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ObjectiveTo understand the contamination and drug resistance characteristics of non-typhoidal Salmonella （NTS） during pig slaughter.MethodsA total of 170 carcasses and environmental samples were collected from two large-scale pig slaughterhouses in May and August 2021 in Shandong Province， China. Whole genome sequencing （WGS） combined with bioinformatics was used to analyze the data of the NTS isolates.ResultsNTS was detected in 29 of 170 pork samples， detection rate was 17.1%. Salmonella typhimurium was the predominant serotype （58.6%， 17/29） in the samples. The results of the drug sensitivity analysis showed that 29 NTS strains had 15 drug resistance spectra， with the highest rate of tetracycline resistance （100.0%， 29/29）， followed by ampicillin and chloramphenicol （79.3%， 23/29）. The multidrug resistance rate was 86.2% （25/29 patients）. Multilocus sequence typing （MLST） showed that ST19 was the main type， accounting for 48.3% （14/29） of cases. Analysis of drug resistance genes showed that they carried mainly tet（A）， tet（B）， tet（M）， blaTEM-1B， blaCMY-97， floR， cmlA1， etc.ConclusionThe phenomenon of NTS contamination exists in some pig slaughterhouses in Shandong Province. NTS has shown resistance to multiple antibiotics， suggesting that attention should be paid to the prevention of NTS in pig slaughterhouses.

Milk production is an important trait that influences the economic value of camels. However, the genetic regulatory mechanisms underlying milk production in camels have not yet been elucidated. We aimed to identify candidate molecular markers that affect camel milk production. We classified Junggar Bactrian camels (9–10-year-old) as low-yield (<1.96 kg/d) or high-yield (>2.75 kg/d) based on milk production performance. Milk fat (5.16 ± 0.51 g/100 g) and milk protein (3.59 ± 0.22 g/100 g) concentrations were significantly lower in high-yielding camels than those in low-yielding camels (6.21 ± 0.59 g/100 g, and 3.93 ± 0.27 g/100 g, respectively) (p < 0.01). There were no apparent differences in gland tissue morphology between the low- and high-production groups. Whole-genome resequencing of 12 low- and 12 high-yield camels was performed. The results of selection mapping methods, performed using two methods (FST and θπ), showed that 264 single nucleotide polymorphism sites (SNPs) overlapped between the two methods, identifying 181 genes. These genes were mainly associated with the regulation of oxytocin, estrogen, ErbB, Wnt, mTOR, PI3K-Akt, growth hormone synthesis/secretion/action, and MAPK signaling pathways. A total of 123 SNPs were selected, based on significantly associated genomic regions and important pathways for SNP genotyping, for verification in 521 additional Bactrian camels. This analysis showed that 13 SNPs were significantly associated with camel milk production yield and 18 SNPs were significantly associated with camel milk composition percentages. Most of these SNPs were located in coding regions of the genome. However, five and two important mutation sites were found in the introns of CSN2 (β-casein) and CSN3 (κ-casein), respectively. Among the candidate genes, NR4A1, ADCY8, PPARG, CSN2, and CSN3 have previously been well studied in dairy livestock. These observations provide a basis for understanding the molecular mechanisms underlying milk production in camels as well as genetic markers for breeding programs aimed at improving milk production. [ABSTRACT FROM AUTHOR]

Shiga toxin‐producing Escherichia coli (STEC) is an important food‐borne pathogen capable of causing severe gastrointestinal diseases in humans. Cattle and sheep are the natural reservoir hosts of STEC strains. Previously, we isolated 56 STEC strains from anal and carcass swab samples of cattle and sheep in farms and slaughterhouses. In this study, we performed whole‐genome sequencing of these isolates and determined their serotypes, virulence profiles, sequence types (STs) and genetic relationships. Our results showed that the 56 isolates belong to 20 different STs, 29 O:H serotypes and 8 stx subtype combinations. The highly prevalent serotypes for bovine and ovine isolates were O8:H25 and O87:H16, respectively. Five serotypes of cattle or sheep isolates are novel. The majority (63%) of cattle isolates contain stx1 + stx2, subtyped into stx1a, stx2a and stx2c. In contrast, most of the sheep isolates contain stx1 only, primarily subtyped into stx1a and stx1c. None of the isolates tested eae‐positive, but virulence factors such as ehxA and espP were present with variable prevalence rates. The prevalence of saa (19.6%) and espP (12.5%) in cattle isolates is much higher than that in sheep isolates, whereas that of subA (34%), katP (14.3%) and ireA (28.6%) in sheep isolates is considerably higher than that in cattle isolates. Core‐genome SNP analysis revealed that the majority of isolates could be clustered based on their serotypes or STs, whereas some clustering is associated with more than one ST or serotype. Five sheep isolates (4 belonging to ST675 and serotype O76:H19 and 1 belonging to ST25 and serotype O128:H2) share STs, serotypes and stx profiles with two hemolytic uremic syndrome–associated enterohemorrhagic E. coli (HUSEC) isolates; a cattle isolate belonging to the same ST as HUSEC isolate HUSEC001 contains all the nine virulence genes tested. These data suggest a potential of the six isolates for causing severe human infections. Collectively, we described the characteristics of cattle and sheep STEC isolates from Xinjiang, China, which may be utilized in comparative studies of other geographic regions and sources of isolation, and for surveillance as well. [ABSTRACT FROM AUTHOR]

