Izdebski R, Fiett J, Urbanowicz P, Baraniak A, Derde L P G, Bonten M J M, Carmeli Y, Goossens H, Hryniewicz W, Brun-Buisson C, Brisse S, Gniadkowski M
Department of Molecular Microbiology, National Medicines Institute, Warsaw, Poland
Department of Molecular Microbiology, National Medicines Institute, Warsaw, Poland.
J Antimicrob Chemother. 2015 Dec;70(12):3230-7. doi: 10.1093/jac/dkv273. Epub 2015 Aug 27.
The objective of this study was to examine Klebsiella oxytoca clonal and phylogenetic diversity, based on an international collection of carriage isolates non-susceptible to expanded-spectrum cephalosporins (ESCs).
The study material comprised 68 rectal carriage K. oxytoca isolates non-susceptible to ESCs recovered in 2008-11 from patients in 14 hospitals across Europe and Israel. ESC resistance was tested phenotypically; genes encoding ESBLs, AmpC cephalosporinases and carbapenemases were amplified and sequenced. The isolates were typed by PFGE and MLST, followed by sequencing of blaOXY genes.
MLST and PFGE distinguished 34 STs and 47 pulsotypes among the isolates, respectively. Six STs were split into several pulsotypes each. Five STs were more prevalent (n = 2-9) and occurred in several countries each, including ST2, ST9 and ST141, which belong to a growing international clonal complex (CC), CC2. Four phylogenetic lineages were distinguished, each with another type of chromosomal OXY-type β-lactamase. Three of these, with OXY-1/-5, OXY-2 types and OXY-4, corresponded to previously described phylogroups KoI, KoII and KoIV, respectively. A single isolate from Israel represented a distinct lineage with a newly defined OXY-7 type. The phylogroups showed interesting differences in mechanisms of ESC resistance; KoI strains rarely overexpressed the OXY enzymes but commonly produced ESBLs, whereas KoII strains often were OXY hyperproducers and carried ESBLs much less frequently. AmpCs (DHA-1) and carbapenemases (VIM-1) occurred sporadically.
The study confirmed the high genetic diversity of the collection of K. oxytoca ESC-non-susceptible isolates, composed of phylogroups with distinct types of OXY-type β-lactamases, and revealed some STs of broad geographical distribution.
本研究的目的是基于一组对超广谱头孢菌素（ESCs）不敏感的国际携带分离株，研究产酸克雷伯菌的克隆和系统发育多样性。
研究材料包括2008年至2011年期间从欧洲和以色列14家医院的患者中分离出的68株对ESCs不敏感的直肠携带产酸克雷伯菌。对ESCs耐药性进行表型检测；扩增并测序编码ESBLs、AmpC头孢菌素酶和碳青霉烯酶的基因。通过PFGE和MLST对分离株进行分型，随后对blaOXY基因进行测序。
MLST和PFGE分别在分离株中区分出34个ST型和47个脉冲型。6个ST型各自又分为几个脉冲型。5个ST型更为常见（n = 2 - 9），且每个都出现在多个国家，包括属于不断扩大的国际克隆复合体（CC）即CC2的ST2、ST9和ST141。区分出四个系统发育谱系，每个谱系具有另一种类型的染色体OXY型β-内酰胺酶。其中三个，具有OXY-1/-5、OXY-2型和OXY-4，分别对应于先前描述的系统发育群KoI、KoII和KoIV。来自以色列的一株分离株代表一个独特的谱系，具有新定义的OXY-7型。这些系统发育群在ESCs耐药机制上表现出有趣的差异；KoI菌株很少过度表达OXY酶，但通常产生ESBLs，而KoII菌株常常是OXY高生产者，且携带ESBLs的频率低得多。AmpCs（DHA-1）和碳青霉烯酶（VIM-1）偶尔出现。
该研究证实了产酸克雷伯菌对ESCs不敏感分离株集合的高度遗传多样性，这些分离株由具有不同类型OXY型β-内酰胺酶的系统发育群组成，并揭示了一些具有广泛地理分布的ST型。
