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Spectrum of disease in bacteraemic patients during a Streptococcus pyogenes serotype M-1 epidemic in Norway in 1988
A Bucher1, P R Martin, E A Høiby
1Department of Infectious Diseases, Ullevål University Hospital, Oslo, Norway.
Abstract:
All 87 known cases of bacteraemia due to Streptococcus pyogenes (beta-haemolytic group A streptococci) occurring during the peak of a nationwide outbreak in Norway (population 4.2 million) between January and June 1988 were reviewed. Clinical features varied widely and appeared largely to be dependent on the patients' age. The case fatality rate ranged from 11% in the age group under 30 years to 44% in patients over 60 years. Clinical complications such as shock, severe renal or respiratory failure or serious local infection occurred particularly in 30-to 59-year old individuals. Shock was manifest in 32% of the patients and carried a 68% case fatality rate. Chronic heart disease in the elderly and pneumonia seemed to be associated with a fatal outcome. In the 25 patients (29%) who died the disease showed a fulminant course, 80% dying within 48 hours after admission. However, 56% of the patients had experienced symptoms for more than two days before admission, suggesting that early diagnosis and treatment might possibly have prevented the development of a serious disease. This study revealed a wide spectrum of clinical manifestations in bacteraemia cases in a unique epidemiological situation caused largely by a single serotype of Streptococcus pyogenes; 89% of the 27 preserved bacteraemia strains carried the M-1 antigen. The observations call attention to the ability of these organisms to cause fulminant clinical illness, indicating a probable increase in both invasiveness and toxicity of group A streptococci responsible for the epidemic.
Insights
During a 1988 Norway outbreak, Streptococcus pyogenes caused severe illness, especially in older adults. Early diagnosis of this invasive bacterial infection is crucial to prevent severe outcomes and fatalities.
Area of Science:
- Infectious Diseases
- Epidemiology
- Bacteriology
Background:
- A nationwide outbreak of bacteraemia due to Streptococcus pyogenes (group A streptococci) occurred in Norway in 1988.
- This event provided a unique epidemiological situation to study the clinical manifestations of this bacterial infection.
Purpose of the Study:
- To review and analyze the clinical features and outcomes of 87 cases of Streptococcus pyogenes bacteraemia during the outbreak.
- To understand the impact of patient age and pre-existing conditions on disease severity and fatality rates.
- To investigate the characteristics of the causative bacterial strains, particularly the M-1 antigen.
Main Methods:
- Retrospective review of all 87 documented cases of Streptococcus pyogenes bacteraemia during the peak outbreak period (January-June 1988).
- Analysis of clinical data, patient demographics, complications, and outcomes, including case fatality rates.
- Microbiological analysis of preserved strains to identify serotype and M-antigen prevalence.
Main Results:
- Clinical presentation varied significantly with age; fatality rates increased from 11% in those under 30 to 44% in patients over 60.
- Severe complications like shock (32% of patients, 68% fatality), renal/respiratory failure, and local infections were common in middle-aged individuals (30-59).
- The majority of strains (89%) carried the M-1 antigen, suggesting a specific, highly invasive serotype was responsible for the epidemic.
Conclusions:
- Streptococcus pyogenes bacteraemia during this outbreak exhibited a wide spectrum of clinical illness, influenced by patient age.
- The organism demonstrated significant invasiveness and toxicity, leading to fulminant disease and high mortality, particularly in older patients.
- Delayed diagnosis (over two days of symptoms before admission in 56% of cases) likely contributed to severe outcomes, highlighting the need for prompt medical attention.