Abstract:
Background: Typhoid fever remains a public health concern in developing countries
especially among the poor who live in informal settlements devoid of proper sanitation
and clean water supply. In addition antimicrobial resistance poses a major challenge in
management of the disease. This study assessed the antimicrobial susceptibility patterns
of Salmonella enterica serotype Typhi (S. Typhi) isolated from typhoid fever cases
(2004-2007).
Methods: A cross sectional study was conducted on 144 archived S. Typhi isolates
(2004-2007) tested against 11 antimicrobial agents by quality controlled disk diffusion
technique. Isolates resistant to ampicillin, chloramphenicol, and cotrimoxazole were
considered Multidrug resistant (MDR). Thirty MDR isolates were selected randomly and
further tested using minimum inhibitory concentration (MIC) E-test.
Results: Sixteen percent (23/144) of the isolates were susceptible to all the antibiotics
tested while 68% were resistant to three or more of the 11 antibiotics tested. The isolates
showed a high susceptibility to ceftriaxone (94%) and gentamicin (97%). A high
percentage of resistance was observed for the conventional first-line antibiotics;
ampicillin (72%), chloramphenicol (72%), and cotrimoxazole (70%). Sixty-nine percent
of the isolates (100/144) showed reduced susceptibility to ciprofloxacin. All the 30
(100%) isolates selected for MIC test were susceptible to amoxicillin-clavulanic acid. All
except one of the 30 isolates were susceptible to ceftriaxone while majority 21 (70%)
recorded an intermediate susceptibility to ciprofloxacin with MIC of 0.12-0.5 μg/mL.
Conclusion: A large proportion of S. Typhi isolates were MDR and also showed reduced
susceptibility to ciprofloxacin. Fluoroquinolone resistance is emerging and this may pose
a challenge in treatment of typhoid in future. There is need for routine surveillance to
monitor this phenotype in clinical settings.