[Study on the molecular mechanism of transferable multiple-antibiotic resistance in extended-spectrum beta-lactamase-producing clinical isolates].
OBJECTIVE
To investigate the molecular mechanism of transferable multiple-antibiotic resistance in extended-spectrum beta-lactamases (ESBLs) producing isolates.


METHODS
Antibiotics susceptibility was tested by E-test method, and multi-resistance plasmids were screened and isolated by extracting transformant plasmids. Inserted gene Cassettes of class 1 integron were amplified and analyzed by polymerase chain reaction (PCR) and DNA sequencing.


RESULTS
Eight of the nine ESBL-producing plasmids were found to comprise class 1 integron sequence, of them 7 harbored 1 or 2 antibiotic resistant gene cassettes which encoding resistance to aminoglycosides (aacA4, aadA2 or aadA5), trimethoprim (dhfrA12 or dfrA17), rifampicin (arr-3) and chloramphenicol (cmlA6). The function of these gene cassettes corresponded to the resistance profiles of their electro-transformants.


CONCLUSIONS
Multi-resistance gene cassettes located on plasmids and mediated by class 1 integron may play an important role in causing the development and dissemination of multiple-antibiotic resistance in ESBL-producing clinical isolates.
Lu
Jian
J
Department of Respiratory Medicine, The Third Affiliated Hospital of Sun Yat-sen university, Guangzhou 510630, China.
Tang
Ying-chun
YC
Wu
Ben-quan
BQ
Zhang
Kou-xing
KX
Zhang
Tian-tuo
TT
Bi
Xiao-gang
XG
Zhu
Jia-xin
JX
Tan
Shu-qing
SQ
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D003001:Cloning, Molecular; D004251:DNA Transposable Elements / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics / Q000302:isolation & purification; D006090:Gram-Negative Bacteria / Q000235:genetics* / Q000302:isolation & purification; D006801:Humans; D019426:Integrases / Q000235:genetics; D032023:Integrons; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D001618:beta-Lactamases / Q000235:genetics*
D000900:Anti-Bacterial Agents; D004251:DNA Transposable Elements; D019426:Integrases; D001618:beta-Lactamases