Diagnostic utility of LAMP PCR targeting bcsp-31 gene for human brucellosis infection

Human brucellosis is a neglected zoonotic disease of significant public health concern. Molecular diagnosis of brucella remains challenging in low resource settings, due to the high infrastructure and cost involved. Loop-mediated isothermal amplification (LAMP) is a rapid point of care polymerase chain reaction (PCR) with the utility of on-field molecular diagnosis and offers a convenient alternative to conventional PCR. In the present study, we developed and evaluated the diagnostic utility of in house LAMP PCR targeting the Brucella genus-specific bcsp-31 gene in patients having febrile illness.

The analytical sensitivity and specificity of bcsp-31 LAMP PCR was first evaluated using brucella (n ​= ​8) and non-brucella cultures (n ​= ​5), along with spiked clinical samples. The overall diagnostic utility of developed LAMP PCR was then further evaluated in 393 human samples suspected of brucellosis.

The developed LAMP PCR could detect as low as 8 ​fg of DNA by visual detection within 35min. We report sensitivity and specificity of the developed LAMP PCR as 90.91% and 99.37%.The accuracy of the developed test assay was found to be 98.60%. In clinical samples, LAMP gave positivity of 20% with the concordance of 89% with conventional PCR.

To conclude, a rapid, efficacious, sensitive LAMP PCR targeting the bcsp 31 gene was developed. The existing LAMP PCR can be used as a point of care screening test in various low resource endemic setting in lieu of conventional PCR for estimation of prevalence data, diagnosis and treatment of brucellosis.