Prevalence of colistin resistance in clinical isolates of Enterobacteriaceae: A four-year cross-sectional study

• Published in: The Journal of infection 2017-12, Vol.75 (6), p.493-498
• Main Authors: Prim, Núria, Turbau, Miquel, Rivera, Alba, Rodríguez-Navarro, Judith, Coll, Pere, Mirelis, Beatriz
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Aged; Aged, 80 and over; Analysis of Variance; Anti-Bacterial Agents - pharmacology; Anti-Bacterial Agents - therapeutic use; Child; Colistin; Colistin - pharmacology; Colistin - therapeutic use; Cross-Sectional Studies; Drug Resistance, Bacterial; Enterobacteriaceae; Enterobacteriaceae - drug effects; Enterobacteriaceae - isolation & purification; Enterobacteriaceae Infections - drug therapy; Enterobacteriaceae Infections - epidemiology; Female; Humans; Male; mcr-1; mcr-2; Microbial Sensitivity Tests; Middle Aged; Prevalence; Prospective Studies; Resistance; Retrospective Studies; Spain - epidemiology; Tertiary Care Centers; Young Adult
• ISSN: 0163-4453; 1532-2742
• DOI: 10.1016/j.jinf.2017.09.008

•Prevalence of colistin resistance in clinical isolates of Enterobacteriaceae was 0.7%.•Plasmid-mediated colistin resistance gene mcr-1 was detected only in Escherichia coli.•Colistin resistance was not restricted to MDR isolates and to clinical settings.•Most colistin-resistant isolates were obtained from patients that had not received colistin previously. The objectives were to determine the prevalence of colistin resistance in clinical isolates of Enterobacteriaceae, and to gain knowledge on the epidemiological and clinical features of the patients. All colistin-resistant Enterobacteriaceae consecutively isolated from clinical samples in our institution from 2012 to 2015, were included in this cross-sectional study. Intrinsic-resistant species were excluded. Minimum inhibitory concentration was performed by gradient diffusion. Detection of plasmid-encoded colistin resistance genes mcr-1 and mcr-2 was performed by amplification. Epidemiological and clinical features were reviewed. Of 13579 Enterobacteriaceae isolates, 91 were colistin-resistant. The overall prevalence of colistin resistance was 0.67%. The rates were higher in Enterobacter cloacae (4.2%) than Escherichia coli (0.5%) and Klebsiella pneumoniae (0.4%). One third of the isolates were multi-drug resistant (MDR). While mcr-2 was not detected, mcr-1 was detected only in E. coli. Regarding these infections, 23% were community-acquired. 89% of the patients had not received colistin previously. There were no significant differences between infections caused by mcr-1 and non-mcr-1-carrying isolates. Colistin resistance was not restricted to MDR isolates and to clinical settings. Most patients had no record of previous administration of colistin.