Prevalence ofSalmonellain Stool During the Vaccine Impact on Diarrhea in Africa (VIDA) Study, 2015–2018

Abstract

Background Non-typhoidal Salmonella (NTS) is a common cause of gastroenteritis in young children, with limited data on NTS serovars and antimicrobial resistance in Africa. Methods We determined the prevalence of Salmonella spp. and frequency of antimicrobial resistance among serovars identified in stools of 0–59 month-old children with moderate-to-severe diarrhea (MSD) and controls enrolled in the Vaccine Impact on Diarrhea in Africa (VIDA) Study in The Gambia, Mali, and Kenya in 2015–2018, and compared with data from the Global Enteric Multicenter Study (GEMS; 2007–2010) and the GEMS-1A study (2011). Salmonella spp. was detected by quantitative real-time PCR (qPCR) and culture-based methods. Identification of serovars was determined by microbiological methods. Results By qPCR, the prevalence of Salmonella spp. among MSD cases was 4.0%, 1.6%, and 1.9% and among controls was 4.6%, 2.4%, and 1.6% in The Gambia, Mali, and Kenya, respectively, during VIDA. We observed year-to-year variation in serovar distribution and variation between sites. In Kenya, Salmonella enterica serovar Typhimurium decreased (78.1% to 23.1%; P < .001) among cases and controls from 2007 to 2018, whereas serogroup O:8 increased (8.7% to 38.5%; P = .04). In The Gambia, serogroup O:7 decreased from 2007 to 2018 (36.3% to 0%; P = .001) but S. enterica serovar Enteritidis increased during VIDA (2015 to 2018; 5.9% to 50%; P = .002). Only 4 Salmonella spp. were isolated in Mali during all 3 studies. Multidrug resistance was 33.9% in Kenya and 0.8% in The Gambia across all 3 studies. Ceftriaxone resistance was only observed in Kenya (2.3%); NTS isolates were susceptible to ciprofloxacin at all sites. Conclusions Understanding variability in serovar distribution will be important for the future deployment of vaccines against salmonellosis in Africa.

Shigellain Africa: New Insights From the Vaccine Impact on Diarrhea in Africa (VIDA) Study

“…Notably Mali had the lowest sensitivity in the detection of Shigella by culture compared to The Gambia and Kenya. Mali also showed poor sensitivity for detection of Salmonella by culture [ 35 ]. The reduced detection by culture may have been due to antibiotic usage [ 36 ] or inadequate specimen transport (temperature and/or time to the laboratory), or culture techniques despite concerted efforts to enhance quality control at each of the sites.…”