title: Effect of higher minimum inhibitory concentrations of quaternary ammonium compounds in clinical E. coli isolates on antibiotic susceptibilities and clinical outcomes.
abstract: Quaternary ammonium compounds (QACs) are cationic surfactants used as preservatives and environmental disinfectants. Limited data are available regarding the effect of QACs in the clinical setting. We performed a prospective cohort study in 153 patients with Escherichia coli bacteraemia from February to September 2008 at University Hospital in Rennes. The minimum inhibitory concentrations (MICs) of antibiotics and QACs alkyldimethylbenzylammonium chloride (ADBAC) and didecyldimethylammonium chloride (DDAC) were determined by the agar dilution method. The capacity of biofilm production was assayed using the Crystal Violet method, and mutation frequencies by measuring the capacity of strains to generate resistance to rifampicin. Logistic regression analysis showed that one of the significant factors related to low MICs for ADBAC (≤16 mg/L) and DDAC (≤8 mg/L), was cotrimoxazole susceptibility (odds ratio: 3.72; 95% confidence interval: 1.22-11.24; P=0.02 and OR: 3.61; 95% CI: 1.56-7.56; P<0.01, respectively). Antibiotic susceptibility to cotrimoxazole was strongly associated with susceptibility to amoxicillin and nalidixic acid (P<0.01). Community-acquired or healthcare-associated bacteraemia, severity of bacteraemia, and patient outcome were independent of the MICs of ADBAC and DDAC. Our findings demonstrate an epidemiological relationship between higher MIC values of QACs in clinical E. coli isolates and antibiotic resistance.
authors.affiliation: Equipe de Microbiologie EA 1254, Université de Rennes 1, Rennes, Université Européenne de Bretagne, France. sylvie.buffet-bataillon@chu-rennes.fr
authors.forename: S
authors.initials: S
authors.lastname: Buffet-Bataillon
authors.forename: B
authors.initials: B
authors.lastname: Branger
authors.forename: M
authors.initials: M
authors.lastname: Cormier
authors.forename: M
authors.initials: M
authors.lastname: Bonnaure-Mallet
authors.forename: A
authors.initials: A
authors.lastname: Jolivet-Gougeon
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D016470:Bacteremia / Q000188:drug therapy* / Q000382:microbiology; D001548:Benzalkonium Compounds / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D018441:Biofilms / Q000187:drug effects; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000188:drug therapy / Q000382:microbiology; D005260:Female; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests / Q000379:methods / Q000592:standards*; D008875:Middle Aged; D009154:Mutation; D011379:Prognosis; D000644:Quaternary Ammonium Compounds / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D016896:Treatment Outcome
chemical_list: D000900:Anti-Bacterial Agents; D001548:Benzalkonium Compounds; D000644:Quaternary Ammonium Compounds; C053645:N,N-dimethyl-N-hexadecyl-1-octadecylammonium