[Objective] This study investigated antibiotic resistance and drug resistant gene profiles of Escherichia coli from retail livestock and chicken meat in Urumqi, Xinjiang to provide basis for prevention and control of resistance surveillance of meat products. [Method] E. coli was isolated from retail livestock and chicken meat samples in different regional fresh nineteen supermarkets in seven districts of Urumqi, including chicken (w = 90), pork (w = 90), beef (w = 84) and mutton (w=89). Those isolates were screened and isolated by McConkey medium and CHROMagar™ Orientation, and identified by specific 16S rDNA. The phylogenetic groups of isolates were analyzed using multiplex PCR, resistance of isolates was determined by K-B disk diffusion method, and corresponding resistant genes were amplified by PCR and sequenced. [Result] A total of 252 strains were isolated from 353 meat samples. The phylogenetic group analysis showed a domination by group A (79. 4%), followed by B1 (12. 3%). The resistance phenotypes test showed that those strains were highly resistant to tetracycline (49. 6%), ampicillin (41. 6%) and sulfame-thoxazole/tritnethopritn (30. 9%) and chloroatnphenicol (26. 6%), but were less resistant to atnikacin (1. 9%), polymyxin B (0. 8%) and ampicillin-sulbactam (0. 4%). The detection of drug resistance genes of tetA, blaTEM, cml1, aadAl, aac, sul1 and blaCTX-M were 90. 4%, 32. 1%, 31. 3%, 27. 4%, 14. 5%, 12. 8% and 9. 2%, respectively, whereas tetE, tetG, blaSHV were not detected. [Conclusion] The contamination of E. coli was serious in commercial livestock and chicken meat in Urumqi. More attention should be paid to retail meat, which plays an important role in spread of bacterial resistance. [ABSTRACT FROM AUTHOR]

Colibacillosis caused by Avian pathogenic Escherichia coli (APEC), including peritonitis, respiratory tract inflammation and ovaritis, is recognized as one of the most common and economically destructive bacterial diseases in poultry worldwide. In this study, the characteristics and inhibitory potential of phages were investigated by double-layer plate method, transmission electron microscopy, whole genome sequencing, bioinformatics analysis and animal experiments. The results showed that phages C-3 and G21-7 isolated from sewage around goose farms infected multiple O serogroups (O1, O2, O18, O78, O157, O26, O145, O178, O103 and O104) Escherichia coli ( E.coli ) with a multiplicity of infection (MOI) of 10 and 1, respectively. According to the one-step growth curve, the incubation time of both bacteriophage C-3 and G21-7 was 10 min. Sensitivity tests confirmed that C-3 and G21-6 are stable at 4 to 50 °C and pH in the range of 4 to 11. Based on morphological and phylogenetic analysis, phages C-3 and G21-7 belong to Enterococcus faecalis (E. faecalis) phage species of the genus Saphexavirus of Herelleviridae family. According to genomic analysis, phage C-3 and G21-7 were 58,097 bp and 57,339 bp in size, respectively, with G+C content of 39.91% and 39.99%, encoding proteins of 97 CDS (105 to 3,993 bp) and 96 CDS (105 to 3,993 bp), and both contained 2 tRNAs. Both phages contained two tail proteins and holin-endolysin system coding genes, and neither carried resistance genes nor virulence factors. Phage mixture has a good safety profile and has shown good survival probability and feed efficiency in both treatment and prophylaxis experiments with one-day-old goslings. These results suggest that phage C-3 and G21-7 can be used as potential antimicrobials for the prevention and treatment of APEC., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Wang, Zhang, Zhang, Tong, Ma, Wang, Liu and Su.)

The bovine Escherichia coli O157:H7 is a major foodborne pathogen causing severe bloody diarrhea, hemorrhagic colitis, and hemolytic uremic syndrome in humans. Cattle are recognized major reservoir and source of E. coli O157:H7. We investigated the antibiotic resistance, molecular profiles, and intrinsic relationship between 21 isolates of E. coli O157:H7 from cattle farms and slaughtering houses in Xinjiang. Using pulsed-field gel electrophoresis (PFGE) molecular typing, two types of PFGE were revealed through cluster analysis, including clusters I and II, with 66 and 100% similarity of PFGE spectra between 21 isolates. We also detected that 18 isolates (86%) carried at least one virulence gene, 16 isolates (76%) carried the eae gene, and 7 (33%) carried the stx1 + stx2 + eae + hly + tccp genes. Eighteen isolates were susceptible to antibiotics. Three isolates were resistant to antibiotics, and two were multidrug resistant. One of the two multidrug-resistant isolates detectably carried the bla CTX-M-121 gene. This is the first finding of the bla CTX-M-121 gene detected in E. coli O157:H7 isolated from cattle in Xinjiang. The bla CTX-M-121 gene is transferable between the bacterial strains via plasmid transmission. The results indicated that E. coli O157:H7 may have undergone clonal propagation in cattle population and cross-regional transmission in Xinjiang, China., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Su, Tong, Zhang, Zhang, Wang, Ma, Zhang, Liu, Xia and Xie.)