Resident bacteria contribute to opportunistic infections of the respiratory tract
Fig 5
S. chromogenes aggravates the infection of Av. paragallinarum.
(A) Scheme of animal models. SPF white leghorn chickens were randomly divided into four groups with six chickens in each group. Bacterial infection (109 CFUs per bird), antimicrobial treatment, evaluation of food and water intake, and observation of clinical symptoms were all completed in the morning of each day. (B) Infection scores of symptoms. (C) S. chromogenes aggravated the clinical symptoms of birds infected with Av. paragallinarum. The difference was compared among the vancomycin treatment group and mono- or coinfection groups. (D) The food intake of each group was recorded every morning before renewal. (E) Body weight was recorded pre- and post-trial, and the weight obtained was calculated using subtraction. (F) Bacterial burden of the nasal cavity and infraorbital sinuses. (G) The bacterial community of the nasal cavity and infraorbital sinuses. (H) Serious tissue damage was observed in birds coinfected with S. chromogenes and Av. paragallinarum. A large number of inflammatory cells infiltrated the epithelial tissue or were contained in the respiratory secretions (a). Epithelial cells were damaged and shed (b). Scale bar = 100 μm. P values were determined by unpaired t-test. The mean of six biological replicates is shown, and error bars represent the standard deviation (SD) (n = 6).