Insights into the epidemiology of methicillin-resistant coagulase-negative Staphylococci carriage in community-based drug users

BACKGROUND Coagulase-negative Staphylococci (CoNS) are opportunistic pathogens. Methicillin-resistant CoNS (MRCoNS) remain a major cause of nosocomial infections, but limited information is available in communities. We, therefore, aimed to investigate the epidemiology of CoNS nasal carriage, especially MRCoNS in community-based drug users. METHODS Drug users were included in the cross-sectional study from three communities in Guangzhou, China. A face-to-face questionnaire was used to collect individual information and nasal swabs were collected to identify CoNS and MRCoNS isolates. Phenotypic and genotypic characterization of MRCoNS isolates were detected by using the disk diffusion method and polymerase chain reaction assays. Factors impacting MRCoNS carriage were assessed and estimated odds ratios (ORs) and 95% confidence intervals (CIs) by using logistic regression models. RESULTS Overall, 353 drug users were eligible and included in the study. The prevalence of CoNS and MRCoNS were 42.78% and 29.18%, respectively. Having a history of being in prison (aOR = 2.16, 95% CI: 1.10-4.22) and a history of heroin snorting in the past 6 months (aOR = 1.87, 95% CI: 1.14-3.05) were risk factors for MRCoNS nasal carriage in drug users. The proportions of multidrug resistance for CoNS and MRCoNS isolates were respectively 54.38% and 66.07%. The predominant multidrug resistance pattern for CoNS and MRCoNS isolates was simultaneously non-susceptible to penicillin, cefoxitin and trimethoprim-sulfamethoxazole. MRCoNS isolates that were positive for erythromycin- (χ2 = 15.49, P < 0.001), tetracycline- (χ2 = 44.88, P < 0.001), penicillin- (χ2 = 3.86, P = 0.049), clindamycin- (χ2 = 4.18, P = 0.028), and gentamicin- (χ2 = 20.66, P < 0.001) resistance genes had significantly higher rates of resistance to corresponding antibiotics. CONCLUSIONS The prevalence of MRCoNS nasal carriage was high in community-based drug users. Drug users with risk factors should be paid greater attention to. The use of antibiotics in drug users needs further investigation and control.