Prevalence and antimicrobial resistance of salmonella strains isolated from blood cultures in Dhaka Division, Bangladesh

Abstract

A total of 1050 Salmonella isolates were collected from 9040 blood cultures at hospital and diagnostic center in
Dhaka Division, Bangladesh. The prevalence of Salmonella typhi was 74.5% (785) and S. paratyphi A were
25.5%. The isolation rate was highest between the age group 25 to 60 months, male showed slightly higher rate
of infection than female. Among all 943 Salmonella typhi isolates studied, 57.4% were found resistant to
ampicillin, 58% found resistant to cotrimoxazol. 58.6% was resistant to chloramphenicol, 9 isolates collected
were ciprofloxacin resistant and 97.8% were found nalidixic acid resistant. On the other hand, all isolates were
sensitive to ceftriaxon and ceftazidim. In E-strip test, we have found that 95 isolates showed between 0.5 g/ml
to 2.0 g/ml and 11 strains showed from >2.0g/ml to very highly resistant (512g/ml). Ciprofloxacin-resistant S.
typhi carrying patients were treated with a third generation cephalosporin and were cured without
complications. Isolates were highly resistant to ampicillin, cotrimoxazole, chloramphenicol, ciprofloxacin and
nalidixic acid, and were susceptible to ceftriaxone. All three isolates were found to be identical by Api 20 E
score (4404552). Digestion of PCR product (195 bp gyrase A) with Hinfl did not make any change, compared to
the undigested product of the same strains, in the electrophoresis banding pattern, indicating the presence of
mutations at both the Ser-83 and ASp-87 sites of the genome GyrA. In contrast, the PCR product from nalidixic
and susceptible control strain cleaved at the sites, ser-83 and asp-87.