Effect of oral antibiotics on intestinal production of propionic acid

Background-Propionic acid derived from colonic bacterial fermentation contr ibutes substantially to overall propionate load in children with disorders of propionate metabolism, and its reduction is important for adequate metab olic control. Aims-To evaluate the in vitro and in vivo effects of antibiotic treatment o n propionate production by colonic bacteria, and plasma propionate concentr ations 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 vanc omycin) on net faecal production of short chain fatty acids including propi onic acid. Courses of oral antibiotics of 7 days duration were used to asse ss the in vivo effects on faecal propionate production and metabolic contro l including plasma propionate concentrations. Results-Metronidazole produced the largest and most consistent reduction (7 7-84%) in the production in vitro of propionate from faecal homogenates. Or al administration of metronidazole reduced faecal propionate production by 43% within 24 hours of treatment; a 7 day course virtually eliminated it fo r the next 3 weeks. These reductions were accompanied by substantially lowe red plasma propionate concentrations during the same period. Conclusions-Intermittent courses of oral metronidazole might be as effectiv e as continuous treatment in reducing gut propionate production in children with disorders of propionate metabolism.