Detection of Haemophilus influenzae by loop-mediated isothermal amplification (LAMP) of the outer membrane protein P6 gene.

It is difficult and time-consuming to distinguish Haemophilus influenzae from the genotypically similar Haemophilus parainfluenzae, which is a commensal of the human oral cavity. The novel nucleic acid amplification technique of loop-mediated isothermal amplification (LAMP), which amplifies DNA under isothermal conditions (63°C) with high specificity, efficiency, and rapidity, was evaluated for H. influenzae detection. A H. influenzae-specific LAMP primer set was designed for the outer membrane protein P6 gene. Primer set specificity was validated using 4 Haemophilus spp. and 13 other species. Within 60 min, LAMP detected 100 or more copies of purified DNA with a sensitivity that was 10-fold higher than that of conventional PCR. This method can be used to differentiate H. influenzae from H. parainfluenzae strains. Thus, LAMP may represent a sensitive and reliable means of diagnosing H. influenzae infection.