Direct amplification of Entamoeba histolytica DNA from amoebic liver abscess pus using polymerase chain reaction

An important and serious complication of intestinal infection with Entamoeba histolytica is the involvement of the liver (hepatic amoebiasis). Hepatic amoebiasis is usually diagnosed by the clinical picture (pain in the right upper quadrant and fever), ultrasound examination and positive serology. However, none of these tests are definitive and the picture overlaps with pyogenic liver abscess caused by bacteria. It is for this reason that the feasibility of using polymerase chain reaction (PCR) for the detection of E. histolytica DNA in liver abscess pus was investigated. A comparative study was done to verify the sensitivity of ten pairs of primers specific for detecting E. histolytica in stools. Samples of liver abscess pus from 22 serology-positive patients were collected under ultrasound guidance; and these were used directly in PCR assays without any prior pre-treatment of the samples. Of the ten pairs of previously published primers tested, two pairs of primers (PI + P2 and P11 + P12) were found to give 100% sensitivity. Based on these results, we recommend that PCR assay can be successfully used to confirm the diagnosis of amoebic liver abscess with the primers identified.