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Haemophilus influenzae causing conjunctivitis in day-care children
S Trottier1, K Stenberg, I A Von Rosen
1Department of Clinical Immunology, Lund University, Sweden.
Insights
Haemophilus influenzae is often carried in the nose but rarely causes conjunctivitis in children. This study suggests eye colonization, not infection, by common nasal strains.
Area of Science:
- Microbiology
- Ophthalmology
- Pediatrics
Background:
- Acute purulent conjunctivitis is common in children.
- Haemophilus influenzae is a known pathogen but its role in conjunctivitis is debated.
Purpose of the Study:
- To investigate the role of Haemophilus influenzae in pediatric acute purulent conjunctivitis during a day-care outbreak.
- To determine if conjunctivitis is caused by specific virulent strains or colonization by nasopharyngeal carriage strains.
Main Methods:
- Culture of nasopharyngeal and eye swabs from children with conjunctivitis (cases) and healthy children (controls).
- Identification of H. influenzae isolates using capsular typing, biotyping, and multi-locus enzyme electrophoresis.
- Assessment of in vitro attachment to epithelial cells.
Main Results:
- H. influenzae was frequently carried in the nasopharynx (53%) but isolated from only 8/20 conjunctivitis cases.
- Eye isolates were typically nonencapsulated and genetically diverse, matching nasopharyngeal strains.
- No evidence of strain spread between day-care centers or increased epithelial cell attachment.
Conclusions:
- The majority of conjunctivitis cases were unlikely caused by H. influenzae.
- Conjunctivitis was likely due to colonization by existing nasopharyngeal H. influenzae strains, not infection by specialized virulent strains.
Abstract:
The role of Haemophilus influenzae in acute purulent conjunctivitis was studied during an outbreak among children in day care. Five day-care centers contributed 20 cases and 35 controls. All the children were subjected to culture of the nasopharynx and the eyes. H. influenzae was carried in the nasopharynx of 53% of the children (range between day care centers, 20 to 91%). Of the 20 children with acute conjunctivitis 8 had eye cultures positive for H. influenzae, 2 had Moraxella and the remaining were culture-negative. Ten colonies of H. influenzae were isolated from each positive culture and identified by capsular type, biotype and multi-locus enzyme electrophoresis. All but one of the isolates were nonencapsulated. They belonged to 4 biotypes and 8 electrophoretic types. The same strain was recovered from the eyes and nasopharynx of the symptomatic children, suggesting that the H. influenzae in the eyes originated from the nasopharynx. There was no evidence for spread of the same H. influenzae strains between day-care centers. Even within each center the Haemophilus strains recovered from the eyes varied among the symptomatic children. The in vitro capacity to attach to oropharyngeal epithelial cells was not increased among the H. influenzae recovered from the eyes. The results question if the majority of conjunctivitis cases were caused by H. influenzae and suggested that eyes were colonized with the nasopharyngeal carrier strain rather than infected by an isolate with special virulence for the eye.