Prevalence of Staphylococcus aureus methicillin-sensitive and methicillin-resistant nasal and pharyngeal colonization in outpatients in Lebanon

Abstract

Background: There is an increasing concern about methicillin-resistant Staphylococcus aureus (MRSA) infections in the community. This study aimed to evaluate the rate of S aureus nasopharyngeal colonization in outpatients as the primary endpoint, and also to study the impact of several possible risk factors, including recent hospitalization, recent surgical procedures, and antibiotic intake.

Methods: A total of 1,526 consecutive outpatients underwent surveillance cultures after completing a questionnaire. Isolated S aureus strains were tested for antibiotic susceptibility. The Pearson χ(2) test was used for statistical analysis. The differences were considered to be statistically significant at a P value <.05.

Results: Out of the 1,526 outpatients tested, 133 (8.7%) carried S aureus in the nose and/or throat. Only 2 of those cases were MRSA, and both were isolated from the nose. One hundred thirty-one patients had methicillin-sensitive S aureus, 13 with simultaneous carriage in the nose and throat. Among the risk factors, a relative working in health care, presence of an intravascular device, recent dental procedure, and health club use were significantly associated with an increased risk of S aureus colonization, with P values of .00, .02, .04, and .00, respectively, calculated by the χ(2) test.

Conclusions: The prevalence of MRSA is still low in our study population within the Lebanese community. The only significant risk factors playing a role in increasing the carriage of S aureus were related to health care exposure.

Keywords: Methicillin-resistant Staphylococcus aureus; Methicillin-sensitive Staphylococcus aureus; Nose and throat carriage; Staphylococcus aureus.