Streptococcus milleri group bacteraemia in North Yorkshire, England (1989-2000)

Though carriage and local infection with organisms of the Streptococcus milleri group (SMG) are regular in clinical practice, bacteraemia is infrequent in man. The objective of the present study was to give an account of our experience with the SMG bacteraemia over a period of 12 yr in North Yorkshire.

The laboratory and clinical records of all clinically significant cases of SMG bacteraemia in our district general hospital catchment (combined population 260,000) were reviewed for the 12 yr period from 1989 to 2000. Viable isolates were recovered, species identified, and minimum inhibitory concentration (MIC) determined.

Twenty nine episodes of infection gave an annual incidence of 0.93 cases per 100,000 population. Infections included abscess, pneumonia, septic arthritis, genital and urinary tract infections, endocarditis and diffuse septicaemia. Patient ages ranged from 18 to 90 yr but most patients were elderly, 82 per cent had evident predisposing conditions and mortality rate was 10 per cent. Species determination of the 22 isolates showed S. anginosus (64%), S. constellatus (27%) and S. intermedius (9%). Nearly all isolates were non-haemolytic and Lancefield grouping showed carriage of the F antigen (in 41%), C (14%) and no detected group (45%). Most of the isolates were susceptible to the antimicrobials tested.

Bacteraemia with SMG organisms was infrequent, often opportunistic and featured a low overall mortality rate. Intra-abdominal sepsis was the local feature in 16 (55%) of the patients and 9 (31%) of the total patient group showed abscess or empyema. There was a low rate of antibiotic resistance in these organisms from bloodstream infection.