Antimicrobial resistance and residues from biofilms in poultry, swine, and cattle farms: a scoping review

Background: The use of antibiotics in livestock has contributed to the spread of antimicrobial resistance (AMR) and biofilms can play a role in its emergence and dissemination. This review aimed to map the literature on AMR, antimicrobial resistance genes (ARGs), and antibiotic residues (ARs) in biofilms from drinking water distribution systems in poultry, swine, and cattle farms. Methods: The review was conducted according to the PRISMA-ScR extension. Four databases (PubMed, Scopus, Agricola, and Web of Science) were searched. Studies were screened in Rayyan. Results: The search yielded 1242 studies. After screening 732 studies, only 4 met the inclusion criteria. These studies focused on poultry (n = 3) and dairy cattle (n = 1), not on swine. Isolation relied on plating methods. Two studies complemented culturing with 16S rRNA sequencing. No studies applied culture-independent techniques. The number of biofilm-derived isolates across studies ranges from 6 to 102. Three studies performed antimicrobial susceptibility testing, using a wide range of antibiotics (16 to 31). One study analyzed ARGs; none quantified ARs. Conclusions: The limited number of studies and lack of standardized methods hinder the generalizability of the findings, underscoring the need for research to clarify biofilms' role in AMR dissemination in livestock farms.