Risk Factors of Nasal Carriage of Methicillin-Resistant Staphylococcus Aureus and its Antibiotic Susceptibility Pattern in Namazi Hospital Healthcare Workers in Shiraz, Iran

Methicillin-resistant Staphylococcus aureus (MRSA) is a major nosocomial pathogen worldwide. The aim of this study was to determine the risk factors of nasal carriage of MRSA and its antibiotic susceptibility pattern among healthcare workers at Namazi Hospital (Shiraz-Iran) In a cross-sectional study from July to November 2006, nasal swabs were taken from 600 stratified randomly selected health care workers. The isolates were identified as S. aureus based on morphology, gram stains, catalase test, coauglase test and DNase Agar. To differentiate Methicillinsusceptible S. aureus (MSSA) and Methicillin Resistant S. aureus (MRSA), agar screen plate was used. All methicillin-resistant isolates were examined for mecA genes existence by PCR performance. The sensitivity patterns of S.aureus isolates were determined by disc diffusion and E-test method. Nasal screening identified 186 (31%) S. aureus carriers of whom, 154 ones (82.8%) were MSSA and 32 ones (17.2%) were MRSA._There was no significant association between related risk factors and gender, age, years of healthcare service and level of education. In the univariate analysis, a statistically significant difference was found only based on occupation (P=0.032) between carriers of MSSA and MRSA. In multivariate analysis(logistic regression), having nursing occupation (p=0.012, OR=3.6, 95%CI=1.3-9.7) was independently associated with MRSA carriage. All of the MRSA strains were sensitive to mupirocin. This study revealed that having nursing occupation is independently associated with MRSA carriage since all S.aureus isolates were susceptible to mupirocin, topical mupirocin could be used successfully to eradicate nasal staphylococcal colonization and carriers.