FREM1 and mastitis: This study found that QA NPs, a composite material combining Ag NPs and the plant-derived drug component quercetin (Kareem & Al-Hamadani, 2016), can strongly inhibit the biofilm formation of an E. coli strain isolated from a dairy cow with mastitis by decreasing transcription of biofilm-associated genes bcsA, csgA, fliC, fimA, motA, and wcaF.