Antimicrobial susceptibility profiling of carbapenem resistant gram-negative bacilli with special reference to ceftazidime-avibactam and ceftriaxone-sulbactam with EDTA

Background: Increased morbidity and mortality rates attributable to multidrug resistant organisms (MDROs) such as carbapenem resistant organisms (CROs) are being increasingly reported ultimately leading to limited therapeutic options. Several potential strategies are being explored to develop new antibiotics for Carbapenem-resistant organisms. Methods: This was a retrospective study where Antimicrobial susceptibility testing for CZA and CSDE was done using the Kirby-Bauer disc diffusion method. Patient’s clinical conditions were assessed by the clinician and demographic details were recorded in the hospital EMR system. The outcome was decided based on the therapeutic effect of the antibiotics on the patients via primary and secondary endpoints. Results: A total of 150 patients were included in the study, 41 (27.3%) were susceptible to CSDE and turned culture negative. The antibiotic susceptibility patterns of different antibiotics were compared against each other, especially with CZA and CSDE. Conclusions: Colistin is still the drug with maximum susceptibility against the gram negative bacterial infections although CSDE and CZA are the novel antibiotics and show promising results and may be used on a case to case basis depending on the pharmacokinetics and pharmacodynamics which could be the limiting factor at times restricting use of Colistin.