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Updated: Feb 20, 2026
Author Spotlight: Advancing Rapid Detection of Respiratory Pathogens Using Microfluidic Chip
Published on: March 29, 2024
Molecular Serotype-Specific Identification of Non-type b Haemophilus influenzae by Loop-Mediated Isothermal
Chika Takano1, Mitsuko Seki1, Dong Wook Kim2,3
1Division of Microbiology, Department of Pathology and Microbiology, Nihon University School of Medicine, Tokyo, Japan.
Abstract:
Over the past four decades, the incidence of meningitis caused by Haemophilus influenzae in children has decreased due to widespread vaccination against H. influenzae type b (Hib). The incidence of invasive diseases due to H. influenzae types not included in the vaccines, however, has increased. At present, there are a limited number of diagnostics available to detect non-type b H. influenzae. To address this issue, we developed a rapid, simple, and cost-effective method for detecting serotypes of H. influenzae. We designed LAMP primer sets based on published sequences for H. influenzae capsular types a, c, d, e, and f. The assay was evaluated to determine test reactivity, specificity, and sensitivity. To support its use in patients with suspected meningitis, we evaluated the detection limit of the non-Hib serotype specific LAMP assay using bacterial genomic DNA-spiked cerebrospinal fluid (CSF) specimens. The reactivity and specificity of the LAMP assays were confirmed using six serotypes and non-typeable H. influenzae strains, plus eight strains of other Haemophilus species and non-Haemophilus genera. The detection limits of the LAMP assay for capsular types a, c, d, e, and f were 102, 102, 102, 103, and 10 copies per reaction, while those of the PCR assay were 104, 104, 103, 103, and 104 genome copies per reaction, respectively. Using DNA-spiked CSF specimens, the detection limit of the LAMP assay was equivalent to that using purified DNA as the template. However, the detection limit of the PCR was reduced from 103 to 104 genome copies per reaction for serotype d and from 103 to 105 genome copies per reaction for serotype e. To the best of our knowledge, this is the first report of a serotype-specific identification assay for H. influenzae using the LAMP method. Our results suggest the potential of LAMP methods for patients with suspected meningitis in resource-limited laboratories or public health surveillance systems.
Insights
A new LAMP assay can rapidly detect non-type b Haemophilus influenzae (H. influenzae) serotypes, crucial for diagnosing meningitis. This cost-effective method shows high sensitivity and specificity, aiding public health surveillance.
Area of Science:
- Molecular Biology
- Clinical Diagnostics
- Microbiology
Background:
- Meningitis caused by Haemophilus influenzae type b (Hib) has declined due to vaccination.
- Invasive diseases from non-type b H. influenzae strains are increasing.
- Limited diagnostic tools exist for non-type b H. influenzae serotypes.
Purpose of the Study:
- To develop a rapid, simple, and cost-effective method for detecting H. influenzae serotypes.
- To create LAMP primer sets for H. influenzae capsular types a, c, d, e, and f.
- To evaluate the diagnostic potential of the LAMP assay for meningitis cases.
Main Methods:
- Designed LAMP primer sets targeting specific H. influenzae capsular types (a, c, d, e, f).
- Evaluated assay reactivity, specificity, and sensitivity using various H. influenzae strains and other bacteria.
- Determined the detection limit of the LAMP assay in DNA-spiked cerebrospinal fluid (CSF) specimens.
Main Results:
- LAMP assays demonstrated high specificity against six H. influenzae serotypes, non-typeable strains, and other bacterial genera.
- The LAMP assay exhibited superior sensitivity compared to PCR, with detection limits as low as 10 copies per reaction for certain serotypes.
- In spiked CSF specimens, the LAMP assay maintained its detection limit, while PCR sensitivity decreased for some serotypes.
Conclusions:
- This study reports the first serotype-specific identification assay for H. influenzae using the LAMP method.
- The developed LAMP assay is a sensitive, specific, and cost-effective tool for identifying non-type b H. influenzae.
- LAMP methods show significant potential for diagnosing meningitis in resource-limited settings and for public health surveillance.
