Clonal distribution of multidrug-resistant Enterobacter cloacae

Abstract

A multilocus sequence typing (MLST) scheme including 7 housekeeping genes was used to evaluate whether the current spread of multidrug-resistant Enterobacter cloacae isolates worldwide might be associated to specific successful clones. Fifty E. cloacae clinical isolates of worldwide origin, with various β-lactamase content, and recovered at different periods of time were studied. Forty-four sequence types were identified, highlighting a high clonal diversity with 3 main lineages. This study revealed that a precise identification of the isolates by sequencing of the chromosomal ampC gene of E. cloacae would provide a significant added value to improve the reliability of the MLST scheme.

Enterobacter cloacae Complex Isolates Harboring bla NMC-A or bla IMI -Type Class A Carbapenemase Genes on Novel Chromosomal Integrative Elements and Plasmids

“…Phylogenetic analysis using the concatenated MLST target sequences (Fig. 1A) was carried out on all bla NMC-A/IMI -harboring strains along with various E. cloacae complex strains belonging to several species or subspecies with known hsp60 cluster types (2) and also with concatenated sequences from the recently identified MDR clonal complex STs ST114, ST171, ST74-78, and ST234 (6)(7)(8) (15). The isolate harboring bla IMI-5 (ST261) clustered closet to E. cloacae UCI39 (ST743), and an isolate harboring bla IMI-1 (ST497) clustered between this branch and E. kobei SMART_635 (ST810).…”

“…have emerged due to the acquisition of mobile elements that carry multiple antimicrobial resistance genes, including extended-spectrum ␤-lactamases (ESBL), such as bla CTX-M- 15 , and carbapenem-hydrolyzing ␤-lactamases (i.e., carbapenemases), including KPC, NDM, and OXA-48 types (1). Based on a multilocus sequence typing (MLST) scheme used in multiple studies, a number these MDR E. cloacae isolates from human clinical and animal origins have been assigned to clonal complexes that have appeared in multiple countries and continents (6)(7)(8). Less often described are Enterobacter isolates harboring the class A chromosomally encoded NMC-A or IMI-type carbapenemases, although NMC-A from E. cloacae NOR-1, isolated in 1990, was one of the first carbapenemases described in Enterobacteriaceae (9).…”

Dissemination of multiresistant Enterobacter cloacae isolates producing OXA-48 and CTX-M-15 in a Spanish hospital

“…Most E. cloacae reported in this study were assigned to STs previously associated with ESBL-and carbapenemase-producers and considered as high-risk international clones (ST45, ST66, ST74 and ST78), with the latter two belonging to the same clonal complex [10,15]. Noteworthy, none of these clones had been previously associated with OXA-48 production.…”

“…MLST was performed for representative isolates with different PFGE profiles (Ecl10, Ecl3, Ecl9, Ecl8, Ecl21, Ecl5 and Ecl7) as described previously [10]. The database available at http://pubmlst.…”

Characterization of a Novel Putative Xer-Dependent Integrative Mobile Element Carrying the bla NMC-A Carbapenemase Gene, Inserted into the Chromosome of Members of the Enterobacter cloacae Complex

“…NMC-A is a serine carbapenemase originally detected in a carbapenem-resistant Enterobacter strain (NOR-1, initially identified as E. cloacae and subsequently reidentified as E. asburiae) isolated from a soft tissue infection in France in 1990 (7,8). The enzyme is able to hydrolyze a broad spectrum of ␤-lactam substrates, with preference for penicillins, narrow-spectrum cephalosporins, and carbapenems (7,9), and together with IMI-type enzymes belongs to a well-defined lineage of molecular class A ␤-lactamases (10).…”