Molecular diversity of chromosomal metallo-β-lactamase genes in Elizabethkingia genus

Elizabethkingia genus is an opportunistic life-threatening pathogen with an intrinsic multidrug-resistant phenotype. It is the only known microorganism with multi-chromosome-borne metallo-beta-lactamase (MBL) genes. To determine the diversity and distribution of MBLs Bla(BlaB) and Bla(GOB) in this genus, comprehensive bioinformatic screening was applied in 109 available Elizabethkingia genomes. A total of 23 and 32 novel Bla(BlaB) and Bla(GOB) variants were found in Elizabethkingia spp., respectively; 12 and 15 clusters were assigned in these Bla(BlaB) and Bla(GOB) based on the amino acid identities and phylogenetic studies. Clustering of some variants did not conform to species-specific clades, which indicated potential interspecies dissemination of MBL genes among Elizabethkingia species. Cloning of representative bla(BlaB) and bla(GOB) into E. coli DH5 alpha resulted in increased and diverse minimum inhibitory concentrations (MICs) to most beta-lactams, including cephalosporins, carbapenems, and beta-lactams-inhibitors. This study extends the database of class B carbapenemases, emphasizing the diversity of different MBL genes in the genus Elizabethkingia, which may represent potential reservoirs of acquired MBLs. (c) 2020 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.