CONCISE REVIEW FOR CLINICIANSEpidemiology, Treatment, and Prevention of Community-Acquired Methicillin-Resistant Staphylococcus aureus Infections
Section snippets
THE CHANGING FACE OF S AUREUS
Shortly after the introduction of penicillin in the 1940s, penicillin-resistant S aureus isolates were described first in hospitals and subsequently in the community.1 Today, the vast majority of staphylococcal isolates carry plasmids encoding a penicillinase-rendering penicillin resistance.
Methicillin, a penicillinase-resistant semisynthetic penicillin, was introduced in 1961. Less than 1 year later, MRSA was reported.1 Today, MRSA is a common nosocomial isolate and accounts for more than 50%
WHAT CONSTITUTES CA-MRSA?
There is no universally accepted definition of what constitutes CA-MRSA. Epidemiologically oriented studies base the definition on the timing of MRSA isolation in culture relative to hospital admission (ie, <24–72 hours), with or without excluding patients with established MRSA risk factors (recent hospitalization, hemodialysis, indwelling catheters, etc).8 Numerous epidemiological studies have suggested that hospitals were the primary MRSA reservoir and that hospital contact accounted for most
POPULATIONS AT RISK
The incidence of CA-MRSA varies regionally, but comprehensive epidemiological studies have not been published recently. Local prevalence data and antibiograms should be updated and monitored. Attendant to this, clinicians need to culture appropriate sources (furuncles, soft tissue abscesses, etc). The incidence of CA-MRSA varies also by age and is reported consistently in younger patients than is nosocomial MRSA.15 Outbreaks have occurred in several discrete patient populations. Identified
CLINICAL SYNDROMES
Skin and soft tissue infections and lower respiratory infections account for much of the current clinical literature about CA-MRSA. Community-acquired MRSA has been reported less frequently in endocarditis, brain abscesses, bacteremia, sinusitis, and musculoskeletal infections.30, 31, 32, 33, 34 Recent reports about CA-MRSA causing necrotizing fasciitis, myositis, osteomyelitis, prosthetic joint infection, and complicated parapneumonic effusions highlight the various clinical settings and
Skin and Soft Tissue Infections
When choosing an empirical antimicrobial for skin and soft tissue infections, one should consider the likelihood that MRSA is the etiologic agent, the severity of the infection, and pertinent host factors including immunologic status (eg, diabetes mellitus and human immunodeficiency virus), allergies, and factors that may impede follow-up. β-Lactam agents currently remain the antimicrobial of choice for most skin and soft tissue infections in many if not most parts of the country. If CA-MRSA is
PREVENTION
There is great interest in measures to abort and prevent CA-MRSA outbreaks. Education of health care providers, patients, caregivers, high-risk populations, and appropriate organizations about CA-MRSA and adherence to basic infection-control principles are key to preventive strategies. Informed physicians are in a better position to recognize, treat, and appropriately counsel patients with CA-MRSA. Data are limited about which specific control interventions may be most effective. Measures that
CONCLUSIONS
Community-acquired MRSA is an emerging infectious cause of morbidity and mortality among previously healthy persons in the United States and worldwide. Accumulating evidence suggests that these heterogeneous strains are particularly suited to community survival and spread. It remains to be seen whether CA-MRSA will become the predominant staphylococcal phenotype in the community, as penicillin-resistant S aureus did. If so, CA-MRSA promises to affect nearly every medical specialty. Primary care
Questions About CA-MRSA
- 1.
Which one of the following patient populations is not associated with CA-MRSA outbreaks?
- a.
Prisoners
- b.
Teachers
- c.
Soldiers
- d.
Athletes
- e.
Alaska Natives
- a.
- 2.
Which one of the following clinical manifestations is not associated with the PVL toxin?
- a.
Endocarditis
- b.
Cellulitis
- c.
Furunculosis
- d.
Necrotizing pneumonia
- e.
Cutaneous abscesses
- a.
- 3.
Which one of the following statements about CA-MRSA therapy is true?
- a.
TMP-SMX monotherapy is adequate when β-hemolytic streptococci infection also is suspected
- b.
Clindamycin is
- a.
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2014, American Journal of Emergency MedicineCitation Excerpt :Our study focused on the evolution of antimicrobial resistance in response to commonly prescribed antibiotics, which in our hospital consists of a combination or single-drug regimen of TMP/SMX, cephalexin, and clindamycin. Cephalexin is known to be ineffective against MRSA [3,4,8,9,11,19], and it was likely given as coverage for the possibility of streptococcal infection. Resistance to TMP/SMX was first identified in 2006; the proportion of MRSA isolates resistant to TMP/SMX remained low overall but slowly increased over the years.
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