Hoffmann Harald, Stindl Sibylle, Ludwig Wolfgang, Stumpf Anita, Mehlen Andre, Monget Daniel, Pierard Denis, Ziesing Stefan, Heesemann Jürgen, Roggenkamp Andreas, Schleifer Karl H
Institute of Microbiology and Laboratory Medicine at the Pneumological Teaching Hospital of the University of Munich, Robert-Koch-Allee 2, D-82131 Gauting, Germany.
J Clin Microbiol. 2005 Jul;43(7):3297-303. doi: 10.1128/JCM.43.7.3297-3303.2005.
Six species and six additional genovars are combined within the so-called Enterobacter cloacae complex, with one of them being the species Enterobacter hormaechei. In a recent population genetic study, two genetic clusters were found in close phylogenetic proximity to the genetic cluster of E. hormaechei. In order to prove the hypothesis that these three genetic clusters belong to the same species, we performed cross-hybridization experiments in microplates with DNAs of representatives of each genetic cluster. The close phylogenetic relationship among the clusters was reflected by their relatively low deltaT(m) values, ranging from 0.3 to 4.8, confirming the hypothesis that the clusters are parts of the same species. These clusters can be distinguished from the other species of the E. cloacae complex, which have deltaT(m) values of 5.6 to 10.3. Forty-eight E. hormaechei strains from the different genetic clusters were phenotypically characterized with 129 biochemical tests. In this way, E. hormaechei could be differentiated from the other species of the E. cloacae complex because it tests negative in the 3-hydroxy-butyrate test. The three genetic clusters of E. hormaechei could also be differentiated from each other by using phenotypic tests. Hence, we propose three new subspecies of E. hormaechei corresponding to genetic clusters VI, VII, and VIII of the E. cloacae complex. E. hormaechei subsp. hormaechei comb. nov. corresponds to the original species description, as it gives negative results for the adonitol, d-arabitol, d-sorbitol, and d-melibiose tests and a positive result for the dulcitol test. E. hormaechei subsp. oharae subsp. nov. gives negative results for the dulcitol, adonitol, and d-arabitol tests and positive results for the d-sorbitol and d-melibiose tests. E. hormaechei subsp. steigerwaltii subsp. nov. gives a negative result for the dulcitol test and positive results for the adonitol, d-arabitol, d-sorbitol, and d-melibiose tests. Among the members of the E. cloacae complex, E. hormaechei seems to be the species most frequently recovered from clinical specimens.
所谓的阴沟肠杆菌复合体包含6个菌种和6个额外的基因变种，其中之一是霍氏肠杆菌（Enterobacter hormaechei）。在最近的一项群体遗传学研究中，发现了两个与霍氏肠杆菌基因簇在系统发育上紧密相邻的基因簇。为了验证这三个基因簇属于同一物种的假设，我们在微孔板中对每个基因簇的代表菌株的DNA进行了交叉杂交实验。这些基因簇之间相对较低的ΔT(m)值（范围为0.3至4.8）反映了它们之间密切的系统发育关系，证实了这些基因簇是同一物种的组成部分这一假设。这些基因簇可以与阴沟肠杆菌复合体的其他菌种区分开来，后者的ΔT(m)值为5.6至10.3。对来自不同基因簇的48株霍氏肠杆菌菌株进行了129项生化试验以进行表型特征分析。通过这种方式，霍氏肠杆菌可以与阴沟肠杆菌复合体的其他菌种区分开来，因为它在3-羟基丁酸盐试验中呈阴性。霍氏肠杆菌的三个基因簇也可以通过表型试验相互区分。因此，我们提出了霍氏肠杆菌的三个新亚种，分别对应阴沟肠杆菌复合体的基因簇VI、VII和VIII。霍氏肠杆菌霍氏亚种（E. hormaechei subsp. hormaechei comb. nov.）与原始菌种描述相符，因为它在阿东醇、D-阿拉伯糖醇、D-山梨醇和D-蜜二糖试验中呈阴性，在卫矛醇试验中呈阳性。霍氏肠杆菌小原亚种（E. hormaechei subsp. oharae subsp. nov.）在卫矛醇、阿东醇和D-阿拉伯糖醇试验中呈阴性，在D-山梨醇和D-蜜二糖试验中呈阳性。霍氏肠杆菌施泰格瓦尔蒂亚种（E. hormaechei subsp. steigerwaltii subsp. nov.）在卫矛醇试验中呈阴性，在阿东醇、D-阿拉伯糖醇、D-山梨醇和D-蜜二糖试验中呈阳性。在阴沟肠杆菌复合体的成员中，霍氏肠杆菌似乎是最常从临床标本中分离出来的菌种。
