Refractory thrombocytopenia as a manifestation of Mycobacterium abscessus complex prosthetic valve endocarditis: a rare and fatal complication

Mycobacterium abscessus complex is one of clinically relevant species of rapidly growing mycobacteria (RGM) 1 and is ubiquitous in the environment, mainly associated with pulmonary infection in patients with underlying lung diseases, such as cystic fibrosis and non-cystic-fibrosis-related-bronchiectasis. 2 Management of systemic infection requires awareness of the variable susceptibility patterns of various RGM. A 72-year-old Indian woman presented with a history of fever on and off for the previous 3 months, which started 3 days post-transcatheter aortic valve implantation (TAVI). Over those 3 months, she had been treated with antibiotics empirically but her fever always recurred after stopping antibiotics. On admission, she had altered mental status, bicytopaenia (haemoglobin, 8.6 g/dl, platelets, 56 × 10 9 /L), acute kidney injury with creatinine 1.8 μmol/L and mild transaminitis (aspartate aminotransferase/alanine aminotransferase: 130/75 U/l). She was started on empirical broad-spectrum antibiotics while awaiting cultures. Trans-thoracic and Trans-esophageal echocardiography did not reveal any vegetations on the aortic valve. Positron emission tomography (PET) computed tomography (CT) showed reactive mesenteric lymph nodes. Auto-immune workup revealed antinuclear antibodies (ANA) weakly positive but ANA subtypes were negative, anti-neutrophil cytoplasmic antibodies (ANCA) immunofluorescence 2+ in 1:10 dilution (atypical pANCA), and MPO/PR3 negative. Cerebrospinal fluid studies showed total cells 120/μL (65% polymorphs and 35% lymphocytes) with toal protein 82 mg/dL and glucose 29 mg/dL. Gene Xpert (CB-NAAT) was negative, Cultures showed no growth. Bone marrow workup was non-contributory. A diagnosis of partially treated bacterial meningitis vs tubercular meningitis was considered. As a result of persistently worsening thrombocytoponia, she was given romiplastim and platelet transfusions. At this point, her blood cultures came back positive for rapidly growing Mycobacterium , which, on species identification, showed M. abscessus complex. Her antibiotics were changed to levofloxacin, azithromycin, amikacin, clofazamine and tigecycline 3,4 and, over the course of few days, her fever gradually responded, mental status improved and platelets stabilised. She was discharged and was doing well at home with normal platelet count. Around 1 month later, the patient developed altered mental status at home with fever. She was re-admitted and had to be intubated in emergency department. There was altered blood in nasogastric tube aspirate. On initial evaluation, her platelet count was 4 × 10 9 /L and CT brain revealed a subarachnoid haemorrhage. Trans-oesophageal echocardiography was repeated and this time revealed a mobile vegetation on the prosthetic valve. As per the request of the next-of-kin, she was put on end-of-life care. Here, we present a case of infective endocarditis, secondary to M. abscessus complex post TAVI. There have been previous case reports of thrombocytopenia in similar scenarios; however, all those reports had a common factor of the use of linezolid for the treatment. Our patient was not given linezolid throughout the course of admission; thus, we suspect that the organism itself was responsible for her thrombocytopenia. Management of systemic infection secondary to non-tuberculous Mycobacterium requires awareness of the variable sensitivity patterns of various RGM. Culture being the only diagnostic modality, a high degree of suspicion is also required in cases presenting as pyrexia of unknown origin, especially in patients with history of recent invasive intervention. However, despite the best of measures, prognosis remains poor for these patients.