Majewski Piotr, Wieczorek Piotr, Łapuć Izabela, Ojdana Dominika, Sieńko Anna, Sacha Paweł, Kłoczko Janusz, Tryniszewska Elżbieta
Department of Microbiological Diagnostics and Infectious Immunology, Medical University of Bialystok, Bialystok, Poland.
Department of Microbiological Diagnostics and Infectious Immunology, Medical University of Bialystok, Bialystok, Poland.
Int J Infect Dis. 2017 Aug;61:70-73. doi: 10.1016/j.ijid.2017.05.016. Epub 2017 Jun 27.
The growing incidence of multidrug-resistant (MDR) bacteria is an emerging challenge in modern medicine. The utility of carbapenems, which are considered 'last-line' agents, is being diminished by the growing incidence of various resistance mechanisms in Gram-negative bacteria. A molecular investigation was performed of an MDR carbapenem-resistant Citrobacter freundii of sequence type 8 (ST8) isolated from a hematology patient with acute myeloid leukemia.
Multilocus sequence typing and analysis of the nucleotide sequence of the class I integron were performed using PCR and Sanger sequencing. Transformation of the resistance plasmid isolated following the alkaline lysis method was performed using chemically competent E. coli TOP10.
Molecular analysis of the carbapenem-resistant C. freundii revealed the presence of the VIM-4 isoenzyme located on the ∼55-kb transferable resistance plasmid. Interestingly, the bla gene was inserted into an unusual gene cassette containing a 169-bp direct repeat of the 3' segment of the bla gene.
All unusual gene cassettes containing VIM-DR (direct repeat) described thus far have been harbored by non-fermenters, i.e., Acinetobacter and Pseudomonas, underscoring the importance of resistance determinant mobility, which may go even beyond genus, family, and order boundaries. Great efforts need to be taken to explore pathways of resistance to 'last-resort' antimicrobials, especially among clinically relevant pathogens.
多重耐药（MDR）细菌的发病率不断上升是现代医学面临的一个新挑战。碳青霉烯类药物被视为“最后一线”药物，但其效用正因革兰氏阴性菌中各种耐药机制发病率的上升而降低。对从一名急性髓系白血病血液学患者中分离出的序列类型为8（ST8）的多重耐药碳青霉烯耐药弗氏柠檬酸杆菌进行了分子研究。
使用聚合酶链反应（PCR）和桑格测序法进行多位点序列分型及I类整合子核苷酸序列分析。采用化学感受态大肠杆菌TOP10对通过碱裂解法分离出的耐药质粒进行转化。
对碳青霉烯耐药弗氏柠檬酸杆菌的分子分析显示，在约55kb的可转移耐药质粒上存在VIM-4同工酶。有趣的是，bla基因被插入到一个不寻常的基因盒中，该基因盒包含bla基因3'端的169bp直接重复序列。
迄今为止描述的所有含有VIM-DR（直接重复序列）的不寻常基因盒都存在于非发酵菌中，即不动杆菌属和假单胞菌属，这突出了耐药决定因子流动性的重要性，其可能甚至超越属、科和目界限。需要付出巨大努力来探索对“最后手段”抗菌药物的耐药途径特别是在临床相关病原体中。
