Distribution, epidemiology, and antimicrobial resistance pattern of gram-negative bacteria isolated from blood: A retrospective study in a tertiary care hospital, Dhaka, Bangladesh

The effective treatment of bloodstream infections caused by gram-negative bacteria (GNB) poses significant challenges as their distribution and resistance patterns vary across geographic locations and healthcare settings. Data on bloodstream infections (BSIs) and antimicrobial resistance patterns (AMR) in Bangladesh are limited. The objective of this study was to address this challenge by analyzing the prevalence, distribution, and resistance patterns-including multidrug-resistant (MDR) and extensively drug-resistant (XDR) status-of Gram-negative bacteria isolated from blood cultures at Dhaka Medical College Hospital, stratified by age, sex, and hospital unit. This retrospective study was conducted between November 2023 to October 2024 in the Department of Microbiology, Dhaka Medical College, Bangladesh. Bacterial blood culture and susceptibility testing records of GNB from both the inpatient department (IPD), intensive care units (ICU), and outpatient department (OPD) samples, irrespective of age and sex, were included and analyzed in this study. Total 3753 blood samples were analyzed in this study period, among them 427 blood samples yield bacterial growth. Out of 427 isolates, gram-negative bacteria were 87.6%, with a slightly higher prevalence in male patients (57.2%). Salmonella spp was the most prevalent isolate from the OPD, while Acinetobacter spp was predominant in IPD and ICU. The highest antimicrobial resistance was observed to ceftazidime in all isolated GNB, except Salmonella spp. Acinetobacter spp was predominantly multidrug-resistant (MDR) (75.4%), and the lowest was Salmonella spp (40.7%). Among 15% extensively drug-resistant (XDR) isolates, the majority were Acinetobacter spp, followed by Pseudomonas spp and Klebsiella spp. The highest prevalence of both MDR and XDR organisms were observed in the ICU. The antibiotic resistance trends display restricted effectiveness of commonly used antibiotics, such as cephalosporins and fluoroquinolones, compelling dependence on last-resort antibiotics- colistin. Systematic local surveillance and epidemiological studies of antimicrobial resistance would assist in taking measures to slow down the spread of resistance.