Abstract
BackgroundAmoebic liver abscess (ALA) and pyogenic liver abscesses (PLA) appear identical by ultrasound and other imaging techniques. Collection of blood or liver abscess pus for diagnosis of liver abscesses is an invasive procedure, and the procedure requires technical expertise and disposable syringes. Collection of urine is a noninvasive procedure. Therefore, there has been much interest shown towards the use of urine as an alternative clinical specimen for the diagnosis of some parasitic infections. Here, we report for the first time the detection of E. histolytica DNA excreted in the urine for diagnosis of the cases of ALA.ResultsE. histolytica DNA was detected in liver abscess pus specimen of 80.4% of ALA patients by a nested multiplex polymerase chain reaction (PCR) targeting 16S-like r RNA gene. The nested PCR detected E. histolytica DNA in all 37 (100%) liver abscess pus specimens collected prior to metronidazole treatment, but were detected in only 53 of 75 (70.6%) pus specimens collected after therapy with metronidazole. Similarly, the PCR detected E. histolytica DNA in 21 of 53 (39.6%) urine specimens of ALA patients. The test detected E. histolytica DNA in only 4 of 23 (17.4%) urine specimens collected prior to metronidazole treatment, but were detected in 17 of 30 (56.7%) urine specimens collected after treatment with metronidazole. The enzyme-linked immunosorbent assay (ELISA) for the detection of lectin E. histolytica antigen in the liver abscess pus showed a sensitivity of 50% and the indirect haemagglutination (IHA) test for detection of amoebic antibodies in the serum showed a sensitivity of 76.8% for the diagnosis of the ALA.ConclusionThe present study for the first time shows that the kidney barrier in ALA patients is permeable to E. histolytica DNA molecule resulting in excretion of E. histolytica DNA in urine which can be detected by PCR. The study also shows that the PCR for detection of E. histolytica DNA in urine of patients with ALA can also be used as a prognostic marker to assess the course of the diseases following therapy by metronidazole. The detection of E. histolytica DNA in urine specimen of ALA patients provides a new approach for the diagnosis of ALA.
Highlights
Amoebic liver abscess (ALA) and pyogenic liver abscesses (PLA) appear identical by ultrasound and other imaging techniques
The sequencing result of polymerase chain reaction (PCR) product of E. histolytica from liver abscess pus and urine specimen showed 99% identities to the sequence deposited in GenBank, [accession number: X56991]
Estimation of minimum number of Entamoeba cells detectable by nested multiplex PCR showed that the detection limit of PCR was found to be approximately 15 E. histolytica cells as even 1.5 μl of template DNA from 1000 E. histolytica cells/100 μl of Tris- ethylenediamine tetraacetic acid (EDTA) (TE) buffer produced a positive signal
Summary
Amoebic liver abscess (ALA) and pyogenic liver abscesses (PLA) appear identical by ultrasound and other imaging techniques. There has been much interest shown towards the use of urine as an alternative clinical specimen for the diagnosis of some parasitic infections. We report for the first time the detection of E. histolytica DNA excreted in the urine for diagnosis of the cases of ALA. Mortality from amoebiasis is mainly due to extraintestinal pathology, of which amoebic liver abscess (ALA) is the most common. Imaging techniques like ultrasound, computed tomography, and magnetic resonance are highly sensitive to detect abscesses in the liver of varied aetiology, fail to distinguish ALA from that of PLA. Less than only 10% of ALA patients have identifiable E. histolytica in stool specimens [4]
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