Streptobacillus moniliformis bacteraemia and septic arthritis in a child

Abstract

Streptobacillus species are zoonotic pathogens colonising the oral cavity and upper respiratory tract of rats and other rodents.1 Transmission occurs via bites or scratches, referred to as rat-bite fever, or ingestion of contaminated food or water, referred to as Haverhill fever.1,2 Streptobacillus species are rarely isolated due to fastidious growth requirements, inhibition by sodium polyanethol sulfonate anticoagulant in blood culture bottles, and susceptibility to commonly-used antibiotics.1 A 12-year-old immunocompetent female with pet mice and rats presented with fever, left shoulder pain, and rash for five days. Examination demonstrated left axillary lymphadenopathy and left glenohumeral joint restricted range of motion, swelling, and warmth. Ultrasound confirmed a moderate glenohumeral joint effusion and subacromial bursitis. Arthroscopic washout of the joint revealed diffuse, non-purulent, synovitis. The synovial fluid cell count was 15,300×106/L with a mononuclear cell predominance. Streptobacillus moniliformis was isolated in culture of blood (paediatric blood culture bottle) and synovial fluid specimens after approximately 72 hours at the microbiology laboratory at Nepean Hospital. The patient admitted to kissing her pet rodents on their mouths and sustaining scratches to the skin of her hands whilst bathing them. She recovered completely with intravenous ceftriaxone for one week then oral amoxycillin for three weeks.