Staphylococcus aureus colonisation in patients from a primary regional hospital

Staphylococcus aureus (SA or S. aureus) is a common pathogen that leads to local and systemic infections in communitarian and hospitalised patients. Staphylococcus colonizing nasal or pharyngeal sites can become virulent and cause severe infections. In this study, we collected 322 pharyngeal exudates and 142 nasal exudates from hospitalised and outpatients for screening purposes. The carriage rates in the pharynx were 27.06% for S. aureus, 11.55% for methicillin-resistant S. aureus (MRSA) and 5.61% for methicillin-oxacillin resistant S. aureus (MORSA). The carriage rates in the nose were 35.38% for S. aureus, 18.46% for MRSA and 13.85% for MORSA. The median multiple antibiotic resistance (MAR) index of SA was 33.33%. The MAR of MRSA was significantly higher than that of methicillin-susceptible strains (MSSA) (45.45% vs. 18.75%, P<0.0001) and the MAR of MORSA was 57.14%. Hierarchical clustering analysis revealed differences in the resistance of methicillin-sensitive, MRSA and MORSA strains. On the whole, our study demonstrates the pattern of distribution of nasal and pharyngeal colonisation with SA, MRSA and MORSA in adults vs. children, inpatients vs. outpatients, ICU patients vs. non-ICU patients, and females vs. males, which can be used for adjusting the screening and decontamination protocols in a hospital. SA is a pervasive pathogen with constantly changing trends in resistance and epidemiology and thus requires constant monitoring in healthcare facilities.