Detection of Giardia lamblia, Cryptosporidium spp. and Entamoeba histolytica in clinical stool samples by using multiplex real-time PCR after automated DNA isolation.

Diagnosis of intestinal parasites in stool samples is generally still carried out by microscopy; however, this technique is known to suffer from a low sensitivity and is unable to discriminate between certain protozoa. In order to overcome these limitations, a real-time multiplex PCR was evaluated as an alternative approach for diagnosing Giardia lamblia, Cryptosporidium spp. and Entamoeba histolytica in stool samples.Therefore, a total of 631 faecal samples were analysed both by microscopy as well as by real-time PCR following automated DNA extraction. Results showed that real-time PCR exhibited sensitivity and specificity of both 100%, whereas traditional microscopy exhibited sensitivity and specificity of 37.5% and 99.8% respectively. As real-time PCR provides simple, sensitive and specific detection of these three important pathogenic protozoan parasites, this technique, rather than microscopy, has become our diagnostic method of choice for the detection of enteric protozoan parasites for the majority of patients.