Comparison of conventional culture methods and two commercial enzyme immunoassays for detection of Salmonella in porcine fecal samples and cecal contents

Diarrhea in growing-finishing swine

Regardless of the etiology of an enteric disease in nursery age to finisher swine, making a prompt and accurate diagnosis is crucial. Eliciting a complete history, assessing clinical signs and pathology, and selecting and interpreting laboratory tests are essential components in achieving this. Early detection and diagnosis of enteric disease is particularly critical in the nursery through finisher phase because of economic impacts. Recurrent topics when discussing control and prevention of enteric diseases are reducing stress and improving pig comfort and reducing or eliminating exposure through sanitation and biosecurity. These are not new concepts; in fact, prior to the advent of antimicrobials, they were the mainstay of treatment of enteric diseases. With concern over the use of antimicrobials in food animal production increasing, exploiting disease ecology to control enteric diseases is increasing in importance. New vaccines and bacterins for postweaning swine enteric diseases are needed tools to exploit the pig's immune system. Recent advances in diagnostic capabilities allow an increase in understanding and exploitation of disease ecology.

Importance of pre-enrichment media for isolation of Salmonella spp. from swine and poultry

The performance of two new (1-day) culture methods, Salmonella Enrichment Broth (SEB) and Revive, and an alternative pre-enrichment broth, designated Universal pre-enrichment broth (UB), was compared to the internationally accepted buffered peptone water (BPW). The study was directed towards detection of Salmonella in 100 faecal samples from porcine and 100 neck-skin samples from poultry. The sensitivity (number of positive cases per method among all the positive cases) of the conventional pre-enrichment in BPW was found to be 0.77 for swine and 0.66 for poultry samples, while a combination of the BPW method with parallel pre-enrichment of the same sample in UB resulted in high sensitivity for swine (0.92) and poultry (0.95) samples. A 2-h pre-enrichment in the non-selective Revive, followed by overnight enrichment in selective broth, resulted in a low sensitivity, particularly for the neck-skin samples (0.16, P = 0.001). The SEB method in the porcine samples resulted in a sensitivity (0.71) comparable to the standard method (P = 0.31). In conclusion, additional pre-enrichment of samples in UB may substantially increase the culture sensitivity. During routine screening of large numbers of samples, it may be advantageous to use SEB rather than standard culturing.