Group C streptococci in human infection: a study of 308 isolates with clinical correlations

Abstract

SUMMARYA collection of 308 clinical isolates of β-haemolytic Lancefield group C streptococci was assembled from laboratories in England. Nigeria and New Zealand. Of these, 276 isolates wereStreptococcus equisimilis. 23S. milleriand nineS. zooepidemicus. Isolates ofS. equisimilisin the African collection, though few, gave higher rates of lactose and raffinose fermentation, aesculin hydrolysis and positive α-galactosidase reactions than those from elsewhere. Erythromycin resistance was found in 1·9% of the English isolates ofS. equisimilis.Strains from superficial infections accounted for 88 % of the collection and were most commonly isolated from the upper respiratory tract, skin or wounds. Amongst the 36 patients yielding isolates from deep sitesS. equisimiliswas found in septicaemia, cellulitis, abscess, peritonitis, septic arthritis, pneumonia, mycotic aneurysm and acute epiglottitis.S. milleriwas found in abdominal abscesses, peritonitis, pleural empyema and osteomyelitis andS. zooepidemicuswas found in septicaemia, pneumonia, meningitis and septic arthritis. Within the collection an unselected general catchment of 214 isolates of group C streptococci from the laboratories in Yorkshire showed the following species: from 199 superficial infections 94%S. equisimilis. 5%S. milleriand 1%S. zooepidemicusand 15 patients with deeper, more agressive infections 67, 27 and 6·7% of these species respectively.