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Updated: Aug 11, 2026
Experimental Human Pneumococcal Carriage
Published on: February 15, 2013
Haemophilus influenzae carriage in children attending French day care centers: a molecular epidemiological study
Henri Dabernat1, Marie-Anne Plisson-Sauné, Catherine Delmas
1Laboratoire de Microbiologie, Centre National de Référence des Haemophilus influenzae, Hôpital Purpan, Toulouse Cédex 9, France. dabernat.h@chu-toulouse.fr
Insights
Nasopharyngeal Haemophilus influenzae colonization in young children is dynamic, with high genomic diversity among non-typeable strains. Most children were vaccinated against H. influenzae type b, and no type b strains were detected.
Area of Science:
- Microbiology
- Epidemiology
- Genomics
Background:
- Haemophilus influenzae is a common bacterium colonizing the nasopharynx, particularly in young children.
- The prevalence of specific serotypes and antimicrobial resistance patterns can vary geographically and over time.
- Vaccination against Haemophilus influenzae type b (Hib) has significantly reduced invasive Hib disease.
Purpose of the Study:
- To analyze the nasopharyngeal carriage of Haemophilus influenzae in healthy children under 3 years old.
- To investigate the prevalence of different H. influenzae strains, including antibiotic resistance and genomic diversity.
- To assess the impact of geographic location and season on H. influenzae colonization patterns.
Main Methods:
- Nasopharyngeal samples were collected from 1,683 healthy children aged under 3 years in three French regions during spring and fall 1999.
- Carrier rates, prevalence of capsulated strains (types b, e, f), and beta-lactamase production were determined.
- Pulsed-field gel electrophoresis (PFGE) was used to analyze the genomic diversity of H. influenzae strains.
Main Results:
- The average H. influenzae carrier rate was 40.9%.
- No type b strains were detected, consistent with high Hib vaccine uptake (98.5%).
- Significant genomic diversity was observed, with 366 distinct PFGE patterns among 663 strains, indicating a dynamic colonization process with limited clonal diffusion.
Conclusions:
- Nasopharyngeal colonization by H. influenzae in young children is a dynamic process characterized by high genomic heterogeneity.
- The study highlights the importance of non-typeable H. influenzae strains and their evolving resistance patterns.
- Geographic and temporal factors play a role in shaping the H. influenzae population structure in the nasopharynx.
Abstract:
The nasopharyngeal Haemophilus influenzae flora of healthy children under the age of 3 years attending day care centers in three distinct French geographic areas was analyzed by sampling during two periods, spring 1999 (May and June) and fall 1999 (November and December). The average carrier rate among 1,683 children was 40.9%. The prevalence of capsulated H. influenzae carriers was 0.4% for type f and 0.6% for type e. No type b strains were found among these children, of whom 98.5% had received one or more doses of anti-Haemophilus b vaccine. Among the strains, 44.5% were TEM-type beta-lactamase producers and nine (1.3%) were beta-lactamase-negative ampicillin-resistant strains. Pulsed-field gel electrophoresis restriction patterns showed a large diversity with 366 SmaI patterns from 663 strains. Among the strains isolated during a given period, 33% were isolated simultaneously in more than one area. In each area, depending on the sampling period, 68 to 72% of the strains had new pulsotypes and persistence of 28 to 32% of the strains was noted. For the 297 beta-lactamase-producing strains, 194 patterns were found. The genomic diversity of these strains was comparable to that of the whole set of strains and does not suggest a clonal diffusion. Among the beta-lactamase-producing strains isolated in November and December, depending on the area, 66 to 73% had new pulsotypes with persistence of only 27 to 33% of the strains. In any given geographic area, colonization by H. influenzae appears to be a dynamic process involving a high degree of genomic heterogeneity among the noncapsulated colonizing strains.
