Heterogeneity of AmpC Cephalosporinases of Hafnia alvei Clinical Isolates Expressing Inducible or Constitutive Ceftazidime Resistance Phenotypes

Ten unrelated Hafnia alvei clinical isolates were grouped according to either their low-level and inducible cephalosporinase production or their high-level and constitutive cephalosporinase production phenotype. Their AmpC sequences shared 85 to 100% amino acid identity. The immediate genetic environment of ampC genes was conserved in H. alvei isolates but was different from that found in other ampC-possessing enterobacterial species.