Escherichia coli is an opportunistic pathogen and a leading cause of Community-Acquired Urinary Tract Infections (CA-UTIs). E. coli can harbor multiple genetic resistant determinants, such as Extended Spectrum Beta-lactamases (ESBL) and Plasmid-Mediated Quinolone Resistance (PMQR) genes, complicating the empirical treatment of UTIs with β-lactams and quinolones. The aim of his study was to characterize ESBL and PMQR genes among E. coli isolates from CA-UTI in Mexicali, Mexico Isolates were collected from January to December 2023. Identification was performed by MALDI-TOF, and ESBL-producing determination and antimicrobial susceptibility by Vitek 2. Detection of ESBL and PMQR, and phylotyping were performed by PCR. Genetic diversity was determined by Enterobacterial Repetitive Intergenic Consensus Polymerase Chain Reaction (ERIC-PCR). Eighty-nine E. coli isolates were collected from CA-UTIs. All exhibited resistance to ciprofloxacin, ceftriaxone, and cefotaxime, while being susceptible to carbapenems and ceftazidime/avibactam. All isolates tested positive for an ESBL gene, with bla_CTX-M (98.9 %) being the most prevalent. Five isolates tested negative for PMQR genes; the remaining showed aac(6')-lb-cr present in 85.3 %. Coexistence between ESBL and PMQR genes was noted in 95.5 %. Most prevalent plylogenetic group was group B2 (74.2 %). This study provides valuable regional data, highlighting a public health problem due to the high prevalence of ESBL and PMQR genes in E. coli responsible for CA-UTI, which are linked to multidrug resistance. Genetic diversity was found, suggesting multiple sources of resistant strains in the community. These findings underline the need for surveillance and control to limit the spread of resistant E. coli, locally and globally. DATA SUMMARY: The authors confirm all supporting data, code, and protocols have been provided within the article or through supplementary data files.

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. (c) 2024 The Author(s). Published by Elsevier Espana, S.L.U. on behalf of Asociacion Argentina de Microbiolog& imath;a. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/).

Stenotrophomonas maltophilia es un bacilo gram negativo, patógeno oportunista, vinculado principalmente a infecciones nosocomiales en pacientes inmunocomprometidos. Su habilidad para permanecer viable en instrumental médico y depósitos como humidificadores de oxígeno, así como su resistencia a antibióticos tanto intrínseca como adquirida hacen que sea un problema importante de salud pública. Las infecciones causadas por este microorganismo suelen ser neumonía y bacteremia, ambas con una elevada tasa de mortalidad sobre todo en unidades de cuidados intensivos. El tratamiento de primera línea sigue siendo Trimetoprim/Sulfametoxazol. Sin embargo, existe gran fluctuación en la efectividad de este medicamento, dependiendo de la cepa causante y la región geográfica; siendo esto considerado de suma importancia para el uso adecuado de antibióticos, medidas preventivas e investigar la incidencia y mecanismos de resistencia de la bacteria.

Community-acquired infections caused by Enterobacterales are a growing public health concern, particularly in border regions where patient mobility may influence resistance patterns. Antimicrobial resistance (AMR) surveillance is critical for establishing local treatment guidelines. The aim of this study was to investigate AMR rates in clinical isolates of Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis obtained from community-acquired infections in Mexicali between 2019 and 2021. A retrospective study was conducted, analyzing 2871 Enterobacterales isolates (E. coli, K. pneumoniae, P. mirabilis). Species identification and antimicrobial susceptibility testing were performed using MALDI-TOF and VITEK 2 systems, interpreted according to CLSI and EUCAST breakpoints. ESBL production was detected in 37.6% of E. coli, 27.7% of K. pneumoniae, and none of the P. mirabilis isolates. Among ESBL producers, ciprofloxacin resistance reached 90.4% in E. coli and 81.0% in K. pneumoniae, indicating a significant level of co-resistance. Carbapenem-resistant K. pneumoniae (n = 13) and one E. coli isolate were also identified, all from community-acquired infections. Resistance patterns varied by infection site, with UTIs accounting for the majority of isolates. The high rates of ESBLs and co-resistance to ciprofloxacin among Enterobacterales highlight the urgent need for targeted AMR surveillance and site-specific empirical treatment strategies.

El presente aborda el aumento progresivo de la resistencia de Pseudomonas aeruginosa a carbapenémicos en la Ciudad de Mexicali, Baja California (2023–2024), lo que ha generado un problema crucial en el ambiente hospitalario. Se realizó un estudio descriptivo y prospectivo con 50 cepas aisladas entre 2023 y 2024. Las muestras fueron cultivadas y se identificaron mediante MALDI-TOF, y se aplicaron pruebas fenotípicas (CarbaNP, mCIM) y genotípicas como PCR (Polymerase Chain Reaction) para detectar carbapenemasas. 17 cepas presentaron resistencia fenotípica y 15 fueron positivas a CarbaNP; la PCR confirmó la presencia de genes de resistencia. Como conclusión, la detección oportuna de carbapenemasas es esencial para guiar tratamientos adecuados y prevenir la diseminación de cepas multidrogorresistentes. Las técnicas empleadas son aplicables en laboratorios clínicos y ofrecen alternativas costo-efectivas y precisas para enfrentar este desafío.

SummaryBackgroundThe global rise of multidrug-resistant (MDR) Pseudomonas aeruginosa has created an urgent need for alternative antimicrobial strategies. Bacteriophages represent a promising approach due to their specificity and lytic activity.MethodsIn this study, two lytic bacteriophages (ϕPsa-1 and ϕPsa-2) were isolated from wastewater samples and characterized using microbiological assays, one-step growth curves, physicochemical stability tests, and whole-genome sequencing coupled with bioinformatic and phylogenomic analyses.ResultsBoth phages exhibited strong lytic activity against P. aeruginosa, with distinct plaque morphologies and infection dynamics. Replication kinetics revealed typical lytic cycles, with differential sensitivity to multiplicity of infection (MOI). Notably, both phages demonstrated high stability across a broad range of temperatures (30–90 °C) and pH conditions (2–12). Genomic analysis showed high sequence similarity and conserved genome organization, clustering within a defined lineage of Pseudomonas-infecting phages, while retaining localized genomic variability that may influence host interaction.ConclusionsThe combined phenotypic and genomic characterization highlights ϕPsa-1 and ϕPsa-2 as robust lytic phages with potential for antimicrobial applications. These findings support their further evaluation as candidates for phage-based strategies to control MDR P. aeruginosa and underscore the importance of integrating functional and genomic analyses for phage selection.