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Update on mechanisms and prevalence of antimicrobial resistance in Haemophilus influenzae
1Department of Pathology, University of Texas Health Science Center, San Antonio 78284-7750.
Abstract:
The prevalence of plasmid-mediated beta-lactamase production among clinical isolates of Haemophilus influenzae has increased globally since this characteristic was first recognized in 1972. Three nationwide surveillance studies conducted in the United States in the 1980s indicated that the rate of beta-lactamase production was approximately 30% among serotype b isolates and approximately 15% among nonencapsulated strains. The American studies also documented strains with resistance to chloramphenicol, tetracycline, trimethoprim-sulfamethoxazole, rifampin, erythromycin, and certain older cephalosporins. Surveillance studies performed at about the same time in Canada, Europe, the United Kingdom, and several developing countries have also documented the prevalence of beta-lactamase-producing isolates and resistance among them to alternative agents such as chloramphenicol and tetracycline. Perhaps of greatest concern has been the isolation of H. influenzae (both serotype b and nonencapsulated strains) in the United States, Europe, and Asia that possess multiple antimicrobial resistance mechanisms. At the present time, H. influenzae isolates have not been detected that are resistant to either third-generation cephalosporins or fluoroquinolones.
Insights
Antimicrobial resistance in Haemophilus influenzae is a growing global concern. While resistance to older antibiotics is common, third-generation cephalosporins and fluoroquinolones remain effective against these bacteria.
Area of Science:
- Microbiology
- Infectious Diseases
- Antimicrobial Resistance
Background:
- Plasmid-mediated beta-lactamase production in Haemophilus influenzae has increased globally since 1972.
- Previous studies in the 1980s showed significant resistance rates in clinical isolates.
Purpose of the Study:
- To document the prevalence of antimicrobial resistance in Haemophilus influenzae.
- To identify emerging resistance patterns and effective treatment options.
Main Methods:
- Analysis of nationwide surveillance studies in the United States.
- Review of international surveillance data from Canada, Europe, the UK, and developing countries.
Main Results:
- Beta-lactamase production rates were ~30% in serotype b and ~15% in nonencapsulated strains in the US.
- Resistance to chloramphenicol, tetracycline, and other agents was documented globally.
- Multiple antimicrobial resistance mechanisms were observed in H. influenzae isolates.
Conclusions:
- Haemophilus influenzae exhibits increasing antimicrobial resistance, particularly plasmid-mediated beta-lactamase production.
- While resistance to older antibiotics is widespread, third-generation cephalosporins and fluoroquinolones remain effective.
- Continued surveillance is crucial to monitor resistance trends and guide treatment strategies.