title: Molecular epidemiology and antimicrobial susceptibility profiles of methicillin-resistant Staphylococcus aureus blood culture isolates: results of the Quebec Provincial Surveillance Programme.
abstract: The objectives of this study were to characterize methicillin-resistant Staphylococcus aureus (MRSA) blood culture isolates and to determine their relative importance in both nosocomial and community-acquired infections. A total of 535 MRSA blood culture isolates were analysed. In vitro susceptibility to 14 agents was determined. The genes nuc, mecA and coding for PVL toxin were identified by PCR. All isolates were characterized by PFGE or spa typing to assess their genomic relationships. Most MRSA isolates were retrieved from nosocomial bloodstream infections (474, 89%) and were of the CMRSA2 genotype. Healthcare-associated (HA)-MRSA bloodstream infections were associated with older age (70-89 years, P = 0·002) and most often secondary to central line infections (P = 0·005). Among MRSA strains associated with community-acquired (CA)-MRSA, 28·8% were isolated in intravenous drug users. CA-MRSA genotypes were more frequently found in young adults (20-39 years, P < 0·0001) with skin/soft tissue as the primary sources of infection (P = 0·006). CMRSA10 genotype was the predominant CA-MRSA strain. All MRSA isolates were susceptible to doxycycline, tigecycline, trimethoprim/sulfamethoxazole and vancomycin. Both the presence of the genes coding for PVL toxin (89·8%) and susceptibility to clindamycin (86·5%) were predictive of CA-MRSA genotypes. Whereas in the USA, HA-MRSA have been replaced by USA300 (CMRSA10) clone as the predominant MRSA strain type in positive blood cultures from hospitalized patients, this phenomenon has not been observed in the province of Quebec.
authors.affiliation: Laboratoire de santé publique du Québec,Institut national de santé publique du Québec,Québec,Canada.
authors.forename: S
authors.initials: S
authors.lastname: Lévesque
authors.affiliation: McGill University Health Centre and Department of Medicine, McGill University,Montréal,Québec,Canada.
authors.forename: A M
authors.initials: AM
authors.lastname: Bourgault
authors.affiliation: Centre hospitalier régional de Trois-Rivières,Québec,Canada.
authors.forename: L A
authors.initials: LA
authors.lastname: Galarneau
authors.affiliation: Centre de santé et des services sociaux de Rivière-du-Loup,Québec,Canada.
authors.forename: D
authors.initials: D
authors.lastname: Moisan
authors.affiliation: Laboratoire de santé publique du Québec,Institut national de santé publique du Québec,Québec,Canada.
authors.forename: F
authors.initials: F
authors.lastname: Doualla-Bell
authors.affiliation: Laboratoire de santé publique du Québec,Institut national de santé publique du Québec,Québec,Canada.
authors.forename: C
authors.initials: C
authors.lastname: Tremblay
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D016470:Bacteremia / Q000453:epidemiology / Q000382:microbiology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D003428:Cross Infection / Q000453:epidemiology / Q000382:microbiology; D005260:Female; D006801:Humans; D008297:Male; D008712:Methicillin / Q000494:pharmacology*; D016106:Methicillin Resistance; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects* / Q000235:genetics*; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D017720:Molecular Epidemiology; D011792:Quebec / Q000453:epidemiology; D013203:Staphylococcal Infections / Q000453:epidemiology / Q000382:microbiology*; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D008712:Methicillin
keywords: Staphylococcus aureus