Diversity and evolution of the class a chromosomal beta-lactamase gene in Klebsiella pneumoniae
Diversity and evolution of the class a chromosomal beta-lactamase gene in Klebsiella pneumoniae
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DOI：
10.1128/aac.48.7.2400-2408.2004
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发表时间：
2004-07-01
影响因子：
4.9
通讯作者：
Brisse, S
中科院分区：
文献类型：
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作者：
Hæggman, S;Löfdahl, S;Brisse, S
本研究对肺炎克雷伯菌染色体A类β-内酰胺酶基因的多样性进行了研究，以探讨该基因的进化。在一组28个菌株中测定了一个789 bp的片段，代表了最近在克雷伯氏菌中鉴定的三个系统发育群，KpI，KpII和KpIII。肺炎杆菌和先前鉴定的不同染色体β-内酰胺酶变体。发现了三组序列，其中两组分别对应于SHV（pI 7.6）和LEN（pI 7.1）家族，另一组更异质，对应于我们命名为OKP的新家族（其他K.肺炎β-内酰胺酶）。三组对氨苄西林、头孢呋辛、头孢噻肟、头孢他啶和氨曲南的敏感性水平以及克拉维酸的抑制作用相似。鉴定出一种新的SHV变异体、七种新的LEN变异体和四种OKP变异体。OKP变体根据核苷酸序列形成两个亚组，一个具有7.8和8.1的pIs，另一个具有6.5和7.0的pIs。管家基因gyrA，编码亚基A的促旋酶，和mdh，编码苹果酸脱氢酶的核苷酸序列，也进行了测定。系统发育分析的三个基因的研究揭示了平行的进化，与SHV，OKP，LEN β-内酰胺酶家族对应的系统发育组KpI，KpII，和KpIII，分别。在对三种β-内酰胺酶家族具有特异性的PCR检测中，对另外34种菌株完全证实了这种对应关系。我们估计系统发育组KpI和KpIII分化的时间在600万到2800万年之间，证实了β-内酰胺酶基因在K.肺炎。
We investigated the diversity of the chromosomal class A beta-lactamase gene in Klebsiella pneumoniae in order to study the evolution of the gene. A 789-bp portion was sequenced in a panel of 28 strains, representative of three phylogenetic groups, KpI, KpII, and KpIII, recently identified in K. pneumoniae and of different chromosomal beta-lactamase variants previously identified. Three groups of sequences were found, two of them corresponding to the families SHV (pI 7.6) and LEN (pI 7.1), respectively, and one, more heterogeneous, corresponding to a new family that we named OKP (for other K. pneumoniae beta-lactamase). Levels of susceptibility to ampicillin, cefuroxime, cefotaxime, ceftazidime, and aztreonam and inhibition by clavulanic acid were similar in the three groups. One new SHV variant, seven new LEN variants, and four OKP variants were identified. The OKP variants formed two subgroups based on nucleotide sequences, one with pIs of 7.8 and 8.1 and the other with pIs of 6.5 and 7.0. The nucleotide sequences of the housekeeping genes gyrA, coding for subunit A of gyrase, and mdh, coding for malate dehydrogenase, were also determined. Phylogenetic analysis of the three genes studied revealed parallel evolution, with the SHV, OKP, and LEN beta-lactamase families corresponding to the phylogenetic groups KpI, KpII, and KpIII, respectively. This correspondence was fully confirmed for 34 additional strains in PCR assays specific for the three beta-lactamase families. We estimated the time since divergence of the phylogenetic groups KpI and KpIII at between 6 and 28 million years, confirming the ancient presence of the beta-lactamase gene in the genome of K. pneumoniae.