Line Probe Assay

Clinical description

LPA is a rapid and accurate test to identify INH and RR strains of MTB. It can be performed either directly from smear-positive sputum samples or from culture isolates.

• If a patient with TB is smear-positive, the sputum contains enough bacilli to perform

an LPA directly on the sputum and DR-TB can be confirmed within two days.

• If the sputum is smear-negative, growth of bacilli should be demonstrated on culture

first (preferably on liquid medium) and then, LPA can be performed on the isolates to check for sensitivity for INH and rifampicin.

• LPA can also be performed to screen for resistance to other second-line TB drugs,

although these results would need careful interpretation.