Community-Associated Methicillin-Resistant Staphylococcus aureus: An Enemy amidst Us.

Abstract

Methicillin-resistant Staphylococcus aureus (MRSA), or multidrug-resistant S. aureus, first reported in the early 1960s in the United Kingdom, are strains of S. aureus that through the process of natural selection developed resistance to all available penicillins and other β-lactam antimicrobial drugs [1]. Although the evolution of such resistance does not cause the organism to be more intrinsically virulent, resistance does make MRSA infections more difficult to treat and thus more dangerous, particularly in hospitalized patients and those with weakened immune systems [2]. MRSA can be spread from one person to another through casual contact or through contaminated objects, and a strain acquired in a hospital or health care setting is called health care–associated methicillin-resistant S. aureus (HA-MRSA) [2]. In fact, MRSA has become an important cause of nosocomial infections worldwide and is currently the most commonly identified antibiotic-resistant pathogen in United States hospitals [3–5]. However, although MRSA has been entrenched in hospital settings for several decades, it has undergone rapid evolutionary changes and epidemiologic expansion, spreading beyond the confines of health care facilities, where it is emerging anew as a dominant pathogen known as community associated-MRSA (CA-MRSA) [6]. The rapid dissemination of CA-MRSA strains among general populations in diverse communities has resulted in increasing reports of outbreaks worldwide [1]. In fact, in some regions, CA-MRSA isolates account for 75% of community-associated S. aureus infections in children, creating a public health crisis in the US [1,7]. In this article, we will provide a brief overview of what is known about the epidemiology and pathogenesis of community- associated MRSA and discuss how they differ from the strains originating in health care settings. Further, therapeutic and preventative measures available to combat the rising spread of this revamped pathogen are also discussed.