1378. Epidemiology of the beta-lactamase resistome among Klebsiella pneumoniae carbapenemase (KPC)-producing Enterobacteriaceae in the Chicago region
Session: Oral Abstract Session: Epidemiology of Resistant Gram Negative Infections
Saturday, October 10, 2015: 10:30 AM
Room: 5--AB

Background: Enterobacteriaceae that produce KPC often carry multiple β-lactamase genes, some conferring broad spectrum β-lactam resistance. Distinct β-lactamase resistome types may serve as markers of strain relatedness to identify potential outbreaks.

Methods: We studied 363 KPC-producing Enterobacteriaceae recovered from 81 distinct hospital point prevalence rectal culture surveys (Chicago region, 2010 - 2014). We characterized the β-lactamase resistome using a multiplex PCR targeting 49 gene families (including carbapenemase, extended spectrum β-lactamase [ESBL], plasmid-mediated AmpC [pAmpC], and narrow spectrum β-lactamase gene families; Acuitas® Resistome Test, OpGen). We identified distinct combinations of β-lactamase genes as ‘resistome types'. For minority resistome types, we assessed temporal-spatial clusters (2 or more KPC-producing Enterobacteriaceae of identical species and resistome type recovered from the same facility/survey date) suggesting intra-facility transmission. We tested cluster significance using binomial methods.

Results: Of the 363 KPC-producing Enterobacteriaceae, 86% were K. pneumoniae, 7% E. coli, and 6% Enterobacter spp.  Including blaKPC, isolates carried a median of 5 β-lactamase genes (range, 1 to 8). SHV-type ESBL genes were detected in 167 isolates (46%); TEM-type ESBL, 17 (5%); CTX-M-type ESBL, 12 (3%); and pAmpC-type, 48 (13%).

Using 23 resistance genes detected, we identified 38 unique β-lactamase resistome types; the 2 most frequent types accounted for 71% of all isolates, and 10 types had ≥1% prevalence (Table).

Of the 69 isolates belonging to minority resistome types, 39 (57%) could be grouped into clusters. For example, for resistome type 6 (n=7), 5 K. pneumoniae isolates were recovered on a single day from one facility (P=0.002).

Conclusion: KPC-producing Enterobactericeae carry multiple β-lactamases, including ESBLs (SHV, TEM, CTX-M) and pAmpC. In our region, most isolates were associated with 2 dominant resistome types that would require whole genome sequencing to resolve transmission linkages. However, facility clustering of minority resistome types suggests that a resistome-based surveillance system can identify potential outbreaks to improve infection control.

Michael Y. Lin, MD, MPH1, Karen Lolans, BS1, Rosie D. Lyles, MD, MHA2, Trevor K. Wagner, PhD3, G. Terry Walker, PhD3, Robert A. Weinstein, MD, FIDSA, FSHEA1,2, Mary K. Hayden, MD, FIDSA, FSHEA1 and for the CDC Prevention Epicenter Program (RAW - PI), (1)Rush University Medical Center, Chicago, IL, (2)Cook County Health and Hospitals System, Chicago, IL, (3)OpGen, Inc., Gaithersburg, MD


M. Y. Lin, None

K. Lolans, None

R. D. Lyles, Chlorox: Employee , Salary

T. K. Wagner, OpGen: Employee , Salary

G. T. Walker, Opgen, Inc.: Employee , Salary

R. A. Weinstein, None

M. K. Hayden, None

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