The contribution of β-lactamases and the porins OmpK35 and OmpK36 to carbapenem resistance in KPC-pr

• 作 者: Xiaofei Jiang Feiyi Ruan Kumar Rajakumar Yanyan Wang Ying Zhang Gang Li Yueru Tian Hong Liu Fuqi Ai YIming Ma Bei Wang
• 机 构: Center of Laboratory Medicine,Huashan Hospital,Shanghai Medical College,Fudan University,Shanghai 20
• 出 处: 第三届中国临床微生物学大会暨微生物学与免疫学论坛
• 发表日期: 2012年8期

　　To investigate the contribution of [β-lactamses and porins OmpK35 and OmpK36 in KPC-2 producing Klebsiella pneumoniae clinical isolates.Methods: 57 consecutive, non-duplicate, carbapenem-resistant K.pneumoniae isolates were collected to perform β-lactamses analysis by IEF, PCR, PCR product sequence and genotyping by MLST.Six representative isolates were selected to perform outer membrane analysis by RT-qPCR and SDS-PAGE.4 of them which express low or normal ompK35 or/and ompK36, has or hasnt DHA-1 or VIM-1 were chosen to perform blaKPC-2 deletion by λ Red recombination.Results: Of 57 isolates studied, fifty belong to ST11, five belong to ST423, one each to ST65 and a novel MLST type,ST977.All six selected isolates produce KPC-2, TEM-1, CTX-M-14, and express similar blaKPC-2, XJ-1 expressing low ompK35 has an IS5 insertion under its ompK35s promoter; a novel Asp135 and Gly136 insertion flanked the PEFXG motif in OmpK36 of XJ-3 and XJ-6 may result into the protein no-function; XJ-4 and XJ-5 express normal ompK36.When blaKPC-2 was deleted, both XJ-1 and XJ-4 show a more than 8 times decrease in MICs to imipenem,meropenem and ertpenem.XJ-3 bearing blaDHA-1 show high MICs to ertpenem and reduce MICs to imipenem and meropenem, X J-5 bearing blaVIM-1 show a modest reduce MICs to imipenem, meropenem and ertpenem.Conclusions: In carbapenem-resistant K.pneumoniae clinical isolates circulating in Shanghai, blaKPC-2, blaDHA-1 and/or blaVIM-1 are the key factors contributing to high-level carbapenem resistance and deficient expression of OmpK35 and/or OmpK36 only serves as a cooperative factor.