Phenotypic and Genotypic Characterization of AmpC Beta-Lactamase in Clinical Isolates of Pseudomonas aeruginosa Findings From a Tertiary Care Hospital.

Background and aim is an opportunistic pathogen responsible for various healthcare-related infections, which are difficult to treat due to intrinsic and acquired resistance. This study aimed to investigate AmpC β-lactamase production using phenotypic and genotypic methods in strains isolated from a tertiary care hospital in Karad, Maharashtra, India. Material and methods Over one year, a descriptive cross-sectional study was conducted at the Department of Microbiology, Krishna Institute Medical Sciences, Krishna Vishwa Vidyapeeth, Karad. Phenotypic detection of AmpC beta-lactamase was performed using the Cefoxitin-Cloxacillin Double-Disc Synergy Test method, and genotypic detection was conducted using conventional polymerase chain reaction (PCR) targeting the bla -derived cephalosporinases (PDC) and bla cephamycinase (CMY) genes. Results Out of 205 clinical isolates of , 110 (53.66%) showed AmpC production phenotypically, while 86 (41.95%) were positive genotypically. The blaPDC gene was detected in 36.10% of isolates, and the blaCMY gene in 10.73% of isolates. Conclusions The study findings indicate that AmpC-β-lactamase stands out as the primary resistance mechanism in strains of  isolated from the hospital. PCR study concluded that blaPDC (36.10 %) was the leading gene responsible for AmpC synthesis among study isolates. Early detection of AmpC beta-lactamase production by employing phenotypic and genotypic methods is crucial for detecting antibiotic resistance. This dual approach enables healthcare professionals to decide on the most effective antibiotics and mitigate the development of resistance.