Methods: A retrospective cohort study of 276 GNB isolates from unique patients, phenotypically identified as ESBL or carbapenemase producers, was performed. Isolates from 5 Chicago hospitals were recovered from children ages 0-18 years hospitalized between 2011 and 2015. DNA microarrays (Check-Points™) to detect ESBL, plasmid-mediated AmpC (pAmpC) and carbapenemase type beta-lactamase (bla) genes were used to query the genetic background. Determinants of quinolone resistance (e.g., QRDR and PMFQR) were investigated. MLST and rep-PCR assessed genetic relatedness, and plasmid replicon typing was conducted.
Results: Median age was 4.8 years, 59% were female, and 46% were outpatients. Most isolates (69%) were from urine. E. coli (64%) was most frequently recovered; and of 272 bla genes detected, the most common was blaCTX-M-1 (49%); 1.4% were CRE (3- blaKPC and 1- blaIMP-13). PMFQR was found in 56/82 (62%) and associated with QRDR mutations in 84% of cases. Overall, pAmpC (blaACT/MIR and blaCMY) were found in 12.3% (34/276) of all isolates and in 65% (22/34) of Enterobacter spp. The predominant ST43 E. coli phylogenetic group was B2 (65%) associated with blaCTX-M-1 group (containing blaCTX-M-15) (69%), and contained plasmid replicon types F1A, F11, F1B. The blaKPC harboring K. pneumoniae (Kp) were non ST258 with replicon I1, A/C. Enterobacter carrying blaACT-MIR contained replicon F11A.
Conclusion: Complex bla genotypes were responsible for the ESBL and carbapenem resistant phenotypes. CRE continues to be sporadic, and blaKPC bearing Kp were non ST258; this contrasts with what is usually found in U.S. adults. The finding of a blaIMP-13 reflects the unwelcome emergence of MBLs into the pediatric population. Transmissible plasmid mediated resistance may be the underlying reason for this emerging health threat in Chicago.
L. K. Logan,
S. H. Marshall, None
T. N. Domitrovic, None
S. D. Rudin, None
F. A. Scaggs, None
X. Zheng, None
N. K. Qureshi, None
M. K. Hayden, None
A. Karadkhele, None
K. C. Hayani, None
N. M. Jacobs, None
R. A. Bonomo, Merck: Grant Investigator and Scientific Advisor , Consulting fee and Research grant
Actavis: Invited Speaker , Speaker honorarium
Allergan: Grant Investigator , Research grant
Wockhardt: Grant Investigator , Research grant
GlaxoSmithKline: Grant Investigator , Research grant
AstraZeneca: Grant Investigator , Research grant
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