An Approach to the Taxonomy of Gram-positive Anaerobic Cocci 1. Isolation and Identification

Abstract

The aim of this study was to collect and identify fresh isolates of Gram-positive anaerobic cocci (GPAC) from clinical materials as a basis for the study of taxonomy of GPAC. A total of 116 strains of GPAC, isolated from clinical materials collected from the Department of Microbiology, in St. Lukes Hospital, Guilford and St. Thomas Hospital, London, were investigated. The reference strains were obtained from the American Type Culture Collection (ATCC), Virginia Polytechnic Institute and State University (VPI) and the National Collection of Industrial Bacteria (NCIB). GPAC were identified on the basis of morphology, biochemical examination and the detection of the end products from the fermentation in peptone yeast extract glucose or chopped meat glucose media by means of Gas Liquid Chromatography (GLC). All of the strains studied were obligately anaerobic Gram-positive cocci (GPAC). They occurred in singles, pairs, tetrads, short or long chains. Peptone yeast extract without addition of carbohydrate supported their growth. The strains grew at 37C. The G.L.C. profiles showed that all strains produced acetic acid and lactic acid. One hundred and three (89%) out of 116 isolates were considered to be different from each other at the species level. These were Peptostreptococcus (Pst.) anaerobius (26.7%), Peptococcus (Pc.) magnus (19%), Streptococcus (Str.) asaccharolyticus (6.9%), Peptostreptococcus (Pst.) micros (3.5%), Peptococcus (Pc.) asaccharolyticus (2.6%), Gaffkya (G.) anaerobia (1.7%), and Megosphaera (M.) elsdenni (0.9%). Thirteen (11.1%) out of 116 strains could not be speciated.