Nasal colonizing vancomycin-resistant and intermediate Staphylococcus aureus among admitted patients

Background: Staphylococcus aureus colonizing the nasal cavity is a potential source of infections. Vancomycin is a mainstay for treating invasive infections caused by penicillin and methicillin-resistant S. aureus (MRSA). Some reports indicate the emergence of vancomycin-resistant S. aureus (VRSA) making it a high-priority pathogen that needs attention. There is a limited report on the epidemiology of VRSA and vancomycin-intermediate S. aureus (VISA) from the Sidama regional state. Objective: The objective of this study was to determine VRSA and VISA among S. aureus colonizing patients admitted at Hawassa University Comprehensive Specialized Hospital (HUCSH), associated factors, and antimicrobial susceptibility profile. Methods: A hospital-based prospective cross-sectional study was conducted from April to June 2023. Socio-demographic and clinical data were collected using an interviewer-administered questionnaire. Nasal swabs were collected from 378 admitted patients. Identification of S. aureus was made using standard bacteriological methods. VRSA was determined by the Epsilometer test (E-test). The antimicrobial susceptibility profile was determined according to the Kirby-Bauer disk diffusion method. Data was analyzed using SPSS version 22. A p<0.05 was taken as a cut point to determine a statistically significant association. Results: Out of the total 92 S. aureus isolated 12 (13.04%), 27(29.3%), 15(16.3%) were VRSA, VISA, and MRSA respectively. The carriage rate of VRSA and VISA among admitted patients were 12(3.2%) with 95% CI: 1.7%-5.5% and 27(7.14%) with 95% CI: 4.8%-10.2% respectively. The overall nasal carriage rate of S. aureus and MRSA was 92(24.3%) with 95% CI: 20.1%-29% and 15(3.97%) with 95% CI: 2.2%-6.5% respectively. Of the VRSA isolates, 11(91.7%) were susceptible to tigecycline. Forty (43.5%) of S. aureus were positive for inducible clindamycin resistance. Participants with a history of hospitalization at the intensive care unit were 37 times more likely to be colonized with VRSA (p=0.001). Participants who have domestic animals were 22 times more likely to be colonized with VRSA (p=0.021). Conclusions: This study indicated a high proportion of VRSA and VISA among S. aureus isolated from hospitalized patients in the study area. More than 80% of VRSA were susceptible to tigecycline. History of hospitalization at the intensive care unit and having domestic animals at home could increase the odds of VRSA colonization.