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

BACKGROUND & OBJECTIVES: 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. METHODS: 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. RESULTS: 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. INTERPRETATION & CONCLUSION: 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.

Report of unusual clinical appearance in bacteraemia with nonhaemolytic M-type 58 Streptococcus pyogenes.

BACKGROUND & OBJECTIVES: The occurrence of haemolytic colonies on blood agar often provides the starting point for the laboratory diagnosis of pyogenic streptococci, while non-haemolytic variants could pass unrecognised, leading to a failure of diagnosis. We report the details of two epidemiologically unrelated patients with bacteraemia featuring M-type 58 Streptococcus pyogenes, a seemingly rare cause of human infection in the UK, and briefly review previous reports of infection with non-haemolytic strains of this species. METHODS: Case notes of the two patients were reviewed. Isolates obtained from clinical specimens were recovered and identified and cultured on horse blood agar to observe pattern of haemolysis. RESULTS: In the first case, of a 75 year-old man with leukaemia and a retropharyngeal abscess, the isolate was consistently non-haemolytic, probably due to a failure to produce streptolysin S as has been described before in a small number of reports involving various M-types. In the second case, of an 84 year-old woman with dermatitis and septicaemia, the organism was principally beta-haemolytic but with no haemolysis on aerobic culture where the colonies were well spaced, a phenomenon thought to be associated with abundant production of serum opacity factor (OF). INTERPRETATION & CONCLUSION: These cases are a reminder that misleading cultural appearances can occur with S. pyogenes and that OF positive strains can produce poor haemolysis on aerobic culture, or fail even to do so at all.

Changing incidence of detected streptococcal bacteraemia in North Yorkshire, England.

BACKGROUND & OBJECTIVES: Streptococcal bacteraemia remains a major and challenging clinical problem throughout the world. The epidemiology of these infections appears to be changing. In the present study we analysed the data collected over a period of 20 yr (1978-1999) to throw light on this. METHODS: Laboratory records of all patients yielding clinically significant, non-pneumococcal, nonenterococcal streptococcal bacteraemia were reviewed for the decades 1978-1988 and 1990-1999 in the two districts (combined population 260,000). RESULTS: From a total of 3134 patients with detected bacteraemia 338 (10.8%) yielded streptococci. The organisms comprised: in the beta-haemolytic group (n=169), GAS (32%), GBS (34%), GCS (5%), GGS (28%), GRS (1%); in the non-haemolytic/Streptococcus milleri group (n=160): S. milleri (21%), S. bovis (10%), S. sanguis (30%), S.mitis (10%), S. oralis (8%) and other 'viridans' streptococci (20%); nine isolates were of anaerobic streptococci. There was a steady increase in the number of blood cultures submitted for investigation during the period and streptococcal isolations of all species rose in proportion (approximately x 2.5) in the second decade compared with the first. Complementary data on the occurrence of necrotising fasciitis and toxic shock syndrome in these districts suggested a real increase in the occurrence of serious forms of GAS infection. INTERPRETATION & CONCLUSION: An increase in the level of detected streptococcal bacteraemia was seen in this part of England over 20 yr, involving a wide variety of different streptococcal species. This represented both improved ascertainment of infection and an increase in the burden of disease in the population.