Molecular characterization and plasmid profiling of Pasteurella  multocida of animal origin

Parkhe, Prapti

Molecular characterization and plasmid profiling of Pasteurella multocida of animal origin

Date

2022-06-04

Authors

Parkhe, Prapti

Publisher

palampur

Abstract

Pasteurella multocida, is a Gram negative opportunistic bacterial pathogen capable of causing several economically important diseases in animals including zoonosis. There are multiple capsular, LPS and virulence genotypes of this organism which are differently associated with various diseases in different hosts. In this study, a total of 75 isolates from different animal host species were studied for their capsule and lipopolysaccharide (LPS) genotypes, virulence-associated genes, antimicrobial susceptibility pattern and plasmid profile. A capsular type B was predominant genotype and its prevalence was recorded 85.3% in bovine, 40% in ovine, 66.7% in porcine and 20.8% in poultry isolates. The percent prevalence of capsular type A was 79.2 in avian followed by 40 in ovine, 33.3 in porcine and 12.2 in bovine isolates. Both rabbit and deer isolates were detected as capsular type A and only one isolate each from bovine and ovine belonged to capsular type D. The isolates were assigned to seven groups based on both capsule and LPS genotype, namely A:L1 (13/29), A:L3 (2/29), A:L6 (6/29), A:non-typeable (8/29), B:L2 (42/44), B:non-typeable (2/41) and D:L3 (2/2). When combining both the typing systems, L1 (44.8%), L2 (95.4%) and L3 (100%) were the most prevalent LPS genotypes found in capsular type A, B and D, respectively. P. multocida displayed significant association of a given capsule type with a particular LPS genotype. Many P. multocida remained untypeable for their LPS genotypes which suggested presence of genomic diversity in primer binding locations of LPS biosynthesis loci. Of the total 12 virulence genes, three (ompH, sodC, and ptfA) showed high prevalence in all capsular types whereas toxA was not detected in any of the genotypes. A large proportion of virulent genes (75 to 100%) were present in non-typeable strains. A given P. multocida genotype with a specific set of virulence associated genes clustered together suggesting a genetic relatedness despite their place of origin. Majority of isolates were susceptible to most antibiotics, however, resistance to tetracyclines, streptomycin and sulfonamides were displayed by 62%, 26% and 24% of isolates. Most MDR isolates belonged to capsular type B (15/17, 88.2%) and the MAR indices ranged from 0.04 to 0.39. Only a single isolate harboured a plasmid of molecular size around 11.6 kb, suggesting rarity of plasmids in studied isolates. Additional studies would be needed to understand completely the role of P. multocida genotypic combinations in disease outcome in different hosts and for their exploration as vaccine candidates. The detailed sequence analysis would provide more insight about various characteristics of the plasmid.