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Objectives To characterize the genetic basis of azithromycin resistance in Escherichia coli and Salmonella collected within the EU harmonized antimicrobial resistance (AMR) surveillance programme in 2014–18 and the Danish AMR surveillance programme in 2016–19. Methods WGS data of 1007 E. coli [165 azithromycin resistant (MIC > 16 mg/L)] and 269 Salmonella [29 azithromycin resistant (MIC > 16 mg/L)] were screened for acquired macrolide resistance genes and mutations in rplDV , 23S rRNA and acrB genes using ResFinder v4.0, AMRFinder Plus and custom scripts. Genotype–phenotype concordance was determined for all isolates. Transferability of mef (C)- mph (G)-carrying plasmids was assessed by conjugation experiments. Results mph (A), mph (B), mef (B), erm (B) and mef (C)- mph (G) were detected in E. coli and Salmonella , whereas erm (C), erm (42), ere (A) and mph (E)- msr (E) were detected in E. coli only. The presence of macrolide resistance genes, alone or in combination, was concordant with the azithromycin-resistant phenotype in 69% of isolates. Distinct mph (A) operon structures were observed in azithromycin-susceptible (n  = 50) and -resistant (n  = 136) isolates. mef (C)- mph (G) were detected in porcine and bovine E. coli and in porcine Salmonella enterica serovar Derby and Salmonella enterica 1,4, [5],12:i:-, flanked downstream by IS CR2 or Tn As1 and associated with IncIγ and IncFII plasmids. Conclusions Diverse azithromycin resistance genes were detected in E. coli and Salmonella from food-producing animals and meat in Europe. Azithromycin resistance genes mef (C)- mph (G) and erm (42) appear to be emerging primarily in porcine E. coli isolates. The identification of distinct mph (A) operon structures in susceptible and resistant isolates increases the predictive power of WGS-based methods for in silico detection of azithromycin resistance in Enterobacterales. [ABSTRACT FROM AUTHOR]

Abstract: The emergence and spread of multiresistant bacteria in natural environments constitute a serious impact on animal and human health. To gain more insight into the role of wild birds as carriers and reservoir of multiresistant Escherichia coli we tested a broad spectrum of common European bird species for the occurrence of E. coli strains and their antimicrobial resistance by minimal inhibitory concentration testing and PCR analysis of several resistance genes. Nine of the 187 E. coli isolates (4.8%) exhibited multiresistant phenotypes including resistances against beta-lactams, aminoglycosides, fluoroquinolones, tetracyclines and sulfonamides. By comparing avian E. coli resistance frequencies with frequencies known for E. coli isolated from livestock and companion animals analogous profiles were identified. Multiresistant E. coli strains were isolated from synanthropic avian species as well as from birds of prey, waterfowl and passerines. By that, all these avian hosts are suggested to represent a considerable reservoir of resistant E. coli strains. Consequently wild birds might constitute a potential hazard to human and animal health by transmitting multiresistant strains to waterways and other environmental sources via their faecal deposits. [Copyright &y& Elsevier]

Objectives: In view of the intercontinental emergence of Escherichia coli clone O25:H4-ST131 producing CTX-M-15 extended-spectrum b-lactamase (ESBL) in human clinical settings it would be of great interest to explore its existence in animals to unravel a possible reservoir function and the origin and transmission of this group of multiresistant strains. Methods: A total of 177 clinical phenotypically ESBL-producing E. coli isolates, mainly obtained from companion animals with urinary tract infections, wound infections and diarrhoea, were collected in a veterinary diagnostic laboratory covering a European-wide service area. They were screened for molecular subtype O25b and multilocus sequence type 131. O25b-ST131 isolates were subsequently tested for ESBL types, and phenotypic and genotypic resistance determinants. Further characterization of the strains was performed by PFGE and virulence gene typing. Results: Ten (5.6%) of 177 phenotypically ESBL-producing E. coli isolates, nine strains from dogs and one strain from a horse, were allocated to the B2-O25b-ST131 lineage. Nine of these isolates harboured a CTX-M-15-type b-lactamase enzyme while one strain possessed an SHV-12-type ESBL. Macrorestriction analysis revealed a cluster formation of six of the animal CTX-M-15-type ESBL-producing strains from five different European countries together with a human control strain constituting a group of clonally related strains at a similarity value of 87.0%. Conclusions: Our findings demonstrate that the group of clonally related human B2-O25:H4-ST131 CTX-M-15-type ESBL-producing E. coli strains is present in companion animals from various European countries. This highlights the possibility of inter-species transmission of these multiresistant strains from human to animal and vice versa. [ABSTRACT FROM AUTHOR]