Universidad del Desarrollo

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Chromosome-Mediated Colistin Resistance in Clinical Isolates of Klebsiella pneumoniae and Escherichia coli: Mutation Analysis in the Light of Genetic Background
(2023)
María Paz Riquelme
;
Jose Rodrigo W Martínez
;
Bárbara Brito
;
Patricia García
;
Paulette Legarraga
Scopus© Citations 4 2
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A multispecies outbreak of carbapenem-resistant bacteria harboring the blaKPC gene in a non-classical transposon element
(2021)
Aniela Wozniak
;
Cristian Figueroa
;
Francisco Moya-Flores
;
Piero Guggiana
;
Claudia Castillo
<jats:title>Abstract</jats:title><jats:sec> <jats:title>Background</jats:title> <jats:p><jats:italic>Klebsiella pneumoniae</jats:italic> is the most frequent KPC-producing bacteria. The <jats:italic>bla</jats:italic><jats:sub>KPC</jats:sub> gene is frequently embedded in Tn4401 transposon, and less frequently in non-Tn4401 elements (NTE<jats:sub>KPC</jats:sub>) variants I-III. The first case of KPC in the UC-CHRISTUS Clinical Hospital was detected in <jats:italic>Pseudomonas aeruginosa</jats:italic>. Soon after this event, KPC was detected in 2 additional <jats:italic>Pseudomonas aeruginosa</jats:italic>, 3 <jats:italic>Escherichia coli</jats:italic>, 3 <jats:italic>Enterobacter cloacae</jats:italic>, 3 <jats:italic>Klebsiella pneumoniae,</jats:italic> and 1 <jats:italic>Citrobacter freundii</jats:italic>, isolated from 6 different patients. We aimed to elucidate the possible mechanisms of genetic transfer and dissemination of the <jats:italic>bla</jats:italic><jats:sub>KPC</jats:sub> gene among isolates of this multispecies outbreak. A molecular epidemiology analysis of the above mentioned clinical isolates (<jats:italic>n</jats:italic> = 13) through Multi-Locus Sequence Typing, plasmid analysis, Pulsed-Field Gel-Electrophoresis, and Whole-genome sequencing (WGS) was performed.</jats:p> </jats:sec><jats:sec> <jats:title>Results</jats:title> <jats:p>High-risk sequence types were found: <jats:italic>K. pneumoniae</jats:italic> ST11, <jats:italic>P. aeruginosa</jats:italic> ST654, and <jats:italic>E. cloacae</jats:italic> ST114. All enterobacterial isolates were not clonal except for 3 <jats:italic>E. coli</jats:italic> isolated from the same patient. WGS analysis in 6 enterobacterial isolates showed that 4 of them had <jats:italic>bla</jats:italic><jats:sub>KPC</jats:sub> embedded in a novel variant of NTE<jats:sub>KPC</jats:sub> designated NTE<jats:sub>KPC</jats:sub>-IIe. Upstream of <jats:italic>bla</jats:italic><jats:sub>KPC</jats:sub> gene there was a 570 pb truncated <jats:italic>bla</jats:italic><jats:sub>TEM-1</jats:sub> gene followed by an insertion sequence that was 84% similar to ISEc63, a 4473 bp element of the Tn3 family. Downstream the <jats:italic>bla</jats:italic><jats:sub>KPC</jats:sub> gene there was a truncated ISKpn6 gene, and the inverted repeat right sequence of Tn4401. The ISec63-like element together with the <jats:italic>bla</jats:italic><jats:sub>KPC</jats:sub> 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. <jats:italic>P. aeruginosa</jats:italic> isolates carried <jats:italic>bla</jats:italic><jats:sub>KPC</jats:sub> gene embedded in a typical Tn4401b transposon in a different plasmid, suggesting that there was no plasmid transfer between <jats:italic>Enterobacteriaceae</jats:italic> and <jats:italic>P. aeruginosa</jats:italic> as initially hypothesized.</jats:p> </jats:sec><jats:sec> <jats:title>Conclusions</jats:title> <jats:p>Most enterobacterial isolates had <jats:italic>bla</jats:italic><jats:sub>KPC</jats:sub> embedded in the same NTE<jats:sub>KPC</jats:sub>-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.</jats:p> </jats:sec>
