Microbiological Spectrum and Antimicrobial Resistance Patterns of Bloodstream Infection Isolates in a Tertiary Care Hospital

Background: Bloodstream infections are among the most serious infectious conditions, associated with high morbidity and mortality, particularly in low- and middle-income countries. The rising burden of antimicrobial resistance further complicates the management of BSIs and necessitates continuous local surveillance.
Objective: To determine the culture positivity rate, microbiological spectrum, and antimicrobial susceptibility patterns of bloodstream infection isolates in a tertiary care hospital in Bangladesh.
Methods: This cross-sectional study was conducted in the Department of Microbiology of a tertiary care teaching hospital in Savar, Dhaka, from June to December 2024. A total of 600 blood samples from clinically suspected BSI cases were processed using standard culture techniques. Bacterial isolates were identified by conventional microbiological methods, and antimicrobial susceptibility testing was performed using the Kirby–Bauer disc diffusion method following CLSI guidelines. Multidrug resistance (MDR) was defined as resistance to more than two classes of antibiotics.
Results: Out of 600 samples, 162 (27.0%) were culture positive. Culture positivity was significantly higher among males than females (30.1% vs. 23.9%, p = 0.041). The highest proportion of positive cases was observed in the 19–40 years age group (30.5%). Gram-negative bacteria predominated among the isolates. Escherichia coli (27.8%) was the most frequently isolated organism, followed by Klebsiella spp. (21.0%) and Salmonella spp. (17.3%). High susceptibility was observed to amikacin (91.0% in Gram-negative isolates) and meropenem (95.0%), although a small proportion of Gram-negative isolates showed meropenem resistance. Multidrug-resistant isolates accounted for 45.7% of all isolates. MDR status showed significant positive correlation with Gram-negative organisms (r = 0.42, p = 0.001) and meropenem resistance (r = 0.36, p = 0.004).
Conclusion: Bloodstream infections remain a significant clinical problem in Bangladesh, with a predominance of Gram-negative pathogens and a high burden of antimicrobial resistance.