Community-associated meticillin-resistant Staphylococcus aureus

Abstract

Meticillin-resistant Staphylococcus aureus (MRSA) is endemic in hospitals worldwide, and causes substantial morbidity and mortality. Health-care-associated MRSA infections arise in individuals with predisposing risk factors, such as surgery or presence of an indwelling medical device. By contrast, many community-associated MRSA (CA-MRSA) infections arise in otherwise healthy individuals who do not have such risk factors. Additionally, CA-MRSA infections are epidemic in some countries. These features suggest that CA-MRSA strains are more virulent and transmissible than are traditional hospital-associated MRSA strains. The restricted treatment options for CA-MRSA infections compound the effect of enhanced virulence and transmission. Although progress has been made towards understanding emergence of CA-MRSA, virulence, and treatment of infections, our knowledge remains incomplete. Here we review the most up-to-date knowledge and provide a perspective for the future prophylaxis or new treatments for CA-MRSA infections.

Figure 1. Global distribution of CA-MRSA as indicated by multilocus sequence type (ST)

Dotted lines indicated possible route of dissemination for the indicated clones. Major CA-MRSA clones are indicated by larger font and color. Colored regions are an estimate of the area in which infections have been reported for the indicated clone (not all are shown). ST1, green; ST8, red; ST30, blue; ST80, gray hatched. +, PVL-positive; −, PVL-negative; ±, combination of PVL-positive and PVL-negative strains isolated from the region.

Figure 2. Rapid progression of radiographic findings in a fatal case of CA-MRSA pneumonia complicating novel H1N1 influenza A infection

(A) Chest radiograph at initial presentation of a patient with symptoms of fevers, headache, myalgias, and non-productive cough. (B) Chest radiograph taken 24 hours later with presence of new infiltrates and signs of consolidation in the right upper lobe, right middle lobe and left lower lobe.