Effect of Various Inoculum Levels of Multidrug-Resistant Salmonella enterica Serovar Heidelberg (2011 Ground Turkey Outbreak Isolate) on Cecal Colonization, Dissemination to Internal Organs, and Deposition in Skeletal Muscles of Commercial Turkeys after Experimental Oral Challenge

Abstract

Salmonella enterica serovar Heidelberg (S. Heidelberg) is a major foodborne pathogen colonizing poultry. The pathogen is associated with a significant number of foodborne outbreaks through contaminated poultry meat, including turkeys. Recently, multidrug-resistant (MDR) strains of S. Heidelberg have emerged as a threat to human public health in the United States. The objective of this study was to determine the cecal colonization, dissemination to internal organs, and the potential for skeletal muscle deposition of an MDR S. Heidelberg isolate from the 2011 ground turkey outbreak in the United States after the experimental oral challenge of poults (young turkeys) and adult turkey hens. In the poult study, two separate experiments using day-old, straight-run, commercial hybrid converter poults were randomly assigned to five challenge groups (0, 10∧2, 10∧4, 10∧6, 10∧8 CFU groups; 12 poults/group; N = 60/experiment) and a week after, treatment groups were challenged separately with 0-, 2-, 4-, 6-, and 8- log10 CFU of S. Heidelberg orally. After 14 days post-challenge, the poults were euthanized, and samples were collected to determine MDR S. Heidelberg colonization in the cecum, dissemination to liver and spleen, and deposition in the thigh, drumstick, and breast muscles. A similar experimental design was followed for the adult turkey hens. In two separate experiments, 11-week-old commercial Hybrid Converter turkey hens (4 hens/group; N = 20/experiment) were challenged with MDR S. Heidelberg and on day 16 post-challenge, birds were euthanized and samples were collected to determine Salmonella populations in the samples. The results indicated that, in turkey poults, the recovery of MDR S. Heidelberg was highest in the cecum followed by spleen, liver, thigh, drumstick, and breast. All tested inoculum levels resulted in more than 3.5 log10 CFU/g colonization in the poult cecum. The cecal colonization, dissemination to internal organs, and tissue deposition of MDR S. Heidelberg were high in poults. The pathogen recovery from the cecum of adult turkey hens ranged from 37.5 to 62.5% in the challenge groups. The results signify the importance of controlling MDR S. Heidelberg in turkeys at the farm level to improve the safety of turkey products.

Prevalence, Serotyping, Molecular Typing, and Antimicrobial Resistance of Salmonella Isolated From Conventional and Organic Retail Ground Poultry

“…Comparative genomic analysis using Whole Genome Sequencing revealed that the S. Heidelberg isolates in the 2011 ground turkey outbreak clustered together when compared to isolates from human, animal, and retail meat sources ( Hoffmann et al, 2014 ). Using an experimental oral challenge experiment in turkey, a recent study showed that the Salmonella isolate causing the 2011 outbreak was high in cecal colonization, dissemination to internal organs, and tissue deposition ( Nair et al, 2018 ). Recently, a food-grade essential oil from pimento leaves was shown to reduce attachment of the 2011 S. Heidelberg isolate to turkey skin ( Nair and Johny, 2017 ).…”

Characterizing the Antimicrobial Function of a Dairy-Originated Probiotic, Propionibacterium freudenreichii, Against Multidrug-Resistant Salmonella enterica Serovar Heidelberg in Turkey Poults

“…A US poultry outbreak isolate of MDR SH was used in the study (GT2011; Nair and Kollanoor-Johny, 2017a , b ; Nair et al, 2018 ). Glycerol stocks of SH stored at −80°C were used for the preparation of working cultures.…”

“…Then the bacterial culture in PBS was serially diluted (1:10) to get a final concentration of 10 7 CFU ml −1 . From this, 100 μl was used in the experiments to inoculate the wells containing 2 ml TSB ( Kollanoor Johny et al, 2010 ; Nair and Kollanoor-Johny, 2017a , b ; Nair et al, 2018 ). For the in vivo study, GT2011 was made resistant to 50 μg ml −1 nalidixic acid sodium salt (NA; CAS.…”

“…In addition, since the resistance is plasmid encoded for the 2011 ground turkey outbreak strains, any confounding due to the potential loss of plasmids in the GIT was taken care by making the strain NA-resistant. The NA-resistant strain (GT2011NAL; Nair and Kollanoor-Johny, 2017b ; Nair et al, 2018 ) were confirmed for resistance to NA by streaking on xylose lysine desoxycholate (XLD; catalog no. C7322, Criterion, Hardy Diagnostics, Santa Maria, CA, United States) containing 50 μg ml −1 of NA (XLD-NA).…”

“…Salmonella Heidelberg (SH) is an emerging Salmonella serovar in poultry, including turkeys, that has high colonization potential and invasion ability ( Nair et al, 2018 ) compared to the most prevalent serovars such as S. Enteritidis ( Borsoi et al, 2011 ). Multistate outbreaks of foodborne salmonellosis occurred in 2011, 2013, and 2014 due to the consumption of poultry products, including ground turkey contaminated with multidrug-resistant (MDR) SH ( CDC, 2011 , 2014a , b ).…”