The potential of Escherichia coli in enteral feeds to cause food poisoning: a study under simulated ward conditions.

The growth of Escherichia coli over a period of 8 h under simulated ward conditions was compared in feeding systems containing either Clinifeed ISO or Nutrient Broth. In both, counts increased from 10(2) to 10(7) ml-1. Other systems containing Clinifeed ISO were inoculated with E. coli and sampled over 24 h. At 8 and 16 h the contaminated reservoir was replaced, refilled or replaced together with the gastric drip line. When the reservoir was replaced or refilled it was always recontaminated by residual organisms. Even when the reservoir and drip line were replaced, although the contents of the reservoir were sterile, E. coli was still detected in feed collected from the end of the fine-bore tube. Experiments with varying numbers of E. coli in the inoculum demonstrated that even one organism in the reservoir could, within 16 h, multiply to a level that might be harmful, especially to compromised patients.