Abstract
A total of 116 strains of anaerobic Gram positive cocci (AG+C) were isolated from different clinical sources. 89% of the isolates were characterised and identified, using the Virginia Polytechnic Institute (VPI) system, and compared with 24 culture collection strains. The original descriptions of the isolates studied have been expanded and brought up to date by including additional characterisation tests. An attempt was made to classify 74 of the clinical isolates on the basis of their susceptability to antibiotics and dyes, and of 48 isolates on the basis of their production of the end-products from four sugars. These experiments demonstrated no significant taxonomic criteria, but cephradine followed by vancomycin were highly active agents against (95% and 97% respectively)the cultures of AG+C. A comparative study of amino acid utilization has been made of 39 strains of AG+C. Fifteen of these were clinical isolates. The remaining 24 were reference strains including all of the available named species of AG+C, and are of clinical importance. This study was based on the ability of the organisms to utilize 18 amino acids, using an amino acid analyzer. Quantitative analysis of the cell wall components of the same reference species was also determined. In general the results of the cell wall study confirms the grouping deduced from the amino acid utilization study as well as those of the conventional VPI system. The data obtained from amino acid utilization were subjected to numerical taxonomic analysis, involving an estimate of Gower's general similarity coefficient and clustered by unweighted pair-grouping arithmetic average (UPGMA) linkage by electronic computer. At a similarity level of 80% or greater, all isolates studied were clustered into seven groups. Group A contained the species anaerobia, Group B contained Pc. asaccharolyticus, Pc. aerogenes and Pc. prevotii. Group C was composed of the strains magnus, Pc. anaerobius, Pc. variabilis, Pc. glycinophilus, Pst. micros and Sarcina ventriculi. Group D contained the species Str. constellatus, Str, morbillorum, Pc. saccharolvticus and Megasphaera elsdenii. Group E contained Pst. parvulus, Str. morbillorum, and Pc. niger. Group F and G contained a single species of Veillonella parvula and Pst. anaerobius, respectively. Four strains were clustered separately, these were two species of Pst. productus, and one of each species of Str. morbillorum and Str. intermedius. The possible value of the cell wall components as a taxonomic character together with the taxonomic implication of the amino acid utilization are discussed.