title: Phylogenetic diversity of ceftriaxone resistance and the presence of extended-spectrum β-lactamase genes in the culturable soil resistome.
abstract: The aim of this study was to determine the phylogenetic diversity of ceftriaxone resistance and the presence of known extended-spectrum β-lactamase (ESBL) genes in culturable soil resistomes. Libraries of soil bacterial isolates resistant to ceftriaxone were established from six physicochemically diverse soils collected in Hawaii (USA) and Israel. The phylogenetic affiliation, ceftriaxone and multidrug resistance levels, and presence of known ESBL genes of the isolates were determined. The soil bacterial isolates were phylogenetically grouped with the Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Actinobacteria, Firmicutes and Bacteroidetes. Ceftriaxone minimum inhibitory concentrations (MICs) largely followed the phylogeny structure and higher levels of ceftriaxone resistance corresponded to higher multidrug resistance. Three distinct blaTEM variants were detected in soil bacterial isolates belonging to nine different genera. In conclusion, the culturable soil resistomes for ceftriaxone exhibited high phylogenetic diversity and multidrug resistance. blaTEM was the only known ESBL detected in the soil resistomes, and its distribution in different phylogenetic groups suggests its ubiquitous presence and/or possible horizontal gene transfer within the soil microbiomes.
authors.affiliation: Department of Civil and Environmental Engineering, University of Hawai'i at Manoa, Honolulu, HI, USA.
authors.forename: Eulyn
authors.initials: E
authors.lastname: Pagaling
authors.affiliation: Institute of Soil, Water and Environmental Sciences, Agriculture Research Organization, The Volcani Center, Bet-Dagan, Israel; Departments of Soil and Water, Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel.
authors.forename: Joao
authors.initials: J
authors.lastname: Gatica
authors.affiliation: Department of Civil and Environmental Engineering, University of Hawai'i at Manoa, Honolulu, HI, USA.
authors.forename: Kun
authors.initials: K
authors.lastname: Yang
authors.affiliation: Institute of Soil, Water and Environmental Sciences, Agriculture Research Organization, The Volcani Center, Bet-Dagan, Israel.
authors.forename: Eddie
authors.initials: E
authors.lastname: Cytryn
authors.affiliation: Department of Civil and Environmental Engineering, University of Hawai'i at Manoa, Honolulu, HI, USA. Electronic address: taoyan@hawaii.edu.
authors.forename: Tao
authors.initials: T
authors.lastname: Yan
mesh_terms: D001419:Bacteria / Q000145:classification*; D002443:Ceftriaxone; D024881:Drug Resistance, Bacterial; D006254:Hawaii; D007557:Israel; D010802:Phylogeny; D012987:Soil; D012988:Soil Microbiology; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D012987:Soil; D002443:Ceftriaxone; D001618:beta-Lactamases
keywords: Ceftriaxone; ESBL genes; Phylogeny; Resistome; Soil; bla(TEM)