title: Prevalence of antiseptic-resistance genes in Staphylococcus aureus and coagulase-negative staphylococci colonising nurses and the general population in Hong Kong.
abstract: Reduced biocide susceptibility in staphylococci is associated with quaternary ammonium compound (qac) gene-encoding efflux proteins. This study compared the prevalence of antiseptic-resistance genes (qacA/B, smr) in staphylococci colonising nurses and non-healthcare workers. Staphylococcus aureus and coagulase-negative staphylococci (CoNS) isolated from 249 nurses were compared for qacA/B and smr positivity with carriage isolates from non-healthcare workers. Associations between qac genes and antibiotic resistance were investigated and minimum inhibitory concentrations (MICs)/minimum bactericidal concentrations (MBCs) to benzalkonium chloride and chlorhexidine determined. Both genes had higher prevalence in CoNS from nurses (OR: 8.4; 95% CI: 5.4-13.2) and qacA/B was more common in nurses'S. aureus isolates than those of the general population (OR: 5.5; 95% CI: 2.7-11.2). Meticillin-resistant S. aureus (MRSA) carriage was low (3.2% nurses; 0.5% general population). The risk of harbouring qacA/B and smr was associated with presence of mecA (OR: 2.9; 95% CI: 1.8-4.8) and contact with MRSA-infected patients (OR: 2.0; 95% CI: 1.0-3.9) in S. aureus and CoNS. S. aureus with qac genes displayed significantly more antibiotic resistance and all gene-positive isolates had higher MICs and MBCs to antiseptics. Increased prevalence of antiseptic-resistance genes in staphylococci from nurses indicates that the hospital environment could exert selective pressure for carriage of these strains. The increased proportion of qac genes in meticillin-resistant strains suggests co-selection of these genes, as does the increased carriage of gene-positive strains by those in contact with MRSA-positive patients. Reduced antiseptic susceptibility may allow persistence of organisms in the presence of low level residues and contribute to survival of MRSA.
authors.affiliation: Department of Health Technology and Informatics, The Hong Kong Polytechnic University, Hong Kong SAR, China.
authors.forename: M
authors.initials: M
authors.lastname: Zhang
authors.forename: M M
authors.initials: MM
authors.lastname: O'Donoghue
authors.forename: T
authors.initials: T
authors.lastname: Ito
authors.forename: K
authors.initials: K
authors.lastname: Hiramatsu
authors.forename: M V
authors.initials: MV
authors.lastname: Boost
mesh_terms: D000891:Anti-Infective Agents, Local / Q000494:pharmacology*; D017920:Antiporters / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics; D002353:Carrier State / Q000453:epidemiology* / Q000382:microbiology; D002710:Chlorhexidine / Q000031:analogs & derivatives / Q000494:pharmacology; D003030:Coagulase / Q000378:metabolism; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D005260:Female; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D008297:Male; D026901:Membrane Transport Proteins / Q000235:genetics; D008826:Microbial Sensitivity Tests; D009296:Nasal Cavity / Q000382:microbiology; D009726:Nurses; D011159:Population Surveillance; D015995:Prevalence; D013203:Staphylococcal Infections / Q000453:epidemiology* / Q000382:microbiology; D013210:Staphylococcus / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics / Q000302:isolation & purification; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification
chemical_list: D000891:Anti-Infective Agents, Local; D017920:Antiporters; D001426:Bacterial Proteins; D003030:Coagulase; D026901:Membrane Transport Proteins; C099272:QacB protein, Staphylococcus aureus; C521590:small multidrug-resistance pump, Staphylococcus aureus; C068498:qacA protein, Staphylococcus aureus; C010882:chlorhexidine gluconate; D002710:Chlorhexidine