title: [Structure and function of class 1 integron in clinical isolates of Klebsiella pneumoniae].
abstract: To investigate molecular mechanism of multi-resistance of Klebsiella pneumoniae and its spreading, 179 strains isolated from different clinical samples in the period of 2002-2007 with serious resistance to 14 anti-bacterial agents were examined. Among them, 118 (65.9%) were resistant to at least two anti-bacterial agents; 36.3% (65/179) were found to contain class 1 integrons. There was a significant difference for resistance rate between the integron positive and the negative groups, especially for antimicrobial agents of aminoglycosides, quinolones and sulfonamides (P<0.01). Gene cassette structures of the class 1 integrons in these bacteria were analyzed and their resistance genes were further cloned and tested for antibiotic resistance activities. Fifteen gene cassettes were identified with dfrA17-aadA5 being the most popular form. Three recombinant plasmids pET28a-dhfr17, pET28a-dhfr17-orfF and pET28a-dhfr17-orfF-aadA2 were cloned from a gene cassette of dhfr17-orfF-aadA2. When introduced into a recipient E. coli strain BL21, all of them rendered resistance to co-trimoxazole, with minimum inhibitory concentration (MIC) value up to 256 µg/µL. The E. coli BL21 carrying pET28a- dhfr17 or pET28a-dhfr17-orfF had the same MIC value of 8 µg/µL to streptomycin as the recipient strain without plasmid. However, the E. coli carrying pET28a-dhfr17-orfF-aadA2 was resistant to streptomycin with MIC level up to 256 µg/µL. In conclusion, class 1 integrons were regularly identified in Klebsiella pneumoniae. They mainly carry resistance genes against antimicrobial agents of aminoglycosides and sulfonamide. Transferable plasmid carrying integrons with resistance genes may play an important role in resistance spreading among bacterial species.
authors.affiliation: School of Laboratory and Life Sciences, Wenzhou Medical University, Wenzhou 325000, China; School of Nursing, Wenzhou Medical University, Wenzhou 325000, China;
authors.forename: Zhang
authors.initials: Z
authors.lastname: Yuejin
authors.affiliation: School of Laboratory and Life Sciences, Wenzhou Medical University, Wenzhou 325000, China.
authors.forename: Chang
authors.initials: C
authors.lastname: Qingli
authors.affiliation: School of Laboratory and Life Sciences, Wenzhou Medical University, Wenzhou 325000, China.
authors.forename: Wang
authors.initials: W
authors.lastname: Qian
authors.affiliation: School of Laboratory and Life Sciences, Wenzhou Medical University, Wenzhou 325000, China; School of Medicine, Lishui College, Lishui 323000, China.
authors.forename: Lu
authors.initials: L
authors.lastname: Junwan
authors.affiliation: School of Laboratory and Life Sciences, Wenzhou Medical University, Wenzhou 325000, China.
authors.forename: Wang
authors.initials: W
authors.lastname: Huan
authors.affiliation: School of Laboratory and Life Sciences, Wenzhou Medical University, Wenzhou 325000, China.
authors.forename: Li
authors.initials: L
authors.lastname: Peizhen
authors.affiliation: School of Laboratory and Life Sciences, Wenzhou Medical University, Wenzhou 325000, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Jun
authors.affiliation: School of Laboratory and Life Sciences, Wenzhou Medical University, Wenzhou 325000, China.
authors.forename: Bao
authors.initials: B
authors.lastname: Qiyu
authors.affiliation: School of Laboratory and Life Sciences, Wenzhou Medical University, Wenzhou 325000, China.
authors.forename: Hu
authors.initials: H
authors.lastname: Yunliang
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D024881:Drug Resistance, Bacterial; D006801:Humans; D032023:Integrons; D007710:Klebsiella Infections / Q000382:microbiology*; D007711:Klebsiella pneumoniae / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D008826:Microbial Sensitivity Tests; D010957:Plasmids / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents