Genetic characterization of selected parasites from people with histories of gastrointestinal disorders using a mutation scanning-coupled approach.

A SSCP analysis and targeted sequencing approach was used for the genetic characterization of some major pathogens from a cohort of 227 people with histories of gastrointestinal disorders. Genomic DNAs from fecal samples were subjected to PCR-amplification of regions in the glycoprotein (gp60) or triose phosphate isomerase (tpi) gene, or the second internal transcribed spacer of nuclear ribosomal DNA (ITS-2). Cryptosporidium, Giardia, and strongylid nematodes were detected in 94, 132 and 12 samples. Cryptosporidium hominis subgenotypes IbA10G2, IdA15G1, IgA17, IgA18, and IfA13G1 were identified in 74.6, 16.9, 5.6, 1.4, and 1.4% of 71 samples, respectively. For Cryptosporidium parvum, subgenotypes IIaA17G2R1 (47.6%) and IIaA18G3R1 (23.8%) were identified in 23 samples. Giardia duodenalis assemblage B (78%) was more common than assemblage A (22%). In addition, DNA of the nematodes Ancylostoma ceylanicum (n = 2), Ancylostoma duodenale (4), Necator americanus (5), and Haemonchus contortus (1) was specifically detected. This is the first report of A. ceylanicum in two persons in Australia and, we provide molecular evidence of H. contortus in a child. This SSCP-based approach should provide a useful diagnostic and analytical tool for a wide range of pathogens.