الفهرس 
cover englishOnly 14 pages are availabe for public view
 |  | from | 169 |  |  |
| | | from | 169 | | |
Abstract
The purpose of this study was to investigate the role of biofilm in poultry farms’ drinking water systems and possible ways to control it. The study was conducted in Al-Ayat-Giza governorate on four-layer chicken houses that received untreated groundwater; a growing pullet house with iron pipes and three production layer houses with polyvinyl chloride (PVC) pipes. A total of eight biofilm samples were collected (two from each house). After swabbing the inner surfaces of drinking water pipes, the heterotrophic bacterial counts were determined for each sample. Afterwards, colonies were purified and subjected to molecular identification using 16S rRNA and applied to the gene bank. The antibiotic sensitivity of the biofilm bacterial isolates was assessed using a total of 31 antimicrobials representing 14 antibiotic groups. The obtained results indicated that the heterotrophic plate count of the (PVC pipes) was higher than that of the (iron pipes). Pseudomonas, Enterococcus, Staphylococcus, and Sphingopyxis spp., were identified from the iron pipes, while Acinetobacter, Pseudomonas, and Bacillus spp. were from identified PVC pipes. Doxycycline, Trimethoprim, and Erythromycin, which were frequently used in commercial poultry farms, showed inefficacy against multiple tested isolates of Enterococcus spp. and Staphylococcus spp. Agar gel diffusion was used to test the efficacy of eight commercial disinfectants against isolated microbes: A (organic acids and copper sulphate), B (acetic acid), C (sodium hypochlorite), D (sodium dichloroisocyanurate), E (potassium peroxymonosulfate), F (hydrogen peroxide), G (cetyl trimethyl ammonium bromide) and H (copper sulphate). The most effective disinfectants were acetic acid followed by potassium peroxy monosulfate, hydrogen peroxide then organic acids & copper sulphate. Afterwards, two consortiums were made from these bacterial isolates according to their origin of isolation, either iron or PVC. The development of biofilm on coupons was confirmed using a scanning electron microscope. The optical density was used to evaluate the efficacy of three disinfectants. Products A, E, and F were chosen to be tested on the biofilm consortiums against biofilm after almost two months. Hydrogen peroxide achieved the best results with PVC coupons after 2 hours and potassium peroxymomsulfate 5% proved to be the best performer after two hours for iron coupons. In conclusion, the biofilm in poultry drinking water is considered a major source of pathogenic bacteria and represents a good medium for the emergence of antibiotic resistance. Moreover, disinfectant’s role on biofilm is more difficult than for planktonic bacteria.