Characterization of BKC-1 Class A Carbapenemase from Klebsiella pneumoniae Clinical Isolates in Brazil
Characterization of BKC-1 Class A Carbapenemase from Klebsiella pneumoniae Clinical Isolates in Brazil
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DOI：
10.1128/aac.00158-15
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发表时间：
2015-09-01
影响因子：
4.9
通讯作者：
Gales, Ana Cristina
中科院分区：
文献类型：
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作者：
Nicoletti, Adriana Giannini;Marcondes, Marcelo F. M.;Gales, Ana Cristina
从巴西圣保罗的两个医疗中心住院的不同患者中回收了3株表现出碳青霉烯类耐药的肺炎克雷伯菌临床分离株。观察到这些对多粘菌素B敏感的分离株对所有β-内酰胺类、喹诺酮类和一些氨基糖苷类耐药。克拉维酸可抑制所有K. pneumoniae分离株属于相同的脉冲场凝胶电泳（PFGE）类型和一种新的序列类型（ST），ST 1781（克隆复合物442 [CC 442]）。通过电穿孔将命名为p60136的10-kb非接合不亲和性Q组（IncQ）质粒转移到大肠杆菌菌株TOP 10细胞中。p60136的全序列分析表明，它由一个动员系统ISKpn 23、磷酸转移酶aph 3A-VI和一个941 bp的开放阅读框（ORF）组成，编码一个313个氨基酸的蛋白质。该ORF被命名为bla（BKC-1）。巴西克雷伯氏菌碳青霉烯酶-1（BKC-1）的pI为6.0，与环境细菌苜蓿中华根瘤菌的β-内酰胺酶具有最高的同源性（63%）。水解研究表明，纯化的BKC-1不仅水解碳青霉烯类，而且还水解青霉素类、头孢菌素类和单环内酰胺类。然而，由于碳青霉烯类的k（cat）值非常低（0.0016至0.031 s（-1）），其水解效率较低。事实上，苯唑西林是BKC-1的最佳底物（k（cat）/K-m，53，522.6 mM（-1）s（-1））。在此，我们报道了一种新的A类碳青霉烯酶，证实了克雷伯菌中β-内酰胺酶的多样性和快速进化。肺炎临床分离株。
Three Klebsiella pneumoniae clinical isolates demonstrating carbapenem resistance were recovered from different patients hospitalized at two medical centers in Sao Paulo, Brazil. Resistance to all beta-lactams, quinolones, and some aminoglycosides was observed for these isolates that were susceptible to polymyxin B. Carbapenem hydrolysis, which was inhibited by clavulanic acid, was observed for all K. pneumoniae isolates that belonged to the same pulsed-field gel electrophoresis (PFGE) type and a novel sequence type (ST), ST1781 (clonal complex 442 [CC442]). A 10-kb nonconjugative incompatibility group Q (IncQ) plasmid, denominated p60136, was transferred to Escherichia coli strain TOP10 cells by electroporation. The full sequencing of p60136 showed that it was composed of a mobilization system, ISKpn23, the phosphotransferase aph3A-VI, and a 941-bp open reading frame (ORF) that codified a 313-amino acid protein. This ORF was named bla(BKC-1). Brazilian Klebsiella carbapenemase-1 (BKC-1) showed a pI of 6.0 and possessed the highest identity (63%) with a beta-lactamase of Sinorhizobium meliloti, an environmental bacterium. Hydrolysis studies demonstrated that purified BKC-1 not only hydrolyzed carbapenems but also penicillins, cephalosporins, and monobactams. However, the carbapenems were less efficiently hydrolyzed due to their very low k(cat) values (0.0016 to 0.031 s(-1)). In fact, oxacillin was the best substrate for BKC-1 (k(cat)/K-m, 53,522.6 mM(-1) s(-1)). Here, we report a new class A carbapenemase, confirming the diversity and rapid evolution of beta-lactamases in K. pneumoniae clinical isolates.