THE IMPORTANCE of antibiotics in medicine is reflected in the tremendous number of scientific papers published on the subject and the many new antibiotics described since penicillin became available. The clinically useful antibiotics at present are derived from the metabolic products of molds or filamentous fungi, from bacteria, and from the Actinomycetes.¹ The search for new antimicrobial agents has encompassed a wide variety of sources,² including human red blood cells, algae, toadstools, hops, the banana, the sweet potato, and even the onion, cabbage, turnip and horse-radish. Clinical studies on such new compounds as viomycin, fumagillin, picromycin,³ and rhodomycin⁴ are in progress. The many rapid developments in this field periodically require evaluation and review. The purpose of this paper is to survey briefly the current status of antibiotics in the treatment of gastrointestinal diseases.

PENICILLINÌý Penicillin⁵ is derived from the mold Pénicillium notatimi. The accepted preparation for clinical use is crystalline