Klebsiella pneumoniae, one of the more critical zoonotic pathogenic bacteria, causes many diseases, including pneumonia, urinary tract infections, bloodstream infections, and sepsis. This study aimed to insulate K. pneumoniae from sheep urine and identify it by microbiological method on MacConkey agar and confirmed with 16S-rRNA sequencing analysis, then study the pathological changes of bacteria in the trachea and lung of rabbits after infected by intranasal instillation route. A total of 24 adult healthy local male rabbits were divided randomly into 2 groups: in the control group, eight animals received 50 µL phosphate buffer saline via intranasal instillation. In contrast, sixteen animals received intranasally a single dose of K. pneumonia at 106 CFU/50 µL PBS/animal in the infected group. Two animals from the infected group and one from the control group were sacrificed at 3 hours, 6 hours, 12 hours, 24 hours, 3 days, 7 days, and 16 days post-infection. A postmortem examination was performed, and any gross lesions were reported. Trachea and lung specimens were then collected and fixed in 10% formalin. The results of the bacterial examination growing on the MacConkey media agreed with the results of molecular confirmed by 16S rRNA sequencing analysis. Macroscopic results highlighted severe lung congestion and white spot areas in the lung tissue. Microscopic changes in the trachea are characterized by acute tracheitis with infiltration of inflammatory cells within a fibro-cartilaginous layer, with sticky exudate consisting of fluid collection and inflammatory cells in the tracheal lumen. as well as bleeding and aggregation edematous fluid recorded in alveolar lumen, with alveolar epithelial sloughing, interstitial pneumonia, bronchiectasis, and bronchiolitis with emphysema. The conclusion of this study could be summarized by addressing the severity of infection at several different times from the Intranasal instillation route with the rapid and dangerous ascending progression of pathological lesions in tracheal and lung disease post-infected rabbits via Intranasal instillation.
Keywords: Klebsiella pneumoniae,16S-rRNA , trachea, lung, rabbit
