¹Aydın Adnan Menderes University, Faculty of Veterinary Medicine, Department of Microbiology, Aydın, Türkiye DOI : 10.9775/kvfd.2024.32343 This study investigated the phylotypes, biofilm formation abilities, antibiotic resistance of enteropathogenic Escherichia coli (EPEC) isolates from cats with diarrhea. From 37 diarrheal cats, 28 E. coli isolates were obtained using conventional methods. Pathotypes and phylotypes were determined via PCR, biofilm formation potential via Congo Red Agar, and resistance profiles against eight antibiotics were examined using the disk diffusion method, evaluated according to the Clinical and Laboratory Standards Institute (CLSI). Chi-square tests assessed relationships between phylogenetic groups, biofilm formation, and MDR statuses. The results were considered statically significant at a 95% confidence interval and significance level of P<0.05. Pathotyping studies showed that 46% (13 isolates) of the isolates were EPEC. 93% of isolates were phylotyped. Seven phylotypes were detected: B2 (22%), C (18%), B1 (18%), D (14%), A (11%), E (7%) and F (3%). Of the isolates 39% formed biofilms and 86% were MDR. No significant association was found between pathotype and biofilm formation or MDR. However, a significant relationship was noted between pathotype EPEC and phylogenetic group B2. The correlation between EPEC pathotype and phylotype B2 in diarrheic cats suggests high pathogenic potential. Multidrug resistance, even in non-biofilm forming isolates, complicates treatment and poses public health risks, underscoring the need for detailed evaluation of E. coli diversity and zoonotic pathogens. Keywords : Antibiotic resistance, Biofilm, Cats, Enteropathogenic Escherichia coli