Prevalence and characteristics of Salmonella spp. isolated from commercial layer farms in Korea.

Salmonellosis is one of the most prevalent foodborne illnesses. The outbreak of this disease is often associated with eggs. In this study, the prevalence and characteristics of Salmonella was surveyed in layer farms in Korea. In addition, the risk factors affecting the prevalence of Salmonella in these farms were also assessed. Of the 32 farms and 67 flocks examined, 19 farms (59.3%) and 34 flocks (50.7%) were observed to be positive for Salmonella contamination. Salmonella was detected in the surrounding environment such as feces (41.8%), dust (40.3%), egg shells (17.2%), as well as the internal egg contents (5.2%). The incidence of Salmonella positives were tended to increase when the flock size is larger (P = 0.021). Differences in the provinces also affected Salmonella prevalence (P < 0.001). The most frequently observed Salmonella serovars in the flocks were Salmonella Bareilly (41.2%), Salmonella Mbandaka (32.4%), and Salmonella Rissen (17.6%). Twenty of the flocks revealed multi-serovar contamination, with the isolation of 2 to 4 serovars. Antimicrobial susceptibility testing revealed that 93 out of 101 isolates were susceptible to the 17 tested antimicrobial agents. The remaining isolates displayed resistance to ampicillin (4.0%), nalidixic acid (3.0%), tetracycline (1.0%), cephalothin (1.0%), and gentamicin (1.0%). As human salmonellosis has been repeatedly correlated to the consumption of poultry products worldwide, continuous studies are required to effectively minimize the Salmonella contamination in layer farms and egg products.

Differences in peripheral and central metabolites and gut microbiome of laying hens with different feather-pecking phenotypes.

Background: Feather pecking (FP) is a maladaptive behavior in laying hens that is associated with numerous physiological traits, including those involving the central neurotransmitter system and the immune system, which have been identified in many species as being regulated by the gut microbiota via the "microbiota-gut-brain" (MGB) axis. Yet, it is unknown whether and how gut microbiota influences FP by regulating multiple central neurotransmission systems and immune system. Methods: This study was measured the prevalence of severe FP (SFP) in the commercial layer farm. The chicken flock with the highest frequency of SFP were selected for FP phenotype identification. Nontargeted metabolomics was performed to investigated the differences in the peripheral and central metabolites and 16S rDNA sequencing was performed to investigated the differences in gut microbiome of laying hens with different FP phenotypes. Correlation analysis was performed to determine the potential mechanism by which the disturbed gut microbiota may modulate host physiology and behavior. Results: The results showed that pullets (12 weeks of age) showed significantly higher SFP frequencies than chicks (6 weeks of age) and adults (22 weeks of age; p < 0.05). Compared to neutrals (N), peckers (P) exhibited the stress-induced immunosuppression with the increased plasma levels of corticosterone and norepinephrine, and the decreased plasma levels of IgA, IL-1, IL-6 and tumor necrosis factor α (p < 0.05). In the cecum, the relative abundances of Bacteroides and Gemmiger were higher in the P group, while Roseburia, Ruminococcus2, Anaerostipes, Lachnospiracea_incertae_sedis and Methanobrevibacter were more enriched in the N group. Moreover, increased plasma levels of L-tryptophan, beta-tyrosine and L-histidine were found in the P group (p < 0.05). Notably, in the P group, hippocampal levels of L-tryptophan, xanthurenic acid, L-histidine and histamine were improved and showed a positive association with L-glutamic acid levels. Plasma levels of L-tryptophan, beta-tyrosine and L-histidine were both positively correlated with Bacteroides abundance but negatively correlated with Methanobrevibacter abundance. Conclusion: Overall, these findings suggest that the development of FP may be affected by the gut microbiota, which regulates the central glutamatergic nerve system by altering the metabolism of tryptophan, histidine and tyrosine.

Molecular Detection of Avian Pathogenic Escherichia coli (APEC) for the First Time in Layer Farms in Bangladesh and Their Antibiotic Resistance Patterns.

