Multi-drug resistant Salmonella enterica serovar Typhi isolates with reduced susceptibility to ciprofloxacin in Kenya

Winnie C Mutai,Samuel Kariuki,Anne W T Muigai,Peter Waiyaki

doi:10.1186/s12866-018-1332-3

Abstract

BackgroundTyphoid 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).MethodsA 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.ResultsSixteen 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.ConclusionA 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.

Highlights

Typhoid fever posses a public health threat, recording high morbidity and mortality rates mainly in developing countries [1, 2]
Typhi isolates that were resistant to ciprofloxacin, ceftriaxone, cefotaxime, amoxicillin-clavulanic acid, nalidixic acid and chloramphenicol by disc diffusion technique were randomly selected from the 98 Multidrug resistant (MDR) isolates for minimum inhibitory concentration (MIC) determination
A high resistant rate was observed among the first-line antibiotics, ampicillin (72%), chloramphenicol (72%) and cotrimoxazole (70%)

Summary

Introduction

Typhoid fever posses a public health threat, recording high morbidity and mortality rates mainly in developing countries [1, 2]. Incidence may vary from one country to another due to dynamics in risk factor exposure levels attributed to the disease; some. The high incidence rates of typhoid fever have been exacerbated by the emergence of S. Typhi strains resistant to antibiotics recommended for treatment. Centers for Disease Control and Prevention (CDC) ranks antibiotic resistant S. Typhi as a serious threat that requires frequent monitoring and prevention to reduce the spread. 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.

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