CTX-M-15 and OXA-10 beta lactamases in multi drug resistant Pseudomonas aeruginosa: First report from Pakistan

- Out of 102 MDR P. aeruginosa isolates, screened for ESBL, MBL and AmpC, 69.6% were beta lactamase producers.
- Among these 19.71% isolates were harboring CTX-M-15 and in 11.26% isolates, OXA-10 was found and there were ESBL, MBL or AmpC producers.
- Co-production of ESBL/MBL, ESBL/AmpC and MBL/AmpC was also documented.
- All CTX-M-15 carried the class A β-lactamase conserved domain while OXA-10 harbored conserved domain of class D β-lactamase.
- CTX-M-15 and OXA-10 among MDR P. aeruginosa isolates are first time reported from Pakistan.

BackgroundPseudomonas aeruginosa is an emerging threat to public health worldwide due to their rapid development of drug resistance including beta-lactamases. The present study was designed to investigate the incidence of β-lactamases and genotypic pattern of CTX and OXA in the clinical isolate of multidrug resistant P. aeruginosa.MethodsIn this study a total of 102 MDR P. aeruginosa isolates obtained from Lady Reading Hospital, Peshawar, Pakistan were subjected to extended spectrum beta lactamase (ESBL), metallo beta lactamase (MBL) and plasmid mediated β-lactamase (AmpC) detection using phenotypic and molecular methods. Furthermore, sequencing of CTX and OXA gene was performed.ResultsOut of 102 MDR P. aeruginosa isolates, 71 (69.6%) were beta lactamase producers. The incidence of ESBL, MBL and AmpC in clinical isolates of P. aeruginosa was found to be 23.94%, 40.84% and 35.21% respectively. Co-production of ESBL and AmpC were also observed in some isolates. There were 14 (19.71%) CTX-M-15 harboring isolates which were ESBL (64.28%), MBL (21.42%) and AmpC (14.28%) producer. Co-production of ESBL/MBL (14.28%), ESBL/AmpC (14.28%) and MBL/AmpC (14.28%) were also observed in the CTX M-15 harboring isolates while 12.28% isolates were not ESBL, MBL or AmpC producer. OXA-10 was detected in 8 (11.26%) isolates which were ESBL (12.5%), MBL (37.5%) and AmpC (12.5%) producer. OXA 10 isolates also exhibit co-production of ESBL/AmpC (12.5%) and MBL/AmpC (12.5%). All CTX-M-15 carried the class A β-lactamase conserved domain while OXA-10 harbored conserved domain of class D β-lactamase.ConclusionThe current study for the first time reported and characterized the CTX-M-15 and OXA-10 among MDR P. aeruginosa isolates from Pakistan. Further efforts are needed to understand the molecular mechanism of drug resistance with CTX and OXA harboring P. aeruginosa isolates.