Carriage of extended-spectrum beta-lactamase-and AmpC beta-lactamase-producing Escherichia coli from humans and pets in the same households.

Extended spectrum beta-lactamase (ESBL)- or AmpC beta-lactamase (ACBL)- producing Escherichia coli are the most common cause of community-acquired multidrug resistant urinary tract infections (UTIs) in New Zealand. The carriage of antimicrobial resistant bacteria has been found in both people and pets from the same household; thus, the home environment may be a place where antimicrobial resistant bacteria are shared between humans and pets. In this study we sought to determine whether household members (pets and people), from households of human index cases with a UTI caused by an ESBL- or ACBL- producing E. coli strain, also carried an ESBL- or ACBL- producing Enterobacteriaceae strain and if so, whether it was a clonal match to the index case clinical strain. Index cases with a community-acquired UTI were recruited based on antimicrobial susceptibility testing of urine isolates. Fecal samples were collected from 18 non-index people and 36 pets across 27 households. Eleven of the 27 households screened had non-index household members (8/18 people and 5/36 animals) positive for ESBL- and/or ACBL- E. coli. Whole-genome sequence analysis of 125 E. coli isolates (including the clinical urine isolate) from these 11 households showed that within seven households the same strain of ESBL-/ACBL- producing E. coli was cultured, from both the index case and another person (5/11 households) or pet dog (2/11 households). These results suggest that transmission within the household may contribute to community spread of ESBL- or ACBL- producing E. coli. IMPORTANCE Enterobacteriaceae that produce extended-spectrum beta-lactamase (ESBL) and AmpC beta-lactamases (ACBL) are important pathogens and can cause community-acquired illnesses such as urinary tract infections (UTIs). Fecal carriage of these resistant bacteria by companion animals may pose a risk for transmission to humans. Our work evaluated the sharing of ESBL- and ACBL- producing E. coli between humans and companion animals. We found that in some households, dogs carried the same strain of ESBL producing E. coli as the household member with a UTI. This suggests that transmission events between humans and animals (or vice versa) are likely to be occurring within the home environment and therefore the community as a whole. This is significant from a health perspective when considering measures to minimize community transmission and highlights that in order to manage community spread, we need to consider interventions at the household level.