Statewide Surveillance for Carbapenem Resistant Enterobacteriaceae through Notifiable Condition Reporting: Washington, October 2012-October 2013

BACKGROUND:  Carbapenem-resistant Enterobacteriaceae (CRE) have been deemed an urgent threat by US Centers for Disease Control and Prevention. The epidemic of Klebsiella pneumoniae carbapenemase (KPC) in Israel and rapid increase in KPC in the Eastern United States are worrying trends. Washington State Department of Health (DOH) conducted surveillance for CRE in 2012-2013 to characterize its prevalence in Washington. This surveillance initiative provided an opportunity to expand laboratory capacity, and improve knowledge about preventing emergence and transmission of MDROs.

METHODS:   DOH began CRE surveillance in October 2012 using notifiable conditions-mandated reporting of rare diseases of public health significance. Laboratories, providers and facilities were requested to report and submit to the Public Health Laboratories (PHL) any Enterobacteriaceae resistant to all third-generation cephalosporins tested and non-susceptible to one or more carbapenem.  Based on confirmatory testing, confirmed CRE were E. coli, Klebsiella spp. or Enterobacter spp. meeting the above criteria; and any other Enterobacteriaceae resistant to all third-generation cephalosporins tested and non-susceptible to two or more carbapenems. Polymerase chain reaction (PCR) was used to identify carbapenemase producing CRE (CP-CRE).

RESULTS: This summary includes all CRE cases reported October 23, 2012-October 31, 2013 that were diagnosed in Washington or Washington residents but were diagnosed elsewhere. Overall, 103 suspected CRE isolates were tested at PHL; 79 isolates from 71 patients were confirmed as CRE, including 40 Enterobacter (51%), 29 Escherichia coli (37%), 7 Klebsiella (9%), 2 Citrobacter (2%), and 1 Proteus (1%). Six isolates produced a carbapenemase as assayed by PCR): 1 KPC, 3 New Delhi metallo-b-lactamases (NDM), and 2 imipenemases (IMP).  Of 71 CRE patients reported in Washington, 46 (59%) were women and 36 (52%) were elderly.  Forty-five cases (63%) were diagnosed in Western Washington, 11 (17%) in Eastern Washington, and 15 (21%) in Oregon.  Four of 6 deaths among the 71 cases (6%) were determined to be due to CRE infection; however, none occurred in CP-CRE cases. The majority of reported CRE cases in Washington were urinary tract infections. Almost all cases had significant underlying conditions and extensive medical exposure in the 6 months prior to diagnosis. Foreign travel or foreign hospitalization in India, China, and the Philippines was seen in 4 out of 5 patients with CP-CRE. Ominously, the KPC case had no reported international travel or health care.   

CONCLUSIONS:  CRE surveillance in Washington demonstrated that CP-CRE remain sporadic. We plan to change our surveillance to better focus on CP-CRE to promptly detect cases and protect patients.