 The GC content (38%) of this gene, its genetic environment, the lack of conjugal transfer and its detection in two reference strains suggest that it is an intrinsic resistance gene located on chromosome.CepA (Chromosomal cephalosporinase from "Bacteroides fragilis" belonging to Ambler class A) is an endogenous cephalosporinase A described in "Bacteroides fragilis".This beta- lactamase is ubiquitous, but frequently inactive.