Salmonella enterica isolates from pasture-raised poultry exhibit antimicrobial resistance and class I integrons

Abstract

Aims: While considerable foodborne pathogen research has been conducted on conventionally produced broilers and turkeys, few studies have focused on free‐range (organic) or pastured poultry. The current surveillance study was designed to isolate, identify and genetically characterize Salmonella from pastured poultry farm environment and from retail samples. Methods and Results: In this study, 59 isolates were collected from two pastured poultry farms (n = 164; pens, feed, water and insect traps) and retail carcasses (n = 36) from a local natural foods store and a local processing plant. All isolates were serotyped and analysed phenotypically (antimicrobial resistance profiles) and genotypically (DNA fingerprints, plasmid profiles and integron analysis). Salmonella enterica was detected using standard microbiological methods. Salmonella Kentucky was the most prevalent serotype detected from the sampled sources (53%), followed by Salmonella Enteritidis (24%), Bareilly (10%), Mbandaka (7%), Montevideo (5%) or Newport (2%). All isolates were resistant to sulfisoxazole and novobiocin, and the majority (40/59) possessed class I integrons shown by PCR detection. Each Salmonella serotype elicited a distinct pulsed‐field gel electrophoresis fingerprint profile, and unique differences were observed among the serotypes. Conclusions: The findings of this study show that Salmonella serotypes isolated from pasture‐raised poultry exhibit antimicrobial resistance and class I integrons. Significance and Impact of the Study: This study demonstrates that despite the cessation of antibiotic usage in poultry production, antibiotic resistant Salmonella may still be recovered from the environment and poultry products.

Population Dynamics of Salmonella enterica Serotypes in Commercial Egg and Poultry Production

“…and conventional farms are compared, Salmonella prevalence is dependent on the individual farm and not the farming system (4,32,118). Regardless of contamination levels, Salmonella serovars dominating conventional production systems also dominate nonconventional systems (79,89,118). Thus, management practices may influence the prevalence but not the serovar of Salmonella detected.…”

“…The genes associated with these resistances included tetB, bla CMY , bla TEM , aacC, aph, strA, sul1, and sul2 (63). Many of these traits have been localized to class 1 and class 2 integrons and identified among S. Heidelberg and S. Kentucky strains (74,89,98,126). However, the prevalence of these resistance elements and their conferred phenotypes in S. Heidelberg appears to depend on the antimicrobial agents used at the production facility (40).…”

“…Several definitions of nonconventional poultry production systems exist, and various housing units are used in these production systems, including fixed houses, portable houses, and pasture pens in free-range operations (41). Consequently, the potential exists for increased bacterial contam-ination on these nonconventional farms due to easier access to transmitting vectors, such as birds, rodents, insects, and/or wild animals (32,79,89).…”

Salmonella Pathogenicity and Host Adaptation in Chicken-Associated Serovars

“…In analyzing the data from the CDC National Salmonella Surveillance Program (http: //www.cdc.gov/ncidod/dbmd/phlisdata/salmonella.htm), the states with the largest numbers of human S. Kentucky infections were generally those associated with higher rates of dairy production rather than poultry production (198,209). Likewise, several studies have utilized pulsed-field gel electrophoresis (PFGE) for the molecular characterization of S. Kentucky isolates from various sources (chickens, dairy cattle, and human infections); the most common profiles associated with human infections were similar/visually indistinguishable from common profiles from cattle but typically distinct from those of poultry (205,(210)(211)(212). Likewise, a majority of S. Kentucky strains isolated from poultry-associated sources fall into the sequence type 152 (ST152) clonal complex, while the majority of those isolated from human patients were of ST198 (205).…”

Gene Expression Analysis ofSalmonella entericaEnteritidis NalRandSalmonella entericaKentucky 3795 Exposed to HCl and Acetic Acid in Rich Medium

“…S almonella enterica serovar Kentucky is the serovar most frequently isolated from chickens and chicken products in the United States (USDA, 2008;Berrang et al, 2009;Lestari et al, 2009;Melendez et al, 2010). A combination of factors may contribute to the prevalence, including resistance to antibiotics and arsenic encountered in poultry environments (Fricke et al, 2009;Joerger et al 2009Joerger et al , 2010Melendez et al, 2010), and plasmids that share virulence factors with avian pathogenic Escherichia coli strains (Fricke et al, subject of the present study, demonstrated that both isolates were killed within 40 min when exposed to HCl-induced pH 2.5; however, when first exposed to acetic acid-containing medium, pH 5.5, Enteritidis Nal R was up to 1000-times less sensitive to HCl-induced pH 2.5 than Kentucky 3795 ( Joerger et al, 2009).…”