Submitted to: Emerging Infectious Diseases
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/2/2002
Publication Date: 3/3/2003
Citation: FEDER, I.E., WALLACE, F.M., GRAY, J.T., FRATAMICO, P.M., CRAY, P.J., PEARCE, R., CALL, J.E., PERRINE, R., LUCHANSKY, J.B. THE ISOLATION OF ESCHERICHIA COLI 0157:H7 FROM INTACT COLON SAMPLES OF SWINE AT A SWINE SLAUGHTER FACILITY. EMERGING INFECTIOUS DISEASES. 2003. vol. 9. No. 3. Interpretive Summary: Escherichia coli O157:H7 was first documented as a human pathogen in 1982 and is the leading cause of hemolytic uremic syndrome (HUS)in the United States. Very small numbers of E. coli O157:H7 can cause HUS, a potentially fatal kidney disease, particularly in children and the elderly. Additionally, E. coli O157:H7 infection can result in a bloody or a non-bloody diarrhea. In the past two decades, disease due to E. coli O157:H7 has been increasing. Cattle feces are the most significant reservoir of E. coli O157:H7 with ground beef being the most common means of human infection. However, contaminated water and other foods have been implicated as vehicles of infection, presumably due to contamination with cattle feces containing E. coli O157:H7. The epidemiology of E. coli O157:H7 has become an important topic, and the need to evaluate other potential E. coli O157:H7 fecal reservoirs has been recognized. E. coli O157:H7 has been found in the feces of swine in Japan and Norway; but, to date, there have been no reports of E. coli O157:H7 isolates from the feces of swine in the United States. In this study, tests were conducted to determine the presence of E. coli O157:H7 in the feces of swine from a slaughterhouse in the United States. Using a bacteriological method, E. coli O157:H7 was isolated from the feces of 2.0% (6/305) of the pig colons tested. The E. coli O157:H7 strains harbored the genes that are necessary for the organism to cause disease. This is the first study that provides evidence that pigs in the United States can harbor potentially pathogenic E. coli O157:H7.
Technical Abstract: The prevalence of Escherichia coli O157:H7 in pig feces was examined at a swine slaughter facility. Fecal samples recovered from the distal colon of 305 eviscerated pigs were enriched in brilliant green bile broth followed by anti-E. coli O157 immunomagnetic bead separation. Beads were plated onto sorbitol MacConkey (SMAC), cefixime/tellurite (CT)-SMAC and Rainbow O157 agars. Non-sorbitol fermenting colonies from SMAC and CT-SMAC agars and black colonies from Rainbow O157 agar were tested for the presence of beta-glucuronidase and the ability to ferment lactose using E. coli broth containing 4-methylumbelliferyl-beta-D-glucuronide (MUG) and MacConkey broth, respectively. Lactose positive and MUG negative isolates that were also O157 positive by latex agglutination were further characterized using the PCR to confirm the presence of the O157-antigen-encoding region (rfbO157), the H7 flagellar (fliCH7), Shiga toxin 1 (stx1), Shiga toxin 2 (stx2), and the intimin protein (eaeA) genes. Six of the 305 fecal samples were positive for the rfbO157, fliCH7, stx1, and eaeA genes. Four of the six were also positive for the stx2 gene. All six were indistinguishable O157:H7 isolates by ribotyping. We show here that pigs in the United States can be a reservoir for E. coli O157:H7.