Phenotypic Detection of Carbapenemase Production in Gram Negative Bacilli from Clinical Isolates in a Tertiary Care Hospital in Telangana

Antimicrobial resistance (AMR) in Gram negative bacteria (GNB) has become a critical health concern across the globe. Unveiling of β-lactamase, extended spectrum β-lactamase (ESBL) and AmpC β-lactamase producing bacteria has led to the development of multidrug-resistant organisms (MDRO’s). Carbapenems are considered to be very effective in morbid infections caused by MDRO’s. Now, the upsurge of carbapenem resistance among GNB is an issue of concern as these infections are very difficult to treat. Rapid and reliable methods to detect these CPO’s in all Microbiology laboratories is essential to streamline the antimicrobial therapy. Accordingly, this study is conducted to determine the enormity of CPO’s among clinical isolates by various phenotypic tests along with differentiation of serine β-lactamases from metallo-β-lactamases. This is a Prospective Cross-sectional study meticulously planned & conducted for a period of one year. Among the 76 suspected Carbapenemase Producing Organisms (CPO’s), 42% were Klebsiella spp. followed by Escherichia coli (25%), Pseudomonas aeruginosa (24%), Citrobacter spp. (5%) and Proteus spp. (4%). Out of the total isolates 82% of the isolates were confirmed as CPO’s by Carba NP test, whereas 93% by mCIM test. 53% of the total isolates tested were Serine-β-lactamase producers and 41% were Metallo-β-lactamase producers. In conclusion, Carba NP test and mCIM in conjunction with eCIM test could be considered as reliable phenotypic diagnostic methods for carbapenemase detection to guide the clinicians for initiating antibiotic therapy.