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Title: Multi-Drug Resistance among Salmonella spp. Isolated from Food Animals

item Cray, Paula
item Jackson, Charlene
item Frye, Jonathan
item Haro, Jovita
item McGlinchey, Beth
item Hall, Mary
item Pearson-Gresham, Cheryl
item Plumblee Lawrence, Jodie
item CRAY, JR, W.C. - Food Safety Inspection Service (FSIS)
item NARRANG, N - Food Safety Inspection Service (FSIS)
item LEVINE, J - Food Safety Inspection Service (FSIS)
item ANANDARAMAN, N - Food Safety Inspection Service (FSIS)

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 4/2/2009
Publication Date: 4/2/2009
Citation: Fedorka-Cray, P.J., Jackson, C.R., Frye, J.G., Haro, J. McGlinchey, B., Hall, M.C., Gresham, C., Plumblee, J.R., Cray, W.C., Narang, N. Multi-Drug Resistance among Salmonella spp. Isolated from Food Animals [abstract]. Conference on Food Safety and Public Health Frontier: Minimizing Antibiotic Resistance Transmission through the Food Chain. April 2-3, 2009, Arlington, Virginia. P. 15.

Interpretive Summary: The United States and Europe have evolved different approaches for controlling Salmonella on raw poultry products. Additionally, the methods used to test poultry products for the presence of Salmonella vary greatly from nation-to-nation. The purpose of this popular article is to discuss the potential implications associated with these differences.

Technical Abstract: Introduction: Since the early 1990’s there has been increasing awareness and concern regarding the development of antimicrobial resistance among bacteria of public health significance. Of particular concern starting in 2000, was the emergence of multiple drug resistant (MDR) Salmonella Newport. However, MDR among Newport isolates appears to be declining while other serotypes exhibit increased MDR. Purpose: The purpose of this study was to determine the trend of MDR among the top Salmonella serotypes by animal source submitted to the animal arm of NARMS from 1997 through 2008. Methods: Isolates submitted to NARMS were tested for susceptibility to 14 core antimicrobials using a custom made panel and a semi-automated broth microdilution system (Sensititre, Trek Diagnostics, Cleveland, OH). Isolates were further characterized by pulsed field gel electrophoresis (PFGE) as part of the USDA VetNet program. MDR is defined as resistance to greater than or equal to 2 antimicrobials. Results: Collectively, and regardless of serotype, from 1997 through 2008 MDR appears most often among Salmonella serotypes originating from turkey (52.1%) compared to swine (38.4%), chickens (30.6%) and cattle (22.9%). MDR for the top 3 serotypes in 2008 by source were (increase, decrease or no change is indicated from 2007): Turkeys - Hadar (84.6%, n=39,increase), Saintpaul (25.0%, n=16,decrease), and Schwarzengrund (22.2%, n=9,increase); swine – Derby (72.0 %, n=25,increase), Infantis (0%, n=15,decrease) and Saintpaul (0%, n=6, no change); chickens - Kentucky (49.3%, n=219,increase), Enteritidis (0.9 %, n=115,decrease) and Heidelberg (23.4 %, n=94, decrease); and cattle – Montevideo (1.9%, n=105,increase), Dublin (87.3%, n=55,increase), and Newport (74.2%, n=31, decrease). PFGE analysis indicated a high degree of heterogeneity among the isolates. Isolates which were indistinguishable by PFGE were not necessarily indistinguishable by phenotypic analysis. Significance: These data indicate that phenotypic and genotypic characterization of MDR varies by serotype and source. Interestingly, MDR Newport is now the third most common serotype among cattle isolates and is exhibiting decreased MDR. Continued monitoring and further characterization of isolates is warranted.