Prevalence, Antimicrobial Resistance, and Relatedness of Salmonella Isolated from Chickens and Pigs on Farms, Abattoirs, and Markets in Sichuan Province, China

Abstract

This study aims at investigating the distribution, antimicrobial resistance, and genetic relationship of Salmonella isolated from 18 farms, their downstream abattoirs, and markets of chickens and pigs in Sichuan province, China. A total of 193 Salmonella isolates were identified from 693 samples with an isolation rate of 26.27% (88/335) in chickens and 29.33% (105/358) in pigs. Salmonella was isolated more frequently in abattoirs and markets than from farms. Serotypes were determined according to the White-Kauffmann-Le Minor scheme and 16 different serotypes were identified, with Derby being the most common, followed by Typhimurium and Meleagridis. Antimicrobial resistance phenotypes and genotypes were studied by using the disk diffusion method and polymerase chain reaction (PCR) amplification, respectively. Overall, 44.04% (n = 85) of all isolates were multidrug resistant (MDR) and resistance to nalidixic acid (51.30%) was the most frequently observed. bla was the most prevalent extended-spectrum β-lactamases gene, and polymyxin resistance gene mcr-1 was present in strains with various serotypes. Multilocus sequence typing indicated that sequence type (ST) had a close relationship with serotype, and 34.20% of all strains were ST40, which was the most prevalent. The unweighted pair group method with arithmetic means (UPGMA) dendrogram of pulsed-field gel electrophoresis showed that Salmonella isolates belonging to the same serovar from different parts of the production chain were highly genetic related, indicating that Salmonella as well as resistance genes could potentially be transmitted from farms to markets. Our study highlights the fact that Salmonella isolates from chicken and pig production chain were frequently exhibiting MDR profiles, and the dissemination of MDR Salmonella from farm to market could pose significant threats to food safety and public health.

Isolation and characterization of Salmonella in pork samples collected from retail and wholesale markets in each season from 2016 to 2018 in Wuhan, China

“…Among them, ST40 (38·27%), ST34 (18·41%) and ST469 (14·46%) were dominant. These results are consistent with some other studies showing that ST40 and ST34 are the most prevalent STs among pig isolates in China (Ma et al ). It is worth noting that ST469, which has been spreading in European countries, is becoming more prevalent in pork samples from its first detection in China (Ma et al ; Patchanee et al ).…”

“…These results are consistent with some other studies showing that ST40 and ST34 are the most prevalent STs among pig isolates in China (Ma et al ). It is worth noting that ST469, which has been spreading in European countries, is becoming more prevalent in pork samples from its first detection in China (Ma et al ; Patchanee et al ). Our results also revealed that the ST distributions were similar between strains from retail markets and wholesale markets, except that ST34 was more prevalent among wholesale market strains, indicating similar risk of Salmonella contamination between the two different markets.…”

“…Several such studies have been performed to investigate Salmonella contamination in pork in China. The prevalence differs greatly as revealed by these studies which range from 32Á2 to 73Á1% (Ma et al 2017;Zhang et al 2018). Moreover, there is no study to investigate the Salmonella prevalence in marketed pork in Central China, which is important pig farming and pork supplying base.…”

Worldwide Epidemiology ofSalmonellaSerovars in Animal-Based Foods: a Meta-analysis

“…Few studies regarding the characterization of the Meleagridis serovar and a plausible explanation of why this serovar is so isolated in swine are found in the literature. Some studies (90)(91)(92)(93) have reported S. Meleagridis is one of the most prevalent in pork serovars, and its characterization by MLST indicates ST463 and ST64 with an MDR profile.…”

Molecular epidemiology and mechanisms of antibiotic resistance inEnterococcusspp.,Staphylococcusspp., andStreptococcusspp. in Africa: a systematic review from a One Health perspective

“…Increasingly, many clinical epidemiologists are adopting the One Health concept in molecular surveillance studies due to the increasing realization that antibiotic resistance in the environment can be transferred to animals and humans or vice versa . In addition, there has been a debate on the possible impact of agricultural and veterinary use of antibiotics on human medicine; as well, the clinical importance of antimicrobial resistance genes found in the environment has been discussed …”