Nasal carriage and antimicrobial resistance of coagulase-negative staphylococci among male healthcare trainees in Southwestern Saudi Arabia: a cross-sectional study

Coagulase-negative staphylococci (CoNS) are increasingly recognized as clinically relevant colonizers in healthcare settings; however, their nasal carriage patterns and antimicrobial resistance profiles remain under-characterized, particularly among healthcare trainees. This study aimed to determine the prevalence, species distribution, clinical associations, and antimicrobial susceptibility patterns of CoNS among male healthcare trainees in Southwestern Saudi Arabia. A cross-sectional study was conducted involving 249 male healthcare trainees at King Khalid University. Nasal swabs were collected and cultured, with bacterial identification performed using the BD Phoenix™ M50 automated system. Antimicrobial susceptibility testing was conducted using disk diffusion in accordance with Clinical and Laboratory Standards Institute (CLSI) guidelines. Logistic regression was used to assess associations between colonization, clinical symptoms, and medical history. Staphylococcus epidermidis was the predominant species (64.3%). Recent antibiotic use was inversely associated with S. epidermidis carriage (OR 0.41; 95% CI 0.24–0.70) and positively associated with Staphylococcus cohnii subsp. cohnii carriage (OR 11.08; 95% CI 3.21–38.31). Staphylococcus warneri showed associations with halitosis (OR 416.25) and runny nose (OR 32.3); however, these estimates had extremely wide confidence intervals due to small sample sizes and should be interpreted as exploratory findings. Resistance profiles varied by species, with S. warneri exhibiting the highest resistance to methicillin markers (37.5%), while all CoNS isolates remained susceptible to vancomycin and linezolid. Healthcare trainees harbor diverse CoNS species with distinct clinical and resistance profiles. The predominance of S. epidermidis alongside the presence of resistant non-epidermidis CoNS species, particularly S. warneri, highlights the clinical relevance of these organisms beyond their traditional classification as benign colonizers. These findings underscore the importance of considering CoNS in surveillance and antimicrobial stewardship efforts within clinical training environments.