Microbiological and molecular profiling of human hydatid cysts reveals high frequency of Klebsiella species.

BACKGROUND: Human cystic echinococcosis (CE), caused by the metacestodes of Echinococcus granulosus, is a significant zoonotic helminth infection with medical and economic concerns in endemic regions. The metacestode, known as hydatid cyst, is frequently populated by some bacterial species. Our knowledge is poor on the nature and significance of interplay between the bacteria and hydatid cysts. This study aimed to investigate the presence of bacterial species in human hydatid cyst. METHODS: A total of 101 human hydatid cyst samples isolated from liver and lungs, were collected and examined using both bacteriological and molecular techniques. The cyst materials were primarily cultured in thioglycolate medium with subsequent specific bacteriological methods of identification including bacterial culture and differential biochemical examinations. Molecular identification was performed through bacterial 16 S rDNA PCR with pan-specific primers. Also, PCR-sequencing on partial mitochondrial cox1 gene was used for molecular identification of E. granulosus isolates. The K1, K2, and RMPA primers were utilized to identify hypervirulent strains of Klebsiella pneumoniae. RESULTS: The results demonstrated that 7 out of 101 samples (6.9%) were tested positive for bacteria. The most frequent bacteria found were Klebsiella species including five K. pneumoniae, one K. oxytoca and one Staphylococcus aureus. Notably two hypervirulent variants of K. pneumoniae were detected. Molecular analysis of the metacestodes indicated the presence of Echinococcus granulosus G1 and E. canadensis G6 genotypes. CONCLUSION: Our study highlighted K. pneumoniae as a common bacterium in hydatid cysts. Further in-depth studies are warranted on the potential association between bacteria and the pathogenesis of E. granulosus. CLINICAL TRIAL NUMBER: Not applicable.