Genetic diversity of carbapenem-hydrolyzing metallo-β-lactamases from Chryseobacterium (Flavobacterium) indologenes

The class B carbapenem-hydrolyzing beta -lactamase IND-1 has been characterized for Chryseobacterium indologenes strain 001. With internal primers for the bla gene for IND-1 (bla(IND-1)) and an internal bla(IND-1) probe, PCR amplifications failed, while hybridization results were positive when DNA from another C, indologenes isolate, strain CIP101026, was used as a template. Thus, a bla(IND)-related gene was cloned from this C, indologenes reference strain. Sequencing of the insert of a recombinant plasmid conferring resistance to carbapenems revealed an open reading frame with a G + C content of 39.9% and coding for a 243-amino-acid preprotein named IND-2, IND-2 shared 80% amino acid identity with IND-I and had a similar broad-spectrum resistance profile, including resistance to carbapenems, It was classified in functional subgroup 3a of class B carbapenem-hydrolyzing beta -lactamases, IND-I and IND-2, despite their genetic diversity, possessed similar kinetic parameters, except that ceftazidime was hydrolyzed less by IND-2, To obtain the entire bla(IND)-related gene sequences of eight other C, indologenes isolates, PCR was performed using internal and external primers, followed by inverse PCR techniques, The likely chromosome-mediated metallo-P-lactamases of the 10 C, indologenes isolates were divided into several groups and subgroups. IND-I, IND-S IND-2a, IND-3, and IND-4 shared 77 to 99% amino acid identity.