Genomic and phenotypic characterization of Pseudomonas aeruginosa isolates from two Mexican cystic fibrosis attention centers.

Thirty-nine clinical isolates of Pseudomonas aeruginosa collected from 11 cystic fibrosis (CF) patients at two CF attention centers over 10 years were subjected to whole genome sequencing (WGS). Phenotypic tests (i.e., elastase, motility, biofilm, growth rate, and antibiotic susceptibility) were performed to correlate results. A single strain of P. aeruginosa was found to persist over time in longitudinal isolates. No transmission between patients or centers was observed. A tendency to lack genes related to pyoverdine, flagellum, pili, and O-antigen was observed, whereas those related to biofilm, phenazine, and pyochelin were conserved among isolates. In a patient with a 10-year follow-up, a single strain of P. aeruginosa persisted and showed a gradual decrease in elastase activity and growth rate, demonstrating an adaptive phenotype.IMPORTANCEThis study investigates the genomic and phenotypic characteristics of Pseudomonas aeruginosa isolates from Mexican cystic fibrosis (CF) patients, an underrepresented group in CF research. To our knowledge, it is the first to use whole genome sequencing (WGS) to study longitudinally collected P. aeruginosa isolates from this population, evaluating both genomic features and clonal relationships. Remarkably, the study includes samples from one patient over 10 years, offering an extended observation time compared to existing literature. Unlike similar studies, which often lack phenotypic testing, this research incorporates various virulence-related phenotypic assays, enhancing our understanding of gene-to-phenotype correlations. Two potential mechanisms for the loss of elastolytic activity were identified. Furthermore, we conduct an in-depth mobilome analysis, an area that remains largely unexplored in CF contexts. Whole genome sequencing data are publicly available through the NCBI SRA database, facilitating further re-analysis for studies on P. aeruginosa in CF, as well as epidemiological and population structure research.

Evaluation of the BD Phoenix Carbapenemase-Producing Organism Panels for the Detection of Carbapenemase Producers in Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa.

The classification of carbapenemases can help guide therapy. The present study evaluated the performance of the CPO detection test, included in the BD Phoenix™ NMIC-501 panel for the detection and classification of carbapenemases on the representative molecularly characterized strains collection from Mexico. Carbapenem non-susceptible isolates collected in Mexico were included. The clinical isolates (n = 484) comprised Klebsiella pneumoniae (n = 154), Escherichia coli (n = 150), and P. aeruginosa (n = 180). BD Phoenix CPO NMIC-504 and NMIC-501 panels were used for the identification of species, antimicrobial susceptibility tests, and detection of CPOs. For the detection of carbapenemase-encoding genes, E. coli and K. pneumoniae were evaluated using PCR assays for blaNDM-1, blaKPC, blaVIM, blaIMP, and blaOXA-48-like. For P. aeruginosa, blaVIM, blaIMP, and blaGES were detected using PCR. Regarding E. coli, the CPO panels had a sensitivity of 70% and specificity of 83.33% for the detection of a class B carbapenemase (blaNDM in the molecular test). Regarding K. pneumoniae, the panels had a sensitivity of 75% and specificity of 100% for the detection of a class A carbapenemase (blaKPC in the molecular test). The Phoenix NMIC-501 panels are reliable for detecting class B carbapenemases in E. coli. The carbapenemase classification in K. pneumoniae for class A carbapenemases has a high specificity and PPV; thus, a positive result is of high value.

Carbapenemase-Encoding Genes and Colistin Resistance in Gram-Negative Bacteria During the COVID-19 Pandemic in Mexico: Results from the Invifar Network.

In this study, we report the carbapenemase-encoding genes and colistin resistance in Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa in the second year of the COVID-19 pandemic. Clinical isolates included carbapenem-resistant K. pneumoniae, carbapenem-resistant E. coli, carbapenem-resistant A. baumannii, and carbapenem-resistant P. aeruginosa. Carbapenemase-encoding genes were detected by PCR. Carbapenem-resistant K. pneumoniae and carbapenem-resistant E. coli isolates were analyzed using the Rapid Polymyxin NP assay. mcr genes were screened by PCR. Pulsed-field gel electrophoresis and whole-genome sequencing were performed on representative isolates. A total of 80 carbapenem-resistant E. coli, 103 carbapenem-resistant K. pneumoniae, 284 carbapenem-resistant A. baumannii, and 129 carbapenem-resistant P. aeruginosa isolates were recovered. All carbapenem-resistant E. coli and carbapenem-resistant K. pneumoniae isolates were included for further analysis. A selection of carbapenem-resistant A. baumannii and carbapenem-resistant P. aeruginosa strains was further analyzed (86 carbapenem-resistant A. baumannii and 82 carbapenem-resistant P. aeruginosa). Among carbapenem-resistant K. pneumoniae and carbapenem-resistant E. coli isolates, the most frequent gene was blaNDM (86/103 [83.5%] and 72/80 [90%], respectively). For carbapenem-resistant A. baumannii, the most frequently detected gene was blaOXA-40 (52/86, 60.5%), and for carbapenem-resistant P. aeruginosa, was blaVIM (19/82, 23.2%). For carbapenem-resistant A. baumannii, five indistinguishable pulsotypes were detected. Circulation of K. pneumoniae New Delhi metallo-ß-lactamase (NDM) and E. coli NDM was detected in Mexico. High virulence sequence types (STs), such as K. pneumoniae ST307, E. coli ST167, P. aeruginosa ST111, and A. baumannii ST2, were detected. Among K. pneumoniae isolates, 18/101 (17.8%) were positive for the Polymyxin NP test (two, 11.0% positive for the mcr-1 gene, and one, 5.6% with disruption of the mgrB gene). All E. coli isolates were negative for the Polymyxin NP test. In conclusion, K. pneumoniae NDM and E. coli NDM were detected in Mexico, with the circulation of highly virulent STs. These results are relevant in clinical practice to guide antibiotic therapies considering the molecular mechanisms of resistance to carbapenems.

Active Surveillance of Antimicrobial Resistance and Carbapenemase-Encoding Genes According to Sites of Care and Age Groups in Mexico: Results from the INVIFAR Network.

We analyzed the antimicrobial resistance (AMR) data of 6519 clinical isolates of Escherichia coli (n = 3985), Klebsiella pneumoniae (n = 775), Acinetobacter baumannii (n = 163), Pseudomonas aeruginosa (n = 781), Enterococcus faecium (n = 124), and Staphylococcus aureus (n = 691) from 43 centers in Mexico. AMR assays were performed using commercial microdilution systems (37/43) and the disk diffusion susceptibility method (6/43). The presence of carbapenemase-encoding genes was assessed using PCR. Data from centers regarding site of care, patient age, and clinical specimen were collected. According to the site of care, the highest AMR was observed in E. coli, K. pneumoniae, and P. aeruginosa isolates from ICU patients. In contrast, in A. baumannii, higher AMR was observed in isolates from hospitalized non-ICU patients. According to age group, the highest AMR was observed in the ≥60 years age group for E. coli, E. faecium, and S. aureus, and in the 19-59 years age group for A. baumannii and P. aeruginosa. According to clinical specimen type, a higher AMR was observed in E. coli, K. pneumoniae, and P. aeruginosa isolates from blood specimens. The most frequently detected carbapenemase-encoding gene in E. coli was blaNDM (84%).