Culture Positive Cases of Enteric Fever and Their Antibiotic Susceptibility Patterns in a Tertiary Care Hospital in Dhaka, Bangladesh

Author(s): Rehana Razzak Khan, Sourav Debnath, SM Ali Ahmed, A S M Nowroz, Chandan Kumar Roy, Ismet Nigar, Shaila Akhtar, Shaheda Anwar

Background: Enteric fever is a systemic bacterial infection caused by Salmonella enterica subspecies enterica serotype Typhi (S. Typhi) or Paratyphi A, B, or C (Paratyphi A, B, or C). It is a significant public health concern in developing countries. Periodic monitoring of sensitivity and resistance patterns is necessary to support therapeutic care at both national and local levels, given the increasing antibiotic resistance observed in their management. Additionally, this will enable the planning of antibiotic recycling whenever possible.

Objective: This study aimed to identify Salmonella, the most prevalent pathogen in bloodstream infections, as well as to determine their demographics, seasonal variations, and antibiotic susceptibility to create a complete picture of how their antibiotic susceptibility has changed over time.

Methods: This retrospective study was conducted in the Department of Microbiology and Immunology, Bangladesh Medical University (BMU), Dhaka, between July 2023 and June 2024. Ten thousand, fifty-three blood samples were collected in adult and pediatric Brain Heart Infusion broth (BHI) bottles for culture, and the bacterial profile was retrieved. The collected samples were cultured using a standard technique in a medical microbiology laboratory. The isolated bacteria were identified by colony morphology, Gram staining, and biochemical reaction. Antibiotic susceptibility was tested by Kirby-Bauer disc diffusion methods per the National Committee for Clinical Laboratory Standards guidelines.

Results: A total of 10053 blood samples were collected, of which 513(5.10%) were culture positive. Among 513 culture growth, the prevailing isolate was Salmonella Typhi 216 (42.10%), followed by Staphylococcus aureus 81(15.80%), Salmonella Paratyphi A 60 (11.70%). Following that, Acinetobacter spp. (10.90%), Klebsiella spp. (9.90%), Pseudomonas spp. (4.30%), E. coli (3.30%), Serratia spp. (0.97%), Burkholderia cepacia (0.60%), Enterobacter spp., and Stenotrophomonas maltophilia (0.39%). The majority of blood culture-positive cases (S. Typhi or S. Paratyphi A) were below 10 years old, with male predominance. There were two surges of enteric fever, the highest prevalence in October through January and March through May. It was found that S. Typhi (13%–19.4 %) and S. Paratyphi A (10- 11.7%) had decreasing resistance to the first-line medications amoxicillin, chloramphenicol, and cotrimoxazole. In cases of enteric fever, the majority of isolates exhibited fluoroquinolone resistance, but none of them exhibited ceftriaxone resistance. There is an increase in azithromycin resistance (85.2%).

Conclusion: The findings of this study highlight the declining resistance to first-line antimicrobials, and it could be reintroduced as an empirical treatment option for enteric fever. Antibiotic use without prescription should be minimized, and prescribing practice should be modified. These results underscore the necessity for judicious use of antimicrobials and the implementation of an antimicrobial stewardship program in tertiary care hospitals across Bangladesh.