Jpn. J. Infect. Dis., 60 (1), 55-58, 2007

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Short Communication

Detection of Haemophilus influenzae by Loop-Mediated Isothermal Amplification (LAMP) of the Outer Membrane Protein P6 Gene

Hirotaka Torigoe1, Mitsuko Seki1,2*, Yoshihisa Yamashita3, Atsuto Sugaya1 and Masao Maeno1,2

1Department of Oral Health Sciences and 2Division of Functional Morphology, Dental Research Center, Nihon University School of Dentistry, Tokyo 101-8310, and 3Department of Preventive Dentistry, Faculty of Dental Science, Kyushu Univesity, Fukuoka 812-8582, Japan

(Received July 21, 2006. Accepted October 27, 2006)

*Corresponding author: Mailing address: Department of Oral Health Sciences, Nihon University School of Dentistry, 1-8-13 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8310, Japan. Tel: +81-3-3219-8128, Fax: +81-3-3219-8138, E-mail:

SUMMARY: 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.

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