A crucial first step in preventing the introduction and spread of harmful microorganisms in poultry farms is biosecurity. The objectives of this investigation were to assess biosecurity measures and the prevalence of different E. coli species in commercial chicken farms in Sharkia province, Egypt. Sensitivity of E. coli strains was identified, and their susceptibility to antibiotics and disinfection was evaluated as well. Four farms provided 21 samples each, for a total of 84 samples. Three samples of each were collected for water, feed, litter, cloaca, wall, hand, and foot boots. All the studied farms obtained a "poor biosecurity" grade, meaning that their overall biosecurity score, which is comprised of 40% external and 36.54% internal biosecurity, was less than 50%. Escherichia coli species were found in 79.76% of the samples. It was isolated from water, feed, litter, cloaca, walls, hands, and foot boots with percentages of 91.6; 83.3; 91.6; 100; 58.3; 58.3 and 75%, respectively. Biosecurity level had significant negative correlations with the isolated E. coil species. Escherichia coli O119 was the most common serotype in litter and the cloaca, while E. coli O1 was the most prevalent serotype in walls and hands. Additionally, serotypes for E. coli O26, O159, O128 and O78 were included. According to the patterns of antibiotic sensitivity, amikacin, nitrofurantoin, gentamycin, and levofloxacin showed intermediate sensitivity, whereas E. coli O119 bacteria were highly sensitive to ciprofloxacin. In the absence and presence of organic matter, Virocid, Cid 2000 and finally Virkon S were the most efficient against E. coli O119. According to this study, there were differences in the investigated farms' biosecurity levels in relation to the occurrence of Escherichia coli. To reduce the introduction and persistence of E. coli in poultry farms, several biosecurity practices and management, including stringent cleaning and disinfection measures should be applied.

A crucial control point for good hygiene is the process of cleaning and disinfecting the slaughterhouse, the animals, the environment, and the hands of the workers. It is a crucial phase in the biosecurity process. By counting the aerobic bacteria, coliforms, Staphylococcus aureus, salmonella, moulds, and yeasts, the current study was designed to assess the abattoir's contamination and its effects. A total of 120 samples were collected, including swabs from the floor, wall, workers' hands, animals' skin, and the outside of the carcass (20 samples/each). Results of aerobic plate count clarified that the highest mean value was recorded in the abattoirs' floors and walls (1.48x106±2.29x105, 9.54x105 ±1.44x105 respectively), which were then followed by the skin, hands of workers and the outer surfaces of the carcass (5.71x104±1.26x104, 5.39x104±1.15x104, 4.50x104 ±1.68x104 respectively). After using disinfectants, chloroxylenol was the most effective disinfection across all tested samples, with the best reduction percentage. The highest mean value of staphylococcus count was recorded in the hands of workers (1.95x105±1.03x105) had the greatest staphylococcus count, followed by the outer surface of the carcass and the skin (6.66x104 ±2.47x104, 6.47x104±1.22x104 respectively). The highest mean value of coliforms count was recorded on the outer surface of the carcasses 43.45±10.61 MPN/cm2, followed by the skin and the hands of the workers (33.90±8.27, 28.90±11.57 MPN/cm2 respectively. Several spp of coliforms were detected such as Citrobacter diversus, Escherichia coli, Enterobacter aerogenes and Klebsiella pneumonia. Staph. aureus was reported depending on coagulase test, the incidence of infection was higher in Carcass than in hands and skin. Moreover, Salmonella incidence was higher in the hands followed by carcass. The abattoir's air samples had high mean value of mould 25.93±2.83 compared to yeast 17.80±3.58 (cfu/plate/minute). Regarding mould, H2O2 showed the best reduction rate followed by chlorine. While regarding yeast, chlorine was the best followed by chloroxylenol. Results of microbiological examination of the collected samples reflected a clear state of contamination in abattoirs environment and the effect of disinfectants.