Haemophilus influenzae Carriage in Children Attending French Day Care Centers: a Molecular Epidemiological Study

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 betalactamase-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-lactamaseproducing 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.Haemophilus influenzae is one of the main bacterial species causing infection in children. Encapsulated strains are responsible for a variety of invasive diseases, the most frequent being meningitis, but epiglottitis, arthritis, pneumonia, and cellulitis also occur (36). These invasive diseases have decreased sharply since the generalization of anti-Haemophilus b (anti-Hib) vaccination (22, 37). Noncapsulated strains frequently cause acute otitis media in children (6,20,29,32). H. influenzae is often part of the nasopharynx flora and is frequently found in the upper respiratory tract of healthy children, with reported carriage rates of up to 60% (12,17,23,32).In the study of Faden et al. (9), 200 children were monitored from birth through to 2 years of age to determine the nasopharyngeal colonization pattern of nontypeable H. influenzae. Forty-four percent of the children were colonized on one or more occasions, and the acquisition rate was greatest in the first year. Colonization mainly involves a dominant strain which can be followed by a series of other strains (1,9,15,24). The level of carriage varies according to different factors, i.e., age, siblings, and living conditions. All of these factors can also have repercussions on the carriage of strains resistant to antibiotics or encapsulated type b strains. Anti-Hib vaccination has led to a sharp drop in the carriage of encapsulated type b strains (33).The turnove...

Characteristics of Streptococcus pneumoniae , Haemophilus influenzae , and Moraxella catarrhalis Isolated from the Nasopharynges of Asymptomatic Children and Molecular Analysis of S. pneumoniae and H. influenzae Strain Replacement in the Nasopharynx

“…The incidences of ␤-lactamase-positive H. influenzae strains isolated from the nasopharynx vary greatly among countries, from 1.8% in The Netherlands (26) to 20% in Portugal (7) and 47.4% in France (4). In this study, only five isolates of H. influenzae (3.7%) produced ␤-lactamase.…”

“…Despite the high consumption of ␤-lactams in Poland, the frequency of ␤-lactamase-positive H. influenzae strains isolated from lower RTIs remains low (16). The data from a recent multicenter study showed that 0% of encapsulated and 4.4% of nontypeable H. influenzae strains isolated between 1996 and 2001 from cases of community-acquired lower RTIs in Poland were ␤-lactamase (4,26). In a previous study in England (14), the overall H. influenzae type b nasopharyngeal carriage rate among children 1 to 4 years old was 3.97% before routine vaccination was introduced, but following the introduction of vaccination, the rate of H. influenzae type b (Hib) isolation decreased to 0.7%.…”

Pharyngeal Colonization Dynamics of Haemophilus influenzae and Haemophilus haemolyticus in Healthy Adult Carriers

“…Thus, understanding the dynamics of H. influenzae colonization forms the foundation for understanding the natural history of diseases caused by this bacterium. While previous studies have investigated H. influenzae pharyngeal colonization among healthy adults (4) and among individuals at risk for H. influenzae infections, such as children attending day care centers (8,14,56), patients with cystic fibrosis (49), and adults with COPD (38,43), no previous reports have documented colonization with H. haemolyticus in population-based studies of healthy adults. Pharyngeal colonization with nonhemolytic H. haemolyticus has only recently been described (16,39).…”

High Rates of Transmission of and Colonization by Streptococcus pneumoniae and Haemophilus influenzae within a Day Care Center Revealed in a Longitudinal Study

“…Among H. influenzae isolates, we observed a high degree of (3,27). Contrary to what was observed for pneumococci, no single dominant clone was identified, but clones with different fitness properties were observed.…”