Background: Prior surveillance has identified Los Angeles County (LAC) as an area with high incidence of carbapenem-resistant Enterobacteriaceae (CRE). Enhanced lab surveillance by the LAC Department of Public Health (DPH) was initiated to identify the prevalence of carbapenemases and other resistance mechanisms within the LAC healthcare community.
Methods: Voluntary enrollment of all clinical microbiology labs began January 2015; submitting labs sent isolate and antimicrobial sensitivity results. Public Health Laboratory (PHL) tested isolates via Maldi-TOF and Nanosphere BC-GN on culture media using Tryptic Soy Broth. CRE was defined as K. pneumoniae, E. coli, and Enterobacter spp. resistant to carbapenems by the submitting laboratorys testing protocol.
Results: Between January and December 2015, a total of 31 labs enrolled: 40 acute care hospitals, 3 long term acute care hospitals, and 1 regional lab representing ~60% of LAC nursing homes. Total 283 isolates received, 82% were K. pneumoniae. KPC (214, 76%) was the most frequently identified carbapenemase. Fifty-four percent submitted by community hospitals (CHs) with an average daily census < 250. Nine labs reported 17 (6%) isolates with both CTX-M and carbapenemase markers identified (Fig. 1); 58% of these isolates were submitted by CHs. Ten labs submitted 27 (9%) isolates for which resistance markers were not identified; 12 (44%) were Enterobacter spp. A third (9) of isolates without resistance markers identified were submitted by CHs.
Conclusion: The identification of organisms that are both CTX-M and CR is alarming. Community hospitals submitted 54%, demonstrating a need for DPH intervention. Compared to prior surveillance showing >90% KPC, this sample signals an emergence of other resistance markers in LAC. LAC DPH developed a response algorithm for when non-KPC resistance in Enterobacteriaceae and other organisms is identified to direct DPH response and intervention. Ongoing surveillance with additional labs, as well as further testing of un-typeable isolates, will provide a more robust assessment of resistance mechanisms throughout LAC to guide targeted prevention and response efforts.
D. Terashita, None
S. Bhaurla, None
L. Mascola, None