Isolation and molecular characterization of E. coli from respiratory infections of poultry in Rayalaseema region of Andhra Pradesh

The Avian Pathogenic E. coli is causing severe economic losses due to multisystem involvement leads to high mortality and morbidity rates in the poultry industry worldwide. In the present study was aimed to isolate, identify and study of molecular variations in one of the common respiratory bacteria E. coli in poultry. A total of 107 oral swabs ,107 tracheal swabs, 107 nasal swabs, 18 tracheal tissues, 22 exudates from infra orbital sinuses, 6 larynx and 24 lung tissue samples were collected from 18 suspected layer poultry farms, located in Rayalaseema region of Andhra Pradesh and these samples were cultured and then molecular detection was done. Out of 18, 16 farms were found to be positive, with percent positivity of 88.88%. Individually, oral swabs 75(70%), tracheal swabs 78(72.8%), nasal swabs75(70%), infraorbital sinus exudates 10 (45.4%) are positive and from out of 18 tracheal tissues,6 larynx tissues and 24 lung tissues samples none of them were positive. Isolation and identification of the E. coli were performed based cultural and conventional methods and genotypically by targeting 16S rRNA gene. The obtained nucleotide sequences were verified by NCBI-BLAST showed homology of 98-99% E. coli 16S rRNA gene. E. coli present isolates (E. coli TP1, TP6, TP7) showed 6 nucleotide substitution at T281C, C352T, A412T, C445T, G454T and A466G and E. coli TP6 showed additional 4 substitution between 22^nd to 24^nd and at 33^rd position (T ’! A). Phylogenetic analysis reveals E. coli TP7 segregated with sequence of MSB2 1A-sc strain of Australia (LR890410), E. coli TP6 segregated with sequence of Human isolate of B-JRPT-4119 strain of USA(CP106756) and E. coli TP1 isolate segregated with group Human isolates of MSB2 1A-sc strain of Australia (LR890410), FH123 strain of Norway (LM995648), 09-02E strain of Pakistan (AP022650). In the present study, E. coli isolates more closely related to Human isolates that were published in NCBI, indicates that most of the extra intestinal pathogenic E. coli strains can cause different systemic diseases both in humans and poultry.