ABSTRACT
Clostridia are frequently present in the normal flora of the human gastrointestinal (GI) tract. This chapter reviews Clostridia as components of the "normal" human GI flora and to review factors which may affect the presence of Clostridia in the gut. Most of gut flora of infants had necrotizing enterocolitis and probably received antimicrobial therapy prior to having cultures performed. Diet has a significant impact on the flora of infants. Motility of the gut is important in determining the distribution of bacteria in the bowel; factors that impair motility may lead to proliferation of bacteria, including Clostridia, within the bowel lumen. The exception to this is the case of newborn infants who have congenital obstruction of the GI tract. Administration of certain antimicrobial agents may have a profound impact on the human fecal flora. The polymyxins, aminoglycosides, and vancomycin are poorly excreted by the liver and undoubtedly have a minimal impact on Clostridia in the gut.
