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Antimicrobial sensitivity of Haemophilus influenzae isolates from bacterial conjunctivitis
N Robinson1, M Miller, P N Levett
1University of the West Indies School of Clinical Medicine and Research, Public Health Laboratory, Ministry of Health, Barbados.
Abstract:
Haemophilus influenzae is one of the common bacterial pathogens which affect children. Resistance to frequently used antibiotics is becoming a significant problem in community isolates of common pathogens. A retrospective review was conducted of the serotypes and antimicrobial sensitivity of H influenzae isolates from bacterial conjunctivitis, over an 18-month period. Data on antimicrobial sensitivity (obtained by the National Committee for Clinical Laboratory Standards disk diffusion method) and beta-lactamase production, and typing results, were analysed. Ninety-nine isolates were recovered, of which 87 were typed. Most isolates were recovered from children under one year of age. Ninety-three percent were unencapsulated and biotypes I and IV were most common. H influenzae type b was recovered only twice. beta-lactamase was produced by 41% isolates while four isolates were ampicillin-resistant but did not produce beta-lactamase. All isolates were sensitive to chloramphenicol and 45% were co-trimoxazole sensitive. H influenzae is commonly isolated from bacterial conjunctivitis in Barbados and, as elsewhere, the majority of isolates are from small children and are non-encapsulated. However, there is a high prevalence of beta-lactamase production, which may serve as a reservoir for transfer to more invasive encapsulated strains of H influenzae within the oropharyngeal flora.
Insights
Antibiotic resistance in Haemophilus influenzae is a growing concern. This study found high rates of beta-lactamase production in non-encapsulated strains causing conjunctivitis in children, potentially impacting invasive strains.
Area of Science:
- Ophthalmology
- Microbiology
- Pediatrics
Background:
- Haemophilus influenzae is a common pediatric bacterial pathogen.
- Antibiotic resistance in common pathogens is a significant public health issue.
- Bacterial conjunctivitis is a frequent childhood infection.
Purpose of the Study:
- To determine the serotypes and antimicrobial sensitivity of H. influenzae isolates from bacterial conjunctivitis.
- To assess the prevalence of beta-lactamase production in these isolates.
- To understand the implications for antibiotic resistance in pediatric infections.
Main Methods:
- Retrospective review of H. influenzae isolates from bacterial conjunctivitis over 18 months.
- Antimicrobial sensitivity testing using the disk diffusion method (NCCLS).
- Analysis of beta-lactamase production and serotyping results.
Main Results:
- Ninety-nine H. influenzae isolates were analyzed, predominantly from infants.
- 93% of isolates were non-encapsulated, with biotypes I and IV being most common.
- 41% of isolates produced beta-lactamase; 4 isolates showed ampicillin resistance without beta-lactamase production.
- All isolates were sensitive to chloramphenicol; 45% were sensitive to co-trimoxazole.
Conclusions:
- H. influenzae causing conjunctivitis in Barbados children are mostly non-encapsulated.
- High beta-lactamase production in these strains may pose a risk for antibiotic resistance transfer.
- Chloramphenicol remains a sensitive treatment option, while co-trimoxazole sensitivity is moderate.