Characterization of Salmonella spp. isolated from chickens in Central China

Abstract

Background: Salmonella is an important zoonotic pathogen, and chickens are one of its main hosts. Every year, Salmonella infections pose a serious threat to the poultry industry in developing countries, especially China. In this study, a total of 84 Salmonella isolates recovered from sick and healthy-looking chickens in central China were characterized by serotyping, MLST-based strain typing, presence of potential virulence factors, and antimicrobial resistance profiles. Result: Data showed that the main serotypes of Salmonella isolates in central China were Salmonella enterica serovar Gallinarum biovar Pullorum, Salmonella enterica serovar Gallinarum biovar Gallinarum, Salmonella enterica serovar Enteritidis and Salmonella enterica serovar Typhimurium, and among them, S. Pullorum was the dominant type in both sick and healthy-looking chickens, accounting for 43.9 and 46.5%, respectively, while S. Enteritidis was only found in healthy-looking chickens. All isolates exhibited higher resistance rates to ampicillin (97.6%), tetracycline (58.3%) and colistin (51.2%), and among these isolates, 49.5% were resistant to more than three drugs in different combinations. S. Enteritidis was the most severe multidrug-resistant serotype, which showed higher resistance rates to colistin, meropenem and ciprofloxacin. Multilocus sequence typing (MLST) revealed that S. Gallinarum and S. Enteritidis isolates were clustered in clade 1, which belonged to two and one STs, respectively. All S. Typhimurium isolates were clustered in clade 3, and belonged to three STs. However, S. Pullorum were distributed in three clades, which belonged to 7 STs. Twenty-seven virulence-associated genes were detected, and expected cdtB, which was absent in all the isolates, the other 26 genes were conserved in the closely related Salmonella serogroup D (S. Enteritidis, S. Pullorum, and S. Gallinarum). Conclusion: Salmonella serogroup D was the major subgroup, and S. Pullorum was the most common type in sick and healthy-looking chickens in central China. Drug resistance assays showed serious multiple antimicrobial resistances, and S. Enteritidis was the most severe drug-resistant serotype. MLST showed that there was correlation between serotypes and genotypes in most Salmonella isolates, except S. Pullorum, which showed complicated genetic diversity firstly. These results provide important epidemiological information for us to control Salmonella in chickens.

Bacillus coagulans protect against Salmonella enteritidis-induced intestinal mucosal damage in young chickens by inducing the differentiation of goblet cells

“…Salmonella enteritidis ( S. enteritidis ) is one of the most frequently isolated foodborne pathogens, which has a wide range of hosts, including humans and various animals ( Eng et al, 2015 ; Jajere, 2019 ). Over 2,500 Salmonella serotypes have been identified, and more than half of them belong to S. enteritidis , which causes death and great economic loss in poultry ( Wang et al, 2020a ; Ehuwa et al, 2021 ). Moreover, contaminated poultry products as carriers of S. enteritidis also pose serious threat to human health, which accounting for millions of foodborne illnesses and deaths per year ( Sylejmani et al, 2016 ; Heredia and Garcia, 2018 ).…”

Serotyping, MLST, and Core Genome MLST Analysis of Salmonella enterica From Different Sources in China During 2004–2019

“…Among these molecular typing methods, MLST was developed to establish analytical microorganism typing ( Maiden et al, 1998 ), recognize evolutionary relationships of Salmonella ( Achtman et al, 2012 ; Ashton et al, 2016 ; Mairi et al, 2020 ; Zhang et al, 2020 ), and determine clonal isolate distributions across various environments and hosts ( Wang M. et al, 2020 ; Zhao et al, 2020 ). In addition, there is a strong correlation between serotypes and sequence types (STs) of Salmonella ( Wang X. et al, 2020 ). However, MLST cannot obtain accurate traceability of Typhimurium and I 4,[5],12:i:- because Salmonella isolates of these two serovars are often divided into the same STs ( Possebon et al, 2020 ).…”

Prevalence and antibiotic resistance of Salmonella isolated from poultry and its environment in the Mekong Delta, Vietnam

“…Salmonella isolated from poultry farms show critically high resistance to ampicillin (100%), amoxicillin (99%), and tetracycline (98%) in Bangladesh [44]. Salmonella isolated from poultry samples also show high resistance to colistin, ciprofloxacin, doxytetracycline, kanamycin, streptomycin, sulfamethoxazole, and tetracycline (42.1-97.6%) [5,6,[14][15][16][17]25]. The resistance patterns commonly observed in Salmonella isolates from poultry include amoxicillin-ampicillin-ciprofloxacin-erythromycin-gentamycin-penicillin-sulfamethaxole-tetracycline (26.4%) and ampicillin-streptomycin-amoxicillin/clavulanic acid-cephalothin-ceftiofur-cefoxitin (39.7%) [24,44].…”

“…Animals with antibiotic-resistant zoonotic Salmonella strains transmit the infection to humans through the food chain [12]. Salmonella strains isolated from poultry farms also show multiple resistance patterns for numerous antibiotics [13][14][15][16][17] and display genetic relationships with the Salmonella strains detected in humans [14,15]. Thus, the antibiotic-resistant Salmonella strains in poultry and farm environments should be carefully monitored.…”