Avian pathogenic Escherichia coli (APEC) causes significant economic losses in poultry industries. Here, we determined for the first time in Bangladesh, the prevalence of APEC-associated virulence genes in E. coli isolated from layer farms and their antibiotic resistance patterns. A total of 99 samples comprising internal organs, feces, and air were collected from 32 layer farms. Isolation was performed by culturing samples on eosin-methylene blue agar plates, while the molecular detection of APEC was performed by PCR, and antibiograms were performed by disk diffusion. Among the samples, 36 were positive for the APEC-associated virulence genes fimC, iucD, and papC. Out of 36 isolates, 7, 18, and 11 were positive, respectively, for three virulence genes (papC, fimC, and iucD), two virulence genes, and a single virulence gene. Although the detection of virulence genes was significantly higher in the internal organs, the air and feces were also positive. The antibiograms revealed that all the isolates (100%) were resistant to ampicillin and tetracycline; 97.2%, to chloramphenicol and erythromycin; 55.5%, to enrofloxacin; 50.0%, to norfloxacin and ciprofloxacin; 19.4%, to streptomycin; 11.1%, to colistin; and 8.33%, to gentamicin. Interestingly, all the isolates were multidrug-resistant (MDR). Spearman's rank correlation coefficient analysis revealed the strongest significant correlation between norfloxacin and ciprofloxacin resistance. This is the first study in Bangladesh describing the molecular detection of APEC in layer farms. Isolated APEC can now be used for detailed genetic characterization and assessing the impact on public health.

The Expanded Role of Roof-Rats (Rattus rattus) in Salmonella spp. Contamination of a Commercial Layer Farm in East Japan.

Rodents serve as amplifiers of Salmonella infections in poultry flocks and can serve as a source of Salmonella contamination in the environment even after thorough cleaning and disinfection. This study aims to determine the dynamics of Salmonella occurrence in rodents and its relation to Salmonella contamination in the layer farm environment, including air dusts and eggs. From 2008 to 2017, roof rats (Rattus rattus), environmental swabs, air dusts, and eggs were collected from an intensive commercial layer farm in East Japan and were tested for Salmonella spp. using standard procedures. In roof rat samples, the Salmonella isolation rate was reached at 10% (95% confidence interval [CI] 8.1-21.9) in which Salmonella Corvallis, Salmonella Infantis, Salmonella Potsdam, and Salmonella Mbandaka were the frequent isolates from the cecal portion of the intestines. On the other hand, the prevalence rate of Salmonella in environmental swabs was at 5.1% (95% CI 2.2-7.4) while air dusts were at 0.9% (95% CI 0.2-1.8). It was observed that the prevalence of predominant Salmonella serotypes shifted over time; in roof rats, it was noted that Salmonella Potsdam gradually replaced Salmonella Infantis. In environmental swabs and eggs, Salmonella Corvallis and Salmonella Potsdam increased significantly while Salmonella Infantis became less frequent. In air dusts, Salmonella Corvallis was observed to decrease and Salmonella Potsdam became more common. Based on our findings, the role of roof rats in the epidemiology of Salmonella in layer farms was expanded from being a reservoir and an amplifier host into a shifting vessel of the most predominant serotypes.

Prevalence and Genetic Analysis of Salmonella enterica from a Cross-Sectional Survey of the New Zealand Egg Production Environment.

Epidemiological evidence suggests that Salmonella on New Zealand eggs is not an important pathway for human salmonellosis. However, robust nationally representative data for Salmonella contamination of eggs is not available to support this. To better understand the exposure of New Zealand commercial eggs to Salmonella, a cross-sectional survey collected data on prevalence and serotypes of Salmonella in the feed, laying sheds (feces, dust, and boot or manure belt swabs), and packhouses (egg contact surfaces) of New Zealand commercial egg layer farms. Salmonella was not detected on 16 of 28 surveyed farms, and 4 farms had only one positive sample. Of the 43 (13.3%) of 323 Salmonella-positive samples, dust samples had the highest prevalence (19 of 67, 28.4%), followed by boot or manure belt swabs (11 of 67, 16.4%), feces (7 of 67, 10.4%), packhouse egg contact surfaces (5 of 87, 5.7%), and feed (1 of 33, 3.0%). A significantly higher prevalence was from caged (33 of 75, 44.0%; P < 0.001) compared with cage-free (4 of 126, 3.2%) systems, yet multiple practices differ between laying systems, which could influence prevalence. Salmonella-positive packhouse samples were only identified on the three farms with the highest laying shed prevalence, and isolates were genetically related (as determined by single nucleotide polymorphism analyses) suggesting cross-contamination between the laying shed and packhouse surfaces. Serotypes isolated included Salmonella Infantis, Salmonella Thompson, Salmonella Typhimurium, Salmonella Anatum, and Salmonella Mbandaka. Importantly, Salmonella Enteritidis, which causes egg-associated outbreaks internationally, was not isolated. Genomic comparisons of isolates supported the presence of a common contamination source in the shed and farm environments rather than multiple sporadic contamination events. This survey establishes a benchmark of Salmonella prevalence and types in the New Zealand egg production environment and provides a reference point for assessing the impact of changes to practices on Salmonella prevalence.

