Title:β-lactam Resistance in Gram-negative Pathogens Isolated from Animals
Volume: 19
Issue: 2
Author(s): Darren Trott
Affiliation:
Keywords:
Extended-spectrum, β-lactamases, Escherichia coli, ST131, livestock, companion animals, antimicrobial resistance
Abstract: Although β-lactams remain a cornerstone of veterinary therapeutics, only a restricted number are actually approved for use in
food-producing livestock in comparison to companion animals and wildlife. Nevertheless, both registered and off-label use of third and
fourth-generation cephalosporins in livestock may have influenced the emergence of plasmid-encoded AmpC β-lactamases (pAmpC)
(mainly CMY-2) and CTX-M extended-spectrum β-lactamases (ESBLs) in both Gram-negative pathogens and commensals isolated from
animals. This presents a public health concern due to the potential risk of transfer of β-lactam-resistant pathogens from livestock to humans
through food. The recent detection of pAmpC and ESBLs in multidrug-resistant Enterobacteriaceae isolated from dogs has also
confirmed the public health importance of β-lactam resistance in companion animals, though in this case, human-to-animal transmission
may be equally as relevant as animal-to-human transmission. Identification of pAmpC and ESBLs in Enterobacteriaceae isolated from
wildlife and aquaculture species may be evidence of environmental selection pressure arising from both human and veterinary use of β-
lactams. Such selection pressure in animals could be reduced by the availability of reliable alternative control measures such as vaccines,
bacteriophage treatments and/or competitive exclusion models for endemic production animal diseases such as colibacillosis. The global
emergence and pandemic spread of extraintestinal pathogenic E. coli O25-ST131 strains expressing CTX-M-15 ESBL in humans and its
recent detection in livestock, companion animals and wildlife is a major cause for concern and goes against the paradigm that Gramnegative
pathogens do not necessarily have to lose virulence in compensation for acquiring resistance.
