Evaluation of the efficacy of chitosan nanoparticles loaded ΦKAZ14 bacteriophage in the biological control of colibacillosis in chickens.

Disease inflicted by avian pathogenic Escherichia coli (APEC) causes economic losses and burden to the poultry industry worldwide. In this study, the efficacy of chitosan nanoparticles loaded ΦKAZ14 (C-ΦKAZ14 NPs) as an oral biological therapy for Colibacillosis was evaluated. C-ΦKAZ14 NPs containing 107 PFU/ml of ΦKAZ14 (Myoviridae; T4-like coliphage) bacteriophage were used to treat experimentally APEC-infected COBB 500 broiler chicks. C-ΦKAZ14 NPs and ΦKAZ14 bacteriophage were administered orally in a single dose. The clinical symptoms, mortality, and pathology in the infected birds were recorded and compared with those of control birds that did not receive C-ΦKAZ14 NPs or naked ΦKAZ14 bacteriophage. The results showed that C-ΦKAZ14 NP intervention decreased mortality from 58.33 to 16.7% with an increase in the protection rate from 42.00 to 83.33%. The bacterial colonization of the intestines of infected birds was significantly higher in the untreated control than in the C-ΦKAZ14 NP-treated group (2.30×109 ± 0.02 and 0.79×103 ± 0.10 CFU/mL, respectively) (P ≤ 0.05). Similarly, a significant difference in the fecal shedding of Escherichia coli was observed on d 7 post challenge between the untreated control and the C-ΦKAZ14 NP-treated group (2.35×109 ± 0.05 and 1.58×103 ± 0.06 CFU/mL, respectively) (P ≤ 0.05). Similar trends were observed from d 14 until d 21 when the experiment was terminated. Treatment with C-ΦKAZ14 NPs improved the body weights of the infected chicks. A difference in body weight on d 7 post challenge was observed between the untreated control and the C-ΦKAZ14 NP-treated group (140 ± 20 g and 160 ± 20 g, respectively). The increase was significant (P ≤ 0.05) on d 21 between the 2 groups (240 ± 30 g and 600 ± 80 g, respectively). Consequently, the clinical signs and symptoms were ameliorated upon treatment with C-ΦKAZ14 NPs compared with infected untreated birds. In all, based on the results, it can be concluded that the encapsulation of bacteriophage could enhance bacteriophage therapy and is a valuable approach for controlling APEC infections in poultry.