In vitro Susceptibility Pattern of Major Gram Negative Isolates to Selected Antimicrobial Agents

Background: The choice of choosing right anti-microbial therapy in hospitals depends on the knowledge of local anti-microbial susceptibility profile. This retrospective study was conducted to assess the in vitro susceptibility pattern of different pathogen isolates to various antibiotics including Cefepime-Amikacin-Antibiotic resistant breakers (ARBs)* in various hospitals across the Jaipur City.

Methods: To characterize the antimicrobial susceptibility pattern of different isolates from various hospitals across the Jaipur City, a retrospective, observational analysis was done for antibiogram data. A total of 1201 Gram negative isolates collected during the period from January 2017 to December 2017 were included in the study. Antibiotic sensitivity testing was done in accordance with the recommendations of Clinical Laboratory Standard Institute (CLSI) guidelines.

Results: Of the total 1201 Gram negative isolates included in this study, 51.6% were from wounds and pus specimens, 40.1% were from respiratory and 8.2% from blood. P. aeruginosa (49.7%) was the most frequently isolated pathogen distantly followed by A. baumannii (21.6%), K. pneumoniae (16.6%) and E. coli (12.1%). The highest susceptibility was reported to polymyxins (100%) including Colistin and Polymyxin B, among all the tested bacteria’s and system wise. Among all the antibiotic tested, (Cefepime-Amikacin-ARBs*) sensitivity ranged for 87.9% to 52% on pathogens (E. coli, K. pneumonia, P. aeruginosa) tested from samples of skin and soft tissue, respiratory tract, blood stream, followed by Meropenem ranged for 78.4% to 55% on pathogens (E. coli, K. pneumonia, P. aeruginosa), followed by ceftazidime-tazobactam ranged for 82.7% to 58% on pathogens (E. coli, K. pneumonia, P. aeruginosa) and 22.7% sensitive for A. baumannii to Cefoperazone sulbactam. Based on pathogen type, E. coli exhibited highest overall susceptibility and the lowest was reported by A. baumannii. The susceptibility of A. baumannii ranged from 1-26% to all the tested antibiotics except polymyxins with 100% susceptibility.

Conclusions: This in vitro susceptibility data suggests that Cefepime-Amikacin-ARBs* can serve as important therapeutic option for the treatment of various resistant Gram-negative bacterial infections to relieve the excess pressure on last resort antibiotics, carbapenems and other drugs including Colistin and polymyxin B. Cefepime-Amikacin-ARBs*on the basis of antimicrobial susceptibility data can be considered as an effective therapeutic option for carbapenems in treating gram negative bacterial infections, and could be considered as a broad spectrum antibiotic sparer’s like carbapenem, colistin and Polymyxin B.