A case of spotted fever group rickettsiosis imported into the United Kingdom and treated with ciprofloxacin: a case report

Rickettsia Aglow: A Fluorescence Assay and Machine Learning Model to Identify Inhibitors of Intracellular Infection

Rickettsia is a genus of Gram-negative bacteria that has for centuries caused large-scale morbidity and mortality. In recent years, the resurgence of rickettsial diseases as a major cause of pyrexias of unknown origin, bioterrorism concerns, vector movement, and concerns over drug resistance is driving a need to identify novel treatments for these obligate intracellular bacteria. Utilizing an uvGFP plasmid reporter, we developed a screen for identifying anti-rickettsial small molecule inhibitors using Rickettsia canadensis as a model organism. The screening data were utilized to train a Bayesian model to predict growth inhibition in this assay. This two-pronged methodology identified anti-rickettsial compounds, including duartin and JSF-3204 as highly specific, efficacious, and noncytotoxic compounds. Both molecules exhibited in vitro growth inhibition of R. prowazekii, the causative agent of epidemic typhus. These small molecules and the workflow, featuring a high-throughput phenotypic screen for growth inhibitors of intracellular Rickettsia spp. and machine learning models for the prediction of growth inhibition of an obligate intracellular Gram-negative bacterium, should prove useful in the search for new therapeutic strategies to treat infections from Rickettsia spp. and other obligate intracellular bacteria.

African Tick Bite Fever Treated Successfully With Rifampin in a Patient With Doxycycline Intolerance

African tick bite fever is the most commonly encountered travel-associated rickettsiosis, occurring in as many as 5% of travelers returning from rural subequatorial Africa. This case report illustrates that rifampin represents an effective alternative to doxycycline for treatment of African tick bite fever in some selective situations.

Rickettsioses and Q fever in travelers (2004-2013)

Rickettsioses (also called typhus) are associated with arthropods, including ticks, mites, fleas, and lice, although Q fever is more frequently acquired through the inhalation of contaminated aerosols or the consumption of milk. These zoonoses first emerged in the field of travel medicine 20 years ago. Here, we review rickettsioses and Q fever in travelers, highlighting cases reported in the past decade. African tick bite fever and Mediterranean spotted fever are the two most frequent spotted fevers. While the presentation of these fevers is typically benign, cardiac and neurological complications due to African tick bite fever have been reported, and Mediterranean spotted fever has been complicated by multi-organ failure and death in a few cases. Murine typhus and Q fever remain difficult to recognize and diagnose because these illnesses often present with only fever. New molecular tools, particularly when deployed with samples obtained from eschar swabs, might be easily implemented in laboratories with PCR facilities. Doxycycline must be introduced upon clinical suspicion of rickettsioses or Q fever and should be considered in cases of fever of unknown origin in travelers who are returning from at-risk geographic areas.