factor: 3.240
Authors: Ruth N Zadoks; John R Middleton; Scott McDougall; Jorgen Katholm; Ynte H Schukken Journal: J Mammary Gland Biol Neoplasia Date: 2011-10-04 Impact factor: 2.673