Invasive multidrug-resistant non-typhoidal Salmonella infections in Africa: zoonotic or anthroponotic transmission?

Abstract

In Africa, multidrug-resistant non-typhoidal salmonellae (NTS) are one of the leading causes of morbidity and high mortality in children under 5 years of age, second in importance only to pneumococcal disease. The authors studied NTS isolates from paediatric admissions at two hospitals in Nairobi, Kenya, and followed the index cases to their homes, where rectal swabs and stools from parents and siblings, and from animals in close contact, were obtained. The majority of NTS obtained from cases were Salmonella enterica serotype Typhimurium (106 out of 193; 54?9 %) and Salmonella enterica serotype Enteritidis (64; 33?2 %), a significant proportion (34?2 %) of which were multiply resistant to three or more antibiotics, including ampicillin, tetracycline, cotrimoxazole and chloramphenicol. Only 23?4 % of NTS were fully susceptible to all 10 antibiotics tested. Of the 32 NTS obtained from contacts (nine adults and 23 children) at the homes of index cases, 21 (65?6 %) isolates were similar by antibiotic-susceptibility profiles and plasmid content, and their XbaI-and SpeI-digested chromosomal DNA patterns were indistinguishable from those of the corresponding index cases. Only three out of 180 (1?7 %) samples from environmental sources, including animals, soil, sewers and food, contained NTS matching those from corresponding index cases. The carriage of NTS in an asymptomatic population was represented by 6?9 % of human contacts from 27 out of 127 homes sampled. This population of carriers may represent an important reservoir of NTS that would play a significant role in the epidemiology of community-acquired NTS bacteraemia in children.

Non-Typhoidal Salmonella Gastroenteritis at a Diarrheal Hospital in Dhaka, Bangladesh, 1996–2011

“…This seasonal peak during the summer months corresponds to reports from other Asian countries. [10][11][12] Similarly, studies in Malawi 13 and Kenya 14,15 describe peaks of NTS disease associated with the rainy season, which may reflect, in part, the seasonal pattern of malaria in those areas, unlikely to be a factor at our site, as well as flooding. Although our data suggest that rainfall-associated contamination of water may be associated with disease transmission, it is likely that both environmental and host behavioral factors play a role in the seasonal variation of NTS, as they do for other enteric infections in Bangladesh.…”

Using next generation sequencing to tackle non-typhoidal Salmonella infections

“…Serovars of NTS are widespread and although commonly associated with specific animals, detailed investigations in Kenya have failed to identify an animal host for the S. Typhimurium strain causing human invasive disease [24,25]. For 137 S. Typhimurium isolates from patients matched with isolates from the food consumed, the animals they kept, and the environment around their home, no common types were found using standard molecular methods [24].…”

Antibiotics effect on salmonella spp .isolated from young chicks in chicken fields

“…The use of antimicrobials in veterinary medicine as food animal growth promoting agents during the past decade has created enormous pressure for selection of antimicrobial resistance among bacterial pathogens worldwide (11,12,13). Nowadays, there is increasing concern about the development of multidrug resistance in bacteria causing zoonosis and having an important animal reservoir, such as Salmonella strains (14,15). The aim of the present study was the isolation and diagnosis of the bacteria that cause bacillary white diarrhea from young chicks, identification the present percentage, and establishment the antibiotic effect on bacteria.…”