An unusual tale of rat-bite fever endocarditis

Abstract

SUMMARYA 49-year-old man presented to our department with an acute history of right leg tenderness, rash, swelling and fever. CT of the chest, abdomen and pelvis and a transoesophageal echocardiogram confirmed the diagnosis of mitral valve infective endocarditis with distal splenic emboli. Positive blood cultures revealed the causative organism to be Streptobacillus moniliformis. The patient was treated with high-dose antibiotics and had mitral valve replacement surgery. BACKGROUND

Streptobacillus moniliformis Mitral Valve Endocarditis and Septic Arthritis: The Challenges of Diagnosing Rat-Bite Fever Endocarditis

“… 7 , 8 Consistent with our patient, approximately 30% of the patients recall no bite or other exposure. 4 , 6 Studies suggest that S. moniliformis may have a predilection for synovial and serosal surfaces. 4 , 9 …”

“…There have been three reviews of all of the previously reported cases of S. moniliformis endocarditis from 1915 to 2014. 6-7 , 10 Since these reviews, two more cases of RBF infectious endocarditis have been reported. 13 , 14 The diagnosis of endocarditis was most often established based on the clinical presentation, that included fever, rashes, and joint pains, a cardiac murmur, often without demonstrating a vegetation on echocardiogram, and a positive blood culture for S. moniliformis.…”

“… 13 , 14 The diagnosis of endocarditis was most often established based on the clinical presentation, that included fever, rashes, and joint pains, a cardiac murmur, often without demonstrating a vegetation on echocardiogram, and a positive blood culture for S. moniliformis. 6-7 …”

“… 2 , 4-5 Nevertheless, S. moniliformis has been successfully recovered from SPS containing blood culture bottles. 6 , 15 Agar-based culture of S. moniliformis requires incubation with 5-10% carbon dioxide and TSA enriched media, while no serologic tests are currently available, making diagnosis challenging using standard practices. 3 , 4-5 …”

Human oropharynx as natural reservoir of Streptobacillus hongkongensis

“…S. moniliformis is the causative agent of streptobacillary rat-bite fever 3 . It is also associated with amnionitis 4 , bacteremia 5 6 7 , brain abscess 8 , cutaneous and subcutaneous abscesses 9 10 , endocarditis 11 12 , female genital tract abscess 13 , palmoplantar pustulosis 14 , septic arthritis 15 16 17 , spinal epidural abscess 18 , splenic abscess 19 , spondylodiscitis with psoas abscess 20 , and synovitis 21 . Microbiologically, S. moniliformis is a Gram-negative facultative anaerobic bacillus that grows in chains.…”