Nasal Colonizing Vancomycin-Resistant and Intermediate Staphylococcus aureus Among Admitted Patients: A Hospital Based Cross-Sectional Study.

Abstract

Background and aim: Staphylococcus aureus colonizing the nasal cavity poses a potential risk for infections. Vancomycin is a primary treatment for invasive infections caused by penicillin and methicillin-resistant S. aureus (MRSA). However, reports of vancomycin-resistant S. aureus (VRSA) have emerged, highlighting it as a high-priority pathogen requiring attention. There is limited information on the epidemiology of VRSA and vancomycin-intermediate S. aureus (VISA) from the Sidama regional state. This study aimed to determine the prevalence of VRSA and VISA among S. aureus colonizing patients admitted to Hawassa University Comprehensive Specialized Hospital (HUCSH), as well as to identify associated factors and assess the 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 obtained from 378 admitted patients, and S. aureus was identified using standard bacteriological methods. VRSA was determined using the Epsilometer test (E-test), while the antimicrobial susceptibility profile was assessed using the Kirby-Bauer disk diffusion method. Data were analyzed using SPSS version 22, with a p-value of < 0.05 considered statistically significant.

Results: Out of 92 isolated S. aureus strains, 12 (13.04%) were classified as VRSA, 27 (29.3%) as VISA, and 15 (16.3%) as MRSA. The carriage rates among admitted patients were 12 (3.2%) for VRSA (95% CI: 1.7-5.5%) and 27 (7.14%) for VISA (95% CI: 4.8-10.2%). The overall nasal carriage rate of S. aureus was 92 (24.3%) (95% CI: 20.1-29%), with MRSA found in 15 (3.97%) (95% CI: 2.2-6.5%). Among the VRSA isolates, 11 (91.7%) showed susceptibility to tigecycline. Additionally, 40 (43.5%) of the S. aureus strains were positive for inducible clindamycin resistance. Patients with a history of hospitalization in the intensive care unit were 37 times more likely to be colonized with VRSA (p = 0.001), while those with domestic animals were 22 times more likely (p = 0.021).

Conclusions: This study revealed a significant proportion of VRSA and VISA among S. aureus isolates from hospitalized patients in the region. More than 80% of VRSA isolates were susceptible to tigecycline. A history of hospitalization in the intensive care unit and ownership of domestic animals were associated with an increased likelihood of VRSA colonization.