Chiasmitis caused by Mycobacterium haemophilum in an immunocompromised adult

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

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.

Meningomyeloencephalitis secondary to Mycobacterium haemophilum infection in AIDS

Infections by opportunistic non-tuberculous mycobacteria (NTM) are rising in global incidence. One emerging, slowly growing NTM is Mycobacterium haemophilum, which can cause skin, lung, bone, and soft tissue infections in immunocompromised patients as well as lymphadenitis in immunocompetent individuals. Detection of this microorganism is difficult using conventional culture-based methods and few reports have documented involvement of this pathogen within the central nervous system (CNS).

We describe the neuropathologic autopsy findings of a 39-year-old man with AIDS who died secondary to M. haemophilum CNS infection. He initially presented with repeated bouts of pyrexia, nausea and vomiting, and altered mental status that required numerous hospitalizations. CSF infectious workups were consistently negative. His most recent admission identified hyperintensities within the brainstem by MRI and despite antibiotic therapies for suspected CNS infection, he died. Autopsy revealed a swollen brain with marked widening of the brainstem. Microscopic examination of the brain and spinal cord showed focal lymphohistiocytic infiltrates, gliosis and neuronal loss that were associated with acid-fast bacilli (AFB). The brainstem was the most severely damaged and AFB were found to congregate along arterial territories lending support to the notion of hematogenous spread as a mechanism for the organisms’ dissemination. 16S rRNA sequencing on formalin-fixed paraffin-embedded tissue enabled post-mortem identification of M. haemophilum. This sequencing methodology may permit diagnosis on CSF intra-vitam.

Intramedullary spinal cord lesions in an immunocompromised host due to Mycobacterium haemophilum

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M. haemophilum can produce severe disease in persons living with HIV/AIDS or other immunocompromised patients.

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The spectrum of disease caused by M. haemophilum may produce life-threatening central nervous system disease.

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The treatment of M. haemophilum when involving the CNS is challenging requiring multi-drug therapy.

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Patients with M. haemophilum central nervous system disease, with and without HIV, should be monitored for IRIS.

Mycobacterium haemophilum is a slow growing acid-fast bacillus (AFB) in the nontuberculous mycobacteria (NTM) group. M. haemophilum typically causes cervicofacial lymphadenitis in children, cutaneous diseases, septic arthritis and osteomyelitis. However, it rarely causes isolated spinal cord disease. We report the first case, to our knowledge, of isolated intramedullary spinal lesions secondary to M. haemophilum. This case involved a patient with newly diagnosed human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS). He developed significant immune reconstitution inflammatory syndrome (IRIS) during his treatment. M. haemophilum should be on the differential for isolated intramedullary spinal lesions, particularly in immunocompromised patients. Given our patient’s severe IRIS, patients with HIV and M. haemophilum infection should be closely monitored for IRIS and treated aggressively. In high risk circumstances such as M. haemophilum spinal disease in patients with HIV, clinicians should consider pre-emptive treatment for IRIS.

The Complete Genome Sequence of the Emerging Pathogen Mycobacterium haemophilum Explains Its Unique Culture Requirements

Mycobacterium haemophilum is an emerging pathogen associated with a variety of clinical syndromes, most commonly skin infections in immunocompromised individuals. M. haemophilum exhibits a unique requirement for iron supplementation to support its growth in culture, but the basis for this property and how it may shape pathogenesis is unclear. Using a combination of Illumina, PacBio, and Sanger sequencing, the complete genome sequence of M. haemophilum was determined. Guided by this sequence, experiments were performed to define the basis for the unique growth requirements of M. haemophilum. We found that M. haemophilum, unlike many other mycobacteria, is unable to synthesize iron-binding siderophores known as mycobactins or to utilize ferri-mycobactins to support growth. These differences correlate with the absence of genes associated with mycobactin synthesis, secretion, and uptake. In agreement with the ability of heme to promote growth, we identified genes encoding heme uptake machinery. Consistent with its propensity to infect the skin, we show at the whole-genome level the genetic closeness of M. haemophilum with Mycobacterium leprae, an organism which cannot be cultivated in vitro, and we identify genes uniquely shared by these organisms. Finally, we identify means to express foreign genes in M. haemophilum. These data explain the unique culture requirements for this important pathogen, provide a foundation upon which the genome sequence can be exploited to improve diagnostics and therapeutics, and suggest use of M. haemophilum as a tool to elucidate functions of genes shared with M. leprae.

IMPORTANCE

Mycobacterium haemophilum is an emerging pathogen with an unknown natural reservoir that exhibits unique requirements for iron supplementation to grow in vitro. Understanding the basis for this iron requirement is important because it is fundamental to isolation of the organism from clinical samples and environmental sources. Defining the molecular basis for M. haemophilium's growth requirements will also shed new light on mycobacterial strategies to acquire iron and can be exploited to define how differences in such strategies influence pathogenesis. Here, through a combination of sequencing and experimental approaches, we explain the basis for the iron requirement. We further demonstrate the genetic closeness of M. haemophilum and Mycobacterium leprae, the causative agent of leprosy which cannot be cultured in vitro, and we demonstrate methods to genetically manipulate M. haemophilum. These findings pave the way for the use of M. haemophilum as a model to elucidate functions of genes shared with M. leprae.

Intraventricular granulomatous mass associated with Mycobacterium haemophilum: A rare central nervous system manifestation in a patient with human immunodeficiency virus infection

We report a rare case of Mycobacterium haemophilum presenting as an intraventricular granulomatous mass with loculated hydrocephalus and seizures in a patient with human immunodeficiency virus. M. haemophilum, a slow-growing mycobacteria, causes localized and disseminated disease among immunocompromised hosts. Central nervous system infection with M. haemophilum is extremely rare. Preoperative laboratory testing of our patient for tuberculosis, toxoplasmosis, sarcoidosis and histoplasmosis were negative. Surgical resection of the mass revealed a caseating granuloma that stained positive for acid-fast bacillus suggesting possible tuberculoma. Despite negative testing for tuberculosis, a polymerase chain reaction analysis was ultimately performed from the resected mass which revealed M. haemophilum. To our knowledge, this is the first case of M. haemophilum presenting as an intraventricular mass. We review the clinical manifestations of this pathogen and discuss the medical and surgical management.