A multispecies outbreak of carbapenem-resistant bacteria harboring the blaKPC gene in a non-classical transposon element
Aniela Wozniak, Cristian Flores Figueroa, Francisco Moya‐Flores, Piero Guggiana, Claudia Castillo, Lina Rivas, José M. Munita, Patricia García
Abstract
Abstract Background Klebsiella pneumoniae is the most frequent KPC-producing bacteria. The bla KPC gene is frequently embedded in Tn4401 transposon, and less frequently in non-Tn4401 elements (NTE KPC ) variants I-III. The first case of KPC in the UC-CHRISTUS Clinical Hospital was detected in Pseudomonas aeruginosa . Soon after this event, KPC was detected in 2 additional Pseudomonas aeruginosa , 3 Escherichia coli , 3 Enterobacter cloacae , 3 Klebsiella pneumoniae, and 1 Citrobacter freundii , isolated from 6 different patients. We aimed to elucidate the possible mechanisms of genetic transfer and dissemination of the bla KPC gene among isolates of this multispecies outbreak. A molecular epidemiology analysis of the above mentioned clinical isolates ( n = 13) through Multi-Locus Sequence Typing, plasmid analysis, Pulsed-Field Gel-Electrophoresis, and Whole-genome sequencing (WGS) was performed. Results High-risk sequence types were found: K. pneumoniae ST11, P. aeruginosa ST654, and E. cloacae ST114. All enterobacterial isolates were not clonal except for 3 E. coli isolated from the same patient. WGS analysis in 6 enterobacterial isolates showed that 4 of them had bla KPC embedded in a novel variant of NTE KPC designated NTE KPC -IIe. Upstream of bla KPC gene there was a 570 pb truncated bla TEM-1 gene followed by an insertion sequence that was 84% similar to ISEc63, a 4473 bp element of the Tn3 family. Downstream the bla KPC gene there was a truncated ISKpn6 gene, and the inverted repeat right sequence of Tn4401. The ISec63-like element together with the bla KPC gene plus Tn4401 remnants were inserted in the Tra operon involved in conjugative transfer of the plasmid. This NTE was carried in a broad host-range IncN plasmid. P. aeruginosa isolates carried bla KPC gene embedded in a typical Tn4401b transposon in a different plasmid, suggesting that there was no plasmid transfer between Enterobacteriaceae and P. aeruginosa as initially hypothesized. Conclusions Most enterobacterial isolates had bla KPC embedded in the same NTE KPC -IIe element, suggesting that this multispecies KPC outbreak was due to horizontal gene transfer rather than clonal spread. This poses a greater challenge to infection control measures often directed against containment of clonal spread.