Intermittent Therapy With Metronidazole for Relapse of Pseudomembranous Colitis

Abstract

<h3>To the Editor.—</h3> Serendipity and the often-martyred guinea pig brought us the solution to both cause and treatment of postantibiotic diarrhea from the benches of three superb laboratories.¹Unfortunately, serendipity neither obeys Sutton's Law nor guarantees its work, since 14% to 20% of patients who dutifully swallow from $180 to $460 worth of vancomycin hydrochloride oral solution (with or without cholestyramine chaser) have a microbiologic and clinical relapse of pseudomembranous colitis.²Unfortunately, the encouraging clinical and economic success of metronidazole ($90 per ten days) as a cheap and effective alternative has been marred by a similar 15% relapse rate.³The speculation that this relapse is related to suboptimal gut levels of antibiotics is certainly not borne out in the case of nonabsorbable vancomycin hydrochloride but is still controversial with the rapid small intestinal absorption of metronidazole. The minimal inhibitory concentration of the organisms isolated in relapse is