Molecular Detection and Characterization of Streptococcus suis Isolated from Pneumonic Lungs of Pigs

Abstract

Background: Among various diseases, respiratory disease is considered a leading cause of mortality in pigs. Streptococcus suis affects respiratory tract and causes pneumonia as an opportunistic pathogen, that impairs animal health and lowers individual and herd performance in swine. Therefore, it becomes important to have an insight of bacterial pneumonia with special reference to Streptococcus suis in pig, so that control measures could be practiced effectively. Methods: Detailed post mortem examination was carried out on 180 pigs. Bacterial isolation was carried out from 127 (70.55%) lungs samples with pneumonic lesions. Further, suspected colonies of S. suis were subjected to Polymerase Chain Reaction for detection of glutamate dehydrogenase gene. Phylogenetic analysis was carried out for the positive S. suis samples. Results: Bacteria isolated were Pasteurella multocida (34.44%), S. suis (28.89%), E. coli (16.67%), Staphylococcus spp. (14.44%), Klebsiella spp. (3.33%) and Salmonella spp. (2.22%). Out of 26 suspected S. suis colonies subjected to Polymerase Chain Reaction, 17 isolates with amplicon size 688 bp were confirmed to be positive for glutamate dehydrogenase gene. The Phylogenetic analysis of glutamate dehydrogenase gene of S. suis from pigs of Assam showed percent identity above 99% with Germany, Canada and China strain of S. suis.