Detecting, stopping new resistant bugs

The Centers for Disease Control and Prevention guidelines to prevent infection with carbapenem-resistant pathogens include the following recommendations. The guidelines should be considered in light of both carbapenem-resistant Klebsiella pneumonia (CRKP) and the New Delhi metallo-beta-lactamase (NDM-1), both of which contain plasmids that can transfer and confer resistance to other gram negative bacteria. (Thus far reported NDM-1 cases in the United States have been linked to travel and/or medical care in India or Pakistan; a travel history may aid case identification for NDM-1.) CRKP (or KPC) is widespread in the U.S. In any case, the laboratory identification of the carbapenem-resistance mechanism is not necessary to guide treatment or infection control practices but should instead be used for surveillance and epidemiologic purposes. Carbapenem resistance and carbapenemase production conferred by NDM-1 is detected reliably with phenotypic testing methods currently recommended by the Clinical and Laboratory Standards Institute, including disk diffusion testing and the modified Hodge test, the CDC reports.

Infection Prevention: All acute care facilities should implement contact precautions for patients colonized or infected with carbapenemase-producing Enterobacteriaceae (CRE). No recommendation can be made regarding when to discontinue contact precautions.1

Laboratory: Clinical microbiology laboratories should follow Clinical and Laboratory Standards Institute guidelines for susceptibility testing and establish a protocol for detection of carbapenemase production (e.g., performance of the modified Hodge test).2 Clinical microbiology laboratories should establish systems to ensure prompt notification of infection prevention staff of all Enterobacteriaceae isolates that are nonsusceptible to carbapenems or Klebsiella spp. (or Escherichia coli isolates that test positive for a carbapenemase).

Surveillance: All acute care facilities should review clinical culture results for the preceding six to 12 months to determine whether previously unrecognized CRE have been present in the facility. If this review identifies previously unrecognized CRE, a point prevalence survey (a single round of active surveillance cultures) should be performed to look for CRE in high-risk units (e.g., intensive care units, units where previous cases have been identified, and units where many patients are exposed to broad-spectrum antimicrobials). If the review does not identify previously unrecognized CRE, monitoring for clinical infections should be continued.

If CRE or carbapenemase-producing Klebsiella spp. or E. coli are detected from one or more clinical cultures OR if the point prevalence survey reveals unrecognized colonization, the facility should investigate for possible transmission by: Conducting active surveillance testing of patients with epidemiologic links to a patient with CRE infection (e.g., patients in the same unit or who have been cared for by the same health care personnel).

Continue active surveillance periodically (e.g., weekly) until no new cases of colonization or infection suggesting cross-transmission are identified. If transmission of CRE is not identified after repeated active surveillance testing, consider altering the surveillance strategy by performing periodic point-prevalence surveys in high-risk units.

In areas where CRE are endemic, an increased likelihood exists for importation of CRE, and the procedures outlined might not be sufficient to prevent transmission. Facilities in such areas should monitor clinical cases and consider additional strategies to reduce rates of CRE, as described in the 2006 Tier 2 guidelines for management of multidrug-resistant organisms in health care settings.3


  1. Centers for Disease Control and Prevention. Guidance for Control of Infections with Carbapenem-Resistant or Carbapenemase-Producing Enterobacteriaceae in Acute Care Facilities. MMWR 2009;58(10):256-260.
  2. Clinical and Laboratory Standards Institute. 2009 Performance Standards for Antimicrobial Susceptibility Testing. Nineteenth information supplement (M100-S19). Wayne, PA: Clinical and Laboratory Standards Institute; 2009.
  3. Siegal JD, Rhinehart E, Jackson L, et al. Centers for Disease Control and Prevention Healthcare Infection Control Practices Advisory Committee. Management of Multidrug-Resistant Organisms in Healthcare Settings, 2006. On the web at: