Lange Felix, Pfennigwerth Niels, Gerigk Sonja, Gohlke Frank, Oberdorfer Klaus, Purr Ingvill, Wohanka Nikolaus, Roggenkamp Andreas, Gatermann Sören G, Kaase Martin
Department of Medical Microbiology, Ruhr-University Bochum, Universitätsstraße 150, Bochum, 44801, Germany.
Medizinische Laboratorien Düsseldorf, Nordstraße 44, Düsseldorf, 40477, Germany.
J Antimicrob Chemother. 2017 May 1;72(5):1334-1339. doi: 10.1093/jac/dkw566.
Characterization of Proteus mirabilis isolates harbouring bla OXA-58 with emphasis on the genetic environment of this resistance determinant.
Strains of P. mirabilis ( n = 37) isolated from different patients were tested for the presence of bla OXA-58 . The genetic context of bla OXA-58 was determined by WGS of two strains and Sanger sequencing. Clonality of the strains was assessed by PFGE. Susceptibility testing was performed by microdilution according to EUCAST.
Four strains isolated in different geographical regions of Germany were positive for bla OXA-58 , and WGS showed that this resistance gene was harboured on a plasmid. Sanger sequencing confirmed the presence of two nearly identical plasmids, 6219 and 6208 bp in size, in all four strains. Upstream of bla OXA-58 an IS Aba 3-like transposase gene was located. The P. mirabilis strains were not clonally related according to PFGE. MICs of meropenem for three of the strains were only just above the EUCAST breakpoint and the Carba NP test was positive for only two of the strains.
To our knowledge, this is the first description of bla OXA-58 in the species P. mirabilis . The resistance gene is harboured by almost identical plasmids in strains not clonally related and from different geographical regions. Apart from an IS Aba 3-like transposase gene upstream of bla OXA-58 the genetic context is different from bla OXA-58 harboured on plasmids in the genus Acinetobacter . With MICs of meropenem well below the EUCAST breakpoint or only just above it and equivocal or false negative results from the Carba NP test, bla OXA-58 can be easily overlooked in P. mirabilis .
对携带blaOXA - 58的奇异变形杆菌分离株进行特征分析，重点关注该耐药决定簇的遗传环境。
对从不同患者分离出的奇异变形杆菌菌株（n = 37）进行blaOXA - 58检测。通过对两株菌株进行全基因组测序（WGS）和桑格测序来确定blaOXA - 58的遗传背景。通过脉冲场凝胶电泳（PFGE）评估菌株的克隆性。根据欧盟药敏试验委员会（EUCAST）的标准，采用微量稀释法进行药敏试验。
在德国不同地理区域分离出的4株菌株blaOXA - 58呈阳性，全基因组测序表明该耐药基因存在于质粒上。桑格测序证实所有4株菌株中均存在两个大小分别为6219和6208 bp、几乎相同的质粒。在blaOXA - 58上游定位有一个ISAba 3样转座酶基因。根据PFGE结果，奇异变形杆菌菌株之间不存在克隆相关性。其中3株菌株美罗培南的最低抑菌浓度（MIC）仅略高于EUCAST的折点，碳青霉烯酶检测（Carba NP试验）仅两株菌株呈阳性。
据我们所知，这是首次在奇异变形杆菌中描述blaOXA - 58。该耐药基因存在于来自不同地理区域、无克隆相关性的菌株中几乎相同的质粒上。除了blaOXA - 58上游的一个ISAba 3样转座酶基因外，其遗传背景与不动杆菌属质粒上携带的blaOXA - 58不同。由于美罗培南的MIC远低于或仅略高于EUCAST折点，且Carba NP试验结果不明确或为假阴性，blaOXA - 58在奇异变形杆菌中很容易被忽视。
