Comparison of Salmonella Serovar Isolation and Antimicrobial Resistance Patterns from Porcine Samples Between 2003 and 2008

Abstract

Abstract. Food-borne Salmonella infections can produce symptoms from mild gastroenteritis to severe systemic disease and death, representing an important public health issue in U.S. livestock and livestock products, which have been implicated as frequent sources of Salmonella contamination. Concerns have been raised about the spread of antibiotic resistance in Salmonella strains, particularly those that originate from food animal sources, as a result of prophylactic and therapeutic antimicrobial use in these species. Longitudinal comparisons of Salmonella serovars isolated from porcine tissues submitted to the Iowa State University Veterinary Diagnostic Laboratory in 2003 and 2008 were conducted to evaluate changes in serovar dynamics and antimicrobial resistance. Incidence of recovered group C Salmonella enterica serovar Choleraesuis var. Kunzendorf decreased between 2003 and 2008, while recovery of group B strains Salmonella Typhimurium var. 5-(formerly, Copenhagen), Salmonella Agona, Salmonella Derby, Salmonella Heidelberg, and Salmonella Typhimurium increased. Significant changes in resistance interpretation were seen in Salmonella Derby with regard to spectinomycin and sulfadimethoxine; in Salmonella Heidelberg with regard to florfenicol, spectinomycin, and sulfadimethoxine; and in Salmonella Choleraesuis var. Kunzendorf, Salmonella Typhimurium, Salmonella Typhimurium var. 5-, and Salmonella Agona with regard to spectinomycin. Only 2 of 293 isolates in 2003 and 5 of 395 isolates in 2008 were resistant to enrofloxacin. Utilizing antibiotics approved for use in food animals to evaluate antimicrobial resistance provides more specific information on the selection pressure exerted on Salmonella populations through the use of these drugs.

Diversity of Salmonella enterica serovar Derby isolated from pig, pork and humans in Germany

“…A reason for these differences might be varying antimicrobial usage regimes in pig production ( [Ling et al, 2001], [Valdezate et al, 2005], [Zhao et al, 2007], and [Xia et al, 2009]). An increased antimicrobial resistance to sulfadimethoxine and spectinomycin has been also reported in S. Derby isolated from U.S. livestock between 2003 and 2008 (Clothier et al, 2010). Genotyping of antimicrobial resistance genes in strains from Southern Brazil and America ( [Michael et al, 2006], [Zhao et al, 2007] and [Anjum et al, 2011]) revealed sul1, sul2, aadA2, tet(A), tet(B), bla TEM and dfrA14.…”

“…Moreover, some studies used pulsed-field gel electrophoresis to elucidate the spread of S. Derby in slaughterhouses (Giovannacci et al, 2001), or to investigate the genetic diversity of the serovar in France ( [Kerouanton et al, 2007] and [Kerouanton et al, 2010]), Spain (Valdezate et al, 2005), Hong Kong (Ling et al, 2001), China (Xia et al, 2009) or Brazil (Michael et al, 2006). Clinical, food and animal isolates showed a wide range of PFGE and antimicrobial resistance profiles, often either implicated streptomycin, tetracycline, or sulfonamides ( [Valdezate et al, 2005], [Michael et al, 2006], [Gebreyes et al, 2004] and [Clothier et al, 2010]). …”

Salmonella Serogroup C: Current Status of Vaccines and Why They Are Needed

“…(Table 3). The reason for targeting S. Choleraesuis in swine is due to its high carriage rate; it constituted 57.3% of isolates from swine in the United States in 2003 (54,55). Moreover, this serovar is documented as among the most invasive Salmonella serovars.…”

Characterization of β-lactamase- and efflux pump-mediated multiple antibiotic resistance in Salmonella Typhimurium

“…This explains the reason why the susceptibilities of all strains to antibiotics were not increased in the presence of CCCP and PAbN [20]. Furthermore, the intrinsic resistance of WT-ST, CI-ST, and CA-ST to antibiotics could cause the decrease in susceptibility regardless of efflux pump activity [21].…”