title: A Snapshot of Co-Resistance to Carbapenems and Tigecycline in Clinical Isolates of Enterobacter cloacae.
abstract: Enterobacter cloacae is one of the most common carbapenem-resistant Enterobacteriaceae (CRE) global wide. Resistance to tigecycline, one of the few therapeutic options for CRE infections, in carbapenem-resistant E. cloacae is of clinical significance. Fourteen E. cloacae clinical isolates (EC1-EC14) co-resistant to tigecycline and carbapenems were studied. Two tigecycline-susceptible/carbapenem-resistant isolates (TS1-TS2) were used for comparison. Genotyping by pulsed-field gel electrophoresis and multilocus sequence typing identified seven pulsotypes and three sequence types (STs). All three STs belonged to the published international clones. Polymerase chain reaction (PCR) and sequence analysis revealed the coexistence of blaSHV-12and blaIMP-8in 11 EC isolates from five pulsotypes/two STs. Reverse transcription PCR demonstrated overexpression of the chromosomal AmpC-like β-lactamase in seven EC isolates (four pulsotypes/two STs) and TS1 (pulsotype F/ST78). Reduced expression of outer membrane protein C (OmpC) was found in three EC isolates (all pulsotype C/ST204), whereas reduced expression of OmpF was found in nine EC isolates (three pulsotypes/two STs) and TS2 (pulsotype G/ST114). Overexpression of the efflux pump AcrB was found in all EC isolates although three showed borderline significance. Multiple mechanisms jointly contributed to the observed co-resistance to tigecycline and carbapenems. Some international clones have infiltrated into Taiwan and acquired various resistance traits independently.
authors.affiliation: 1 Department of Nephrology, Tainan Municipal Hospital , Tainan, Taiwan .|2 Department of Internal Medicine, Tainan Municipal Hospital , Tainan, Taiwan .
authors.forename: Ling-Fu
authors.initials: LF
authors.lastname: Huang
authors.affiliation: 3 Department of Clinical Laboratory, Tainan Municipal Hospital , Tainan, Taiwan .
authors.forename: Chao-Tai
authors.initials: CT
authors.lastname: Lee
authors.affiliation: 4 Department of Laboratory Medicine, Chang Gung Memorial Hospital, Chang Gung University , College of Medicine, Taoyuan, Taiwan .
authors.forename: Lin-Hui
authors.initials: LH
authors.lastname: Su
authors.affiliation: 2 Department of Internal Medicine, Tainan Municipal Hospital , Tainan, Taiwan .|5 Department of Infectious Diseases, Tainan Municipal Hospital , Tainan, Taiwan .
authors.forename: Chin-Lu
authors.initials: CL
authors.lastname: Chang
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D015373:Bacterial Typing Techniques; D015780:Carbapenems / Q000494:pharmacology*; D002999:Clone Cells; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D016521:Electrophoresis, Gel, Pulsed-Field; D016972:Enterobacter cloacae / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D004756:Enterobacteriaceae Infections / Q000453:epidemiology / Q000382:microbiology / Q000635:transmission; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D008826:Microbial Sensitivity Tests; D008911:Minocycline / Q000031:analogs & derivatives* / Q000494:pharmacology; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000235:genetics / Q000378:metabolism; D058885:Multilocus Sequence Typing; D018272:Porins / Q000235:genetics / Q000378:metabolism; D013624:Taiwan / Q000453:epidemiology; D000078304:Tigecycline; D001618:beta-Lactamases / Q000235:genetics / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D015780:Carbapenems; D008911:Minocycline; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D018272:Porins; D000078304:Tigecycline; D001618:beta-Lactamases; C113724:OmpC protein; C109237:OmpF protein; C048795:AmpC beta-lactamases
keywords: Enterobacter cloacae; IMP-8; carbapenem resistance; efflux; international clones; tigecycline resistance