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United States Department of Agriculture

Agricultural Research Service

Title: SALMONELLOSIS OUTBREAK AND SUBSEQUENT SUBCLINICAL INFECTION IN A NEBRASKA BEEF HERD ATTRIBUTABLE TO CLONAL SALMONELLA ISOLATES OF IDENTICAL PFGE GENOTYPE BUT VARIABLE SEROLOGIC PHENOTYPE)

Author
item Keen, James
item Snell, Robert
item He, Yongsheng
item Laegreid, William

Submitted to: Meeting Abstract
Publication Type: Abstract only
Publication Acceptance Date: 10/7/1997
Publication Date: N/A
Citation:

Interpretive Summary:

Technical Abstract: An outbreak of clinical salmonellosis in a 150 head beef cow-calf herd in the Nebraska sandhills was identified by the sudden death of several cows in summer 1996. Over the following year (8/96 to 8/97), no additional clinical cases of salmonellosis occurred and feces and sera from all cows and calves were collected quarterly. Feces were cultured for Salmonella and sera were tested for anti-Salmonella antibodies by blocking ELISA using anti-Salmonella monoclonal antibodies. Initially, a majority of cows and calves were fecal-culture Salmonella positive. Four Salmonella serovars were isolated from the herd including two serogroup B [S. typhimurium (ST) and S. typhimurium copenhagen (STC)], and two serogroup C1 [S. thompson, and S. oranienburg]. Most cows and calves were infected with ST or STC, and many cattle were infected with both ST and STC at a given sampling time. Fecal prevalence rapidly decreased during winter until only a single cow was fecal-positive by 1/97. Pulse-field gel electrophoresis (PFGE) patterns of all ST and STC isolates from the herd were identical; PFGE patterns from the C1 isolates were different from each other and from the ST/STC. These data suggest that the outbreak and subclinical infections were likely attributable to a single genotype ST-STC clone with the capability (by an unidentified mechanism) to vary its O-antigenic factors and thereby vary its serotype between ST and STC.

Last Modified: 8/24/2016
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