Isolation and identification of the bacteria-infected hydatid cysts of livestock animals were carried out. The study lasted for five months. A total of 302 slaughtered livestock were checked to find hydatid cyst naturally infected livers and lungs of sheep and goat at local Mosul abattoir/ Nineveh/ Iraq. Each cysts' aspirated fluid was cultured separately on blood or nutrient agar at 37C for 24 hours then detected secondary bacteria. Each bacterium was incubated independently with 1000 viable protoscolices in a culture tube containing tryptic soy broth at 37°C and examined every two hours for 6 hours, followed by 12, 24, 36, and 48 hours afterward. The degeneration rate of protoscolices resulting from treatment with bacteria isolated depending on viability was studied in vitro. The results were revealed that the liver was the preponderant affected organ in sheep and goats. About 57.1% of sheep and 50% of goats harbored fertile cysts. Escherichia coli, Klebsiella pneumonia, Staphylococcus aureus, Proteus mirabilis, and Pseudomonas aeruginosa bacteria were observed in the infected cysts. The most common bacteria infect the cyst was Escherichia coli. The protoscoleces treated with the bacterial isolates had completely deteriorated, whereas 97% of protoscoleces throughout the control groups were still alive and intact even after completing the incubation time. The experiments detect a significant time-dependent scolicidal effect on decreased viability of protoscolices in vitro study. This could pave the door for more research into the scolicidal validity of bacteria or their by-products as protoscolices both in vitro and in vivo.