"Capnocytophaga" spp. can be resistant to third-generation cephalosporins, but remain susceptible to imipenem, cefoxitin, and amoxicillin combined with clavulanic acid. Although resistant strains are most frequently isolated in oral cavities, their prevalence is worrying, (Jolivet-Gougeon et al., 2008; Sixou et al., 2006). The CfxA broad spectrum beta- lactamases (CfxA, CfxA2 and CfxA3) belong to the group 2e of Bush classification. This class includes beta-lactamase enzymes with significant activity against cephalosporins and monobactams, rather than penicillins. Following the characterization of CfxA beta- lactamase in "B. vulgatus" and CfxA2 beta-lactamase in "P. intermedia" (nucleotide Genbank under accession number AF118110), a new group 2e of Bush classification named CfxA3 (nucleotide GenBank under accession number AF472622) has been characterized in "C. ochracea" E201 (Jolivet-Gougeon et al. 2004). The cfxA3 gene has 99% identity with cfxA of "B. vulgatus" and cfxA2 of "P. intermedia". The analysis of the 966 bp nucleotide sequence showed that the gene encoding beta-lactamase CfxA3 in "C. ochracea" E201 differs from cfxA gene of "B. vulgatus" by substitution of two amino acids (K272E and Y239D) and from cfxA2 gene of "P. intermedia" by a substitution of one amino acid (Y239D). CfxA3 was different from CfxA2 because of an aspartic acid in place of tyrosine (at position 239) and from CfxA because of a glutamic acid instead of a lysine (at position 272). In 2005, Handal et al. (2005b) identified a novel Ambler class A beta-lactamase called CSP-1 from a NOR "C. sputigena" strain, resistant to amoxicillin and first and second generation cephalosporins. The new beta- lactamase had 32% homology with CfxA, 41% with CblA and 38% with CepA.