A 76-year-old man with liver cirrhosis caused by chronic hepatitis C was admitted to the intensive care unit. He had a history of thoracoplasty for the treatment of pulmonary tuberculosis. Two days before admission, he experienced common cold-like symptoms and consulted a doctor at a nearby medical clinic. However, his symptoms worsened, and on the morning of admission he lost consciousness at home. He was transported immediately to our hospital by ambulance, during which he required cardiopulmonary resuscitation. A return of circulation was observed on arrival at our hospital. His vital signs included a consciousness level of E1V1M1 on the Glasgow Coma Scale, body temperature 34.4 C, blood pressure 63/46 mmHg, and heart rate 66 beats per minute. Loss of light reflex was observed. Laboratory studies on admission revealed signs of inflammation (white blood cell count 13,330 cells/mL, C-reactive protein 2.16 mg/dL), elevated liver enzyme levels (aspartate transaminase 459 U/L, alanine transaminase 171 U/L), and mild renal dysfunction (creatinine 1.38 ng/dL). A chest radiograph revealed right upper and lower lobe consolidation with collapse of the left chest wall caused by his previous thoracoplasty (Figure 1).
Gram staining of endotracheal-aspirated sputum revealed a large number of neutrophils, and light microscopy at high magnification (1000x) showed numerous fibrous constituents (Figure 2A-E). The same specimens were analyzed using immunohistochemistry with DAPI (4',6-diamidino-2-phenylindole) staining (Invitrogen, Carlsbad, CA) for DNA detection (Figure 2A), anti-human histone H3 mouse monoclonal antibody (MABI0001, MAB Institute Inc, Sapporo, Japan) for histone (Figure 2B), and anti-human neutrophil elastase rabbit polyclonal antibody (GTX72042, GeneTex Inc, Irvine, CA) for neutrophil elastase (Figure 2C). Figure 2D is a merged photograph of Figure 2A-C. The specimens were visualized using a fluorescence microscope (BZ-9000, Keyence Corporation, Osaka, Japan).
The findings suggested that the fibrous structures in sputum were mainly NETs, defined as extracellular string-like structures that are simultaneously immunoreactive for DNA, histone H3, and neutrophil elastase. A number of Gram-negative coccobacilli, some of which had been phagocytosed by neutrophils, were observed at high magnification (1000x, Figure 3).
Despite immediate administration of broad-spectrum antibiotics upon admission, the patient died on the day following hospitalization. H. influenzae was later isolated and detected in both sputum and blood from the culture performed on admission. The blood culture results identified nontypable H. influenzae (Denka Seiken Co, Ltd, Tokyo, Japan), and we diagnosed invasive disease caused by nontypable H. influenzae infection with multilobar pneumonia and bacteremia/sepsis in a patient with liver cirrhosis post thoracoplasty.