AJM Theme Issue: Infectious Disease
Clinical research study
Fifteen-Year Study of the Changing Epidemiology of Methicillin-Resistant Staphylococcus aureus

The data in this article was presented in part at the 43rd Annual Meeting of the Infectious Diseases Society of America, San Francisco, California, October 6 to 9, 2005; Abstract 1043.
https://doi.org/10.1016/j.amjmed.2006.01.004Get rights and content

Abstract

Purpose

The study’s purpose was to elucidate the evolutionary, microbiologic, and clinical characteristics of methicillin-resistant Staphylococcus aureus (MRSA) infections.

Methods

MRSA cases from military medical facilities in San Diego, from 1990 to 2004, were evaluated and categorized as community-acquired or nosocomial. Sequence type, staphylococcal chromosomal cassette gene type, and Panton-Valentine leukocidin gene status were determined for a subset of isolates.

Results

Over the 15-year period, 1888 cases of MRSA were identified; 65% were community acquired. The incidence (155 infections/100 000 person-year in 2004) and household-associated cases rapidly increased since 2002. Among persons with community-acquired MRSA, 16% were hospitalized and only 17% were initially given an effective antibiotic. Community-acquired MRSA cases compared with nosocomial MRSA cases were more often soft-tissue and less often urinary, lung, or bloodstream infections (P < .001). Patients with community-acquired MRSA were younger (22 vs 64 years, P < .001) and less likely to have concurrent medical conditions (9% vs 98%, P < .001). Clindamycin resistance increased among community-acquired MRSA isolates during 2003 and 2004 compared with previous years (79% vs 13%, P < .001). Genetically, nosocomial MRSA isolates were significantly different than those acquired in the community. Although community-acquired MRSA isolates were initially diverse by 2004, one strain (staphylococcal chromosomal cassette type IV, sequence type 8, Panton-Valentine leukocidin gene positive) became the predominant isolate.

Conclusions

Community-acquired and intrafamilial MRSA infections have increased rapidly since 2002. Our 15 years of surveillance revealed the emergence of distinct community-acquired MRSA strains that were genetically unrelated to nosocomial MRSA isolates from the same community.

Section snippets

Methods

We evaluated all positive cultures for MRSA at U.S. military clinics and the tertiary hospital in San Diego from 1990 to 2004. Our patient population consisted of 247,000 active duty military personnel, dependents (including spouses and children), and retirees of the armed services. All cultures obtained at U.S. naval medical clinics in the San Diego area are referred to the Naval Medical Center San Diego microbiology laboratory. MRSA was defined by the Clinical Laboratory Standards Institute23

Methicillin-Resistant Staphylococcus aureus Cases from 1990 to 2004

A total of 1888 MRSA isolates were found over a 15-year period at our institution; data to establish the case as community-acquired or nosocomial MRSA were available on 1846 isolates (97.8%). Of these, 1208 (65.4%) were community-acquired MRSA cases and 638 (34.6%) were nosocomial MRSA cases (Figure 1). Of the 1888 isolates, 1533 (81.2%) represented an MRSA infection, 348 (18.4%) represented a colonization, and 7 (0.4%) could not be classified. Community-acquired MRSA was the cause of the

Discussion

To our knowledge, this is the first single-site study that compares community-acquired MRSA and nosocomial MRSA isolates over a 15-year time period. Our report demonstrates that the incidence of community-acquired MRSA infections has dramatically increased since 2002 and that an increasing proportion of community-acquired MRSA cases are the result of intrafamilial spread. The community-acquired and nosocomial MRSA isolates from this study, which examines a single geographic location, are both

Conclusion

Community-acquired MRSA infections and household-related cases have dramatically increased since 2002. Most community-acquired MRSA involves the soft tissues; infections may be severe. Although a prime opportunity existed for nosocomial MRSA to spread and become established as community-acquired MRSA strains in this defined community, our 15 years of surveillance revealed the emergence of distinct MRSA strains uniquely adapted to the community. Further research on other specific virulence

References (44)

  • Four pediatric deaths from community-acquired methicillin-resistant Staphylococcus aureus, Minnesota and North Dakota, 1997-1999

    MMWR Morb Mortal Wkly Rep

    (1999)
  • C.E. Zinderman et al.

    Community-acquired methicillin-resistant Staphylococcus aureus among military recruits

    Emerg Infect Dis

    (2004)
  • Methicillin-resistant Staphylococcus aureus in correctional facilities—Georgia, California, and Texas, 2001-2003

    MMWR Morb Mortal Wkly. Rep

    (2003)
  • D.M. Nguyen et al.

    Recurring infections in a football team

    Emerg Infect Dis

    (2005)
  • S.V. Kazakova et al.

    A clone of methicillin-resistant Staphylococcus aureus among professional football players

    N Engl J Med

    (2005)
  • E.D. Charlebois et al.

    Origins of community strains of methicillin-resistant Staphylococcus aureus

    Clin Infect Dis

    (2004)
  • E.A. Eady et al.

    Staphylococcal resistance revisited: community-acquired methicillin-resistant Staphylococcus aureus—an emerging problem for the management of skin and soft tissue infections

    Curr Opin Infect Dis

    (2003)
  • P.D. Fey et al.

    Comparative molecular analysis of community- or hospital-acquired methicillin-resistant Staphylococcus aureus

    Antimicrob Agents Chemother

    (2003)
  • S. Deresinski

    Methicillin-resistant Staphylococcus aureus: an evolutionary, epidemiologic, and therapeutic odyssey

    Clin Infect Dis

    (2005)
  • H.F. Chambers

    The changing epidemiology of Staphylococcus aureus?

    Emerg Infect Dis

    (2001)
  • R.S. Daum et al.

    A novel methicillin-resistance cassette in community-acquired methicillin-resistant Staphylococcus aureus isolates of diverse genetic backgrounds

    J Infect Dis

    (2002)
  • B.A. Diep et al.

    Widespread skin and soft-tissue infections due to two methicillin-resistant Staphylococcus aureus strains harboring the genes for Panton-Valentine leucocidin

    J Clin Microbiol

    (2004)
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    This work was supported by the Department of Defense.

    The views expressed in this article are those of the authors and do not reflect the official policy or position of the Department of the Navy, Department of Defense, or United States Government.

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