Detection and Whole-Genome Analysis of tigecycline resistant Escherichia coli in poultry and meat samples in Türkiye

The emergence and dissemination of tigecyline resistant Enterobacterales (TRE) in animals is a critical issue. This study aimed to investigate the presence of TRE in the gut of healthy avians as well as meat samples. A total of 940 ceacal samples from 94 commercial poultry flocks were collected at slaughter and a total of 335 meat samples [(chicken (n = 159), turkey (n = 4) and beef/lamb (n = 172)] were collected from supermarkets and butcher shops. Out of 960 samples, 146 (19.21 %) samples from chicken farms and 24 (13.3 %) from turkey farms were positive for TRE. Forty-nine Escherichia coli isolates were determined to carry the tet(X4) gene by PCR and exhibited multi-drug resistance. Whole-genome short-read sequencing (WGS) on all tet(X4) positive E. coli isolates and long-read sequencing on a selection of five isolates were carried out. WGS identified four ST types (ST206 being the most dominant, ST609, ST744 and ST189), indicating significant homogeneity among tigecyline resistant E. coli strains. In 47 isolates, the tet(X4) gene was transferrable to E. coli EC600 and it was found to be located on the IncX1 plasmid. Additionally, all tet(X4)-positive E. coli isolates also harbored other resistance genes, including floR, aadA2 and tet(A). In this study, the identification of tet(X4) carrying E. coli in healthy chicken and meats suggests the likely source of food-producing animals for humans. Therefore, active surveillance of critical priority lineages of TRE should focus on to contain the potential public health risk.