Effects of Disinfectant Treatments on the Bacterial Flora of the Umbilicus of Neonatal Foals1

Abstract

One hundred thirty-nine foals were evaluated for the effects of umbilical treatment methods on the types and numbers of bacteria found on the umbilicus. The umbilicus was cultured aerobically and anaerobically at 10 min following birth upon the natural severing of the umbilical cord. The umbilical stump was treated with one of four disinfectants and then cultured again, when the foals were 6 h of age, before a second treatment. The following treatments were evaluated: group A, 2% iodine; group B, 0.5% chlorhexidine diacetate; group C, 1% povidone iodine; group D, 7% iodine tincture; and group E, no treatment. Coagulase-negative staphylococci were the most prevalent organisms found in the umbilical stump at birth (59% of all foals); diphtheroids were the next most common (40%). All other bacteria and fungi identified had a prevalence of less than 20%, most less than 10%. The change in bacterial flora at 6 h was similar between the groups receiving the 2% iodine and 1% povidone iodine dips. These two groups had approximately the same frequency ranking of microflora seen at birth, and both showed an increase in the relative number of colonies that could be recovered at 6 h. Group B had a prevalence pattern similar to that for groups A, B, and E at 6 h but had significantly reduced bacterial numbers. While 7% iodine produced potent bacterial reductions, complications of rapid desiccation, sloughing of adjacent skin, and breaking off of the desiccated stump, leaving a patency, mitigate against its use. Chlorhexidine (0.5%) appeared to be the most effective of the treatments in reducing bacterial numbers without tissue destruction.