Disseminated Mycobacterium chimaera Presenting as Vertebral Osteomyelitis

Disseminated Mycobacterium chimaera infection in a patient with adult-onset immunodeficiency syndrome: case report

BACKGROUND

Patients with adult-onset immunodeficiency syndrome due to anti-interferon-γ autoantibodies (AIGAs) are susceptible to disseminated Mycobacterium avium complex (MAC) infections. M. chimaera, a newly identified MAC species, is distinguished from the others due to the reduced virulence. Previous cases of disseminated M. chimaera infection have been linked to cardiothoracic surgery. Reports of disseminated M. chimaera in patients without a history of cardiothoracic surgery are rare.

CASE PRESENTATION

A 57-year-old Asian man, previously healthy, presented with fever, dry cough, exertional dyspnea, and decreased appetite. The delayed resolution of pneumonia despite antibiotic treatment prompted further imaging studies and biopsies from the lung and lymph node. The fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) demonstrated intense uptake in lung consolidations and diffuse lymphadenopathy. Cultures of the specimens obtained from sputum, blood, stool, lung tissue, and lymph node grew M. chimaera. Further immunological evaluation disclosed the presence of neutralizing AIGAs, which possibly led to acquired immunodeficiency and disseminated M. chimaera infection.

CONCLUSIONS

We herein present the first case of adult-onset immunodeficiency due to AIGAs complicated with disseminated M. chimaera infection. Further immunological evaluation, including AIGAs, may be warranted in otherwise healthy patients who present with disseminated mycobacterial infection.

Disseminated Mycobacterium chimaera Following Open-Heart Surgery, the Heater-Cooler Unit Worldwide Outbreak: Case Report and Minireview

Invasive cardiovascular infections by Mycobacterium chimaera associated with open-heart surgery have been reported worldwide since 2013. Here, we report a case of a 61 year old man, without any other particular medical background, who underwent cardiac surgery for replacing part of the ascending aorta by a bio-prosthetic graft. Eighteen months later, the patient was painful at the lower back with fever. A pyogenic vertebral osteomyelitis due to M. chimaera associated to graft infection was diagnosed after 6 months of sub-acute infection. The patient presented a disseminated disease with cerebral lesions, chorioretinitis, and chronic renal failure. Despite adequate antimicrobial treatment and graft explantation, the patient died after 6 years. We reviewed the literature on M. chimaera infections associated with open-heart surgery. The worldwide outbreak has been explained by airborne bioaerosol generated by the 3T heater–cooler unit (HCU) used during cardiac by-pass surgical procedures. These infections are difficult to diagnose because of a long latency period (up to several years), with no specific symptoms and a highly specialized microbiological diagnosis. The treatment is based on antibiotics and surgery. These infections are also difficult to treat, since the mortality rate is high around 50%. Prevention is necessary by modifying the use of HCUs in operating rooms.

Mycobacterium chimaera infection masquerading as a lung mass in a healthcare worker

Mycobacterium chimaera, a nontuberculous mycobacterium, is a member of the Mycobacterium avium complex (MAC). This microorganism has recently gained significant notoriety for its association with outbreaks in patients exposed to contaminated heater –cooler devices used during open heart surgeries.

We report a case of Mycobacterium chimaera pulmonary infection in a healthcare worker who presented with cough, low grade fever and weight loss with evidence of a lung mass that was initially thought to be a tumor on CT scan imaging. The patient underwent partial left lung lobectomy and pathology revealed necrotizing granulomas with acid fast bacilli and a culture grew M. chimaera. The patient received combination antimycobacterial therapy according to susceptibility results for twelve months with complete resolution of his symptoms and radiographic findings.

Infection Control investigation could not find a source of infection in the hospital where he worked during the last ten years. However, the patient rotated in different hospitals before coming to work at this facility and assisted in surgeries in several operating rooms where the heater-cooler devices in question were used.