Introduction: To date, surgery has been the treatment of choice for hydatid cyst, with regard to danger of leakage of hydatid cyst contents into viscera and production of secondary cysts, after spread of protoscolices. Different scolicidal agents get injected into cyst for preventing the secondary cyst production, which may cause different side effects in host, especially in the surrounding tissues. In this research, the scolicidal effects of bacterial extract isolated from infected hydatid cyst was evaluated.

Methods: In this experimental-laboratorial study, at first, isolation and identification of the infecting bacteria of hydatid cyst were performed at the level of species. Then, total the bacterial extract was prepared by sonication method, and serial dilutions (1.1, 1.2, 1.4, 1.8, 1.16, 1.32 and 1.64) were prepared using sterile saline as the solvent. The obtained alive larvae at the times of 5, 10, 20, 40 and 60 minutes were placed in those dilutions and mean of dead protoscoleces were determined using eosin exclusive staining method.

Results: The identified bacteria isolated from the infected hydatid cysts were as follows: E. coli, Staphylococcus aureus, S. saprophyticus, Proteus mirabilis and Pseudomonas aeruginosa. The extract of isolated bacteria at the mentioned times had no considerable scolicidal effects. For example, the whole extract of P. aeruginosa after 60 minutes of exposure showed a maximum of 13.17%. scolicidal effect.

Conclusion: The results of this study showed low scolicidal effect of bacterial extracts isolated from hydatid cyst. Degeneration of scolices in infected cysts can be due to other reasons than bacterial extract.