Synergistic and Independent Intestinal Effects of Curcumin, Green Tea, Garlic Extracts, and Ciprofloxacin in Broilers Experimentally Infected with Escherichia coli O78

<title>Abstract</title> <p>Avian pathogenic Escherichia coli (APEC), particularly serotype O78, is the principal etiological agent of avian colibacillosis, a disease that causes significant morbidity, mortality, and economic losses throughout the poultry sector. Although ciprofloxacin is a conventional treatment, the rise of antimicrobial resistance necessitates the evaluation of sustainable, natural alternatives leading this study to evaluate the combined and independent intestinal effects of curcumin, green tea, and garlic extracts, with or without ciprofloxacin, in broiler chickens experimentally infected with E. coli O78. Eight groups, including negative and positive controls, individual extract treatments, and combination regimens were randomly assigned to a total of 245 chicks. Birds were orally challenged at Day 14 with 1× 108 CFU of the pathogen. Clinical signs, mortality, gross intestinal lesion scores, microbiological re-isolation rates, quantitative E. coli counts, and duodenal histopathology were assessed at day 19 (5 dpi) and day 25 (11dpi). The untreated infected group showed typical colibacillosis with 20% mortality, severe hemorrhagic enteritis, 100% re-isolation at day 19 (5 dpi), and the highest intestinal E. coli loads (8.2 ± 0.3 and 6.8 ± 0.2 log₁₀ CFU/g). Phytogenic monotherapies significantly reduced mortality, lesion severity, and bacterial counts compared with the positive control, while curcumin and green tea and ciprofloxacin alone completely prevented mortality and improved intestinal recovery. The triple combination achieved the most pronounced improvements among the evaluated treatments, with zero mortality, the lowest lesion and histopathological scores, undetectable bacterial re-isolation in the evaluated samples by day 25 (11 dpi), and the greatest reduction in intestinal bacterial load (3.2 ± 0.2 and 2.5 ± 0.2 log₁₀ CFU/g). These findings suggest that curcumin, green tea, and garlic possess intestinal protective and antibacterial properties against APEC O78. Their combination with a reduced dose of ciprofloxacin may represent a promising antibiotic-reduction strategy for controlling colibacillosis in broilers, although further studies with larger sample sizes and additional outcome measures are warranted.</p>