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Invasive Haemophilus influenzae in Manitoba, Canada, in the postvaccination era

Raymond S W Tsang1, Samira Mubareka, Michelle L Sill

  • 1Vaccine Preventable Bacterial Disease Section, National Microbiology Laboratory, 1015 Arlington Street, Winnipeg, Manitoba, Canada R3E 3R2. raymond_tsang@phac-aspc.gc.ca

Journal of Clinical Microbiology
|April 7, 2006
PubMed

Insights

Invasive Haemophilus influenzae disease in Manitoba shows a shift, with serotype a and nonserotypeable (NST) strains becoming dominant. Serotype a strains are clonal and primarily affect young children, while NST strains are diverse and more common in adults.

Area of Science:

  • Microbiology
  • Epidemiology
  • Genetics

Background:

  • Haemophilus influenzae is a significant cause of invasive bacterial diseases.
  • Historically, serotype b strains were the most common cause of invasive disease.
  • Recent epidemiological shifts necessitate updated characterization of circulating strains.

Purpose of the Study:

  • To investigate the serotype, biotype, genotype, and antibiotic susceptibility of Haemophilus influenzae isolates from invasive disease cases in Manitoba, Canada.
  • To identify trends in the epidemiology of invasive Haemophilus influenzae infections.

Main Methods:

  • Isolates were characterized by serotyping, biotyping, and antibiotic susceptibility testing.
  • Pulsed-field gel electrophoresis (PFGE) was used for DNA fingerprinting.
  • Multilocus sequence typing (MLST) was employed for genotypic analysis.

Main Results:

  • Serotype a and nonserotypeable (NST) strains constituted the majority of the 52 invasive isolates.
  • Serotype a isolates were predominantly biotype II, genetically clonal (ST-23), and associated with younger patients (
  • NST isolates were genetically diverse, belonging to 18 different sequence types, and more frequently isolated from older patients.

Conclusions:

  • The epidemiology of invasive Haemophilus influenzae disease in Manitoba appears to be changing, with a rise in serotype a and NST strains.
  • Serotype a strains exhibit clonal expansion, whereas NST strains represent a genetically diverse population.
  • Increased ampicillin resistance was observed in NST isolates compared to serotypeable strains.

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