The Zoonotic Potential of Poultry-Associated Nitrofurantoin-Resistant Escherichia coli

Escherichia coli is the most common cause of urinary tract infection (UTI) in humans. Nitrofurantoin is the most frequent UTI therapy in the United Kingdom. Here we identify poultry as a potential zoonotic reservoir of nitrofurantoin resistant (NFT-R) and pre-resistant (one mutation away from NFT-R) E. coli . We found NFT-R E. coli excreted by dogs fed a raw meat diet, as well as NFT-R and pre-resistant E. coli contaminating chicken meat sold for human consumption and chicken-based raw dog food. By whole genome sequence analysis, with reference to additional data from public repositories, we identified NFT-R or pre-resistant E. coli clones. These were ST919/8874, ST665, ST6805, ST69, ST752 and ST7529, which were dominated by isolates from poultry sources in Europe, though the ST752 clone is globally disseminated. Five of these clones included isolates from human clinical samples, of which several were confirmed urinary isolates. Our findings have important implications for public health and domestic hygiene, particularly for people being treated for UTI. They also increase concerns about the roles of raw-fed dogs as vectors for the entry of resistant E. coli into the home. It is likely that nitrofuran use in poultry production was the initial driver for the emergence of NFT-R on poultry farms. Therefore, whilst NFT-R E. coli sample-level positivity in poultry meat was far lower than resistance to more recently used fluoroquinolones, NFT-R and pre-resistant E. coli appear to have persisted among poultry flocks despite 30 years of zero legal use in Europe.