Evaluation of Different Diagnostic Techniques for Detection of Cryptosporidium spp. in Faecal Specimens

DOI: 10.21276/sjams.2017.5.9.58 Abstract: Cryptosporidium spp. is a 4-6 μm coccidian parasite causing mild to fulminant diarrhoea especially in immunocompromised persons. It remains largely under-diagnosed by using current routine diagnostic techniques in microbiology laboratories. The aim of our study was to compare four different diagnostic techniques for the detection of Cryptosporidium spp. in faecal specimens in cases of both acute and chronic diarrhoea. The present study was carried out in the Department of Microbiology for the detection of Cryptosporidium spp. in stool samples collected from 177 children suffering from diarrhoea. All the stool samples were examined microscopically after concentration by the formol-ether sedimentation technique. Sediments were examined by iodine-stained wet mount preparations and were stained with two staining techniques – Modified Ziehl Neelsen (Z-N) and Safranine methylene blue staining techniques. Samples were further subjected to Enzyme Linked Immunosorbent Assay (ELISA). Chi-square and z tests were used to compare differences between the groups. A p value of ≤ 0.05 was considered significant. ELISA gave the highest rate of positivity (12.99%) followed by Safranine methylene blue staining and Z-N staining in which the yield was 11.9%. The wet mount preparation technique yielded the lowest number of positive samples (9%). We considered cryptosporidiosis to be a definite diagnosis if the organisms were found in any two of the four techniques. The overall prevalence of Cryptosporidium spp. was found to be 11.9%. Both the conventional staining methods and ELISA had similarities in sensitivity and sensitivity patterns. The conventional staining methods were found to be more cost-effective in comparison to ELISA but were found to be time-consuming, labour-intensive and required greater skill and experience.