A 59-year-old man was admitted to our hospital because he was experiencing severe respiratory distress. He had been diagnosed with intestinal catarrh when he was 1 year old, nephritic syndrome when he was 13 years old, and pleuritis when he was 57 years old. He was an HBV carrier, but not immunocompromised. He did not have a history of tuberculosis. He lived in a rural district composed mainly of paddy fields and worked as an engineer in an office. He was an ex-smoker, having quit smoking at the age of 30 years. Six months before hospital admission, he presented with edema of the left leg and low-grade fever. At the time of presentation, he tested positive for anti-Chlamydia pneumoniae immunoglobulin antibodies and was treated with clarithromycin. He experienced symptom relief with this treatment within a few weeks. However, 4 months before hospital admission, soon after the treatment was discontinued, he developed low-grade fever, a skin eruption resembling folliculitis in the left upper arm, and adenopathy of multiple lymph nodes. Two weeks before hospital admission, he presented with bilateral swelling of the fingers and feet (Fig. 1A). Further, the skin eruption had progressed to ulceration (Fig. 1B). Isolates from the ulcer exudate were cultured and revealed cutaneous infection with mycobacterial species. He was therefore referred to our department. Chest X-ray (CXR) findings were normal, but computed tomography (CT) revealed the presence of tiny miliary nodules in both lung fields (Fig. 2A). Five days before admission, the patient developed a fever (temperature >38  C). He was urged to admit himself to our hospital because of severe respiratory distress. Physical examination revealed tachypnea and 80% oxygen saturation in room air. Prominent inspiratory crackles were heard over both lower lung fields. CXR showed diffuse bilateral infiltration (Fig. 3), and CT revealed the presence of multiple nodules and infiltrates in both lung fields (Fig. 2B). Blood gas analysis in room air revealed a partial pressure of oxygen in arterial blood (PaO2) of 46 mmHg and a pH of 7.46. The other blood parameters were as follows: hemoglobin level, 11.3 g/dL, was within normal limits; leukocyte count, 14.4 x 103 cells/L, was high; and C-reactive protein level, 20.8 mg/L, was high. The brain natriuretic peptide level was 30.0 pg/mL, which was within the normal limits.
We initiated treatment with a broad-spectrum panel of antimicrobial agents, namely, meropenem and ciproxacin, along with methylprednisolone pulse therapy. However, over the next 24 hours, the patient developed severe respiratory failure (PaO2/fraction of inspired oxygen [PF ratio] <200) and required intubation and mechanical ventilation with positive end-expiratory pressure. Intubation was followed by bronchoscopy with bronchoalveolar lavage (BAL). Positive results were obtained in Ziehl-Neelsen staining of a sputum smear and BAL fluid, but negative results were obtained for Gram staining. We therefore strongly suspected mycobacterial infection. Although M. tuberculosis and the MAC were not detected in polymerase chain reaction analysis of the patient's samples, we continued to suspect a miliary mycobacterial infection. Therefore, we initiated treatment with a 4-drug regimen comprising rifampicin 450 mg/day, isoniazid 300 mg/day, pyrazinamide 1500 mg/day, and streptomycin 1 g/day. Meropenem and ciproxacin were discontinued 17 days after hospital admission because the patient's condition improved. Skin biopsy which was done at 1 weak after admission revealed diffuse infiltration of mixed inflammatory cells in the dermis, which was consistent with the diagnosis of cutaneous NTM infection (Fig. 4). CXR and CT revealed a gradual improvement in the patient's condition, and the patient was weaned off mechanical ventilation 23 days after admission. About 1 month after admission, we identified M. szulgai in cultures of the sputum, skin ulcer exudate, and BAL fluid using the colorimetric microdilution plate hybridization method. About 2 months after admission, the bilateral infiltrates had almost completely disappeared from the lungs (Fig. 2C), and the patient was discharged.
(B) CT scan obtained upon admission, showing shadows and nodules on both lung fields.