TRENDS OF ANTIBIOTIC RESISTANCE IN MULTIDRUG-RESISTANT PATHOGENS ISOLATED FROM BLOOD CULTURES IN A FOUR-YEAR PERIOD

Abstract

Background: Multidrug-resistant organisms cause to serious infections with significant morbidity and mortality in the worldwide. These organisms have been identified as urgent and serious threats. The aim of this study was to determine the prevalence and changes of antibiotic resistance of multidrug-ressistant pathogens isolated from blood cultures over a four-year period in a tertiary-care hospital. Methods: Blood cultures were incubated in blood culture system. Positive signalling blood cultures were subcultured on 5% sheep-blood agar. Identification of isolated bacteria was performed using conventional or automated identification systems. Antibiotic susceptibility tests were performed by disc diffusion and/or gradient test methods, if necessary, by automated systems. The CLSI guidelines were used for interpretatiton of antibiotic susceptibility testing of bacteria.Results: The most frequently isolated Gram-negative bacteria was Escherichia coli (33.4%) followed by Klebsiella pneumoniae (21.5%). ESBL positivity was 47% for E. coli, 66% for K. pneumoniae. Among E. coli, K. pneumoniae, Pseudomonas aeruginosa and Acinetobacter baumannii isolates, carbapenem resistance was 4%, 41%, 37%, and 62%, respectively. Carbapenem resistance of K. pneumoniae isolates has increased from 25% to 57% over the years, and the highest rates (57%) was occured during the pandemic period. It is noteworthy that the aminoglycoside resistance in E. coli isolates gradually increased from 2017 to 2021. The rate of methicillin-resistant S. aureus (MRSA) was found to be 35.5%. Conclusions: Increased carbapenem resistance in K. pneumoniae and A. baumannii isolates is noteworthy, but carbapenem resistance in P. aeruginosa decreased. It is of great importance for each hospital to monitor the increase in resistance in important microorganisms, especially isolated from invasive samples, in order to take the necessary precautions in a timely manner. Future studies involving clinical data of patients and bacterial resistance genes are warranted.