The acute phase response in pigs experimentally infected with Escherichia coli and treated with systemic bactericidal antibiotics

Abstract

The objective of this study was to monitor the acute phase response (APR) in pigs experimentally infected with a known enterotoxogenic strain of Escherichia coli ( E. coli) followed by treatment with a systemic bactericidal antibiotic to evaluate a model of acute enterotoxemia. The APR was determined by measuring rectal temperature (RT) and serum concentration of cortisol (CS), C-reactive protein (CRP), haptoglobin (HG), tumor necrosis factor-alpha (TNF-α), and interferon-gamma (IFN-γ). Twenty-four single source, male, 24-day-old, crossbred pigs were used for this study. Twelve of the pigs were non-surgically cannulated for blood collection and 12 were used for RT monitoring. All pigs received an oral dose of E. coli K88 (2.4×10 8 colony-forming units). Five hours later, six pigs in each group received an intramuscular injection of 0.5 ml of saline and the remaining six received an intramuscular injection of antibiotic (25 mg of Ceftiofur HCl in 0.5 ml). Data collection occurred hourly from −1 to 5 h post- E. coli, then every 30 min between 5 and 8 h, and at 24 h post- E. coli. Prior to antibiotic treatment, RT increased ( P<0.0001) in both treatment groups. After antibiotic treatment, RT, CS, and CRP were all higher in the antibiotic treatment groups ( P<0.05) compared to the saline groups. An increase in HG and IFN-γ ( P<0.01) was observed in both groups, while TNF-α remained unchanged. Results indicate that systemic bactericidal antibiotic treatment post- E. coli induces an APR similar to that in other studies using different models of enterotoxemia. Therefore, we propose that this approach of eliciting an acute enterotoxemia provides a more natural scenario encountered in a swine production unit.