Susceptibility Profile of Beta-lactam/ Beta-lactamase Inhibitor Combinations against Multidrug Resistant Gramnegative and Positive Bacteria at a Tertiary Care Centre in Northern India: A Retrospective Study

Introduction: Currently, Antimicrobial Resistance (AMR) is a major global public health concern. Infections caused by resistant microorganisms are more difficult to treat in humans and animals, leading to longer illnesses, higher mortality rates, and increased medical expenses. Aim: To determine the susceptibility profile of five beta-lactam/ beta-lactamase inhibitor combinations for gram-negative and gram-positive bacteria. Materials and Methods: This was a retrospective study conducted in the Department of Microbiology at SGPGIMS, Lucknow, Uttar Pradesh, India, from January 2022 to January 2023. The analysis evaluated the susceptibility of CeftazidimeAvibactam (CZA), Tazobactam-Piperacillin (TZP), TicarcillinClavulanic Acid (TCC), Ampicillin-Sulbactam (SAM), and Cefoperazone-Sulbactam (SCF). These combinations were used for gram-negative and gram-positive bacteria isolated from various specimens. A total of 1,648 samples were tested for these combinations. The isolates were identified using conventional methods and Matrix-Assisted Laser Desorption/ Ionisation Time-of-Flight (MALDI-TOF). Antibiotic Susceptibility Testing (AST) was performed by the Kirby-Bauer disc diffusion method on Mueller-Hinton agar (MHA). Results: Out of the 1,648 samples (756 urine, 382 pus, 322 blood, and 188 sputum), the beta-lactam/beta-lactamase inhibitor combinations were tested. The most susceptible combination found in this study was CZA (76%), followed by TZP (60.7%), TCC (50%), SAM (38.2%), and SCF (31%). Conclusion: CZA demonstrated better susceptibility compared to other beta-lactam/beta-lactamase inhibitor combinations. Recently discovered beta-lactam/beta-lactamase inhibitor combinations can be utilised as carbapenem-sparing agents for treating ESBL-producing Enterobacteriaceae (ESBL-PE), Pseudomonas aeruginosa, and Acinetobacter baumannii.