Abstract
Campylobacteriosis is one of the most dangerous avian infections, which should be accurately diagnosed to be differentiated from other enteric pathogens. Furthermore, infected broilers serve as a major reservoir for domestic farm animals and humans. The goal of this investigation was to investigate the presence of Campylobacter jejuni isolated from samples of apparently healthy and diseased broilers collected from different farms at different localities in Kafr El-Sheikh Governorate. Moreover, to investigate the effect of antibiotic and mixture of organic acid supplementation to the broiler chicks on their protective effect against artificial infection with Campylobacter jejuni, immunity, and serum biochemistry. One hundred samples were collected from broiler chickens suffering from diarrhea and mortality. The incidence of Campylobacter jejuni was 72% and the recorded isolates were subjected to biochemical tests, which proved the results. Susceptibility of Campylobacter jejuni isolates to 8 antimicrobial agents showed that Campylobacter jejuni isolates were multidrug-resistant (MDR) to all of the antibiotics except fosfomycin only were sensitive by (85.71 %). Campylobacter jejuni isolates were distinguished from other Campylobacter spp. using the uniplex PCR-targeting mapA gene that gave specific amplicon at 589 bp. Campylobacter jejuni isolates were also evaluated for the presence of virulence genes (cdtA and cdtB) by using PCR assay, which gave specific amplicon at 165 and 620 base pairs, respectively. A total of 120 broiler chicks (day-old) free from Campylobacter jejuni were divided into 4 equal groups, 30 chicks each; group 1 was kept as control. Chicks of groups 2, 3, and 4 were infected orally with 1 ml of Campylobacter jejuni containing 1x108 viable organism/ml in phosphate-buffered saline (PBS) at 14th days of old. Group 2 was kept as an infected control group; group 3 received a mixture of organic acids from 1st day of age in water (2ml/liter), and group 4 received antibiotic (fosfomycin) in water (0.5gm/liter) for 5 successive days beginning from 48 hrs post-infection. Our results showed that the birds that received a mixture of organic acids (G3) and antibiotic (G4) showed more favorable clinical signs, mortality rate, post mortem lesions, and recovery rate. A decrease in the mean values of serum ALT and AST, uric acid, and lipid profiles and an increase in mean values of antioxidant enzymes (SOD and CAT) were recorded that may provide evidence for the hepato and renoprotective effects of organic acids. It is possible to draw a conclusion that organic acid can be used as an antibiotic alternative due to its antibacterial effect and positive impact on the liver, kidney functions and antioxidant enzymes.

Key words: Campylobacter jejuni, organic acids and diseased broilers.