Libisch Balázs, Balogh Boglárka, Füzi Miklós
Department of Bacteriology, National Center for Epidemiology, Gyali ut, Budapest, Hungary.
Curr Microbiol. 2009 Feb;58(2):111-6. doi: 10.1007/s00284-008-9285-7. Epub 2008 Oct 23.
The aim of this study was to identify class 1 integrons from extended-spectrum and metallo-beta-lactamase-negative, multidrug-resistant Pseudomonas aeruginosa clinical isolates from Hungary and to characterize the isolates by phenotypic and molecular methods. Fourteen selected P. aeruginosa isolates resistant to ceftazidime, gentamicin, and ciprofloxacin were subjected to serotyping, random amplification of polymorphic DNA (RAPD), integron content analysis, and a phenotypic test to detect high-level production of AmpC. Four representative isolates were further analyzed by multilocus sequence typing. Two P. aeruginosa multidrug-resistant clonal lineages were identified with a countrywide distribution. The first lineage is characterized by serotype O4, RAPD genotype A, sequence type ST175, and the presence of a class 1 integron harbouring aadB and aadA13 gene cassettes in its variable region. The second lineage is characterized by serotype O6, RAPD genotype B, sequence type ST395, and a class 1 integron carrying a single aadB cassette. The corresponding isolates were recovered from altogether 11 towns in Hungary. ST175 and ST395 are the presently calculated founders of two distinct P. aeruginosa clonal complexes that appear to have a wide geographical distribution also outside Hungary. The multidrug-resistant phenotype associated with these two clonal lineages might have contributed to an increase in their frequency and to their subsequent diversification. Both P. aeruginosa lineages displayed > or =8-fold synergy with boronic acid/ceftazidime combinations, suggesting an AmpC-mediated resistance to ceftazidime. Our observations underscore the role of class 1 integrons in the spread of aminoglycoside resistance by clonal dissemination among P. aeruginosa clinical isolates in Hungary.
本研究的目的是从匈牙利产超广谱和金属β-内酰胺酶阴性、多重耐药的铜绿假单胞菌临床分离株中鉴定1类整合子，并通过表型和分子方法对分离株进行特征分析。对14株对头孢他啶、庆大霉素和环丙沙星耐药的铜绿假单胞菌分离株进行血清分型、随机扩增多态性DNA（RAPD）分析、整合子含量分析以及检测AmpC高水平产生的表型试验。对4株代表性分离株进一步进行多位点序列分型。鉴定出两个在全国范围内分布的铜绿假单胞菌多重耐药克隆谱系。第一个谱系的特征为血清型O4、RAPD基因型A、序列型ST175，其可变区存在携带aadB和aadA13基因盒的1类整合子。第二个谱系的特征为血清型O6、RAPD基因型B、序列型ST395，以及携带单个aadB基因盒的1类整合子。相应的分离株共从匈牙利的11个城镇中分离得到。ST175和ST395是目前计算得出的两个不同铜绿假单胞菌克隆复合体的奠基者，这两个复合体似乎在匈牙利以外也有广泛的地理分布。与这两个克隆谱系相关的多重耐药表型可能促使它们的频率增加并随后发生多样化。两种铜绿假单胞菌谱系与硼酸/头孢他啶组合均表现出≥8倍的协同作用，提示存在AmpC介导的对头孢他啶的耐药性。我们的观察结果强调了1类整合子在匈牙利铜绿假单胞菌临床分离株中通过克隆传播导致氨基糖苷类耐药性扩散中的作用。
