Characterization of resistance to selected antibiotics and Panton-Valentine leukocidin-positive in a healthy student population at a Malaysian University.

INTRODUCTION

This study aims to assess the antimicrobial susceptibility profiles of strains isolated from university students and to determine the prevalence of constitutive and inducible clindamycin resistance, the latter being able to cause therapeutic failure due to false in vitro clindamycin susceptibility.

METHODS

strains were isolated from the nasal swabs of 200 health sciences students of a Malaysian university. Twelve classes of antibiotics were used to evaluate the antimicrobial susceptibility profiles with the macrolide-lincosamide-streptogramin B (MLS) phenotype for inducible clindamycin resistance determined by the double-diffusion test (D-test). Carriage of resistance and virulence genes was performed by PCR on isolates that were methicillin resistant, erythromycin resistant and/or positive for the leukocidin gene, (n=15).

RESULTS

Forty-nine isolates were viable and identified as with four of the isolates characterized as methicillin-resistant (MRSA; 2.0%). All isolates were susceptible to the antibiotics tested except for penicillin (resistance rate of 49%), erythromycin (16%), oxacillin (8%), cefoxitin (8%) and clindamycin (4%). Of the eight erythromycin-resistant isolates, iMLS was identified in five isolates (three of which were also MRSA). The majority of the erythromycin-resistant isolates harbored the gene (four iMLS) with the remaining iMLS isolate harboring the gene.

CONCLUSION

The presence of MRSA isolates which are also iMLS in healthy individuals suggests that nasal carriage may play a role as a potential reservoir for the transmission of these pathogens.