The use of saliva as a diagnostic fluid has been increasingly reported worldwide in the last decade. Technological advancement has taken place during the past few years enabling the use of saliva as a clinical specimen to diagnose disease and predict disease progression (1).
Initially, saliva was used as a clinical specimen for antibody detection in the diagnosis of infectious diseases. Detection of salivary antibody was found to be useful for the diagnosis of bacterial infections caused by Helicobacter pylori, Shigella, and Borrelia burgdorferi (2-4) and various viral infections, such as hepatitis A, hepatitis B, hepatitis C, measles, mumps, rubella, rotavirus, dengue, parvovirus B 19, and HIV (5-11). Detection of salivary antibody has also been studied for the diagnosis of some parasitic infections caused by Toxoplasma gondii, Schistosoma mansoni, Taenia solium, and Entamoeba histolytica (12-15).
Subsequently, saliva has also been used for the detection of antigen in the diagnosis of pneumococcal pneumonia (16), hepatitis B virus, measles, mumps, and rubella (17-20). There is only one report till date on the detection of salivary lectin antigen of E. histolytica for the diagnosis of amoebic liver abscess (ALA) with a sensitivity and specificity of 22% and 97.4% respectively (21).
The reports on the use of saliva for the detection of DNA for the diagnosis of infectious diseases, however, are limited (22-26). The polymerase chain reaction (PCR) has been used for facilitating diagnosis of viral infections, such as Epstein-Barr, cytomegalovirus, human herpes virus 6, 7, and 8, and rabies using saliva (22-25). The PCR has also been evaluated for the detection of H. pylori-associated peptic ulcer, by demonstration of H. pylori DNA in saliva (26). However, reports on the detection of DNA in saliva of patients with parasitic infection, even amoebiasis, is still lacking. In the present study, we, therefore, made an attempt to detect E. histolytica DNA, possibly released in the saliva of ALA patients by applying a 16S-like rRNA gene-based nested multiplex PCR (NM-PCR) assay. ALA is a condition which is the most important and serious extra-intestinal manifestation of amoebiasis, which is associated with high morbidity and mortality. An early and specific diagnosis of the condition followed by immediate treatment reduces morbidity and mortality due to the disease to a great extent.
MATERIALS AND METHODS
The present study was conducted in the Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER) Hospital, Puducherry, India, during August 2005-March 2006.
Patients with ALA (n=28): The study included 28 ALA patients; diagnosis was done on the basis of radiological, symptomatological and laboratory criteria (27,28), such as: (a) ultrasonography revealing a space-occupying lesion in the liver suggestive of an abscess; (b) clinical symptoms, such as pain in the right hypochondrium, lower chest, back, or tip of the right shoulder, and fever; (c) distended and/or tender liver, generally without jaundice; (d) chest radiograph showing raised right dome of the diaphragm; (e) treatment with anti-amoebic drugs, e.g. metronidazole, results in improvement of the condition; (f) positive indirect haemagglutination (IHA) of serum antibody showing a titre (=1:128) against E. histolytica; and (g) liver aspirate appeared like anchovy sauce but was bacteriologically sterile.
In the present study, the 28 ALA patients included eight patients on whom the metronidazole therapy was not initiated and 20 patients on whom the metronidazole therapy was already initiated.
Patients with pyogenic liver abscess (PLA) and other diseases of the liver (n=21): The study included cases of PLA (n=13), hydatid cyst in liver (n=2), liver hepatoma (n=1), liver cirrhosis (n=3), and viral hepatitis (n=2). …