Fatal disseminated Mycobacterium haemophilum infection involving the central nervous system in a renal transplant recipient

Abstract

Mycobacterium haemophilum is a slow growing nontuberculous mycobacterium which prefers cooler temperatures and requires iron for growth. It usually causes skin and soft tissue infections in immunocompromised hosts and cervical lymphadenitis in healthy children. We present the case of fatal disseminated M. haemophilum in an immunocompromised host with central nervous system (CNS) involvement. Our case is a 65-year-old Hispanic male with history of end-stage renal disease status post renal transplantation six years prior (on maintenance immunosuppression with mycophenolate, tacrolimus and prednisone), diabetes mellitus type 2, coronary artery disease, ventricular arrhythmias with implantable cardioverter defibrillator, prior stroke and cochlear implant. In the four months preceding admission to our institution he had frequent hospitalizations for altered mental status (AMS), sepsis syndromes and failure to thrive. Two months prior to presentation he developed progressive swelling and redness of the wrists, right third and left fifth digits. Computed tomography (CT) showed extensive cellulitis in distal right forearm and hand with chronic osteomyelitis. Serial incision and drainage (I&D) of right wrist yielded positive AFB stain and growth on AFB culture. PCR was negative for Mycobacterium tuberculosis. Patient was started on rifampin, clarithromycin and ethambutol. Two days later patient developed AMS and severe septic shock requiring transfer to our facility. CT head revealed indeterminate lesion in the left frontal lobe along with nonspecific hypodensities in the pons and thalamus. Repeat CT upper extremities showed osteomyelitis of distal radius and small hand bones with adjacent abscesses. I&D also revealed bilateral tenosynovitis. Cultures were resent. With suspicion for rapidly growing mycobacterial infection, the regimen was changed to linezolid, imipenem and azithromycin. Several changes in antimicrobials were necessary throughout hospitalization due to complicated hospital course. Unfortunately, despite aggressive measures, patient developed multiorgan failure culminating in death 10 days after starting anti-mycobacterial drugs. On the day of death, the organism was identified as M. haemophilum. Susceptibilities were not done as patient had died. On autopsy the brain was noted to have multiple abscesses containing AFB. The organism also grew from the wrists and right finger cultures. M. haemophilum of the CNS is extremely rare and has been reported in HIV or AIDS patients. To our knowledge this is the first reported case of M. haemophilum brain abscesses in a patient without HIV/AIDS. Because of its fastidious growth requirements, M. haemophilum usually shows on acid fast stains but does not grow on routine AFB cultures. Although it prefers lower temperatures for growth and is usually limited to skin and soft tissues, disseminated disease occurs in immunocompromised patients and has high mortality. It is usually treated with a multi drug regimen including clarithromycin, rifampin, ciprofloxacin and amikacin.