Prevalence, risk factors, phenotypic and molecular characteristics for methicillin-resistant Staphylococcus aureus carriage in community-based drug users in Guangzhou, China

Abstract Background: Staphylococcus aureus ( S. aureus ) and methicillin-resistant Staphylococcus aureus (MRSA) remained the predominant cause of infections in drug users. The cross-sectional study aimed to elucidate the prevalence, risk factors, phenotypic and molecular characteristics of S. aureus and MRSA carriage among community-based drug users. Methods: Eligible drug users were asked to complete questionnaires and collect nasal swabs during May and December 2017 in Guangzhou, China. Swabs were processed for identification of S. aureus and MRSA. Antimicrobial susceptibility test and polymerase chain reaction assays were used to detect phenotypic and molecular characteristics for identified isolates. Univariate and multivariate logistic regression analyses were used to assess risk factors for S. aureus and MRSA carriage. Results: Overall, the prevalence of S. aureus and MRSA carriage in 353 drug users were 15.01% and 6.79%, respectively. Cohabitation was a risk factor for S. aureus (adjusted OR=8.80, 95% CI: 1.89-40.99) and MRSA (adjusted OR=14.30, 95% CI: 2.67-76.46) carriage. The proportions of multidrug resistance were respectively 72.41% and 89.47% for S. aureus and MRSA isolates and were simultaneously resistant to penicillin, erythromycin and clindamycin. The results of clonal complexes and sequence types for S. aureus and MRSA isolates were diverse. The proportions of virulence genes were high for MRSA isolates. Conclusion: The prevalence of S. aureus nasal carriage was lower while the prevalence of MRSA nasal carriage was moderate. Phenotypic and molecular characteristics of MRSA isolates revealed serious antibiotic resistance, indicating the cross-circulation of MRSA isolates, and imply high opportunity of virulence-related diseases. Decolonization might be considered for drug users with MRSA carriage, especially for those with risk factors.