This means that the outcome which is E.Coli diarrhoea in this case, is associated with the exposure, the alphalpha sprouts. The confidence interval is 7.5 to 545.7. Since the confidence interval does not include 1, the Odds ratio is significant, indicating that there is a positive association between exposure and outcome. Confidence interval is an interval estimate of population parameter, measuring as the interval which is likely to include the parameter given. Most of the times, the confidence interval is qualified as "95% confidence interval." The end points of this interval are known as confidence limits. In this case, the end points are 7.5 and 545.7.
Just because there is statistical association between alphalpha sprouts and E.Coli diarrhoea, it does not mean that there exists a cause-effect relationship between alphalpha sprouts and E.CColi diarrhoea. There are five aspects which have to be examined before determining the causality. The first one is the strength of association. In this case, it is the Odds ratio. The greater the Odds ratio, the greater is the association. The Odds ratio is 29 which means that the strength of association is significant. Other four aspects which need to be determined are dose-response relationship, consistency of association, temporally correct association and biological plausibility. Since we do not have information about these aspects, it cannot be positively said that there exists a cause-effect relationship between alphalpha sprouts and E.Coli