Effect of oral antibiotics on intestinal production of propionic acid.

BACKGROUND Propionic acid derived from colonic bacterial fermentation contributes substantially to overall propionate load in children with disorders of propionate metabolism, and its reduction is important for adequate metabolic control. AIMS To evaluate the in vitro and in vivo effects of antibiotic treatment on propionate production by colonic bacteria, and plasma propionate concentrations in a child with propionic acidaemia. METHODS In vitro fermentation techniques were used to study the effects of addition of antibiotics (metronidazole, clindamycin, erythromycin, and vancomycin) on net faecal production of short chain fatty acids including propionic acid. Courses of oral antibiotics of 7 days duration were used to assess the in vivo effects on faecal propionate production and metabolic control including plasma propionate concentrations. RESULTS Metronidazole produced the largest and most consistent reduction (77-84%) in the production in vitro of propionate from faecal homogenates. Oral administration of metronidazole reduced faecal propionate production by 43% within 24 hours of treatment; a 7 day course virtually eliminated it for the next 3 weeks. These reductions were accompanied by substantially lowered plasma propionate concentrations during the same period. CONCLUSIONS Intermittent courses of oral metronidazole might be as effective as continuous treatment in reducing gut propionate production in children with disorders of propionate metabolism.