Quinolone resistant Escherichia coli in Norwegian poultry and their impact on humans

Antimicrobial resistance has been recognized by the WHO as a global threat to public health. Fluoroquinolones are considered one of the critically important antimicrobial agents that are to be reserved for treatment of bacterial infections in humans. Food contaminated with resistant bacteria may play an important role in human acquisition of resistant bacteria. Quinolone resistant Escherichia coli (QREC) are common in low numbers in Norwegian poultry and poultry meat. The QREC-risk project aims to determine what impact Norwegian poultry may have as a possible source for human QREC carriage and infections, whether these poultry QREC are important as human pathogenic bacteria by themselves or whether they may transfer their resistance genes to other pathogenic bacteria. The project is characterizing QREC from poultry and humans by genome comparison. In total 200 QREC isolates, 100 from poultry and 100 from humans have been whole genome sequenced. The results show that there is considerable genetic variation among the isolates with a variety of detected sequence types, though some of these do contain both poultry and human isolates. Most of the isolates have chromosomal mutations that cause reduced susceptibility to quinolones, while some of the isolates have acquired quinolone resistance genes either in combination with chromosomal mutations or as the only resistance mechanism. The occurrence of mutations in chromosomal genes which is considered important to the reduced susceptibility to quinolones and/or the occurrence of mobile genes appear to be in agreement with the MIC values for ciprofloxacin and nalidixic acid. The occurrence of acquired genes is in general higher in human isolates compared to poultry isolates.

Antimicrobial resistance has been recognized by the WHO as a global threat to public health, and fluoroquinolones are considered one of the critically important antimicrobial agents that are to be reserved for treatment of bacterial infections in humans. Recently, it has become clear that there is a relatively high occurrence of quinolone resistant Escherichia coli (QREC) in Norwegian poultry and poultry meat. This is of concern as food contaminated with resistant bacteria may play an important role in human acquisition of resistant bacteria. Therefore, in-depth knowledge about QREC and their epidemiology is crucial for making accountable choices through the whole supply chain, and can form a basis for correct recommendations to the consumers with regard to possible acquisition of QREC from the poultry reservoir. The QREC-risk project aims to determine what impact Norwegian poultry may have as a possible source for human QREC carriage and infections, whether these poultry QREC are important as human pathogenic bacteria by themselves or whether they may transfer their resistance genes to other pathogenic E. coli. The project will characterize QREC from poultry and compare them with QREC from humans to provide the basis for assessing whether there may have been transmission of this type of resistant bacteria from Norwegian produced poultry to the human population. The comparison will be based on whole genome sequencing of poultry isolates from live animals and meat, and human isolates from human infections and healthy carriers. The data analyses will include molecular epidemiological typing, characterization of resistance genes and virulence associated genes extracted from the whole genome sequences. More thorough comparative analyses will be performed to determine the level of whole genome similarity.