A case of Mycobacterium chelonae osteomyelitis in renal transplant.

Investigators in Miami report what they believe is the first case of Mycobacterium chelonae osteomyelitis without pulmonary or skin involvement in a renal transplant recipient.

The case, described by Lillian Abbo, MD, an infectious disease fellow at the University of Miami, was in a 40-year-old man with 23-year history of systemic lupus erythematosus (SLE) and had who been on dialysis for 14 years. He received a cadaveric kidney transplant in December 2005.

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In March 2006, he presented with a four-week history of pain and swelling in the dorsum of the right foot at the level of the fifth metatarsal and great toe. On examination, he had evidence of osteomyelitis and no superficial skin nodules or disseminated disease. Predisposing factors appeared to be mild trauma he had recently sustained as well as his prolonged history of steroid use for SLE.

The patient’s medications included tacrolimus 9 mg/day, mycophenolate mofetil 500 mg/day, prednisone 6 mg a day, valganciclovir 450 mg/day, and trimethoprim/sulfamethoxazole 160/800 mg/day. The patient ended up undergoing amputation of the affected metatarsal bone. Two weeks later, the soft tissue and bone cultures became positive for M. chelonae.
She and a colleague, Claudio Tuda, MD, an infectious disease faculty member at Mount Sinai Medical Center in Miami, reviewed 100 cases of cutaneous M. chelonae infections. They found that 72% of them were immunosuppressed at the time of infection and 62% were receiving corticosteroids. Drs. Abbo and Tuda said it has not been established whether the types of immunosuppressive medications are important factors predisposing to mycobacterial infections in transplant recipients, but cell-mediated immunity is thought to play a major role in mycobacterial infections.
“We were very surprised to see this case,” Dr. Abbo told Renal & Urology News. “We think it is important to bring this case to the attention of nephrologists because this type of infection is notoriously resistant to anti-tuberculosis medications and so susceptibility testing really is required for the management of it.”
As of October 2006, only three cases of atypical mycobacterial osteomyelitis in solid organ transplant recipients have been reported, Dr. Abbo said.