Study of Mechanisms Leading to Multidrug-Resistant K. pneumoniae and A. baumannii

描述(申请人提供)：医院获得的细菌对抗生素的耐药率已经达到了危机的程度，特别是在美国东北部的医疗机构。特别是，两种病原体肺炎克雷伯菌和鲍曼不动杆菌对所有常用抗生素都产生了抗药性。对所有β-内酰胺类(包括碳青霉烯类)、氟喹诺酮类和氨基糖苷类耐药的菌株已有文献记载。临床医生经常使用多粘菌素抗生素来治疗这些多药耐药细菌，但这些药物的毒性问题仍然存在，已有多粘菌素耐药菌株的报道。对于感染这些多重耐药病原体的患者，尚无已知的有效治疗方法。本研究将分析导致肺炎克雷伯菌和鲍曼不动杆菌多重耐药的三种分子机制：1)β-内酰胺酶，2)孔素缺乏，3)抗生素外排系统。利用实时逆转录聚合酶链式反应，将检测编码β-内酰胺酶、外膜蛋白和外排系统的基因在高耐药菌株中的表达，并将它们的表达与敏感菌株中的表达进行比较。此外，所谓的调控基因将通过DNA测序来表征，以确定特定的突变是否会影响许多这些抗性基因的基因控制。最终，了解这些细菌是如何对抗生素产生如此抗药性的，对于开发新型抗菌剂将是重要的。例如，开发新型的β-内酰胺酶抑制剂或外排系统抑制剂可能会对其中一些菌株有用。 耐多药肺炎克雷伯菌和鲍曼不动杆菌在医院内和医院内的传播已成为一个严重的公共卫生问题。尽管提高了认识和感染控制努力，但这些病原体的出现和传播一直是无情的。由多重耐药细菌引起的医院感染的临床和经济后果令人震惊。

DESCRIPTION (provided by applicant): Antibiotic resistance rates among hospital-acquired bacteria have reached crisis proportions, particularly in health care facilities in the northeastern United States. In particular, two pathogens, Klebsiella pneumoniae and Acinetobacter baumannii, have developed resistance to all commonly-used antibiotics. Isolates resistant to all beta-lactams (including carbapenems), fluoroquinolones, and aminoglycosides have been documented. Clinicians often resort to the use of polymyxin antibiotics for therapy of these multidrug-resistant bacteria, however toxicity concerns surround these agents, and polymyxin-resistant strains have been reported. For patients with infections with these multidrug-resistant pathogens, no known effective therapy exists. This study will analyze three molecular mechanisms contributing to multidrug resistance in K. pneumoniae and A. baumannii: 1) beta-lactamases, 2) porin deficiencies, and 3) antibiotic efflux systems. Using real time reverse transcriptase PCR, expression of genes encoding beta-lactamases, outer membrane porins, and efflux systems will be measured in highly-resistant strains and their expression will be compared to that found in susceptible isolates. In addition, purported regulatory genes will be characterized by DNA sequencing, to determine if specific mutations affect the genetic control of many of these resistance genes. Ultimately, understanding how these bacteria become so resistant to antibiotics will be important for the development of novel antibacterial agents. For example, the development of novel beta-lactamase inhibitors or efflux system inhibitors may prove useful against some of these isolates. The inter- and intra- hospital transmission of strains of multidrug-resistant K. pneumoniae and A. baumannii has become a serious public health issue. Despite heightened awareness and infection control efforts, the emergence and spread of these pathogens has been relentless. The clinical and economic consequences of nosocomial infections due to multidrug-resistant bacteria are staggering.