Quantitative Aspects of the Intestinal Yeast Flora of Swine

SUMMARY: Minimum numbers of viable organisms of the yeast species occurring in the digestive tract of 57 pigs were determined in samples from six sites in each animal (stomach, three sites in the small intestine, caecum, rectum). In 27 animals (47·4%) Candidaslooffii was found in one or more sites in numbers ranging from less than 300 to 9,000,000 viable organisms/g. wet sample. The trend was an increase in numbers towards the anus, with highest counts in the rectum and next highest counts in the caecum. The food eaten influenced the numbers of C. slooffii; food rich in starch apparently increased, while food rich in cellulose and proteins decreased, these numbers. The pig appears to constitute a suitable host for the obligate intestinal saprophyte C. slooffii. Other yeast species found at one or more sites in numbers above 100/g. wet sample (in brackets the number of positive animals) were: Candida krusei (8); Saccharomyces cerevisiae (6); Pichia membranaefaciens (6); C. albicans (3); S. tellustris (C. bovina) (2); S. chevalieri (2); S. oleaceus (2); S. carlsbergensis (2); C. parapsilosis (2); C. tropicalis (2); S. italicus var. melibiosi (1); S. steineri (1); C. utilis (1); Torulopsis glabrata (1); not identified (1). Analysis of the counts of the three most frequent species showed an increase in the anal direction. It is concluded that C. krusei, P. membranaefaciens and S. cerevisiae are facultative intestinal saprophytes of swine.