Blood Culture and Widal Test as Diagnostic Tools for Enteric Fever with Antibiogram in a Tertiary Care Centre at Dhaka in Bangladesh

Background: Enteric fever still exists as one of the major public health issue occurring in our country. Antimicrobials are the mainstays of treatment of typhoid fever. Due to rapidly growing antibiotic resistance, Salmonella spp. is required to be periodically tested for susceptibility patterns. This will also enable planning of rational use of antibiotics.

Objective: To observe the diagnostic accuracy of enteric fever by blood culture and Widal test in a tertiary care center, at Savar, Dhaka; Bangladesh. Antimicrobial sensitivity pattern of this study will guide to modify recent changes in the trends of antimicrobial use at the local level.

Methodology: Blood samples were collected from 2194 febrile patients with clinically suspected enteric fever cases at a Tertiary Care Outdoor Centre from January 2017 to March 2020. Blood culture was performed to isolate S. typhi and S. paratyphi. Widal tests were done for the determination of antibody titer. An antibody titer of ≥1:80 for anti TO and anti TH were taken as a cut off value to indicate recent infection of typhoid fever. Antibiotic susceptibility testing was carried out using modified disk diffusion (Kirby–Bauer) technique.

Results: Out of 111 Salmonella isolates, 74 (5%) were S. typhi and 37 (25%) were S. paratyphi A. Total 697 samples were positive for Widal test. A large number of isolates showed resistance to commonly used antibiotics such as nalidixic acid (94.6%), chloramphenicol (87.3%), amoxicillin (76.6%), cephradine (53.1%), azithromycin (46.8) etc. Resistance to cefixime and cefipime, ceftriaxone tended to increase than past. Imipenem, moxifloxacin and cefuroxime are escalating resistance which is alarming.

Conclusion: Blood culture is the most reliable among the diagnostic methods but it needs 5 to 7 days for delivery of final report. This delay leads to late diagnosis as well as provision of irrational usage of antibiotics. It is concluded that widal test would remain relevant as a diagnostic tool for enteric fever, which is more convenient, cheaper and faster than the other molecular tests. Our study revealed the antibiotic susceptibility of Salmonella isolates will be recommended for addressing the drug resistance.