Alterations in the fecal flora of an individual frequently lacking coliforms.

An individual who usually completely lacked or had very low numbers of coliforms in his stool over a period of 19 months was identified. The subject's levels of clostridia and aerobic lactobacilli were elevated as compared with those of our control group. However, these elevated populations of microorganisms were not related to the number of coliforms present in stool samples. The number of coliforms was inversely related to the number of anaerobic lactobacilli. In addition, the absence of coliforms was always accompanied by the absence of fungi. Populations of other prominent groups of intestinal flora were not significantly affected by the number of coliforms present in the intestnal tract. Since ankylosing spondylitis was the only physical abnormality of the subject, the intestinal flora of other individuals positive for histocompatibility antigen B27 who had this disease were examined but were found to be normal. The absence of coliforms from the normal flora of the intestinal tract of the subject had no apparent effect on his general health.