TABLE 2.
Microorganisms of interest in AMR monitoring programs focused on both zoonotic foodborne pathogens and commensals in healthy livestock and major animal pathogensa,b
| Organism | Animal context | Human context |
|---|---|---|
| Methicillin-resistant Staphylococcus pseudintermedius (primary animal pathogen) | Recently emerged and spread epidemically in companion animals | Infections in humans are rare, can be a reservoir of SCCmec-associated resistance genes |
| Enterotoxigenic Escherichia coli, Mannheimia haemolytica, Pasteurella multocida, Histophilus somnus, Actinobacillus pleuropneumoniae (primary animal pathogens) | Relevant to pig and veal production, may drive use of third-generation cephalosporins; major reason for antimicrobial use in feedlot cattle and pigs; resistance to first-choice antimicrobials could result in increased use of third-generation cephalosporins and fluoroquinolones | Multidrug-resistant strains coming through the food chain would drive use of broad-spectrum cephalosporins and carbapenems in humans; uncommon to rare human pathogens |
| MRSA (zooanthroponotic pathogen/commensal in animals) | Livestock-associated MRSA; some human MRSA subtypes now adapted to animal hosts (i.e., horses and dogs) | Major human AMR surveillance organism; veterinarians in clinical practice have a higher rate of MRSA nasal carriage than the general population |
| ExPEC (zooanthroponotic pathogen/commensal in animals) | Some human-associated multidrug-resistant subtypes (e.g., ST131, ST648, ST354) can colonize and cause infections in dogs | Major human AMR surveillance organism; similarity between canine, avian, and human strains carrying ESBLs suggests potential for cross-transmission |
| Multidrug-resistant Salmonella (e.g., S. enterica serovars Newport, Typhimurium) (zoonotic foodborne pathogens) | Propensity to develop AMR under antimicrobial selection pressure in livestock production; in particular, resistance to critically important antimicrobials | Eggs and meat often implicated in outbreaks; invasive disease in humans often treated with fluoroquinolones in adults and third-generation cephalosporins in children |
| Fluoroquinolone-resistant Campylobacter (zoonotic foodborne pathogen) | Major foodborne risk bacteria associated with poultry; fluoroquinolone use a major selection pressure in livestock systems | Undercooked poultry meat and cross-contamination of fresh food often implicated in outbreaks; macrolides (in children) and fluoroquinolones are the treatments of choice for complicated infections |
| Commensal Enterococcus spp. (commensal indicator organism in livestock)Commensal E. coli. (commensal indicator organism in livestock) | Gram-positive indicator organism in many surveillance programs; vancomycin resistance related to avoparcin use; streptogramin resistance related to virginiamycin use.Have been shown to be reservoirs of plasmid-associated resistance of public health significance (e.g., ESBL and plasmid-borne AmpC β-lactamases). | Historical use of avoparcin and other Gram-positive spectrum growth promoters linked to vanA type vancomycin resistance in human isolatesGram-negative indicator organisms, frequently harbour multidrug resistance on mobile genetic elements with potential for horizontal movement into human ExPEC |
a
Adapted from Shaban et al. (11).
b
ESBL, Extended spectrum β-lactamase; MRSA, methicillin-resistant Staphylococcus aureus; ExPEC, multidrug-resistant extraintestinal pathogenic E. coli.