Salmonella Contamination in Layer Farms in China: Detection and Genetic Analysis.

Salmonella is the most common cause of foodborne illnesses worldwide. Poultry eggs are a major contamination source of Salmonella. The prevalence of Salmonella has been effectively reduced since a series of measures were taken to reduce contamination in egg-laying houses. In the present study, 1,512 environmental samples obtained from layer farms of different production scales were screened in a voluntary Salmonella survey study. Contaminations were detected using a PCR method. Genetic relationships among Salmonella samples were specified using molecular typing by enterobacterial repetitive intergenic consensus (ERIC)-PCR. The survey results showed that two layer farms, located in the Shandong and Hebei provinces, were contaminated with Salmonella. Thirty-one samples from these two farms, including feed, drinking nipples, egg collection belt, air inlets and outlets, air, overshoes, and eggshells, were identified as Salmonella-positive. It was observed that certain samples within the henhouses as well as in the egg collecting areas showed relatively high genetic similarities. The survey conclusively revealed minor Salmonella contamination in northern China. Moreover, various areas within the layer farms were identified as part of the propagation chain of Salmonella. Furthermore, evidence of cross-contamination of Salmonella was found in the laying houses and egg collection areas, even between these two regions. Therefore, it is necessary to establish routine Salmonella detection and subsequent environmental control measures in order to decrease the prevalence of Salmonella.

Recovery of Salmonella isolated from eggs and the commercial layer farms.

BACKGROUND: Salmonella is recognized as a common bacterial cause of foodborne diarrheal illness worldwide, and animal or its food products have been the most common vehicles of the Salmonella infections. This study aimed to investigate the distribution of Salmonella in two commercial layer farms and to determine the genetic relatedness between these strains. The Salmonella isolates were serotyped by slide agglutination using commercial antisera and analyzed for genetic relatedness using pulsed-field gel electrophoresis (PFGE). RESULTS: The internal environment had the highest prevalence of Salmonella (14/15, 93.3%), followed by external environment (60/96, 62.5%) and egg samples (23/84, 27.3%). The prevalence of Salmonella in the environment was significantly higher than that in egg samples (p < 0.05). The occurrence of Salmonella in the internal environment (93.3%) was relatively higher than in the external environment (55.6-77.2%). The 111 isolates were distributed among 15 PFGE types, and the PFGE results suggested that there existed cross-contamination between these strains not only from eggs, but also from the environments. CONCLUSIONS: The findings indicated ongoing Salmonella cross-contamination inside or outside of the layer farms, and that Salmonella could also spread along the egg production line.

Phage and MLVA typing of Salmonella enteritidis isolated from layers and humans in Belgium from 2000-2010, a period in which vaccination of laying hens was introduced.

The aim of the study was to characterize isolates of Salmonella enterica serovar Enteritidis (S. Enteritidis) obtained from humans and layer farms in Belgium collected during 2000-2010. Three periods were compared, namely (i) before implementation of vaccination (2000-2004), (ii) during voluntary vaccination (2005-2006) and (iii) during implementation of the national control program (NCP) for Salmonella including mandatory vaccination against S. Enteritidis (2007-2010). The characteristics compared across time periods were distributions of phage type and multiple-locus variable number tandem-repeat assay (MLVA). While PT4 and PT21 were predominantly isolated in Belgium in layers and humans before 2007, a significant reduction of those PTs was observed in both populations in the period 2007-2010. The relative proportion of PT4b, PT21c and PT6c was found to have increased considerably in the layer population since 2007. In the human population, PT8, PT1 and the group of 'other' PTs were more frequently isolated compared to the previous periods. When comparing the proportion of the predominant MLVA types Q2 and U2, no significant difference was found between the layer and human population in the three periods and between periods within each category (layer and human). A significant difference in isolate distribution among MLVA clusters I and II was found between human and layer isolates recovered during Period 3 and in the human population between Period 1 and 3. Results suggest that the association between S. Enteritidis in layers and the occurrence of the pathogen in humans changed since implementation of the NCP in 2007.