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Updated: Sep 25, 2025
Super-resolution Imaging of Proteus mirabilis Biofilm by Expansion Microscopy
Published on: July 18, 2025
Multivalvular infective endocarditis with Proteus mirabilis
Amber Bux1, Ahmad Mustafa1, Muhammad Niazi1
1Department of Internal Medicine, Staten Island University Hospital, Staten Island, NY, USA.
Abstract:
Proteus species belong to the Enterobacteriaceae family and are gram-negative-rods, commonly known to cause urinary tract infections and asymptomatic bacteriuria in elderly patients with risk factors such as diabetes mellitus and urinary catheterization. However, Proteus species are rarely known to cause infective endocarditis. We present a case of an 85-year-old female who presented due to decreased responsiveness with urine and blood cultures growing Proteus mirabilis. While she was being treated for her urinary tract infection, her echocardiogram showed vegetation on the left coronary cusp of the aortic valve and left pulmonic valve leaflet. Uncontrolled tachyarrhythmias and new-onset atrial fibrillation complicated the hospital course. Later, she became bradycardic during the hospital stay, and all rate-control medications were held. Unfortunately, she went into cardiac arrest and spontaneous circulation could not be established with resuscitation attempts and she expired. To our knowledge, this is a rare case of native valve infective endocarditis secondary to Proteus mirabilis, leading to uncontrolled tachyarrhythmias and death.
Insights
Proteus mirabilis, a common UTI bacterium, rarely causes infective endocarditis. This case highlights a fatal instance in an elderly woman with uncontrolled arrhythmias.
Area of Science:
- Infectious Diseases
- Cardiology
- Microbiology
Background:
- Proteus species, gram-negative rods in the Enterobacteriaceae family, are frequent causes of urinary tract infections (UTIs) and asymptomatic bacteriuria.
- Risk factors for UTIs include advanced age, diabetes mellitus, and urinary catheterization.
- Infective endocarditis caused by Proteus species is exceptionally rare.
Observation:
- An 85-year-old female presented with decreased responsiveness.
- Blood and urine cultures identified Proteus mirabilis.
- Echocardiography revealed vegetations on the aortic and pulmonic valves.
Findings:
- The patient developed uncontrolled tachyarrhythmias, including new-onset atrial fibrillation.
- Subsequent bradycardia led to the discontinuation of rate-control medications.
- Despite resuscitation efforts, the patient expired due to cardiac arrest.
Implications:
- This case underscores the potential for Proteus mirabilis to cause severe native valve infective endocarditis.
- The infection led to life-threatening cardiac arrhythmias and a fatal outcome.
- Highlights the importance of considering rare pathogens in infective endocarditis, especially in elderly patients with comorbidities.
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