Molecular Epidemiology of Salmonella Typhi among Patients Attending Garissa Provincial General Hospital

Abstract

Typhoid and paratyphoid fever a food and water-borne disease is caused by Salmonella enterica serotype Typhi (S. Typhi) and S. enterica serotype Paratyphi. The disease is an important cause of illness and death especially among children in developing countries majorly due to poor sanitation and unsafe food and water. Quantification of salmonella burden is therefore crucial not only for management but also for preventative measures. This cross-sectional study therefore determined the epidemiology and antimicrobial resistance patterns in bacterial etiologies of enteric fever among patients attending Garissa County Referral Hospital, (GCRH) located in a semi-arid region of North Eastern Kenya. Blood and stool samples were obtained from 379 consenting patients and a detailed sociodemographic questionnaire was administered. Isolation and identification of Salmonella Typhi, S. Paratyphi A and S. Paratyphi B were done by conventional culture, PCR and Vitek-2 compact detection method. Antimicrobial susceptibility testing was done using Kirby-Bauer’s disc diffusion method. Multidrug resistance was defined as co-resistance to ampicillin, chloramphenicol and co- trimoxazole. The mean (± standard deviation - SD) age of the participants was 37.3 (±13.3) years ranging (18 to 95 years). The majority of the participant 54.4% were female, 58% married, 39.3% had secondary level education, 75.2% had body temperature >37.1oC, while 58.8% had headache. There were 7.4% participants who had laboratory confirmation of typhoid while 35.1% had history of typhoid fever. Eight of the 379 (2.1%) participants were positive for Salmonella spp by Vitek and PCR Salmonella-specific gene (invA). Of the 8 Salmonella isolates there were S. Typhi (n=2; 25%), S. Paratyphi A (n=2; 25%) and S. Paratyphi B (n=4; 50%). Resistance to ampicillin, tetracycline, gentamycin, chloramphenicol, nalidixic acid and trimethoprim-sulfamethoxazole was 100%, 87.5%, 75%, 50%, 25% and 25%, respectively. All isolates were susceptible to ciprofloxacin. Half of all S. Typhi, S. Paratyphi A and B were multidrug-resistant. In multivariate analysis, the factors associated with Salmonella infection included laboratory confirmation of typhoid (OR 66.6, 95% CI 5.8-757.2), often eating outside homestead (OR 5.3, 95% CI 1.4-12.4), family eating from a common plate (OR 6.1, 95% CI 1.2-21.2), taking locally prepared cold drinks (OR 6.9, 95% CI 1.4-32.3), family wash hands in common basin (OR 7.3, 95% CI 1.9-31.2) and monthly income Kshs <20,000.00 (<200USD) (OR 0.2, 95% CI 0.003-0.8). The isolation of a large proportion of MDR S. Typhi, S. Paratyphi A and B is worrying. Although these isolates were susceptible to fluoroquinolones, there is need for routine surveillance to monitor susceptibility to the initial first line antibiotics. Addressing issues of contaminated food, water, sanitation and hygiene and low socio-economic status is likely to prevent and reduce the burden on enteric fever in this region.