Food animal-associated Salmonella challenges: Pathogenicity and antimicrobial resistance

National Farm Medicine Center, Marshfield Clinic Research Foundation, Marshfield, WI 54449, USA.
Journal of Animal Science (Impact Factor: 1.92). 05/2008; 86(14 Suppl):E173-87. DOI: 10.2527/jas.2007-0447
Source: PubMed

ABSTRACT Salmonellosis is a worldwide health problem; Salmonella infections are the second leading cause of bacterial foodborne illness in the United States. Approximately 95% of cases of human salmonellosis are associated with the consumption of contaminated products such as meat, poultry, eggs, milk, seafood, and fresh produce. Salmonella can cause a number of different disease syndromes including gastroenteritis, bacteremia, and typhoid fever, with the most common being gastroenteritis, which is often characterized by abdominal pain, nausea, vomiting, diarrhea, and headache. Typically the disease is self-limiting; however, with more severe manifestations such as bacteremia, antimicrobial therapy is often administered to treat the infection. Currently, there are over 2,500 identified serotypes of Salmonella. A smaller number of these serotypes are significantly associated with animal and human disease including Typhimurium, Enteritidis, Newport, Heidelberg, and Montevideo. Increasingly, isolates from these serotypes are being detected that demonstrate resistance to multiple antimicrobial agents, including third-generation cephalosporins, which are recommended for the treatment of severe infections. Many of the genes that encode resistance are located on transmissible elements such as plasmids that allow for potential transfer of resistance among strains. Plasmids are also known to harbor virulence factors that contribute to Salmonella pathogenicity. Several serotypes of medical importance, including Typhimurium, Enteritidis, Newport, Dublin, and Choleraesuis, are known to harbor virulence plasmids containing genes that code for fimbriae, serum resistance, and other factors. Additionally, many Salmonella contain pathogenicity islands scattered throughout their genomes that encode factors essential for bacterial adhesion, invasion, and infection. Salmonella have evolved several virulence and antimicrobial resistance mechanisms that allow for continued challenges to our public health infrastructure.

  • International Journal of Food Engineering 01/2012; 8(3). DOI:10.1515/1556-3758.2847 · 0.46 Impact Factor
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    ABSTRACT: The present study was undertaken to determine the prevalence of Salmonella in 270 raw meat samples (90 each of fresh beef, ground beef, and beef burger) purchased on nine occasions from various supermarkets and butchers' shops in Mansoura city, Egypt. Using conventional biochemical identification, Salmonella species were recovered from 23.3% (21/90), 20% (18/90), and 12.2% (11/90) of fresh beef, ground beef and beef burger samples, respectively with an overall prevalence of 18.5% (50/270) among all the meat products examined. Higher prevalence were obtained based on molecular identification, by detecting gyrB and invA genes, which verified the presence of Salmonella species in 30.0% (27/90), 26.7% (24/90), and 16.7% (15/90) of fresh beef, ground beef, and beef burger samples, respectively with an overall prevalence of 24.4% (66/270) among all the meat products. tested. Of the 2635 presumptive colonies tested, 228 were biochemically identified as Salmonella, while 272 were molecularly identified as Salmonella, which were all positive for the enterotoxin (stn) virulent gene. Of the 272 serologically tested strains, 266 were serologically identified into six Salmonella serovars, while 6 strains were untypable. Salmonella Typhimurium and Salmonella Enteritidis were the most prevalent serovars with an incidence of 38.2% (104/272) and 34.6% (94/272), respectively. The other four serovars identified were Salmonella Haifa, Salmonella Muenster, Salmonella Virchow, and Salmonella Anatum were detected at lower prevalences of 11%(30/272), 7.4%(20/272), 4% (11/272) and 2.6%(7/272), respectively. Interestingly, the antimicrobial susceptibility testing indicated that all of the 100 Salmonella serovars tested were multidrug resistant (resistant to three or more antibiotics). Our findings demonstrated that the retail beef products tested were widely contaminated with multidrug-resistant Salmonella and such contamination may constitute a major public health concern.
    Food Control 04/2014; 38:209-214. DOI:10.1016/j.foodcont.2013.10.027 · 2.82 Impact Factor
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    ABSTRACT: Chicken hatchlings (CH) contaminated with non-Typhoidal Salmonella involves a degree of disease risk to the importing country. The potential national and international trade impacts from Salmonella enterica serotypes and repertoire of virulence genes garners attention because of its distinctive multi-drug resistant characteristics and its international spread which poses a threat to the public health. Eighteen Salmonella enterica isolates were recovered from the CH (imported: 13/110, 11.8% and domestic: 5/80, 6.3%). The serotypes that were recovered from the imported CH were Enteritidis (3/13, 23%), Typhimurium (2/13, 15.4%), Dublin (2/13, 15.4%), Shagoua (2/13, 15.4%), Hindmarch (2/13, 15.4%) and Inganda (1/13, 15.4%) and one untypable (1/13, 15.4%). From the domestic CH the serotypes isolated were Enteritidis (1/5, 20.0%), Typhimurium (1/5, 20.0%), Dublin (1/5, 20.0%), and Infantis (2/5, 40.0%). These strains were screened for 11 potential virulence genes (invA, avrA, ssaQ, mgtC, siiD, sopB, gipA, sodC1, sopE1, spvC, and bcfC) by polymerase chain reaction. All 18 isolates were resistant to at least one of 14 antibiotics used in this study. All isolates were primarily 100% resistant to lincomycin and 100% susceptible to ciprofloxacin and colistine sulphate. The high rate of resistance in S. Enteritidis strains, sometimes to multiple drugs, may complicate future options for treating human infections. The carriage of virulence-associated genes in these isolates suggests that they could cause serious disease and give rise to public health problems if they were to be dispersed in the general human population complicating future options for human treatment. The findings provide useful information for public health projects in Egypt and that the implementation of the Codex Committee on Food Import and Export Inspection and Certification Systems (CCFICS) to develop principles and guidelines in this area has become a must and that food control should cover both export and import.


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May 21, 2014