Hirakata Yoichi, Srikumar Ramakrishnan, Poole Keith, Gotoh Naomasa, Suematsu Takashi, Kohno Shigeru, Kamihira Shimeru, Hancock Robert E W, Speert David P
Division of Infectious and Immunological Diseases, Department of Pediatrics, University of British Columbia, Vancouver, British Columbia, V5Z 4H4 Canada.
J Exp Med. 2002 Jul 1;196(1):109-18. doi: 10.1084/jem.20020005.
Pseudomonas aeruginosa is an important opportunistic human pathogen. Certain strains can transmigrate across epithelial cells, and their invasive phenotype is correlated with capacity to cause invasive human disease and fatal septicemia in mice. Four multidrug efflux systems have been described in P. aeruginosa, however, their contribution to virulence is unclear. To clarify the role of efflux systems in invasiveness, P. aeruginosa PAO1 wild-type (WT) and its efflux mutants were evaluated in a Madin-Darby canine kidney (MDCK) epithelial cell monolayer system and in a murine model of endogenous septicemia. All efflux mutants except a deltamexCD-oprJ deletion demonstrated significantly reduced invasiveness compared with WT. In particular, a deltamexAB-oprM deletion strain was compromised in its capacity to invade or transmigrate across MDCK cells, and could not kill mice, in contrast to WT which was highly invasive (P < 0.0006) and caused fatal infection (P < 0.0001). The other mutants, including deltamexB and deltamexXY mutants, were intermediate between WT and the deltamexAB-oprM mutant in invasiveness and murine virulence. Invasiveness was restored to the deltamexAB-oprM mutant by complementation with mexAB-oprM or by addition of culture supernatant from MDCK cells infected with WT. We conclude that the P. aeruginosa MexAB-OprM efflux system exports virulence determinants that contribute to bacterial virulence.
铜绿假单胞菌是一种重要的人类机会致病菌。某些菌株能够穿过上皮细胞，其侵袭表型与在小鼠中引发侵袭性人类疾病和致命败血症的能力相关。在铜绿假单胞菌中已描述了四种多药外排系统，然而，它们对毒力的贡献尚不清楚。为了阐明外排系统在侵袭性中的作用，在麦迪逊-达比犬肾（MDCK）上皮细胞单层系统和内源性败血症小鼠模型中对铜绿假单胞菌PAO1野生型（WT）及其外排突变体进行了评估。与WT相比，除了缺失mexCD-oprJ的突变体外，所有外排突变体的侵袭性均显著降低。特别是，缺失mexAB-oprM的菌株在侵袭或穿过MDCK细胞的能力方面受损，并且无法杀死小鼠，而WT具有高度侵袭性（P < 0.0006）并导致致命感染（P < 0.0001）。其他突变体，包括缺失mexB和缺失mexXY的突变体，在侵袭性和小鼠毒力方面介于WT和缺失mexAB-oprM的突变体之间。通过用mexAB-oprM互补或添加来自感染WT的MDCK细胞的培养上清液，缺失mexAB-oprM的突变体的侵袭性得以恢复。我们得出结论，铜绿假单胞菌MexAB-OprM外排系统输出有助于细菌毒力的毒力决定因素。
