A bundled intervention was successful in preventing horizontal spread of KPC-producing gram-negative rods in a long-term acute care hospital, despite ongoing admission of patients colonized with KPC producers.

Klebsiella pneumoniae carbapenemase (KPC) production in Gram-negative bacilli is an increasing problem worldwide. Rectal swab surveillance is recommended as a component of infection prevention programs, yet few screening methods are published. We compared detection of KPC-producing Klebsiella pneumoniae and Escherichia coli in surveillance specimens by 2 methods: (i) inoculation of swabs in tryptic soy broth containing 2 g/ml imipenem followed by plating to MacConkey agar (MAC) (method 1) and (ii) streaking swabs on MAC onto which a 10-g ertapenem disk was then placed (method 2). Simulated rectal swab specimens of challenge isolates from a collection of well-characterized K. pneumoniae and E. coli strains and salvage rectal swab specimens collected from patients at 4 different health care facilities over a 7-month period were tested. The gold-standard comparator was bla KPC PCR testing of isolates. Method 1 detected 4/9 (44%) KPC-positive challenge isolates. By method 2, 9/9 KPC-positive challenge isolates exhibited zones of inhibition of <27 mm; all KPC-negative isolates exhibited zones of inhibition greater than 27 mm. The sensitivity and specificity of method 1 for detection of KPC-positive K. pneumoniae and E. coli in 149 rectal swab specimens were 65.6% (95% confidence interval [CI], 46.8% to 80.8%) and 49.6% (95% CI, 40.3% to 58.9%), respectively. With method 2, a zone diameter of <27 mm had a sensitivity of 97.0% (95% CI, 82.5% to 99.8%) and specificity of 90.5% (95% CI, 83.3% to 94.9%) for detection of KPC in rectal swab specimens. Direct ertapenem disk testing is simpler, more sensitive, and more specific than selective broth enrichment with imipenem for detection of KPCproducing K. pneumoniae and E. coli in surveillance specimens.