Epidemiology of KPC-Producing Enterobacteriaceae in a Chicago Hospital

Background:

Northwestern Memorial Hospital (NMH) is an 854–bed academic medical center in Chicago, IL.   The emergence of Klebsiella pneumoniae carbapenemase (KPC) production among Enterobacteriaceae is concerning both for limited treatment options and risk of transmission.  Carbapenem-resistant Enterobacteriaceae (CRE) are identified at NMH as follows:  clinical isolates with an MIC to ertapenem of > 2 and rectal surveillance cultures testing intermediate or resistant by ertapenem disk undergo confirmatory PCR for KPC utilizing primers directed at the plasmid-mediated KPC gene.   A series of cases of KPC-producing CRE was reviewed to address infection prevention and treatment strategies.

Objective:

To develop strategies to prevent transmission and to treat KPC infections.

Methods:

The Microbiology Laboratory identified all KPC isolates from Feb 2009 to Oct 2010.  The medical record was reviewed to develop an epidemiological profile.  A multidisciplinary team developed guidelines for antimicrobial susceptibility testing, laboratory reporting and therapeutic interventions.

Results:

Thirty six patients had KPC identified.  Of these, 21 (58%) were female.  The mean age was 59 years (range 22-86).  All patients had significant underlying medical conditions.  Of the isolates, 33 (92%) were K. pneumoniae, 2 (5%) E. coli, and 1 (3%) E. cloacae.  Sites included 20 (56%) urine, 5 (14%) multiple sites, 4 (11%) respiratory tract, 2 (6%) wound, 1 (3%) blood, 1 (3%) peritoneal fluid, and 3 (8%) from surveillance rectal swabs.  Seven patients (19%) were colonized only.

Prior to admission, 28 (85%) had exposure to healthcare facilities.  Eight (22%) expired.  Of the 28 who survived, 21 (71%) were discharged to long-term care or rehabilitation facilities.  Fifteen (42%) were readmitted to NMH after their first recognized KPC isolate.

Due to the possibility of transmission and high rate of readmission, an alert was developed in the IC electronic surveillance system for new isolates and readmission of patients with prior isolates of CRE.  Given the rapid emergence of this pathogen, the protocol developed instructed clinicians on the importance of source control, potentially effective drugs and drug combinations with proposed dosing strategies, automatic laboratory testing for colistin and tigecycline, instructions not to treat colonization, and mandates for infectious diseases consultations.

Conclusions:

KPC-producing Enterobacteriacea are emerging pathogens among patients with severe underlying medical conditions and extensive exposure to healthcare settings.  They are associated with significant morbidity and mortality.  Use of electronic surveillance can rapidly identify new or readmitted patients with KPCs, facilitating institution of appropriate isolation precautions.  A multidisciplinary approach to the management of KPCs can help align efforts for detection, reporting, and management of these organisms within an institution.