Distribution of gram negative bacteria isolated from blood culture and antibiotic resistance rates

Abstract

Objective: Bacteremia is a serious condition that causes hospitalization and increases mortality. Gram negative bacteria are frequently isolated as causative agents. The aim of this study was to evaluate the distribution and antimicrobial resistance of the gram negative bacteria isolated from blood cultures in our hospital. Methods: Gram negative bacteria isolated from blood culture samples sent to the microbiology laboratory between 2016-2019 were retrospectively analyzed. The blood cultures were performed by BacT/ALERT 3D (bioMérieux, France) and Render-BC128 (China). Bacterial identification and antibiotic susceptibility tests were performed using conventional methods and BD Phoenix 100 (BD Phoenix System, Beckton Dickinson, ABD) automated systems. Results: A total of 10,315 blood cultures obtained from hospitalized patients between 2016 and 2019 were evaluated. Microbial growth was detected in 3,177 (30.8%) of the blood cultures. Gram negative bacteria were isolated in 873 (27.5%) blood cultures and were included in the study. Among gram negative bacteria, Escherichia coli (38.7%) and Klebsiella pneumoniae (12.3%) species are the most common pathogens. In our study, E. coli strains showed the highest resistance to ampicillin (76.6%), K. pneumoniae and other Enterobacterales species to amoxicillin-clavulonate (65.9% and 43.9%), Acinetobacter baumannii to carbapenems (95.4%), Pseudomonas aeruginosa to ciprofloxacin (26.1%). The most susceptible antibiotics were carbapenems and amikasin for Enterobacterales, amikasin and gentamycin for P. aeruginosa, amikasin and trimethoprim-sulfamethaxazole for A.baumannii. Conclusion: In our study, the frequency of gramnegative bacteria growth in blood culture was found to be 27.5%, similar to literature data. It was observed that the determined bacterial distribution was compatible with different studies. Blood culture is the most important test in the diagnosis of bacteremia and in directing the right treatment. The distribution of microorganisms isolated in bacteremia and their antibiotic resistance rates changes by center. For this reason, it was think that each hospital should determine its own data at regular intervals and guide antibiotic selection according to these results.