52 Loop-mediated isothermal amplification PCR (LAMP) for the rapid identification of invasive meningococcal disease in the emergency department

Background

Despite successful vaccination programmes meningococcal disease (MD) remains the leading infectious cause of septicaemia and death in children in the UK and Ireland.^1,2 The early diagnosis of MD significantly improves outcomes with reduced morbidity and mortality.^1,2 The early stages of MD are often indistinguishable from a simple viral illness making an early positive diagnosis of MD difficult.¹ Hibergene have developed a commercially available bedside Loop-mediated isothermal AMPlification PCR (LAMP-MD) test that is a highly sensitive 0.89 (95%CI 0.72–0.96) and specific 1.0 (95%CI 0.97–1.0) for identifying children with invasive MD (4) (figure 1).

Figure 1

Aims

The aims of this RCEM funded study were:

Assess the ease of use and suitability for the ED

Determine the time taken to perform the test

Independently verify LAMP-MD performance against TaqMan quantitative PCR.

Method

The LAMP-MD was assessed for practicality and ease of use within the ED including an assessment of training needs, footprint and health and safety requirements.

For verification of the Hibergene LAMP-MD analyser and assay we used dry nasopharyngeal swabs sent for viral screening. Additional verification was undertaken using N. meningitidis genomic DNA spiked over a range of concentrations. This included serotypes A, B, C, W, X and Y and a dilution series to determine the limit of detection. All samples were then analysed using real time TaqMan qPCR.

Results

The LAMP-MD analyser was easy to use and could be accommodated in the ED

The mean time for detection of Meningococcal DNA was 14.01 min

Detection of meningococcal serogroups A, B, C, W, X and Z was confirmed

The detection limit for dry nasopharyngeal swabs was below 2 genomic copies per µl

No non-specific amplification was observed in 17 randomly selected negative clinical swabs

The LAMP-MD assay was 100% sensitive and specific relative to real-time TaqMAN PCR.

Conclusion

LAMP-MD is a practical, rapid point of care test that can reliably detect all Meningococcal serotypes in less than 15 min.

Funding has been secured to perform a PERUKI supported study to investigate the potential for LAMP-MD in the diagnosis of meningococcal disease in children.

References

Meningitis Research Foundation. Meningococcal Meningitis and Septicaemia Guidance Notes2014.

Ó Maoldomhnaigh, et al. Invasive meningococcal disease in children in Ireland. PMID: 27566800.

NICE. Management of petechial rash.

Bourke TW, et al. Diagnostic accuracy of loop-mediated isothermal amplification as a near-patient test for meningococcal disease in children. PMID: 25728843.

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