Background/Objectives: Pseudomonas aeruginosa is an opportunistic pathogen frequently implicated in healthcare-associated infections, particularly ventilator-associated pneumonia and other device-related infections. The global emergence of carbapenem-resistant P. aeruginosa (CRPA) represents a major clinical challenge due to its limited therapeutic options and high mortality rates. Methods: Relevant clinical data were obtained from medical records. Isolates were identified via 16S PCR, and antimicrobial susceptibility testing was performed using the Vitek2 Compact system following CLSI guidelines. Carbapenemase genes (blaGES, blaKPC, blaIMP, blaNDM, blaVIM) were detected via PCR. Clonal relationships were determined via RAPD-PCR, and some sequence types were assigned according to the global P. aeruginosa MLST database. Results: In this study, 40 non-duplicate CRPA isolates were collected from 35 patients in a tertiary-care hospital in Mexico. Most isolates originated from adult patients, predominantly from tracheal aspirates (32.5%) and urine cultures (25.0%). Mechanical ventilation was the most common invasive device associated with infection, and the overall mortality rate reached 14.3%. Antimicrobial susceptibility testing showed that 95% of isolates exhibited a multidrug-resistant phenotype, with high resistance rates to ciprofloxacin (70.0%) and β-lactams. Carbapenemase genes were detected in 55% of isolates, mainly bla_IMP, bla_GES, and bla_VIM, either alone or in combination. Notably, this is the first report of ST309 (bla_IMP), ST411 (bla_GES + bla_IMP), and ST167 (bla_GES + bla_VIM) carrying carbapenemase genes in Mexico. Conclusions: These findings highlight the persistence and genetic diversity of CRPA circulating in hospital settings and emphasize the urgent need for strengthened genomic surveillance and infection control programs to prevent the spread of these high-risk multidrug-resistant clones.

Background:Enterococcus spp. is the third leading cause of healthcare-associated infections in the American continent, often because of the virulence factors that protect the bacterium against host defenses and facilitate tissue attachment and genetic material exchange. In addition, vancomycin, considered a last-resort treatment, has shown reduced efficacy in Enterococcus spp. strains. However, the relationship between bacterial resistance and virulence factors remains unclear. This study intends to evaluate the prevalence of glycopeptide-resistant genotypes and virulence factors in Enterococcus spp. strains. Methods: Over six months, 159 Enterococcus spp. strains causing nosocomial infections were analyzed. Multiplex PCR was performed to identify species, glycopeptide-resistant genotypes, and 12 virulence factors. Results: The most abundant species identified were Enterococcus faecalis and E. faecium. Vancomycin resistance was observed in 10.7% of the isolates, and the vanA genotype was present in 47% of resistant samples. The main virulence factors detected were acm (54%), which is related to cell adhesion; gel E (66%), a metalloproteinase linked to tissue damage; and the sex pheromones cpd (64%) and ccf (84%), which are involved in horizontal gene transfer. A significant association was found between the prevalence of acm, ccf, and cpd in VRE isolates, indicating the potential dissemination of genes to emerging strains via horizontal gene transfer. In addition, a new E. faecium, which displayed five virulence factors and harbored the vanA sequence type, was identified and registered as ST2700. Conclusions:Enterococcus faecalis and E. faecium are clinically critical due to multidrug resistance and virulence factors like acm, which aids host colonization. Genes ccf and cpd promote resistance spread via horizontal transfer, while the emerging ST2700 strain requires urgent monitoring to curb its virulent, drug-resistant spread.