A 75-year-old woman was admitted to our institution with a 2-week history of cough, sputum production, and fever. She had undergone right middle and right lower lobectomy for a double lung cancer 13 years earlier and recently underwent chemotherapy for tumor recurrence in the right thoracic cavity just before admission. On physical examination, the patient was thin with a body mass index of 16.9. She was febrile, with a body temperature of 37.8  C, but all other vital signs were normal. Vesicular sounds were weak on right chest auscultation. Chest X-ray and computed tomography (CT) revealed that compared with a previous study, there was a new contractive consolidation with cavity in the remaining right upper lobe (Fig. 1). Laboratory tests showed elevation of inflammatory markers: white blood cell count (WBC) 9180/muL and C-reactive protein (CRP) 9.87 mg/dL. We clinically diagnosed bacterial pneumonia; intravenous imipenem (IPM)/cilastatin (CS) was administered, but symptoms did not improve. Since fungal infection was a differential diagnosis of the CT findings, we added micafungin (MCFG). Treatment with IPM/CS and MCFG was continued for 2 weeks, but there was no improvement.
On further test, 3 sputum acid-fast bacillus (AFB) smears yielded a positive result of 2+, but polymerase chain reaction for tuberculosis and Mycobacterium avium complex (MAC) were both negative. We assumed the causative organism to be NTM other than MAC, including the progressive and rapidly growing Mycobacterium abcessus. With this in mind, we continued IPM/CS at 1000 mg/day and started LVFX at 250 mg/day and CAM at 800 mg/day. Symptoms, laboratory tests, and chest X-ray and CT improved after initiation of LVFX and CAM (Fig. 2). AFB culture of all 3 sputum specimens was positive for NTM. DNA-DNA hybridization (DDH mycobacteria; Kyokuto Pharmaceuticals, Tokyo, Japan) identified M. triviale in one sputum specimen, but could not detect the specific NTM from the other two specimens. We assumed negative conversion of sputum AFB smear, and culture was noted 2 weeks after initiating pharmacotherapy with LVFX and CAM. We considered that the pathogenic bacteria do not contradict M. triviale by the result of DNA-DNA hybridization and the clinical course.
We suggested additional intake of anti-tuberculosis drugs, but the patient declined and we reluctantly continued treatment with only LVFX and CAM for 12 months; IPM/CS were discontinued after symptom resolution. Twelve months after completing pharmacotherapy with LVFX and CAM, there have been no clinical manifestations of recurrence and sputum AFB smear and culture have remained negative.
Chest X-ray and CT after treatment. A) Chest X-ray after medication shows resolution of the consolidation in the right lung field.