Evaluation of microscopy and PCR for detection of Dientamoeba fragilis.

Introduction: Dientamoeba fragilis (D. fragilis) diagnosis is an intestinal protozoan parasite globally found in rural and urban areas and is attracting a growing interest. Its prevalence in stool varies from 0.2% to more than 19% depending upon the population studied. Materials and Methods: This study was based on the examination of 100 stool samples of randomly referred cases in a rural area in Motobus district, Kafr El-Sheikh governorate, Egypt. Our aim was to investigate the presence of D. fragilis in stool of the examined individuals using conventional polymerase chain reaction (PCR) compared to wet mount and trichrome stain with confirmation of infection by transmission electron microscopy. Results: D. fragilis was detected in 13/100 of the stool samples examined using wet mount smears, while trichrome stain detected 17/100. Conventional PCR diagnosed 41 cases of D. fragilis in the studied group. A very good agreement was found between wet mount and trichrome stain for diagnosing D. fragilis, while there was fair agreement between conventional PCR and both microscopy methods. Transmission electron microscope was performed on pooled positive samples that revealed the internal structures of D. fragilis trophozoite with its characteristic nucleus. Conclusions: PCR technique was superior to microscopy for the detection of D. fragilis. Trichrome stain remains vital for microscopic diagnosis.

Performance of formalin ethyl acetate, percoll sedimentation and ELISA for the detection of Cryptosporidium infection in asymptomatic children.

This study aimed to assess the performance of formalin ethyl acetate (FEA)/modified Ziehl-Neelsen (MZN), and percoll technique/MZN for the diagnosis of cryptosporidiosis among asymptomatic children compared to ELISA coproantigen. The study was conducted on 100 children in a rural area in Kafr El-Sheikh governorate. Stool samples were collected and examined by the three techniques. Microscopic examination revealed the presence of acid-fast stained oocysts and non-acid fast ghost oocysts. The overall prevalence rate was 7% with an infection intensity of 1-5 oocysts/oil immersion field. FEA/MZN technique showed the highest diagnostic performance (5%) with 71.4% sensitivity and 98% negative predictive value (NPV) compared to the other techniques. ELISA revealed 3% prevalence, 42.9% sensitivity and 96% NPV. Percoll/MZN gave the lowest prevalence, sensitivity and NPV (1%, 14.29% and 93.9% respectively). Agreement fluctuated between moderate and poor regarding FEA/MZN versus ELISA and percoll/MZN versus both techniques. In conclusion, FEA/MZN gave the top diagnostic performance, yet it missed some positive cases. Its combination with ELISA coproantigen might prove beneficial for Cryptosporidium diagnosis. Percoll technique needs more validation by modifying the density gradient, speed of centrifugation, and staining methods.

Intestinal Microsporidia Infection in Leukemic Children: Microscopic and Molecular Detection.

BACKGROUND: Microsporidia infection was originally described as an immunocompromised associated pathogen. Limitations to correct microscopic diagnosis of microsporidia include size of the organism presenting a challenge even to a highly competent laboratory expert. OBJECTIVE: The present study aimed to detect microsporidia infection among leukemic children. The performance of modified trichrome stain and PCR in the diagnosis of microsporidia was evaluated with further speciation. METHODS: Stool samples of 100 leukemic children on chemotherapy were examined microscopically for microsporidia. DNA was extracted from all samples. Amplification was performed by conventional and nested PCR. Sequencing of amplified products was performed on unspeciated samples. RESULTS: Microsporidia were detected in 23% of the children by MTS and 29% by PCR. The 29 positive samples were subjected to PCR for speciation. Enterocytozoon bieneusi was found to predominate in 20 cases, Encephalitozoon intestinalis in three cases, two cases had co-infection, and the remaining four samples were not amplified with either E. bieneusi or E. intestinalis specific primers. By DNA sequencing of the unspeciated samples, three samples shared high homology with Encephalitozoon hellem and one sample with Encephalitozoon cuniculi. Referring to PCR as a gold standard, MTS exhibited 72.4% sensitivity and 97.2% specificity with 90% accuracy. Among a number of studied variables, diarrhea and colic were significantly associated with microsporidia infection when diagnosed by either technique. CONCLUSION: The use of sensitive and discriminative molecular tools will contribute to determining the true prevalence of microsporidiosis and possibly their potential transmission source depending on species identification.

Genotype analysis of T. gondii strains associated with human infection in Egypt.

The distribution of Toxoplasma gondii genotypes varies from one geographic area to another. The present study aimed to determine T. gondii genotypes associated with human infection in Egypt. Individuals seropositive for anti-toxoplasma IgG and IgM (group I, n = 50) or for specific IgG only (group II, n = 50) were enrolled. Of the participants, 75 % were asymptomatic pregnant women. The others presented with lymphadenitis (n = 21), chorioretinitis (n = 3), and unexplained hepatomegaly (n = 1). Using nested PCR, T. gondii GRA6-coding fragment was amplified from DNA extracted from blood samples of participants. Amplification was successful in 12 samples with nonsignificant difference between both groups but with a significant association with the presence of toxoplasmosis-related manifestations. Restriction fragment length polymorphism analysis of these samples revealed the presence of type I in seven samples and atypical types in five samples. Both typical and atypical strains were detected in individuals of both groups with no bias towards specific clinical presentation.