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The relatedness of the equine-associated Escherichia colistrain ST1250 and its single- and double-locus variants (ST1250-SLV/DLV), obtained from horses in Europe, was studied by comparative genome analysis. A total of 54 isolates of E. coliST1250 and ST1250-SLV/DLV from healthy and hospitalized horses across Europe (Czech Republic [n = 23], The Netherlands [n = 18], Germany [n = 9], Denmark [n = 3], and France [n = 1]) from 2008 to 2017 were subjected to whole-genome sequencing.

ABSTRACTIn the community, close contacts between humans and dogs may promote the transfer of extended-spectrum beta-lactamase/plasmidic AmpC cephalosporinase (ESBL/pAmpC) genes. Large-scale prevalence studies on ESBL/pAmpC carriage in dogs are rare, and data on ESBL/pAmpC plasmids are even more limited. Here, a considerable rate of 18.5% ESBL/pAmpC carriers was found among 368 unrelated healthy dogs in Paris, France. This prevalence is much higher than the one found in healthy humans in the same city (6%) but close to that recently reported in dogs in China (24.5%). All isolates were identified as Escherichia coli, except one Salmonella entericaand one Klebsiella pneumoniaeisolate. The sequence type 131 (ST131) clone was rare (2/73 isolates). Interestingly, two plasmids (blaCTX-M-1/IncI1/ST3 and blaCMY-2/IncI1/ST2) were unexpectedly highly predominant, raising the question of their successful spread. Considering that CTX-M-1 was recently found to be equally as abundant as CTX-M-15 in healthy Parisian subjects, the question of dogs being a CTX-M-1 reservoir for humans is open. Such a high prevalence of the blaCMY-2/IncI1/ST2 plasmid may result from the use of cephalexin in veterinary medicine, as previously demonstrated experimentally. In all, our study points out healthy urban dogs as a potential source of ESBL/pAmpC genes that can further disseminate to the human community.

ABSTRACTStreptococcus uberisis an environmental pathogen commonly causing bovine mastitis, an infection that is generally treated with penicillin G. No field case of true penicillin-resistant S. uberis(MIC > 16 mg/liter) has been described yet, but isolates presenting decreased susceptibility (MIC of 0.25 to 0.5 mg/liter) to this drug are regularly reported to our laboratory. In this study, we demonstrated that S. uberiscan readily develop penicillin resistance in laboratory-evolved mutants. The molecular mechanism of resistance (acquisition of mutations in penicillin-binding protein 1A [PBP1A], PBP2B, and PBP2X) was generally similar to that of all other penicillin-resistant streptococci described so far. In addition, it was also specific to S. uberisin that independent resistant mutants carried a unique set of seven consensus mutations, of which only one (Q554E in PBP2X) was commonly found in other streptococci. In parallel, independent isolates from bovine mastitis with different geographical origins (France, Holland, and Switzerland) and presenting a decreased susceptibility to penicillin were characterized. No mosaic PBPs were detected, but they all presented mutations identical to the one found in the laboratory-evolved mutants. This indicates that penicillin resistance development in S. uberismight follow a stringent pathway that would explain, in addition to the ecological niche of this pathogen, why naturally occurring resistances are still rare. In addition, this study shows that there is a reservoir of mutated PBPs in animals, which might be exchanged with other streptococci, such as Streptococcus agalactiae, that could potentially be transmitted to humans.

ABSTRACTDrinking water has rarely been recognized as a source of antimicrobial resistance for humans, and only in low-income countries. Here, a sequence type 48 Escherichia coliisolate carrying the blaCTX-M-1IncI1/ST3 plasmid was recovered from drinking water in France. This plasmid was similar to other blaCTX-M-1IncI1/ST3 plasmids found previously in animals and humans. Our findings highlight the possible human transfer of extended-spectrum β-lactamase (ESBL) genes through drinking water in high-income countries.

Bivalves are filter-feeding animals and markers of bacterial pollution. We report a massive spread of blaCTX-M-15through dominant Escherichia coliand Klebsiella pneumoniaelineages and/or plasmid subtypes (F31:A4:B1) as well as the presence of OXA-23-producing Acinetobacter baumanniisequence type 2 (ST2) in seafood, highlighting a direct risk for the consumer.