Loop-mediated isothermal amplification assay for detection of Haemophilus influenzae type b in cerebrospinal fluid

J Clin Microbiol. 2011 Oct;49(10):3621-6. doi: 10.1128/JCM.00515-11. Epub 2011 Aug 10.

Abstract

Haemophilus influenzae type b (Hib) is one of the leading causes of meningitis in developing countries. To establish and evaluate a novel loop-mediated isothermal amplification (LAMP) assay for Hib, we designed a LAMP primer set targeting the Hib-specific capsulation locus. LAMP detected 10 copies of purified DNA in a 60-min reaction. This indicated that the detection limit of LAMP was >100-fold lower than the detection limits of both a PCR for the detection of bexA and a nested PCR for Hib (Hib PCR). No H. influenzae, other than Hib or control bacteria, was detected. Linear determination ranged from 10 to 1,000,000 microorganisms per reaction mixture using real-time turbidimetry. We evaluated the Hib LAMP assay using a set of 52 randomly selected cerebrospinal fluid (CSF) specimens obtained from children with suspected meningitis. For comparison, the CSF specimens were tested using a conventional Hib PCR assay. Hib was detected in 30 samples using LAMP and in 22 samples using the Hib PCR assay. The Hib PCR showed a clinical sensitivity of 73.3% and a clinical specificity of 100% relative to the Hib LAMP assay. These results suggest that further development and evaluation of the Hib LAMP will enhance the global diagnostic capability for Hib detection.

Publication types

  • Comparative Study
  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacteriological Techniques / methods*
  • Cerebrospinal Fluid / microbiology*
  • DNA Primers / genetics
  • Haemophilus influenzae type b / genetics
  • Haemophilus influenzae type b / isolation & purification*
  • Humans
  • Meningitis, Haemophilus / diagnosis*
  • Meningitis, Haemophilus / microbiology*
  • Molecular Diagnostic Techniques / methods*
  • Nucleic Acid Amplification Techniques / methods*
  • Sensitivity and Specificity
  • Temperature
  • Time Factors

Substances

  • DNA Primers