The First Case of Mycobacterium interjectum Pulmonary Disease in Japan: A Case Report.

We herein report a case of Mycobacterium interjectum pulmonary disease (M. interjectum-PD) that improved considerably after azithromycin (AZM), rifampicin (RFP), and ethambutol (EB) therapy. A 69-year-old woman, managed locally for suspected NTM-PD based on chest computed tomography (CT) findings was referred to our hospital for worsening productive cough six years after the initial diagnosis. High-resolution chest CT showed right middle and left lower lobe bronchiectasis with middle and centrilobular nodules. Bronchial washing and sputum culture yielded M. interjectum. Treatment with AZM, RFP, and EB resulted in sputum culture conversion, and the chest CT findings subsequently improved. This is the first reported case of M. interjectum-PD in Japan.

Efficacy of three sputum specimens for the diagnosis of Mycobacterium avium complex pulmonary disease.

BACKGROUND: In Mycobacterium avium complex pulmonary disease (MAC-PD), diagnosis requires a positive culture from at least two separate expectorated sputum specimens. The optimal number of sputum examinations remains unclear. OBJECTIVE: This study sought to elucidate the diagnostic yield of acid-fast bacilli in MAC-PD using 3 sputum specimens and to clarify the clinical characteristics of patients with MAC-PD diagnosed using 3 sputum specimens. Furthermore, we investigated the correlation between increased number of sputum specimens and diagnostic yield. METHODS: We reviewed the medical records of 139 patients with MAC-PD diagnosed at Toho University Omori Medical Center for whom at least three sputum specimens were examined before treatment from November 2014 through June 2021. Patients were classified into the 3-sputum diagnosed and the non-3 sputum diagnosed groups based on diagnostic procedure; clinical and radiological characteristics were compared. We also assessed diagnostic yield with the increased number of sputum specimens. RESULTS: Diagnostic yield with 3 sputum specimens was 16.5% (23/139). The 3-sputum diagnosed group had a lower body mass index [18.6(17-19.5) vs. 19.5(18-21.5); p = 0.014], and higher chest CT score [9(6.5-13) vs. 6(4-9); p = 0.011] including cavitary lesions (39.1% vs. 19%; p = 0.037) compared with the non-3 sputum diagnosed group. When the number of sputum specimens was increased to 6, the diagnostic yield increased to 23.7% (33/139). CONCLUSION: Diagnostic yield with 3 sputum specimens was 16.5%. Patients diagnosed using 3 sputum specimens had more severe chest CT findings including cavitary lesions. Increasing the number of sputum specimens to 6 improved diagnostic yield by 7.2%.

Co-infection with Nocardia spp. in a patient with Mycobacterium avium complex pulmonary disease: A case report.

Mycobacterium avium complex pulmonary disease (MAC-PD) is sometimes accompanied by co-infection with other pathogenic microorganisms such as Pseudomonas aeruginosa and Haemophilus influenzae. However, co-infection with Nocardia spp. has been rarely reported. We report on a patient diagnosed as having co-infection with Nocardia after treatment for MAC-PD, which was successfully treated using trimethoprim-sulfamethoxazole (TMP-SMX). A 74-year-old woman with MAC-PD was admitted to our hospital to undergo re-examination for pathogenic microorganisms because chest computed tomography (CT) findings did not improve after treatment for MAC-PD. She underwent bronchoscopy and Nocardia spp. was detected from bronchoalveolar lavage fluid culture. Chest CT findings improved after 6 months of treatment using TMP-SMX. Co-infection with other pathogenic microorganisms should be considered when chest CT findings worsen after adequate treatment of MAC-PD. Chest CT findings of Nocardia pulmonary disease in immunocompetent patients can mimic those of MAC-PD and should therefore be differentiated one from the other.

Impact of chronic co-infection in pulmonary Mycobacterium avium complex disease after treatment initiation.

BACKGROUND: The impact of co-infection with other pathogenic microorganisms after initiation of treatment for Mycobacterium avium complex pulmonary disease (MAC-PD) has not been clearly described. This study sought to clarify the clinical outcomes of co-infection with MAC after antimycobacterial therapy for MAC. METHODS: Co-infection status was defined as the detection of pathogenic microorganisms other than MAC in at least two consecutive sputum cultures 6-24 months after initiation of treatment. Chest computed tomography (CT) findings and culture results were compared between co-infection and MAC alone groups. RESULTS: The co-infection and MAC alone groups comprised 12 and 36 patients, respectively. The proportion of patients with sputum culture positive for MAC after 24 months of therapy did not differ significantly between the two groups [25% (3/12) vs. 16.7% (6/36); p = 0.671]. The proportion of patients with improved chest CT score after 24 months of starting treatment compared to baseline was significantly lower for the co-infection group than for the MAC alone group [16.7% (2/12) vs. 79.4% (27/34); p < 0.001]. In the co-infection group, median CT score values at 12 and 24 months did not differ from baseline. However, the MAC alone group showed significant improvement at 12 and 24 months compared with baseline. CONCLUSIONS: In the patient group with co-infection of other pathogenic microorganisms after treatment initiation for MAC there was no impact on therapeutic efficacy compared to the MAC alone group. However, therapeutic intervention interfered with improvement in chest CT findings such as nodule formation, bronchiectasis, infiltration, and cavitary lesions.