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A 24-year-old woman who worked on a farm in Connecticut developed fever, chills, vomiting, and a truncal maculopapular rash 3 weeks before presentation. One week after symptom onset, she remained febrile (maximum temperature, 39.6°C [103.2°F]) and the rash spread to her palms and soles, with some progression to pustules (Figure, left panel). She developed right knee pain, followed by pain in other joints. Two weeks after symptom onset, she presented to a local emergency department, reporting inability to stand due to severe joint pain. Results of tests for sexually transmitted infections and respiratory viruses were negative. She was presumptively diagnosed with a viral illness and discharged home with supportive care. Approximately 3 weeks after symptom onset, she presented to the emergency department again with persistent fever, worsening arthralgia, back pain, and progressive purpuric and pustular rash. Her vital signs were unremarkable. White blood cell count was 12 100/μL (reference range, 4000/μL-10 000/μL), with 84% neutrophils. Urinalysis results and levels of serum electrolytes and liver enzymes were within normal limits. Gram stain of blood culture is shown in the Figure (right panel).
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Rat bite fever
A. Inquire about rodent and other animal exposures
The key to the correct diagnosis was symptoms of persistent fever, migratory polyarthralgias, and purpuric rash extending to the palms and soles. When questioned, the patient recalled a rat bite 3 days before symptom onset. Based on this history, pustule fluid and blood were submitted for culture. Blood cultures became positive, and Gram stain revealed filamentous gram-negative bacilli in “nests,” with occasional bulbous swellings. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry failed to identify the organism, but 16S rDNA sequencing identified Streptobacillus moniliformis, the causative agent of rat bite fever. No growth occurred from pustule fluid cultures.
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Corresponding Author: Sonali D. Advani, MBBS, MPH, Section of Infectious Diseases, Department of Medicine, Yale School of Medicine, Yale New Haven Hospital, 20 York St, Hunter 527, New Haven, CT 06510 (email@example.com).
Published Online: April 19, 2019. doi:10.1001/jama.2019.4799
Conflict of Interest Disclosures: Dr Peaper reported serving on the scientific advisory board of Tangen Biosciences. No other authors reported disclosures.
Additional Contributions: We thank the patient for providing permission to share her information.
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