Effect of inactivation of the global oxidative stress regulator oxyR on the colonization ability of Escherichia coli O1:K1:H7 in a mouse model of ascending urinary tract infection
Effect of inactivation of the global oxidative stress regulator oxyR on the colonization ability of Escherichia coli O1:K1:H7 in a mouse model of ascending urinary tract infection
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DOI：
10.1128/iai.74.1.461-468.2006
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发表时间：
2006-01-01
影响因子：
3.1
通讯作者：
Rosen, H
中科院分区：
文献类型：
--
作者：
Johnson, JR;Clabots, C;Rosen, H
为了在宿主尿路中生存，引起尿路感染 (UTI) 的大肠杆菌菌株可能必须克服强大的氧化应激，包括中性粒细胞的氧依赖性杀伤机制。因此，我们通过确定 oxyR 失活对 CBA/J 和 C57BL（野生型和 p47(phox-/-)）小鼠实验尿毒力的影响，评估了大肠杆菌的全局氧应激调节剂 OxyR 作为 UTI 中可能的毒力因子。将野生型大肠杆菌菌株 Ec1a (O1:K1:H7) 的 oxyR 和 oxyS 基因替换为卡那霉素抗性盒，以产生 oxyRS 突变体。在肉汤或人尿液中的体外生长过程中，oxyRS 突变体表现出与 Ec1a 相同的对数期生长速率（肉汤）和平台密度（肉汤和尿液），尽管其滞后期（肉汤）延长或浓度（尿液）初始下降。该突变体以及其他野生型 ExPEC 菌株的 oxyRS 突变体在体外表现出对 H2O2 抑制的敏感性显着增加，与 oxyRS 失活时观察到的生长动力学改变一样，这种情况可通过在多拷贝数质粒上恢复 oxyR 来逆转。在 CBA/J 小鼠中，在经尿道接种小鼠后 48 小时收获的尿液、膀胱和肾脏培养物中，Ec1a 显着胜过其 oxyRS 突变体（超过 1 log(10)），而 oxyR 互补突变体表现出与亲本相同或更强的定植能力。尽管 C57BL 小鼠对实验性 UTI 的敏感性低于 CBA/J 小鼠，但野生型和 p47(phox-/-) C57BL 小鼠也同样容易受影响，并且与 CBA/J 小鼠一样，无论 p47(phox) 基因型如何，Ec1a 的 oxyR 突变体在 C57BL 小鼠中也同样减弱。在大肠杆菌参考集合中，94% 的菌株呈 oxyR 阳性。这些发现满足了 Koch 的第二个和第三个分子假设，即 oxyR 作为大肠杆菌中的候选毒力促进因子，并表明 oxyR 是未来针对大肠杆菌引起的尿路感染预防性干预措施的广泛流行的潜在目标。他们还表明，中性粒细胞吞噬细胞氧化酶对于防御大肠杆菌 UTI 并不重要，并且 OxyR 保护宿主环境中大肠杆菌免受的主要氧化应激并非源自吞噬细胞。
To survive within the host urinary tract, Escherichia coli strains that cause urinary tract infection (UTI) presumably must overcome powerful oxidant stresses, including the oxygen-dependent killing mechanisms of neutrophills. Accordingly, we assessed the global oxygen stress regulator OxyR of Escherichia coli as a possible virulence factor in UTI by determining the impact of oxyR inactivation on experimental urovirulence in CBA/J and C57BL (both wild-type and p47(phox-/-)) mice. The oxyR and oxyS genes of wild-type E. coli strain Ec1a (O1:K1:H7) were replaced with a kanamycin resistance cassette to produce an oxyRS mutant. During in vitro growth in broth or human urine, the oxyRS mutant exhibited the same log-phase growth rate (broth) and plateau density (broth and urine) as Ec1a, despite its prolonged lag phase (broth) or initial decrease in concentration (urine). The mutant, and oxyRS mutants of other wild-type ExPEC strains, exhibited significantly increased in vitro susceptibility to inhibition by H2O2, which, like the altered growth kinetics observed with oxyRS inactivation, were reversed by restoration of oxyR on a multiple-copy-number plasmid. In CBA/J mice, Ec1a significantly outcompeted its oxyRS mutant (by >1 log(10)) in urine, bladder, and kidney cultures harvested 48 h after perurethral inoculation of mice, whereas an oxyR-complemented mutant exhibited equal or greater colonizing ability than that of the parent. Although C57BL mice were less susceptible to experimental UTI than CBA/J mice, wild-type and p47(phox-/-) C57BL mice were similarly susceptible, and the oxyR mutant of Ec1a was similarly attenuated in C57BL mice, regardless of the p47(phox) genotype, as in CBA/J mice. Within the E. coli Reference collection, 94% of strains were positive for oxyR. These findings fulfill the second and third of Koch's molecular postulates for oxyR as a candidate virulence-facilitating factor in E. coli and indicate that oxyR is a broadly prevalent potential target for future preventive interventions against UTI due to E. coli. They also suggest that neutrophill phagocyte oxidase is not critical for defense against E. coli UTI and that the major oxidative stresses against which OxyR protects E. coli within the host milieu are not phagocyte derived.