Evaluation of formalin-ether sedimentation and trichrome staining techniques: its effectiveness in detecting Entamoeba histolytica/dispar/moshkovskii in stool samples.
This study was conducted to evaluate two routinely microscopic diagnostic methods in comparison with single-round PCR assay as the reference technique to detect Entamoeba histolytica/dispar/moshkovskii. Examination was performed on 500 stool samples obtained from Orang Asli communities in different states of Malaysia using formalin-ether sedimentation, trichrome staining and single-round PCR techniques. Ninety-three stool samples were detected E. histolytica/dispar/moshkovskii positive by routine microscopy, while single-round PCR detected 106 positive samples. Additional positives detected by PCR assay were eventually confirmed to be negative by both microscopic techniques. Detection rate of E. histolytica/dispar/moshkovskii was highest in combination techniques (18.6%), followed by trichrome staining (13.4%) and formalin-ether sedimentation (11.2%) techniques. Single-round PCR detected 21.2% of the stool samples. The sensitivity and specificity of formalin-ether sedimentation and trichrome staining techniques compared to the reference technique were 31.1% (95% CI: 29.0-36.0) and 94.2% (95% CI: 89.8-98.9), and 53.8% (95% CI: 46.0-76.2) and 97.5% (95% CI: 92.8-99.1), respectively. However, the sensitivity [59.4% (95% CI: 48.9-78.5)] of the method increased when both techniques were performed together, but the specificity decreased to 92.4% (95% CI: 81.0-98.0). The agreement between the reference technique, trichrome staining and combination techniques were statistically significant by Kappa statistics (trichrome staining: K = 0.592, p < 0.05; combination techniques: K = 0.543, p < 0.05). Hence, the combination technique is recommended to be used as a screening method in the diagnosis of E. histolytica/dispar/moshkovskii infections either for clinical or epidemiological study.
Department of Parasitology and Medical Entomology, Faculty of Medicine, Universiti Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, 50300 Kuala Lumpur, Malaysia.
Tengku Shahrul
TS
Anuar
Hesham M
HM
Al-Mekhlafi
Mohamed Kamel
MK
Abdul Ghani
Edariah
E
Abu Bakar
Siti Nor
SN
Azreen
Fatmah Md
FM
Salleh
Norhayati
N
Moktar
D000293:Adolescent; D000328:Adult; D000368:Aged; D002498:Centrifugation / Q000379:methods; D002648:Child; D002675:Child, Preschool; D004748:Entamoeba histolytica / Q000302:isolation & purification*; D004749:Entamoebiasis / Q000175:diagnosis*; D005243:Feces / Q000469:parasitology*; D005260:Female; D006801:Humans; D008296:Malaysia; D008297:Male; D008853:Microscopy / Q000379:methods*; D008875:Middle Aged; D010274:Parasitology / Q000379:methods*; D012680:Sensitivity and Specificity; D013194:Staining and Labeling / Q000379:methods; D055815:Young Adult