Browsing by Author "Munita, José M."

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    A Multicenter Study To Evaluate Ceftaroline Breakpoints : Performance in an Area with High Prevalence of Methicillin-Resistant Staphylococcus aureus Sequence Type 5 Lineage
    (2019) Khan, Ayesha; Rivas, Lina M.; Spencer, María; Martínez, Rodrigo; Lam, Marusella; Rojas, Pamela; Porte, Lorena; Silva, Francisco; Braun, Stephanie; García Cañete, Patricia; Valdivieso, Francisca; Mvlhauser, Margareta; Lafourcade, Mónica; Miller, William R.; Arias, César A.; Munita, José M.
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    A multispecies outbreak of carbapenem-resistant bacteria harboring the blaKPC gene in a non-classical transposon element
    (2021) Wozniak Banchero, Aniela; Figueroa, Cristian; Moya-Flores, Francisco; Guggiana, Piero; Castillo, Claudia; Rivas Jiménez, Lina María; Munita, José M.; García Cañete, Patricia
    Abstract Background Klebsiella pneumoniae is the most frequent KPC-producing bacteria. The blaKPC gene is frequently embedded in Tn4401 transposon, and less frequently in non-Tn4401 elements (NTEKPC) 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 blaKPC 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 blaKPC embedded in a novel variant of NTEKPC designated NTEKPC-IIe. Upstream of blaKPC gene there was a 570 pb truncated blaTEM-1 gene followed by an insertion sequence that was 84% similar to ISEc63, a 4473 bp element of the Tn3 family. Downstream the blaKPC gene there was a truncated ISKpn6 gene, and the inverted repeat right sequence of Tn4401. The ISec63-like element together with the blaKPC 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 blaKPC 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 blaKPC embedded in the same NTEKPC-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.
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    Real-World Performance of Susceptibility Testing for Ceftolozane/Tazobactam against Non-Carbapenemase- Producing Carbapenem-Resistant Pseudomonas aeruginosa
    (2022) Rivas, Lina; Martinez, José R.W.; Munita, José M.; Alcalde-Rico, Manuel; Olivares Pacheco, Jorge; García Cañete, Patricia; Olivares-Pacheco J.; Moreno, María Victoria; Rojas, Pamela; Wozniak Banchero, Aniela; Miller, William; Arias, Cesar A.; Khan, Ayesha
    Ceftolozane/tazbactam (C/T) is a potent anti-pseudomonal agent that has clinical utility against infections caused by non-carbapenemase, producing-carbapenemresistant Pseudomonas aeruginosa (non-CP-CR-PA). Accurate, precise, and reliable antimicrobial susceptibility testing (AST) is crucial to guide clinical decisions. However, studies assessing the performance of different AST methods against non-CP-CR-PA (the main clinical niche for C/T), are lacking. Here, we evaluated performance of gradient strips (Etest and MIC test strip [MTS], and disk diffusion [DD]) using CLSI breakpoints. Additionally, we assessed the performance of DD using EUCAST breakpoints. For all susceptibility tests, we used a collection of 97 non-CP-CR-PA clinical isolates recovered from 11 Chilean hospitals. Both gradient strips and DD had acceptable performance when using CLSI breakpoints, yielding a categorical agreement (CA) of .90% and 92%, respectively. In contrast, DD using EUCAST breakpoints performed suboptimally (CA 81%). MTS yielded a higher essential agreement (EA, .90%) than Etest (84%). Importantly, the performance of all methods varied significantly when the isolates were stratified by their degree of susceptibility to other anti-pseudomonal b-lactams. All methods had 100% CA when testing isolates that were pan-susceptible to all b-lactams (Pan-β-S). However, the CA markedly decreased when testing isolates resistant to all b-lactams (Pan-β-R). Indeed, the CA was 81% for Etest (six errors), 78% for MTS (seven errors), and 78% and 56% for DD when using CLSI (seven errors) or EUCAST breakpoints (14 errors), respectively. Our results suggest that all manual AST methods have strikingly decreased performance in the context of Pan-β-R P. aeruginosa with potentially major clinical implications.