Comparison of gdh polymerase chain reaction-restriction fragment length polymorphism and tpi assemblage-specific primers for characterization of Giardia intestinalis in children

Abstract

Background: Giardia is a diarrheagenic eukaryotic parasite that consists of at least eight morphologically identical but genetically distinct genotypes. Human giardiasis is caused mainly by A and B assemblages. Aim and objectives: The study aimed to compare the performance of gdh polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and tpi assemblage-specific primers in genotyping of G. intestinalis . Materials and Methods: Stool samples of 315 children were microscopically screened for G. intestinalis . Positive samples were genotyped using tpi assemblage-specific primers and gdh semi-nested PCR-RFLP techniques. Results: The prevalence of Giardia was 18.1%. The detected genotypes using tpi and gdh approaches were assemblage A (15.8% vs. 12.7%) and assemblage B (36.8% vs. 74.5%) as single infections and mixed assemblages A and B (47.4% vs. 12.7%). The two approaches showed a moderate agreement (kappa index = 0.413, P < 0.001). PCR-RFLP of gdh gene revealed that sub-assemblages BIII and BIV were equally detected (30.9% each). The remaining samples were equally divided between sub-assemblage AII, mixed BIII and BIV, and mixed AII and BIII (12.7% each). A significant association was detected between the retrieved sub-assemblages and the presence of symptoms. Conclusions: Although both approaches confirmed the predominance of assemblage B, the use of assemblage-specific primers is more effective in elucidating the true picture of mixed assemblage infection.

From microbes to molecules

“…[ 1 ] Two of the original articles, one from India and another from Egypt, deal with the molecular characterization of Giardia intestinalis . [ 2 3 ] The importance of oxidative stress due to malarial infection in pregnancy has been described in an original article,[ 4 ] whereas another article has investigated the various modalities for the diagnosis of visceral leishmaniasis. [ 5 ] A report from Assam focuses on the prevalence of neurocysticercosis and epilepsy,[ 6 ] whereas another one from Australia describes the importance of molecular epidemiological markers for Strongyloides stercoralis .…”