Frequency of Disinfectant Resistance Genes in Pediatric Strains of Methicillin-Resistant Staphylococcus aureus

摘要: Resistance to chlorhexidine gluconate (CHG) and quaternary ammonium compounds (QACs) is a potential public health threat, given widespread use of these agents for routine hospital cleaning, skin antisepsis, patient decolonization.1–3 Development tolerance CHG QACs among methicillin-resistant Staphylococcus aureus (MRSA) isolates can be mediated by energy-dependent multidrug efflux proteins, which show increased expression in response selective pressure from disinfectant use.4 Plasmid-encoded pump genes qac A/B smr confer both QACs, along with other compounds, including intercalating dyes cationic biocides.5,6 The have been found MRSA varying frequencies globally, mostly tertiary-care adult pediatric populations.6 Here we describe an evaluation clinical the presence resistance smr, CHG. Two hundred eighty-one 2004 through 2009 were selected randomly Vanderbilt Children’s Hospital Repository, de-identified collection unique obtained emergency room or hospitalized general patients infection. Repository approved Institutional Review Board maintained as dataset limited information. All identified University Laboratory according Clinical Standards Institute standards prior repository transfer. Isolates cultured overnight on blood agar at 37°C, purified genomic DNA was used template repetitive-element, sequence-based polymerase chain reaction determine genetic classification strains (DiversiLab System, Biomerieux). evaluated PCR using previously published primers.7,8 Minimum bactericidal concentrations (MBCs) subset 5 positive strains, negative controls, determined broth microdilution methods 20% w/v digluconate solution (Sigma-Aldrich Corp., St. Louis, Mo.).1 A Fisher Exact Test performed statistical significance. Of 281 repository, 201 (71.5%) belonged USA300, current epidemic clone United States. Of remainder, 31 (11.0%) USA100, USA500, 18 (6.4%) pulse types. Genes detected 18.5% (52/281); 13.9% contained only, 4.3% harbored A/B, 1 isolate qacA/B. Non-USA300 significantly more likely harbor than USA300 (Figure 1; P = 0.0175). MBC testing 15 (5 positive, positive) serial dilutions showed that all had MBCs less 16 μg/mL, well below recommended in-use concentration 2000 μg/mL.6 No significant differences noted between controls. Figure 1 Presence type. qacA/B (P 0.0175). We moderate prevalence plasmid-encoded (18.5%) this random sample isolates, similar studies US populations.9 In our study, belonging type associated community-associated epidemic, non-USA300 possess genes. Nearly 15% however, also pumps capable conferring CHG. This unexpected finding clone’s predominant association community-onset infection, since considered healthcare-associated exposure. This study has generalizability because it represents single center may not apply geographic regions. nature attached did allow emergence over time, relationship specific infections, such device-associated infection. CHG gained increasing role infection prevention arsenal reducing threatens efforts directed against multi-drug resistant organisms. widely surgical daily bathing critically-ill commonplace. Randomized Evaluation Decolonization vs Universal Clearance Eliminate (REDUCE) trial universal decolonization nasal mupirocin reduced rates bloodstream infections community intensive care unit setting.3 popularity strategies will further increase settings. Thus, important consider mechanisms might survive exposure setting. Staphylococcus possesses chromosomal plasmid-mediated targeting wide range antimicrobials disinfectants. Previous evaluations activity gene-positive shown evidence elevated those strains.1, 6 Another overexpression S. disinfectants.4 Our no isolates. Reassuringly, harboring phenotypic reported date. In summary, report demonstrates population, Ongoing genotypic help gauge effectiveness future utilizing