A case of severe Mycobacterium thermoresistibile pneumonia

Abstract

Mycobacterium thermoresistibile is a thermotolerant nontuberculous mycobacterium which can rarely result in human infection. Although immunosuppression has been identified as a risk factor for infection, it is possible that mycobacterial laboratories may have previously under-recognized M. thermoresistibile as standard mycobacterial incubation temperatures are suboptimal for culture of this organism. Here, we present a case of severe M. thermoresistibile pneumonia associated with achalasia requiring life support in the intensive care unit. We speculated that the interplay between specific host and environmental risk factors contributed to acquisition of infection. Infection with this fastidious organism required prolonged treatment with multiple antimicrobials and adjunctive therapeutic drug monitoring which led to clinical cure despite residual lung injury. We also reviewed literature documenting cases of human infection with M. thermoresistibile. The diagnosis of M. thermoresistibile requires a high degree of clinical suspicion considering its association with immunosuppressive conditions, postulated environmental inoculation and eponymous culture growth characteristics.

Keywords: Mycobacterium thermoresistibile; achalasia; lung injury; rare lung diseases; respiratory infections (non‐tuberculous).

FIGURE 1

Clinical course and radiological findings. (A) Computed tomography of the chest 12 months prior to presentation demonstrating right lower lobe consolidation and ground glass infiltrate with mediastinal setting image highlighting achalasia associated oesophageal dilatation. (B) Chest x‐ray at presentation demonstrating dense right lung consolidation. (C) Computed tomography of the chest at presentation confirming severe right lung consolidation and less severe left lung disease. (D) Computed tomography at the end of treatment demonstrating bronchiectasis and peri‐bronchial fibrosis.

FIGURE 2

Histopathological findings. (A) Haematoxylin & eosin, 400× magnification. The image, taken from the edge of the core biopsy, shows a centrally necrotic granuloma comprised of aggregated epithelioid and multinucleated histiocytes associated with lymphocytes and small numbers of neutrophils. (B) Ziehl‐Neelsen stain, 400× magnification. The image highlights a magenta‐staining microorganism centrally within the granuloma, consistent with an acid‐fast bacillus.