To analyze the characteristics of fosA and fosA 3 in Enterobacter cloacae isolated from aspirated and catheterized urine culture specimens of companion pets in Taiwan. A total of 19 E. cloacae isolates from pets with urinary tract infection were screened for the presence of fosA , fosA 3, and fosC2 and for the genetic context of them by PCR amplification and sequencing. The transferability, resistance phenotypes, plasmid replicon typing properties and genetic environments of fosA - and/or fosA 3-positive strains were characterized. Five E. cloacae isolates were positive for fosA and three coharbored fosA and fosA 3. No fosC determinant was detected. Transconjugants of fosA 3 were successfully acquired, while the acquisition of fosA transconjugants was failed. The minimum inhibitory concentrations (MICs) of the three fosA 3-positive isolates and their transconjugants were ≥256 mg/L, whereas the MICs of the five fosA -positive isolates ranged from 64 mg/L to 256 mg/L. Three plasmid replicons ( InC FrepB, InC L/M, and InC HI2) were identified in fosA - and fosA3 -positive E. cloacae isolates. Different genetic contexts lay in the downstream region of fosA and fosA 3, respectively. Eight distinct patterns based on the similarity value of more than 80% were typed for all the 8 fosA -positive isolates. In conclusion, the fosA concomitant with fosA 3 were found in E. cloacae isolates. The fosA 3 not only exhibits stronger activity of inactivating fosfomycin than fosA but also possesses stronger potential to spread than fosA . Different genetic backgrounds exist in these fosA - and fosA3 -positive isolates, and different mobile elements may confer the dissemination of fosA and fosA3 .