Dissemination of SHV-12 and characterization of new AmpC-type beta-lactamase genes among clinical isolates of enterobacter species in Korea.
To determine the prevalence and genotype of an extended-spectrum beta-lactamase and new chromosomal AmpC beta-lactamases among clinical isolates of Enterobacter species, we performed antibiotic susceptibility testing, pI determination, induction tests, transconjugation, enterobacterial repetitive consensus (ERIC) PCR, sequencing, and phylogenetic analysis. Among the 51 clinical isolates collected from a university hospital in Korea, 6 isolates have been shown to produce SHV-12 and inducible AmpC beta-lactamases. These also included three isolates producing TEM-1b and one strain carrying TEM-1b and CMY-type beta-lactamases with a pI of 8.0. The results from ERIC PCR revealed that six isolates were genetically unrelated, suggesting that dissemination of SHV-12 was responsible for the spread of resistance to extended-spectrum beta-lactams in Korea. Six genes of inducible AmpC beta-lactamases that are responsible for the resistance to cephamycins (cefoxitin and cefotetan), amoxicillin, cephalothin, and amoxicillin-clavulanic acid were cloned and characterized. A 1,165-bp DNA fragment containing the ampC genes was sequenced and found to have an open reading frame coding for a 381-amino-acid beta-lactamase. The nucleotide sequence of four ampC genes (bla(EcloK992004.1), bla(EcloK995120.1), bla(EcloK99230), and bla(EareK9911729)) shared considerable homology with that of AmpC-type class C beta-lactamase genes of gram-negative bacteria, especially that of the chromosomal ampC gene (bla(EcloMHN1)) of Enterobacter cloacae MHN1 (99.9, 99.7, 99.6, and 99.6% identity, respectively). The sequences of two ampC genes (bla(EcloK9973) and bla(EcloK9914325)) showed close similarity to the chromosomal ampC gene (bla(EcloQ908R)) of E. cloacae Q908R (99.7% identity). The results from phylogenetic analysis suggested that six ampC genes could originate from bla(EcloMHN1) or bla(EcloQ908R).
Lee
Sang Hee
SH
Department of Genetic Engineering, Youngdong University, Chungbuk 370-701, South Korea. sanghee@youngdong.ac.kr
Kim
Jae Young
JY
Shin
Sang Heum
SH
An
Young Jun
YJ
Choi
Young Wook
YW
Jung
Yeun Chang
YC
Jung
Ha Il
HI
Sohn
Eui Suk
ES
Jeong
Seok Hoon
SH
Lee
Kye Joon
KJ
D001426:Bacterial Proteins; D003227:Conjugation, Genetic; D004754:Enterobacter / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D004756:Enterobacteriaceae Infections / Q000382:microbiology*; D006801:Humans; D007525:Isoelectric Focusing; D007723:Korea; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012091:Repetitive Sequences, Nucleic Acid; D017422:Sequence Analysis, DNA; D018440:beta-Lactam Resistance; D001618:beta-Lactamases / Q000737:chemistry / Q000235:genetics*; D047090:beta-Lactams / Q000494:pharmacology
D001426:Bacterial Proteins; D047090:beta-Lactams; C107198:beta-lactamase SHV-12; C048795:AmpC beta-lactamases; D001618:beta-Lactamases