[Microbiological characteristics and spectrum of infections of 108 Streptococcus anginosus isolated].

Background: The aim of the present study was to assess the key microbiologic characteristics aid in the identification of Streptococcus anginosus in the laboratory and know the spectrum of clinical infections it produces.

Methods: From March 1991 to April 1992 all the isolated strains of clinical significant samples were collected. For identification the API 20 STREP (BioMérieux) system was used. The histories of the patients with infection by S. anginosus were retrospectively reviewed to collect clinical and microbiologic data of interest.

Results: The 108 strains of St. anginosus isolated were diminute colonies on sheep blood agar with CO2 enrichment. They had a characteristic smell, were beta-hemolitic or non hemolitic and of the Lancefield group A, C, F, G or not groupable. All had invariable biochemical features in the API 20 STREP: produced acetone and alkaline phosphatase, hydrolized arginine, did not hydrolize hypurate nor did they ferment ribose. Streptococcus anginosus produced purulent infections of different localization: abdominal, head-neck, pleuro-pulmonary, muscle-skeletal, skin and soft tissues and miscellaneous. Most of these infections were polymicrobial (81.5%).

Conclusions: St. anginosus was easily identified in the laboratory by its morphologic characteristics and biochemical reaction in the API 20 STREP. It produced a wide variety of supurative infections, some being severe: cerebral, pulmonary, hepatic, empyema abscess. The identification of this microorganism at a species level should contribute to better recognition as a pathogen of occassionally severe supurative infections.