Detection of extended spectrum β-lactamase in Pseudomonas spp. isolated from two tertiary care hospitals in Bangladesh

Aerobic bacterial culture was performed on aseptically collected swabs and only growth of Pseudomonas was considered for further species identification and ESBL production along with serotyping of Pseudomonas aeruginosa. Antimicrobial susceptibility testing was carried out using the Kirby-Bauer agar diffusion method and ESBL production was detected on Mueller Hinton agar by double-disk synergy technique using Amoxicillin-Clavulanic acid with Ceftazidime, Cefotaxime, Ceftriaxone and Aztreonam. Culture yielded 120 Pseudomonas spp. and 82 of them were biochemically characterized for species. Pseudomonas aeruginosa was found to be the predominant (90.2%) species. Of 82 isolates tested for ESBL, 31 (37.8%) were ESBL positive with 29 (93.5%) as Pseudomonas aeruginosa, the remaining 2 (6.5%) were Stenotrophomonas maltophilia and Ralstonia pickettii. Antibiogram revealed Imipenem as the most effective drug (93.3%) among all antimicrobials used against Pseudomonas spp. followed by Aminoglycosides (63.7%).ESBL producing Pseudomonas spp. was found to be a frequent isolate from two tertiary care hospitals in Bangladesh, showing limited susceptibility to antimicrobials and decreased susceptibility to Imipenem in particular, which is a matter of great concern.The worldwide emergence of multi-drug resistant bacterial strains is a growing concern, especially infections caused by Pseudomonas spp. and P. aeruginosa in particular. P. aeruginosa is an opportunistic pathogen with innate resistance to many antibiotics and disinfectants including anti-pseudomonal Penicillins, Ceftazidime, Carbapenems, Aminoglycosides and Ciprofloxacin [1]. Infections due to P. aeruginosa are seldom encountered in healthy adults; but in the last two decades, the organism has become increasingly recognized as the etiological agent in patients with impaired immune defenses [2]. Pseudomonads are more versatile than Enterobacteriaceae in acquiring drug resistance by various mechanisms. The production of extend