Salmonella Contamination in Broiler Synovial Fluid: Are We Missing a Potential Reservoir?

High-resolution serotyping reveals Salmonella surveillance challenges in the turkey industry

Despite extensive Salmonella controls used at processing, 5.5% of salmonellosis cases are linked to turkey. This study had two objectives: i) to summarize USDA-FSIS turkey Salmonella verification program data and ii) to evaluate Salmonella through turkey production and processing of 22 flocks. In objective 1, USDA-FSIS data shows the average Salmonella prevalence in ground turkey from 2016-2022 was 15.9%, and that the leading serovar changes frequently. For objective 2, bootsocks (n=22) were collected on-farm right after load-out. At processing, pre-scald wingtips (n=6 composites of 10/flock), pre-chill wingtips (n=6 composites of 10/flock), mechanically separated turkey (MST; n=6 bins/flock) and ground turkey (n=6 bins/flock) were collected. Salmonella prevalence was determined by a commercial qPCR and culture confirmed. In 33.2% of PCR-positive samples, Salmonella was not confirmed by culture, highlighting a discrepancy between molecular and culture detection. On-farm, 8/22 flocks were Salmonella positive, compared to 21 flocks that were positive at one or more processing locations, including 18 flocks that were positive in at least one final product sample. A logistic regression showed higher Salmonella prevalence in pre-scald (53.8%) than in pre-chill (18.2%), MST (27.3%) or ground turkey (26.5%). CRISPR-SeroSeq analysis of 148 culture positive samples detected 18 Salmonella serovars and showed 35.1% of samples contained multiple serovars. In 16 flocks, one or more serovars detected in final products were absent from any upstream samples. Two thirds of final product samples containing serovar Typhimurium typed as a live-attenuated Typhimurium vaccine strain. Salmonella on-farm and at pre-scald did not reflect Salmonella observed in final product. This data underscores the complexity of serovar tracking in turkey production and highlights challenges to identify surveillance samples that accurately represent Salmonella in turkey products.

The Genomic Characteristics of an Arthritis-Causing Salmonella pullorum

Salmonella enterica subsp. enterica serovar Gallinarum biovar pullorum (Salmonella pullorum) is an avian-specific pathogen that has caused considerable economic losses to the poultry industry. High endemicity, poor implementation of hygiene measures, and lack of effective vaccines hinder the prevention and control of this disease in intensively maintained poultry flocks. In recent years, the incidence of arthritis in chicks caused by Salmonella pullorum infection has increased. In this study, four Salmonella pullorum strains were identified from the livers, spleens, and joint fluids of Qingjiaoma chicken breeders with arthritis clinical signs, and an arthritis model of chicks was successfully established using SP206-2. Whole genome sequencing of the SP206-2 strain showed that the genome was 4,730,579 bp, 52.16% GC content, and contained 5007 genes, including 4729 protein-coding regions. The genomic analysis of four arthritis-causing isolates and three diarrhea-causing isolates showed that the genome of arthritis-causing isolates was subject to nonsynonymous mutations, shift mutations, and gene copy deletions. An SNP phylogenetic tree analysis showed that arthritis-causing isolates are located in a different evolutionary branch from diarrhea-causing isolates. Further differential genes analysis showed that the genome of arthritis-causing isolates had missense mutations in genes related to substance metabolism and substance transport, as a result of adaptive evolution.

Research Note: Hypervirulent arthritis-causing Salmonella Pullorum isolated from Chinese native chicken breeds significantly decreased growth performance of chicks

Pullorum disease is characterized by white diarrhea resulting from infection by S. Pullorum, but arthritis associated with S. Pullorum infection has become increasingly frequent recently, especially in Chinese native chicken flocks. In this study, we isolated and identified 4 S. Pullorum strains from the Qingjiaoma chicken breeders with arthritis symptoms. The LD₅₀ of the isolate 20JS04 was 1.33 × 10⁶ CFU, which was considered as a highly virulent strain in chicks. Reproducible arthritis symptoms were observed in the experimentally chickens infected with the isolate 20JS04, and the disease occurrence was 27.78% (5/18). In addition to the characteristics of high virulence and induced-arthritis, our results confirmed that the arthritis-causing isolate 20JS04 had greater negative impact on BW, ADFI, and ADG, compared with the white diarrhea-causing S. Pullorum standard strain CVCC526 (P < 0.05). These results suggest that the pathogenic diversity of S. Pullorum in China deserves more attention and stringent measures should be taken to control salmonellosis.

Prevalence and antimicrobial resistance phenotypes of Salmonella species recovered at various stages of broiler operations in Hathazari, Bangladesh

Background and Aim: Dissemination of multidrug-resistant (MDR) Salmonella through food chains has serious health implications, with higher rates of morbidity and mortality. Broiler meat remains a major reservoir of Salmonella contamination. The lack of proper hygiene in local broiler operations has, therefore, prompted this research into the assessment of Salmonella contamination in local shops and associated antimicrobial resistance (AMR) phenotypes. Materials and Methods: A total of 55 broiler samples including skin, meat, and swab samples from chopping and dressing sites were included in the study. The samples were collected from broiler shops in Hathazari, Bangladesh, and screened for the presence of Salmonella strains using culture-based methods. The isolates were biochemically characterized and further tested for AMR to eight common antibiotics using the disk diffusion technique. Results: Salmonella contaminations were identified in 29% (16/55) of the broiler samples. Swab samples collected from the chopping sites appeared to be contaminated in higher proportions (33%) than those collected from the dressing areas (25%). On the other hand, the skin samples (50%) were detected with a higher percentage of contamination than the meat samples (25%). All Salmonella isolates showed resistance toward at least one of the eight antibiotics used. Although none of the isolates was resistant to all antibiotics, 18.75% showed resistance to a maximum of seven antibiotics. Resistance to nalidixic acid was most prevalent (87.5%), followed by sulfamethoxazole-trimethoprim (81.25%), erythromycin (81.25%), tetracycline (75%), streptomycin (56.25%), ampicillin-clavulanic acid (50%), chloramphenicol (43.75%), and cefotaxime (18.75%). The resistance patterns of the isolates were found to be highly diverse. The most frequently observed pattern was the following: Ampicillin-clavulanic acid-sulfamethoxazole-trimethoprim-nalidixic acid-tetracycline-chloramphenicol-streptomycin-erythromycin. Conclusion: The relatively high prevalence of MDR strains in the samples underlies an urgent need for surveillance and control measures concerning hygiene and antibiotic use in local broiler operations.

Salmonella and Shiga Toxin-Producing Escherichia coli in Products Sampled in the Food Safety and Inspection Service Raw Pork Baseline Study

The Food Safety and Inspection Service (FSIS) conducts microbiological baseline studies to determine national prevalence of select foodborne pathogens in federally inspected meat and poultry products and to obtain data for risk assessments. The FSIS conducted a baseline study from 1 June 2017 through 31 May 2018 to characterize and determine the prevalence of Salmonella and assess the occurrence of Shiga toxin-producing Escherichia coli (STEC) in a variety of raw pork products. In total, 4,014 samples from slaughter and processing establishments were analyzed for Salmonella; a subset of these samples (1,395) from slaughter establishments were also analyzed for STEC. Analyses determined that the national prevalence of Salmonella in raw pork products was highest in comminuted products (28.9%), followed by intact cuts (5.3%) and nonintact cuts (3.9%). Less than 1% of samples analyzed were positive for the top seven STEC. Our findings indicate there is a need for additional pathogen reduction strategies for raw pork products.