Group C streptococci isolated from throat swabs: a laboratory and clinical study.

Abstract

AIMS: To determine the prevalence of beta haemolytic, Lancefield group C streptococci in throat swabs taken in routine clinical practice, and correlate the species identified with presenting clinical features. METHODS: One year, laboratory based prospective study, using a questionnaire to elicit clinical information. RESULTS: 4.4% of throat swabs yielded group C streptococci, of which 38% belonged to S equisimilis and 53% to S anginosus-milleri group (SAM). Pyrexia was more common in patients with S equisimilis, but other clinical features did not differ significantly between the two groups. No S zooepidemicus was isolated. CONCLUSIONS: Species identification of group C streptococci from throat swabs does not appear to be clinically useful in this patient population. However, the prevalence and spectrum of organisms is similar to that reported in N America, where studies suggest a possible role in some cases of severe pharyngitis. Observational studies such as this lack power to resolve the issue of pathogenicity, for which a placebo controlled trial of antibiotic treatment is ideally required.