Multilocus sequence typing for understanding the genetic diversity of Cryptosporidium spp. if combined with H. Pylori in diarrheic immunocompetent Egyptian children

Background: Since genotypic variation of H. pylori is associated with the existence of virulence factors, different genotypes and subtypes of Cryptosporidium spp. have been responsible for human cryptosporidiosis. Objective: To investigate usefulness of multilocus sequence typing (MLST) to analyze the genetic diversity of H. pylori and Cryptosporidium spp. co-infection in diarrheic immunocompetent Egyptian children. The secondary objective is to determine the detection rate of each pathogen, and co-infection rate, as well as its associated factors. Subjects and Methods: This cross-sectional study included 305 immunocompetent diarrheic children. Faecal samples were collected and processed using molecular screening techniques to detect and differentiate Cryptosporidium spp. and H. pylori. Cryptosporidium spp. were genotyped by amplifying the 18S rRNA gene and the Cryptosporidium oocyst wall protein (COWP) gene using nested PCR followed by restriction fragment length polymorphism (RFLP). Wherase H. pylori strains were identified using PCR to detect the UreA and CagA genes. The study also analyzed sociodemographic and clinical parameters to determine associated factors with Cryptosporidium-H. pylori co-infection. Results: Out of study population, 12.1% had Cryptosporidium spp., predominantly C. hominis (81.1%); while H. pylori DNA was found in 41.0%, with predominance of the CagA+ strain (40.8%). Among the 37 Cryptosporidium-positive cases, 27 (73%) had a co-infection with H. pylori, and 14 (51.9%) were identified with CagA+ strain. Significant associations were recorded between cryptosporidiosis and factors such as age, gender, source of water and milk, and abdominal pain, while H. pylori infection correlated significantly with age, vomiting, and abdominal pain. Co-infections were associated with vomiting and fever, particularly noting that CagA+ H. pylori strain significantly correlated with more severe symptoms, indicating its higher pathogenic potential. Conclusion: This study underscores the complex interplay between H. pylori and Cryptosporidium spp. in immunocompetent children in Egypt, emphasizing the role of genetic diversity and strain-specific virulence in disease manifestation.