A case of respiratory co-infection with Aspergillus spp. and an uncommon non-tuberculosis mycobacterium, Mycobacterium szulgai

Abstract

Background: We report what is thought to be the first case of respiratory co-infection with Aspergillus spp. and Mycobacterium szulgai, a rare species of non-tuberculosis mycobacterium (NTM) in the literature. Case Description: A 58 y old lady with progressive breathlessness and productive cough, was found to have cavitatory disease and nodularities on CT-chest four ys post lobectomy for metastatic breast carcinoma. Aspergillus specific-IgG was raised, and high-volume sputum culture yielded Aspergillus spp. She was treated with Itraconazole for chronic pulmonary aspergillosis (CPA). Mycobacterium culture yielded M.szulgai. After one y of Itraconazole, Aspergillus specific-IgG normalized, high-volume fungal culture was negative, and symptoms improved. However 4 of 5 sputum samples yielded M.szulgai, thus NTM treatment (Ethambutol, Moxifloxacin and Azithromycin) was commenced. Rifampicin was excluded because of Itraconazole interactions. NTM therapy was stopped shortly after starting because of intolerance. CT-chest revealed regression of nodularities but increased size and thickness of one cavity with a new air-fluid level. Itraconazole was stopped, and NTM treatment (Rifampicin, Ethambutol and Azithromycin) commenced. Discussion: Pulmonary aspergillosis and NTM-lung disease have similar presentations, making it difficult to determine the contribution of each to individual patient symptoms. ATS/IDSA criteria for NTM-disease diagnosis requires ≥2 positive sputum samples, and exclusion of other causes. Thus, CPA was our initial diagnosis. M.szulgai represents <1% of NTM isolates in NTM disease. There is little in the literature regarding M.szulgai, thus significance of positive isolates is unclear. Mycobacterium avium complex (MAC), the commonest cause of NTM disease is clinically significant 25% of times. In contrast M.szulgai positive sputum is clinically significant in 43–76% of cases. Clinical significance of MAC increases with more positive sputum samples, this could possibly be extrapolated to M.szulgai. Thus M.szulgai was deemed clinically significant with our case, supported by worsening cavitation on CT-chest. Conclusion: Detection of M.szulgai in sputum culture is clinically significant in the majority of cases. However, the diagnosis in patients with symptoms that can be attributed to other pathologies is challenging. This is particularly so with rare infections. This case highlights the value of implementing and monitoring response to therapy to identify the cause of symptoms.