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Bringing Culture to the Uncultured: Coxiella burnetii and Lessons for Obligate Intracellular Bacterial Pathogens

2013; Public Library of Science; Volume: 9; Issue: 9 Linguagem: Inglês

10.1371/journal.ppat.1003540

1553-7374

Anders Omsland, Ted Hackstadt, Robert A. Heinzen,

Rabies epidemiology and control

Human diseases caused by obligate intracellular bacterial pathogens result in significant morbidity and mortality. Obligate intracellular bacteria that replicate in the cytoplasm of host endothelial cells include Rickettsia prowazekii, Rickettsia rickettsii, and Orientia tsutsugamushi (etiologic agents of epidemic typhus, Rocky Mountain spotted fever, and scrub typhus, respectively). Residing in specialized vacuolar compartments are Anaplasma phagocyophilum and Ehrlichia chaffensis (agents of febrile illnesses that have tropisms for neutrophils and monocytes, respectively) and Chlamydia trachomatis, which targets mucosal epithelia and causes blinding trachoma and sexually transmitted diseases. Coxiella burnetii preferentially colonizes mononuclear phagocytes during natural infection where it inhabits a specialized vacuole with properties of a phagolysosome [1]. The pathogen causes a debilitating influenza-like illness in humans called Q (query) fever, a disease that has received recent notoriety due to a large outbreak in the Netherlands [2]. The absolute reliance of obligates on a eucaryotic host cell for growth imposes significant experimental constraints, not the least of which is difficulty in establishing pathogen genetic systems. However, C. burnetii was recently liberated from its host cell by a medium that supports axenic (host cell–free) growth. Here, we provide a brief overview of the systematic approach used in C. burnetii media development and discuss how insight gained from this success could facilitate development of axenic media for other obligate intracellular bacterial pathogens.