Scopus© Citations 21 3
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Role of the multi-drug efflux systems on the baseline susceptibility to ceftazidime/avibactam and ceftolozane/tazobactam in clinical isolates of non-carbapenemase-producing carbapenem-resistant Pseudomonas aeruginosa
(2022)
María José Contreras-Gómez
;
José R. W. Martinez
;
RIVAS JIMENEZ, LINA MARIA
;
Juan A. Ugalde
;
Roberto Riquelme-Neira
<jats:p>Carbapenem-resistant <jats:italic>Pseudomonas aeruginosa</jats:italic> (CRPA) is one of the pathogens that urgently needs new drugs and new alternatives for its control. The primary strategy to combat this bacterium is combining treatments of beta-lactam with a beta-lactamase inhibitor. The most used combinations against <jats:italic>P. aeruginosa</jats:italic> are ceftazidime/avibactam (CZA) and ceftolozane/tazobactam (C/T). Although mechanisms leading to CZA and C/T resistance have already been described, among which are the resistance-nodulation-division (RND) efflux pumps, the role that these extrusion systems may play in CZA, and C/T baseline susceptibility of clinical isolates remains unknown. For this purpose, 161 isolates of non-carbapenemase-producing (Non-CP) CRPA were selected, and susceptibility tests to CZA and C/T were performed in the presence and absence of the RND efflux pumps inhibitor, Phenylalanine-arginine β-naphthylamide (PAβN). In the absence of PAβN, C/T showed markedly higher activity against Non-CP-CRPA isolates than observed for CZA. These results were even more evident in isolates classified as extremely-drug resistant (XDR) or with difficult-to-treat resistance (DTR), where CZA decreased its activity up to 55.2% and 20.0%, respectively, whereas C/T did it up to 82.8% (XDR), and 73.3% (DTR). The presence of PAβN showed an increase in both CZA (37.6%) and C/T (44.6%) activity, and 25.5% of Non-CP-CRPA isolates increased their susceptibility to these two combined antibiotics. However, statistical analysis showed that only the C/T susceptibility of Non-CP-CRPA isolates was significantly increased. Although the contribution of RND activity to CZA and C/T baseline susceptibility was generally low (two-fold decrease of minimal inhibitory concentrations [MIC]), a more evident contribution was observed in a non-minor proportion of the Non-CP-CRPA isolates affected by PAβN [CZA: 25.4% (15/59); C/T: 30% (21/70)]. These isolates presented significantly higher MIC values for C/T. Therefore, we conclude that RND efflux pumps are participating in the phenomenon of baseline susceptibility to CZA and, even more, to C/T. However, the genomic diversity of clinical isolates is so great that deeper analyzes are necessary to determine which elements are directly involved in this phenomenon.</jats:p>
Scopus© Citations 2 1
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Real-World Performance of Susceptibility Testing for Ceftolozane/Tazobactam against Non-Carbapenemase-Producing Carbapenem-Resistant Pseudomonas aeruginosa
(2022)
RIVAS JIMENEZ, LINA MARIA
;
Manuel Alcalde-Rico
;
José R. W. Martínez
;
María Victoria Moreno
;
Pamela Rojas
<jats:p> Ceftolozane/tazbactam (C/T) is a potent anti-pseudomonal agent that has clinical utility against infections caused by non-carbapenemase, producing-carbapenem-resistant <jats:named-content content-type="genus-species">Pseudomonas aeruginosa</jats:named-content> (non-CP-CR-PA). Accurate, precise, and reliable antimicrobial susceptibility testing (AST) is crucial to guide clinical decisions. </jats:p>
19Scopus© Citations 2

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