Contributed by Chris Gilbert, MD, William Pasculle, ScD, and Karin Byers, MD
The patient is a 45 y/o caucasian male with no significant past medical history who was well until May of 2007. He works as a machinist and at that time had a small wire penetrate the thenar eminence of his right hand. For several days he had a small amount of purulent drainage which resolved spontaneously. In June of 2007 his right 2nd finger became swollen and he was prescribed a 5 day course of Prednisone that provided temporary improvement followed by injections into the 2nd and 4th metacarpal joints and the wrist when the swelling returned.
Over the following months the patient had persistent swelling and arthralgias of the wrist and 2nd and 4th fingers of the right hand until he was finally seen and evaluated by a rheumatologist. Careful history taking revealed a family history of unspecified arthritis and fibromyalgia. Blood tests were non-contributory with the exception of an elevated ESR of 27 mm/h. The patient was diagnosed with Rheumatoid arthritis and treated with hydroxychloroquine and prednisone without improvement leading to further evaluation by an orthopedic surgeon.
An MRI of the hand, ordered by his surgeon, showed diffuse edema with enhancement surrounding the superficial flexor tendons, no drainable collection, flexor tendonitis and tenosynovitis with mild myositis, focal cellulitis near the 4th MCP joint, no osteomyelitis, and no abscess.
After consultation with his surgeon the patient underwent tenosynovectomy of the carpal tunnel at the end of January 2008. During surgery he was noted to have inflammation of the tenosynovium and a mass encompassing the flexor tendons. This was resected. Based on the imaging, history, and findings at surgery infection was suspected. The tissue was sent to surgical pathology and microbiology. Surgical pathology described non-caseating epithelioid granulomas in the synovium and skeletal muscle. An acid fast stain was negative.
The aerobic culture bottle was negative on day 2.
The fungal culture was negative on day 3.
The mycobacterial culture bottle was positive on day 3.
A DNA probe was negative for MTB, MAC, and M. gordonae.
The mycobacterial culture bottle was subcultured to: Lowenstein-Jensen media (light and dark), at 25ºC (selective for M. szulgai), at 30ºC (selective for M. marinum, etc), at 35ºC (selective for MTB, etc), at 42ºC (selective for M. xenopi), and a blood agar plate to test for contamination.
On day 27 the mycobacterial culture bottle was additionally subcultured to: Bactec 12B with Fastidious Organism Supplement (FOS) at 30ºC, Bactec 12B with FOS at 35ºC, and Bactec PZA at 35ºC (selective for M. genavense).
On day 32 an FOS bottle was detected positive however an AFB stain was negative. Nevertheless, this broth was subcultured to a 7H11 agar plate with Factor X strip at 30ºC and a Chocolate agar plate at 30ºC.
On day 44 the blood agar plate showed tiny colonies after careful inspection.
On day 51 satellite growth around the X strip and growth on the Chocolate agar plate was seen.
Subsequent acid fast stain was positive.
A sample was sent off for 16S ribosomal DNA sequencing.