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Invasive group A streptococcal infections, clinical manifestations and their predictors, Montreal, 1995-2001

Maria-Graciela Hollm-Delgado1, Robert Allard, Pierre A Pilon

  • 1Direction de Santé Publique, Montréal, Québec, Canada.

Emerging Infectious Diseases
|February 12, 2005
PubMed

Insights

Invasive group A streptococcal infections (IGASI) showed a rising risk of pneumonia but a falling risk of soft-tissue infections between 1995-2001. Host and environmental factors, not specific M1/M3 serotypes, likely influenced these clinical changes.

Area of Science:

  • Infectious Diseases
  • Epidemiology
  • Microbiology

Background:

  • Invasive group A streptococcal infections (IGASI) pose a significant public health concern.
  • Understanding temporal trends and clinical manifestations of IGASI is crucial for effective public health strategies.
  • Previous research has not fully elucidated the factors driving changes in IGASI clinical presentations.

Purpose of the Study:

  • To analyze the incidence and clinical manifestations of IGASI in Montreal from 1995 to 2001.
  • To investigate temporal trends in the occurrence of pneumonia and soft-tissue infections associated with IGASI.
  • To explore the role of specific serotypes and host/environmental factors in IGASI clinical outcomes.

Main Methods:

  • Passive population-based surveillance was employed to identify IGASI cases.
  • Data on clinical manifestations, serotypes, patient demographics, and underlying conditions were collected.
  • Statistical analyses, including odds ratios and confidence intervals, were used to assess temporal trends and associations.

Main Results:

  • A total of 306 IGASI cases were identified, with an average annual incidence of 2.4 per 100,000 persons and a 14% mortality rate.
  • The incidence of pneumonia among IGASI cases significantly increased from 0.06 to 0.50 per 100,000 between 1995 and 2000 (OR=1.21).
  • Conversely, the odds of soft-tissue infections decreased (OR=0.86), while serotypes M1 and M3, though common, were not linked to specific manifestations.

Conclusions:

  • Temporal shifts in IGASI clinical patterns, specifically an increase in pneumonia and decrease in soft-tissue infections, were observed.
  • The development of specific clinical manifestations appears to be influenced more by host and environmental factors than by the infecting serotype.
  • Further research is needed to identify the specific host and environmental factors contributing to these observed temporal changes in IGASI.

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