Isolation, Molecular Characterization, and Pathological Findings of Important Bacterial Respiratory Infections in Goats of Eastern Plain Zone of Uttar Pradesh, North India

Small ruminants, particularly goats are susceptible to respiratory diseases. Respiratory diseases, especially pneumonia and associated mortality causes significant threat to the goat farming due to substantial economic losses in the eastern plain zone of Uttar Pradesh, India. Among the respiratory infections in goats, Pasteurella spp., Escherichia coli (E. coli), Klebsiella spp. and Staphylococcus spp. infections in eastern plain zone of Uttar Pradesh had been studied limited. To determine the occurrence of respiratory diseases among goats, the current study was designed with an objective of isolation, identification and molecular characterization of organisms responsible for respiratory infections, especially Pasteurella spp., E. coli, Klebsiella spp. and Staphylococcus spp. A total of 150 samples were collected during postmortem examination of goats and processed for isolation of respiratory pathogens, genomic characterization, pathological lesions, localization of organisms in tissues by immunohistochemistry, and scanning electron microscopy (SEM). Out of 150 samples, 40.66% of E. coli, 26% Pasteurella spp., 20% Klebsiella spp., and 13.33% Staphylococcus spp. were identified in the respiratory tract of goats based on their typical morphology, colony characteristics, bio-chemical properties, and motility. The samples crucial for diagnosis of respiratory bacterial pathogens were lungs, followed by heart blood, nasal swabs, and tracheal swabs. Gross pathological lesions were consolidation in cranio-ventral and cranio-lateral lobes of lungs, congestion, hemorrhages, and fibrinous pleuritis. Histopathological lesions were bronchopneumonia with infiltration of neutrophils, hemorrhages, and necrotic regions contained spindle-shaped/elongated “oat cells or streaming leukocytes”. Loss of cilia was noticed by SEM. In lungs and intestine, Pasteurella spp. and E. coli antigen were localized in the cytoplasm of neutrophils, alveolar macrophages, bronchiolar epithelial cells, and intestinal mucosa. Extraintestinal pathogenic E. coli was found in the dead goats with pneumonia. Most of the isolated Pasteurella strains were having similarities with Pasteurella multocida based on the phylogenetic analysis targeting 16S rRNA gene. Results of the present study confirmed the circulation of Pasteurella spp., E. coli, Klebsiella spp. and Staphylococcus spp. among goats in field conditions in eastern plain zone of Uttar Pradesh and necessary control measures should be formulated with effective vaccination strategies in small ruminants for the control of respiratory infections to reduce the economic losses to goat farmers.