Dissemination of multiple carbapenem resistance genes in an in vitro gut model simulating the human colon. (15th April 2019)

• Record Type: Journal Article
• Authors: Rooney, C M; Sheppard, A E; Clark, E; Davies, K; Hubbard, A T M; Sebra, R; Crook, D W; Walker, A S; Wilcox, M H; Chilton, C H
• Is Part Of: Journal of antimicrobial chemotherapy. Volume 74:Number 7(2019)
• Page Start: 1876
• Page End: 1883
• Publication Date: 2019-04-15
• Subjects: Anti-infective agents -- Periodicals; Chemotherapy -- Periodicals; 615.58
• DOI: 10.1093/jac/dkz106
• Languages: English
• ISSNs: 0305-7453

Abstract

Abstract: Background: Carbapenemase-producing Enterobacteriaceae (CPE) pose a major global health risk. Mobile genetic elements account for much of the increasing CPE burden. Objectives: To investigate CPE colonization and the impact of antibiotic exposure on subsequent resistance gene dissemination within the gut microbiota using a model to simulate the human colon. Methods: Gut models seeded with CPE-negative human faeces [screened with BioMérieux chromID ® CARBA-SMART (Carba-Smart), Cepheid Xpert ® Carba-R assay (XCR)] were inoculated with distinct carbapenemase-producing Klebsiella pneumoniae strains (KPC, NDM) and challenged with imipenem or piperacillin/tazobactam then meropenem. Resistant populations were enumerated daily on selective agars (Carba-Smart); CPE genes were confirmed by PCR (XCR, Check-Direct CPE Screen for BD MAX ™ ). CPE gene dissemination was tracked using PacBio long-read sequencing. Results: CPE populations increased during inoculation, plateauing at ∼10 5 log10 cfu/mL in both models and persisting throughout the experiments (>65 days), with no evidence of CPE 'washout'. After antibiotic administration, there was evidence of interspecies plasmid transfer of bla KPC-2 (111742 bp IncFII/IncR plasmid, 99% identity to pKpQIL-D2) and bla NDM-1 (∼170 kb IncFIB/IncFII plasmid), and CPE populations rose from <0.01% to >45% of the total lactose-fermenting populations in the KPC model. Isolation of a bla NDM-1 K. pneumoniae with one chromosomal single-nucleotide variant compared with the inoculated strain indicated clonal expansion within the model. Antibiotic administration exposed a previously undetected K. pneumoniae encoding bla OXA-232 (KPC model). Conclusions: CPE exposure can lead to colonization, clonal expansion and resistance gene transfer within intact human colonic microbiota. Furthermore, under antibiotic selective pressure, new resistant populations emerge, emphasizing the need to control exposure to antimicrobials.