Occurrence and Distribution of Environmental Pseudomonas aeruginosa From Hospitals in Bangladesh Reveals Diverse Strain Families, Multidrug Resistance, and Biofilm Formation.

Pseudomonas aeruginosa is a major nosocomial pathogen capable of developing multidrug resistance, forming biofilms, and disseminating antimicrobial resistance genes via mobile genetic elements. This study investigated the occurrence, antimicrobial resistance, lecB sequence diversity, and biofilm-forming capacity of environmental P. aeruginosa isolates from three hospitals in Jashore, Bangladesh. Among 231 environmental samples collected from 29 sites in high-risk hospital units, 36 isolates were confirmed by lecB gene sequencing. Sequence analysis classified 77.8% of isolates as PAO1-like and 22.2% as PA14-like, indicating genetic diversity. Biofilm formation was detected in 97.2% of isolates, with no significant difference between strain families. Phenotypic susceptibility testing revealed widespread multidrug resistance, with the highest resistance to ceftazidime (97.2%) and tetracycline (91.7%). Two operation theatre isolates (A40 and 2SW) exhibited extensive drug resistance within the tested antimicrobial panel. Polymerase chain reaction detected blaSHV (55.6%), floR (33.3%), aac(6')-Ib (33.3%), blaTEM (27.8%), and blaOXA-48 (11.1%), while class 1 integrons occurred in 55.6% of isolates and were associated with floR and blaTEM. Whole-genome sequencing identified intrinsic resistance determinants and the mobile resistance genes tmexCD-toprJ and crpP. These findings highlight genetically diverse, multidrug-resistant, integron-positive, biofilm-forming P. aeruginosa in Bangladeshi hospital environments, underscoring the need for routine environmental surveillance and strengthened infection prevention.