Detection of Cryptosporidium infection by modified ziehl-neelsen and PCR methods in children with diarrheal samples in pediatric hospitals in Tehran

ABSTRACT

The aim of this study is evaluation of molecular assay and the standard staining method. Cryptosporidium is a protozoon from coccidian subclass, which is one of the most important causes of diarrhea in children and immunocompromised individuals around the world. Diagnosis and treatment are necessary for mentioned cases. Usual diagnostic method for this parasite is fecal smear preparation, modified ziehl-neelsen staining, microscopic consideration and oocyst observation. A totally of 2510 stool samples collected from children with diarrhea of 4 pediatric hospitals. Direct smears prepared from fresh fecal samples and from the sediment of formalin-ether method of the same samples. The smears stained with modified ziehl-neelsen method then considered with microscope. The 30 positive samples with staining method considered with DNA extraction and PCR method for cryptosporidiosis infection determination and sensitivity evaluation. 114 random negative samples considered with DNA extraction and PCR method for cryptosporidiosis infection diagnosis and specificity evaluation. 30 positive cases from 2510 fecal samples detected by modified ziehl-neelsen staining and PCR method. We did not have any false positive cases by staining method but 2 cases of negative samples by staining method were positive by PCR technique, which informed us of 2 false negative. The positive samples sequenced for reconfirmation. Thus, sensitivity of staining method was computed to be 94% and specificity was 100% but sensitivity and specificity of PCR method was calculated to be 100%.