Staphylococcus aureus carriage among hemodialysis outpatients: risk factors, antimicrobial resistance, and molecular characterization

BACKGROUND: Staphylococcus aureus (S. aureus) carriage is prevalent among hemodialysis outpatients and may be associated with frequent healthcare contact and vascular access use. The aim of the study was to determine the prevalence of S. aureus carriage, factors associated with carriage, antimicrobial resistance patterns, and selected resistance and virulence genes among hemodialysis outpatients. METHODS: A cross-sectional observational study was conducted in 2018-2021. Eighty-one hemodialysis outpatients and 81 age-matched adults without kidney disease were included. S. aureus isolates were identified using standard microbiological methods, and antimicrobial susceptibility testing was performed according to EUCAST criteria. Multiplex real-time PCR was used for the detection of resistance genes (ermA, ermC, mecA, tetM, tetK) and the lukF-PV associated virulence gene. Factors associated with carriage were assessed using structured interviews and electronic medical records. Categorical variables were compared using chi-square or Fisher's exact tests, and continuous variables using Mann-Whitney U-test. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated. Significance level - p < 0.05. RESULTS: Eighty-one hemodialysis outpatients (39.5% female; mean age 62.0 years) were enrolled. S. aureus carriage was detected in 38.3% and was significantly higher than in controls (p = 0.041). In univariable analyses, S. aureus carriage was associated with hemodialysis access type, dialysis vintage, recent hospitalization, antimicrobial use, gastroesophageal reflux disease, atrial fibrillation, anemia, and secondary hyperparathyroidism (all p < 0.05). In exploratory multivariable analysis, only atrial fibrillation remained associated with carriage. Resistance to penicillin was observed in 69.7% of isolates, tetracycline in 6.1%, and erythromycin/clindamycin in 3.0%. No methicillin-resistant S. aureus (MRSA) isolates were detected; pvl was detected in 1/33 (3.0%) hemodialysis isolates and in 3/52 (5.8%) isolates overall. CONCLUSIONS: Compared to healthy controls, hemodialysis patients were more frequently colonized with S. aureus. The observed resistance and virulence profiles provide local epidemiological data from Lithuania. The selected resistance and virulence gene profiles provide descriptive molecular data but do not allow conclusions regarding lineages or transmission patterns.