Antibiotic susceptibilities and microorganisms isolated from blood cultures of inpatients in a secondary state hospital in Türkiye

Purpose: The aim of this study was to evaluate the bacterial species distribution and antibiotic susceptibility in blood cultures obtained from patients in a secondary care center in Mersin, Türkiye. Materials and Methods: Blood culture specimens of inpatients sent to the microbiology laboratory between January 2022 and December 2023 were retrospectively analyzed to determine the etiologic agents of bloodstream infections and to evaluate their antimicrobial susceptibility. Samples were processed using the BD Bactec FX40 automated blood culture system (BD, USA), which allows continuous monitoring and rapid detection of microbial growth. Typing of causative agents in positive cultures and antimicrobial susceptibility testing were performed using conventional methods and the Vitek2 Compact automated system. Results: Microbial growth was observed in 369 (42.7%) of 864 patients. Of the microorganisms isolated, 79.4% (293) were Gram-positive bacteria, 18.2% (67) were Gram-negative bacteria and 2.4% (9) were yeasts. Escherichia coli (26.9%) was the most frequently isolated Gram-negative bacterium followed by Acinetobacter baumannii (20.9%), Enterobacter cloacae (13.4%), Klebsiella pneumoniae (13.4%) and Pseudomonas aeruginosa (13.4%). Among Gram-positive bacteria, coagulase-negative staphylococci (81.2%) and Staphylococcus aureus (10.2%) were most frequently isolated. Methicillin resistance was found in 30.0% of S. aureus and 71.8% of coagulase-negative staphylococci. No resistance to vancomycin, tigecycline or daptomycin was observed. Extended-spectrum β-lactamase production was detected in 44.4% of E. coli and 55.5% of Klebsiella spp. Conclusion: This study highlights the local prevalence of bacterial isolates in bloodstream infections and emphasizes the need for routine monitoring of etiologic agents and antibiotic susceptibility to prevent resistance and aid rational antibiotic use.