Résumé
To detect and isolate the Gram-positive aerobic and facultative- anaerobic bacteria in hatching eggs. Prospective longitudinal study. One hundred and twenty eggs from the broiler breeder stock and hatchery and 30 new-hatched chicks. Bacteiological studies were done in five different developing stages: immediatley after laying, before and after disinfecting, before moving from setter to hatcher and from new hatched chicks. Furthermore, two different samples were taken from the shell and the yolk of each egg. Eggs were washed with Nutrient-Broth Media, sotred in 37[degree sign] C for 24 hours and finally transferred to blood agar containing potassium telorite. Yolk samples were directly transferred to blood agar containing potassium telorite. This process was repeated similarly for those samples from yolk sac of 18-day-old embryos and newborn chicks. Exact fisher test. The contamination rate of eggshells in different stages were 96.66%, 100%, 100% and 90%, respectively. Bacillus cereus, B. subtilis, B. polymixa and B. coagulans were isolated in 44.15%, 64.16%, 7.4% and 2.5% of cases, respectively. Staphylococcus aureus and S. saprophyticus were isolated from one yolk [3.3%] and tow yolk sacs [6.6%]. Any bacteria was isolated from yolk sac of 18 - day- old embryos. The source of such contamination is mostly related to eggshells. In spite of routine managing programs in breeder stocks[ such as selection, cleaning, and disinfection of eggs] it dose not effect to reduce Gram positive bacteria on egg shells and contamination of eggs in setter. Hence, yolk sac infection occurs and causes mortality in chicks