Erythromycin and anaerobes: in vitro aspects.

Anaerobic organisms are being increasingly recognised as important causes of serious infection in man. Sampling procedures, transport of specimens and laboratory techniques need to be constantly monitored and improved if the causative organisms are to be consistently recovered from clinical specimens. Once the organisms have been isolated, their susceptibility to antibiotics should be determined so that the clinician can base his antibiotic therapy on reliable laboratory results. There are many variables in the sensitivity testing of anaerobes--these may account for the difficulty reported by some workers in obtaining consistently reliable results with some antibiotics, including erythromycin. These problems can be largely overcome if a standardised procedure is adopted. It is clear from the published data that erythromycin has considerable in vitro activity against many strains of anaerobic bacteria, both sporing and non-sporing. There is a broad spectrum of activity with some strains being very sensitive and a few strains being resistant. M.I.C. values range from 0.04 microgram./ml. to 20 microgram./ml. or more. Further studies are now needed to assess the role of erythromycin in the treatment of anaerobic infections in vivo.