Risk Factors for Infection: Community-Acquired Resistant Pathogens

George H. Karam, MD
Paula Garvey Manship Professor of Medicine, Division of Infectious Diseases, Louisiana State University School of Medicine, Baton Rouge, Louisiana

    It was not long ago when the suspicion of antimicrobial-resistant microorganisms was largely restricted to hospitalized patients. In recent months, however, there has been an increase in resistance in the community setting due to the growing dissemination of organisms such as community-associated methicillin-resistant Staphylococcus aureus, extended-spectrum β-lactamase (ESBL)-producing Escherichia coli, quinolone-resistant E coli,

and strains of Clostridium difficile that are now resistant to quinolones. Some experts have warned that we have returned to a preantibiotic era for certain infections.¹ The spread of ESBL-producing organisms is an important contributor to treatment failure and the growing problem of antimicrobial resistance in hospitals around the world.^2,3 Fluoroquinolone resistance by E coli is increasing rapidly among hospitalized patients,⁴ but clinicians often have a limited understanding of the extent of resistance within their institutions. Failure to recognize fluoroquinolone resistance in E coli and Klebsiella pneumoniae infection delays the selection of appropriate therapy and has been shown to increase mortality.⁵ Recent outbreaks of fulminant C difficile may reflect several factors, including modifications of genes that encode for suppression of bacterial toxins, the spread of fluoroquinolone resistance, and inadequate infection control measures. Although human activity clearly affects the emergence and spread of antimicrobial resistance, resistance can also emerge in microbes even without human intervention.¹

   Dosing and administration of antibiotics for community-acquired infections are often not well standardized or are based on relatively limited support from controlled clinical trials. New education efforts and patient guidelines from the Centers for Disease Control and Prevention, the Infectious Diseases Society of America, and the American Medical Association may help clinicians to better recognize and manage resistant infections. In addition, recent efforts by the Centers for Medicare and Medicare Services (CMS) and others have increasingly focused on the avoidance of preventable infection-related events among hospitalized patients, including catheter-associated urinary tract infections, vascular catheter-associated infections, and several other infections that occur following elective procedures.⁶

   The intersection of 2 important recent trends—increased community antimicrobial resistance and increased morality with inadequate antibiotic therapy—creates a challenge for the clinician to understand the potential for resistance in the community, and to make better decisions about antimicrobial therapy.

References
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4. Lockhart SR, Abramson MA, Beekmann SE, et al. Antimicrobial resistance among Gram-negative bacilli causing infections in intensive care unit patients in the United States between 1993 and 2004. J Clin Microbiol. 2007;45:3352-3359.
5. Lautenbach E, Metlay JP, Bilker WB, et al. Association between fluoroquinolone resistance and mortality in Escherichia coli and Klebsiella pneumoniae infections: the role of inadequate empirical antimicrobial therapy. Clin Infect Dis. 2005;41:923-929.
6. Graves N, McGowan JE Jr. Nosocomial infection, the Deficit Reduction Act, and incentives for hospitals. JAMA. 2008;300:1577-1579.