Abstract

Introduction

Methicillin-resistant strains of S aureus are resistant to all β-lactam antibiotics and frequently to many other antibiotic classes.

CA-MRSA (Community acquired) has a greater spectrum of antimicrobial susceptibility including to sulfa drugs, tetra cyclines, and clindamycin. CA-MRSA are more easily treated, though more virulent than HA-MRSA. About 75 percent of CA-MRSA infections are localized to skin and soft tissue.

β -lactam  resistance is due to an alteration of the penicillin-binding protein PBP 2a, which is encoded by the chromosomal gene mec A. Once introduced into a microbial population, mec A may be transferred horizontally and recombined among methicillin-susceptible S aureus (MSSA) cells. This has led to the global spread of MRSA in association with increasing geographic mobility of infected patients and carriers of the organism.