Vol. 11, Special Issue 1 (2022)

Author(s):
Dinesh Mittal, Kushal Grakh, Manesh Kumar, Anand Prakash, Ramesh Kumar and Pankaj Kumar

Abstract:
Avian Pathogenic E. coli (APEC) is the causative agent of avian colibacillosis, accounting for vast economic losses to the poultry industry in form of morbidity, mortality, and carcass condemnation The E. coli strains of the various phylogroups also differ in their genotypic and phenotypic characteristics, their ability to cause disease and their ecological niche. In the present study, 64 E. coli isolates comprising of APEC (n=50) and non-APEC (n=14) were phylogrouped. The combination of phylogenetic markers viz., chuA, yjaA, DNA fragment TspE4.C2, arpA and trpA was used to amplify target specific fragments using PCR for phylogrouping. The results classified E. coli isolates (n=64) into A (28.1%), B1 (12.5%), D (10.9%), F (7.9%), B2 (6.2%), E (1.6%) and Clade I (1.6%). Sixteen E. coli isolates (25%) were untypable/unknown and none of E. coli isolates belonged to phylogroup C. A total of 6.2% E. coli isolates were either grouped to Clade I or Clade II. The phylogrouping of APEC isolates indicated that most of APEC isolates were untypable/unknown category (30%) followed by phylogroup A (24%). None of APEC isolates in the present study fall under phylogroup E and C. Similarly, among non-APEC isolates phylogroup A dominance was observed (6/14) followed by phylogroup B1 (3/14). The study revealed that phylogroup A is widely circulating among APEC as well as non-APEC pathotypes in Haryana. The circulation of unknown phylogroups warrants further investigation in phylogrouping protocols and methods, as there might be possibility of existence of newer phylogroups of APEC. The study further provided insight to the newer phylogroups of APEC as well as non-APEC isolates, generating valuable data which may be helpful in perceiving the origin and pathogenicity of APEC isolates on the basis of phylogrouping.