First report in China of Enterobacteriaceae clinical isolates coharboring blaNDM-1 and blaIMP-4 drug resistance genes.
OBJECTIVE
To describe the identification of two carbapenem-resistant, NDM-1 and IMP-4, carbapenemases coproducing Enterobacteriaceae isolates recovered from hospitalized patients in China. Both Klebsiella pneumoniae clinical isolates (Kpn922 and Kpn9599) were resistant to meropenem and imipenem and were subjected to additional antibiotic susceptibility testing. Polymerase chain reaction (PCR) and sequence analyses were used to characterize bacterial carbapenemase resistance genes, extended-spectrum β-lactamases, plasmid-mediated AmpC enzymes, quinolone resistance, and 16s RNA methylase. Genetic relatedness was determined using pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Plasmids were analyzed by S1-PFGE and Southern blot.


RESULTS
PCR analyses revealed that the Kpn922 isolate carried blaNDM-1, blaIMP-4, blaTEM-1, and blaSHV-1 genes, while Kpn9599 carried blaNDM-1, blaIMP-4, blaTEM-1, and blaSHV-12 genes. MLST determined that the two isolates were ST1043 and ST571 sequence types. Southern blot analyses revealed that metallo-β-lactamase genes were plasmid borne in both isolates. Plasmids ∼300 kb simultaneously carried blaNDM-1 and blaIMP-4.


CONCLUSIONS
Coexistence of blaNDM-1 and blaIMP-4 in these clinical isolates may herald the emergence of a new pattern of drug resistance. Surveillance of carbapenemases, particularly metallo-β-lactamases, in Enterobacteriaceae is urgently needed to control and prevent the spread of these resistance determinants in China.
Department of Laboratory Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology , Wuhan, People's Republic of China .
Zhongju
Z
Chen
Yue
Y
Wang
Lei
L
Tian
Xuhui
X
Zhu
Li
L
Li
Bei
B
Zhang
Shaozhen
S
Yan
Ziyong
Z
Sun
D000293:Adolescent; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics; D015780:Carbapenems / Q000494:pharmacology; D002681:China; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D004755:Enterobacteriaceae / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification*; D004756:Enterobacteriaceae Infections / Q000188:drug therapy / Q000382:microbiology; D006761:Hospitals; D006801:Humans; D015378:Imipenem / Q000494:pharmacology; D007710:Klebsiella Infections / Q000188:drug therapy / Q000382:microbiology; D007711:Klebsiella pneumoniae / Q000187:drug effects / Q000254:growth & development / Q000302:isolation & purification; D008297:Male; D000077731:Meropenem; D010957:Plasmids / Q000235:genetics; D015363:Quinolones / Q000627:therapeutic use; D013845:Thienamycins / Q000494:pharmacology; D001618:beta-Lactamases / Q000235:genetics*
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D015780:Carbapenems; D015363:Quinolones; D013845:Thienamycins; D015378:Imipenem; C425142:beta-lactamase IMP-4; D001618:beta-Lactamases; C552864:beta-lactamase NDM-1; C063912:carbapenemase; D000077731:Meropenem