[Investigation of the beta-lactam resistance profile in Pseudomonas aeruginosa strains in Mexicali: 2019-2021].

Pseudomonas aeruginosa is a Gram-negative bacillus capable of developing in humid environments and animal tissue. The interest in this bacterium lies in its ability to cause opportunistic diseases in patients with cystic fibrosis and healthcare-associated infections (HAIs). The objective of our study was to characterize the resistance profile of strains causing HAIs isolated in hospitals within our community, from January 2019 to December 2021. This descriptive, prospective, and cross-sectional study involved the isolation of strains from January 2019 to December 2021 at the Autonomous University of Baja California (UABC). The identification of the strains was carried out using Matrix-Assisted Laser Desorption/Ionization-Time of Flight (MALDI-TOF) mass spectrometry, and the detection of beta-lactam resistance was performed according to the criteria of the Clinical and Laboratory Standards Institute as stipulated in the CLSI M100-S27 document. A total of 649 samples were obtained from January 2019 to December 2021, including sputum (335 samples), urine (119 samples), and wounds (91 samples). Resistance to carbapenems was 38.94% for meropenem and 21.97% for imipenem. For cephalosporins, there was a 21.05% resistance rate for cefepime, 22.9% for ceftazidime, and 24.78% for ceftolozane-tazobactam. The prevalence of antimicrobial resistance has increased over time, which is attributable to both selective pressure and the evolution of the microorganisms themselves.