Evaluation of ceftazidime-avibactam efficacy in gram negative bacteria

Abstract

In recent years, the emergence of multidrug-resistant Enterobacterales and Pseudomonas aeruginosa strains has become a serious problem due to high morbidity/mortality rates and difficulty in treatment.Treatment options are very limited in infections caused by carbapenem-resistant microorganisms.Ceftazidime/avibactam (CZA) is a newly developed cephalosporin/beta-lactamase inhibitor combination for the treatment of infections caused by resistant Gram negative microorganisms.In this study, the in vitro activity of CZAagainst various carbapenem resistant Gram negative microorganisms was evaluated.122 carbapenem-resistant Gram negative bacteria species were included in the study. Identification of the strains and their antimicrobial susceptibility were performed using conventional methods as well as a BD Phoenix (Bec tonDickinson, MD, USA) fully automated system. Ceftazidime-avibactam susceptibility was determined using the disk diffusion method (Bioanalyse, Ankara, Turkey) and the gradient diffusion test (Liofilchem MIC strip test, Italy).In carbapenem-resistant K. pneumoniae strains, gentamicin/amikacin susceptibility was found in 14 strains (14.3%) and ceftolozane-tazobactam susceptibility was found in only one strain. In P. aeruginosa strains, gentamicin/amikacin susceptibility was seen in 8 strains (33.3%) and piperacillin tazobactam susceptibility was found in 7 strains (29.2%), and other than these all strains were found to be resistant to all the other antibiotics studied. CZA susceptibility rates in carbapenem resistant K. pneumoniae and P. aeruginosa strains were found to be 85.7% and 83.3%, respectively.ESBL production and carbapene mase activity were positive in the strains included in the study.The results obtained from this study show that CZA can be a treatment alternative in carbapenem-resistant Gram negative bacterial infections. More studies are needed in order to monitor the resistance status of these new treatment options against the increasing resistance threat in hospitals and to determine the appropriate treatment option.