Determination of Antibiotic Susceptibility Pattern and Multiple Antibiotic Resistance (MAR) Index of Blood-borne Pathogens in People with Bloodstream Infections (BSIs) in a Tertiary Care Hospital, Dhaka

Bloodstream infections are serious, often life-threatening conditions caused by bacteria in the blood, leading to sepsis, organ failure, and high mortality worldwide, especially in children and developing countries. Their treatment is increasingly complicated by antimicrobial resistance, making blood culture essential for accurate diagnosis and effective therapy. Aim of the study was to detect antimicrobial susceptibility and multiple antibiotic resistance (MAR) index of blood-borne pathogens from suspected patients with bacteremia in Dhaka city, Bangladesh which is a prime contributor to antibiotic resistance. A total of 498 blood samples were collected from male and female participants of different age groups who attended the hospital for treatment purposes with symptoms of BSI. The study was conducted in the laboratory of Thyroid Care and Diagnostic Centre (TCDC) in Dhaka city from December 2024 to June 2025. Only 9.8% (n=49) of positive samples were primarily detected by BacT/Alert microbial detection system; further identification was done by conventional microbiological methods. Of 49 positive samples, we identified five bacterial isolates (73.5% gram-positive and 26.5% gram-negative) and their antibiotic sensitivity testing was done by Kirby-Bauer disc diffusion method. The most causative agent for blood infections was Salmonella spp., 42.8% (n=21) and least prevalent was Streptococcus pneumonia,6.1% (n=3). Frequency of male participants were marginally more than females, (51% males vs. 49% females). Moreover, most of the positive cases (34.7%, n=17) were observed in people above 50 years and least infected (12.2%, n=6) between 31-40 years. In case of gram-negative and-positive bacteria, moderate to high (60-80%) sensitivity was observed against aminoglycoside antibiotic- amikacin (AK) along with cephalosporin antibiotics- cephradine (CE) and ceftriaxone (CRO) except for Klebsiella spp. and Staphylococcus spp. which showed low sensitivity (40%) against amikacin. On the contrary, low to moderate resistance of the isolates were revealed against most of the antibiotics tested. Low to high (0.1 to 0.5) MAR index were manifested against six classes of fourteen antibiotics. MAR indexes for five isolates revealed 4.1% (n=2) with MAR index greater than 0.2 and 85.7% (n=42) less than 0.2; the most prevalent was 0.28 in most of the isolates. This study will help the healthcare providers to select an appropriate antibiotic for typical patients with bacterial infections as treatment is often prescribed ‘empirically’ without antibiotic susceptibility testing.