The Use of Penicillin and Streptomycin in the Routine Cultivation of Amebae from Fecal Specimens

Abstract

Summary 1. Four hundred and twelve fecal specimens from two surveys were used to evaluate (a) the effect of adding antibiotics to the culture medium employed in the diagnosis of intestinal amebae and (b) cultivation as a diagnostic technique in comparison with other procedures performed on the same specimen. The cultivation routine included the examination of permanently stained films prepared from culture sediments preserved in PVA-fixative. This type of examination facilitated the identification of organisms and increased the number of infections found. 2. The addition of small amounts of penicillin G sodium and streptomycin sulfate to LER medium significantly increased the number of infections of intestinal amebae found in both old, normally passed specimens (Survey I) and fresh, post-cathartic specimens (Survey II). In general, the individual species reacted similarly to the addition of the antibiotics. 3. As a diagnostic technique, cultivation was ineffective with old, normally-passed specimens, but superior to the other techniques used (concentration and stained smears) when fresh, post-cathartic specimens were examined. These results indicate that cultivation would not be a worthwhile routine technique for laboratories that usually receive mailed specimens (for example, public health laboratories), but would be advisable in clinics and hospitals. When fresh specimens are available, it is believed that a good routine consists of a cultivation technique (including stained preparations) for the identification of trophozoites and a concentration technique for the recovery of cysts.