The role of animals as a source of antimicrobial resistant nontyphoidal Salmonella causing invasive and non-invasive human disease in Vietnam

Abstract

Background Nontyphoidal Salmonella (NTS) are associated with both diarrhea and bacteremia. Antimicrobial resistance (AMR) is common in NTS in low-middle income countries, but the major source(s) of AMR NTS in humans are not known. Here, we aimed to assess the role of animals as a source of AMR in human NTS infections in Vietnam. We retrospectively combined and analyzed 672 NTS human and animal isolates from four studies in southern Vietnam and compared serovars, sequence types (ST), and AMR profiles. We generated a population structure of circulating organisms and aimed to attribute sources of AMR in NTS causing invasive and noninvasive disease in humans using Bayesian multinomial mixture models. Results Among 672 NTS isolates, 148 (22%) originated from human blood, 211 (31%) from human stool, and 313 (47%) from animal stool. The distribution of serovars, STs, and AMR profiles differed among sources; serovars Enteritidis, Typhimurium, and Weltevreden were the most common in human blood, human stool, and animals, respectively. We identified an association between the source of NTS and AMR profile; the majority of AMR isolates were isolated from human blood ( p < 0.001). Modelling by ST-AMR profile found chickens and pigs were likely the major sources of AMR NTS in human blood and stool, respectively; but unsampled sources were found to be a major contributor. Conclusions Antimicrobial use in food animals is hypothesized to play role in the emergence of AMR in human pathogens. Our cross-sectional population-based approach suggests a significant overlap between AMR in NTS in animals and humans, but animal NTS does explain the full extent of AMR in human NTS infections in Vietnam.

A review and meta-analysis of non-typhoidal Salmonella in Vietnam: Challenges to the control and antimicrobial resistance traits of a neglected zoonotic pathogen

“…*The total number of prevalence estimates was from 26 studies selected for meta-analyses of phenotypic AMR prevalence of NTS. Six studies conducted on humans with NTS diarrhea [ 20 , 22 , 25 , [69] , [70] , [71] ], 3 on invasive NTS infections [ 27 , 28 , 72 ], 2 studies on human with NTS enteric carriage [ 19 , 70 ], 12 studies in pigs [ 7 , 33 , 35 , 36 , 38 , 40 , 42 , 47 , 51 , 52 , 69 , 71 ], 9 studies in poultry [ 7 , 19 , 35 , 38 , 40 , 42 , 53 , 69 , 71 ], 6 studies on aquaculture [ 35 , 40 , 59 , 60 , 69 , 73 , 74 ] and 6 studies on cattle [ 35 , 40 , 42 , 58 , 69 , 71 ].…”

“…A study characterizing sequence type and AMR patterns of NTS isolates from humans and animals indicated overlapping between sources. Accordingly, NTS in human blood were likely to have greater similarity (54%) to chicken isolates whereas NTS in human stools could be largely (40%) attributed to pig isolates [ 72 ]. In contrast, another study showed that S. typhimurium isolates from humans and animals (duck, pig and chicken) clustered into distinct clades in the phylogeny indicating limited evidence for the transmission of this pathogen [ 76 ].…”

Analysis of Antimicrobial Resistance in Non-typhoidal Salmonella Collected From Pork Retail Outlets and Slaughterhouses in Vietnam Using Whole Genome Sequencing

“…Food safety is of global concern and the common serotypes identified in this study have been linked to human illness in Vietnam ( 69 , 70 ). In this study we used a collection of NTS from two studies of the pork value chain to understand the serotypes that are found on pork meat presented to customers, especially in context with increasing customer awareness and desire for safe food products.…”

Animal sources of antimicrobial-resistant bacterial infections in humans: a systematic review

“…One article provided a framework for any high-or low-income country in South or South-East Asia (SSEA) [21]. Twenty-four studies were designed in the context of specific countries , and four were sub-national [45][46][47][48]. Most national and sub-national studies were conducted in North American and European countries, but three studies originated from SSEA countries [35,46,47].…”