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Effect of the thyroid on faecal shedding of E. coli O157:H7 and Escherichia coli in naturally infected yearling beef cattle *
Author(s) -
Schultz C.L.,
Edrington T.S.,
Schroeder S.B.,
Hallford D.M.,
Genovese K.J.,
Callaway T.R.,
Anderson R.C.,
Nisbet D.J.
Publication year - 2005
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1111/j.1365-2672.2005.02705.x
Subject(s) - hormone , beef cattle , biology , escherichia coli , zoology , triiodothyronine , thyroid , feces , body weight , thyroid hormones , medicine , endocrinology , microbiology and biotechnology , biochemistry , gene
Aims: To determine if thyroid function affects faecal shedding of Escherichia coli O157:H7. Methods and Results: Eight yearling cattle ( n = 4 per treatment group), previously identified as shedding E. coli O157:H7, received either 0 or 10 mg 6‐ N ‐propyl‐2‐thiouracil (PTU) kg −1 BW day −1 for 14 days to reduce serum concentrations of the thyroid hormones, T 3 and T 4 . Animals were monitored daily for changes in faecal shedding of E. coli O157:H7 and E. coli (EC) for the 14‐day treatment period and an additional 7 days post‐treatment. Body weight was measured weekly and serum concentrations of T 3 and T 4 were determined every 3 days. No differences in faecal shedding of E. coli O157:H7 were observed during the 14‐day treatment period. However, compared with control animals, a greater percentage of PTU‐treated cattle ejected E. coli O157:H7 on day 16 (100 vs 25%) and 18 (75 vs 0%) of the post‐treatment period. Serum T 3 was lower in PTU‐treated cattle during the 14‐day treatment period and greater on day 18 of the post‐treatment period. Conclusion: Cattle with chemically altered thyroid hormones had similar shedding patterns of faecal E. coli O157:H7 and EC during the 14‐day treatment period. However, faecal shedding of E. coli O157:H7 tended to be greater, and serum concentrations of T 3 , were greater for PTU‐treated cattle immediately following the termination of PTU treatment. Significance and Impact of the Study: Short‐term chemical inhibition of thyroid hormones had minimal effects on faecal shedding of E. coli O157:H7 in naturally infected cattle. However, a hyperthyroid state as observed postdosing might play a role in the seasonal shedding of E. coli O157:H7 in cattle.