CHARACTERIZATION OF MECHANISMS OF QUINOLONE RESISTANCE IN PSEUDOMONAS-AERUGINOSA STRAINS ISOLATED INVITRO AND INVIVO DURING EXPERIMENTAL ENDOCARDITIS
CHARACTERIZATION OF MECHANISMS OF QUINOLONE RESISTANCE IN PSEUDOMONAS-AERUGINOSA STRAINS ISOLATED INVITRO AND INVIVO DURING EXPERIMENTAL ENDOCARDITIS
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DOI：
10.1128/aac.33.5.624
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发表时间：
1989-05-01
影响因子：
4.9
通讯作者：
BRYAN, LE
中科院分区：
文献类型：
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作者：
CHAMBERLAND, S;BAYER, AS;BRYAN, LE
研究了Tn5插入诱变后分离的铜绿假单胞菌菌株和培氟沙星治疗实验性主动脉内膜炎期间出现的耐药菌株对喹诺酮类药物的耐药机制。体外选择突变体Qr-1和Qr-2对喹诺酮类药物的耐药性与对几组抗微生物药物的交叉耐药有关，包括。β。-内酰胺类，四环素和氯霉素。还观察到诺氟沙星摄取显著减少。经细胞醚渗透后，这两个分离株的DNA合成与亲本菌株（PAO1）一样对诺氟沙星敏感。这些结果表明，外膜通透性的改变是这些分离株耐药的主要决定因素。这种细胞通透性的改变与菌株Qr-1中外膜蛋白G（25.5千道尔顿）的减少和40千道尔顿外膜蛋白的损失有关。实验性心内膜炎治疗期间出现的喹诺酮类药物耐药性与外膜通透性的改变（诺氟沙星摄取减少）和DNA合成对诺氟沙星的敏感性降低有关。耐药仅限于喹诺酮类药物和氯霉素。对于这些菌株，诺氟沙星对DNA合成的抑制剂量（50%）与药物mic相同，这表明尽管鉴定出渗透性变化（可能是由于脂多糖的变化），但喹诺酮细胞内靶点敏感性的改变构成了耐药性的主要决定因素。此外，在这些分离株中发现了DNA合成的两种不同水平的诺氟沙星耐药，这表明铜绿假单胞菌中可能至少有两种不同的药物靶点改变。
Mechanisms of resistance to quinolones were characterized in Pseudomonas aeruginosa strains isolated after Tn5 insertional mutagenesis and in resistant strains that emerged during pefloxacin therapy of experimental aortic endocarditis. Quinolone resistance achieved in in vitro-selected mutants Qr-1 and Qr-2 was associated with cross-resistance to several groups of antimicrobial agents, including .beta.-lactams, tetracycline, and chloramphenicol. A significant reduction of norfloxacin uptake was also observed. After ether permeabilization of the cells, DNA synthesis of these two isolates was as susceptible to norfloxacin as DNA synthesis of the parent strain (PAO1). These results indicate that alteration of outer membrane permeability is the primary determinant of resistance in these isolates. This altered cell permeability was correlated with reduction of outer membrane protein G (25.5 kilodaltons) and loss of a 40-kilodalton outer membrane protein in strain Qr-1. Resistance of quinolones that emerged during experimental endocarditis therapy was associated with both modification of outer membrane permeability (decreased uptake of norfloxacin) and decreased susceptibility of DNA synthesis to norfloxacin. Resistance was limited to quinolones and chloramphenicol. For these strains, norfloxacin inhibitory doses (50%) for DNA synthesis were identical to the drug MICs, suggesting that despite the identification of a permeability change, perhaps due to changes of lipopolysaccharide, the alteration of the quinolone intracellular target(s) susceptibility consitutes the primary determinant of resistance. Also, two distinct levels of norfloxacin resistance of DNA synthesis were found in these isolates, indicating that at least two distinct alterations of the drug target(s) are possible in P. aeruginosa.