Preliminary investigations of the distribution of Escherichia coli O149 in sows, piglets, and their environment.

Little is known about the sources and kinetics of enterotoxigenic Escherichia coli colonization in pigs during the pre-and post-weaning period. In this study, farrowing pens, sows, and piglets were tested for the presence of E. coli O149 by real-time polymerase chain reaction (PCR) after bacterial culture pre-enrichment on 2 farms, one with a history of post-weaning diarrhea (problem farm - PF) and the other without such a history (non-problem farm - NPF). Unlike those on the PF, the sows from the NPF did not carry E. coli O149 before parturition, although they were colonized to frequencies similar to animals on the PF soon afterwards. Most piglets from the NPF were colonized within a week after birth, whereas only a small proportion of those on the PF were colonized during that period. No difference was observed in the frequency of piglet colonization at the 2 farms either at weaning or during the following week. Post-weaning diarrhea (PWD), which is caused by enterotoxigenic E. coli (ETEC), is a multifactorial disease. The presence of ETEC alone is not always sufficient for the disease to develop. Many other factors are considered to be associated with the occurrence of PWD, including feed type (1,2), feeding regimen (1,3,4), the presence of other infectious agents (3,5), weaning age, and weight (6). Weaning, which is considered to be a major physiological and psychological stress factor, is critical for the disease to occur (7). Although piglets are already colonized with ETEC before weaning (4,8), on many farms, clinical disease occurs only after weaning (1). Both sows (9,10) and the environment (6) could be possible sources of infection for piglets, but results from previous studies have not resolved this issue because of the low sensitivity of ETEC detection methods. This study provides preliminary data based on a sensitive detection method for E. coli O149 in pigs and their environment. The results demonstrate the potential of real-time PCR for future studies on this topic.