The patient was a 28-year-old Asian female farmer. Due to fever and shortness of breath after spontaneous abortion (one week earlier), which aggravated over the next two days, she was admitted to the Department of Critical Care Medicine, the First Affiliated Hospital of Xi'an Jiaotong University, Xi' an, Shaanxi, China on October 17, 2019.
The patient had received IVF-ET treatment due to an obstruction in the fallopian tube, and the pregnancy was successfully established on July 12, 2019. However, vaginal bleeding began on October 8, 2019. On October 10, 2019, she had a spontaneous abortion on the way to the hospital and underwent uterine clearance at the Northwest Women's and Children's Hospital, Xi' an, Shaanxi, China. During treatment, the patient started feeling cold and developed shortness of breath, fever, and chills. Her body temperature was 38.7  C, and she had an occasional, mainly dry cough, accompanied by dizziness and general fatigue. She went to the Shaanxi Women's and Children's Hospital, where a five-day oral treatment with cefpodoxime proxetil was initiated; however, there was no improvement in her condition. Two days before admission to the intensive care unit (October 15), she complained of worsening shortness of breath. Her body temperature at the time was 38  C, and she had an occasional cough. She was admitted to the local hospital one day before admission into the intensive care unit (October 16); chest computed tomography (CT) revealed scattered ground-glass dense opacities in both the lungs. Furthermore, we noticed a few nodular shadows in the upper lobes of both the lungs of the patient (Figure 1A and B). With a diagnosis of severe pneumonia, she was referred to the emergency department of the First Affiliated Hospital of Xi'an Jiaotong University. Her body temperature peaked at 40  C, which was accompanied by shivering. Oxygen was supplied using a mask at 5-8 L/min, and oxygen saturation fluctuated between 90-93%. Infection-related indices, such as white blood cell count (WBC), neutrophilic granulocyte percentage (NEUT), and procalcitonin (PCT), increased; thus, cefoperazone sodium/sulbactam sodium and moxifloxacin were administered as an anti-infection therapy. However, the patient's shortness of breath worsened, and her respiratory rate increased. The pulse oxygen saturation decreased to 89%, and the patient was connected to a non-invasive ventilator to assist breathing. Six hours later, the patient still had dyspnea and became irritable The oxygen saturation fell to 44%. Arterial blood gas analysis revealed type I respiratory failure.
Physical examination of the patient revealed the following: a body temperature of 36.9  C, a heart rate of 123 beats/min, a respiratory rate of 26 breaths/min, and blood pressure of 86/54 mmHg. She was conscious, but had an emaciated body. Ventilation was assisted via a ventilator and tracheal tube intubation. The breathing sound of both lungs was rough, and few wet rales were heard. There was no abnormality in heart and abdominal examination, and slight pitting edema in the lower limbs was observed.
The laboratory test results after admission are listed in Table 1. The imaging results are listed in Table 2.  
On October 17, 2019, she was admitted to the Department of Critical Care Medicine and was initially diagnosed with severe pneumonia, acute respiratory distress syndrome (ARDS), septic shock, and moderate anemia. The patient was administered anti-infective moxifloxacin therapy. Due to septic shock, the patient was given fluid rehydration (initial fluid volume: 30 mL/kg) and administered noradrenaline to raise her blood pressure. Thymopetidum injection was used to enhance immunity, and vitamin C was used as an anti-inflammatory agent. A bedside chest X-ray scan revealed double-lung pneumonia (Figure 2A). Fiberoptic bronchoscopy was performed on the same day, and small amounts yellow sputum, scabbing, and mucosa were observed. The alveolar lavage fluid was collected for etiological examination. On the second day of admission, her body temperature peaked to 38  C; her blood pressure was 109/84 mmHg under noradrenaline treatment (0.2 microg/kg/min), the concentration of oxygen inhaled using mechanical ventilation was 80%, and she was still short of breath and sweating. The patient was given sedation and analgesic treatments. The PCT increased from 8.89 to 18.24 ng/mL, and the C-reactive protein (CRP) level was as high as 142.4 mg/L. The causative pathogen remained unknown, and anti-infection treatment was administered. However, the levels of relevant infection-related markers continued to rise. Therefore, anti-infection treatment with meropenem and linezolid was started on October 19. The treatment led to a gradual improvement in infection indices. On October 21, the PCT was 2.24 ng/mL, blood leukocyte count was 4.49x109/L, the proportion of neutrophils was 82.2%, blood pressure (BP) was 110/70 mmHg after stopping noradrenaline treatment, heart rate (HR) was 86 bpm, respiration rate (RR) was 18 breaths per minute, and the saturation of pulse oxygen (SpO2) was 98%. The use of the ventilator was reduced, positive end-expiratory pressure (PEEP) was 8 cm H2O, and the fraction of inspiration O2 (FiO2) was 45%. Arterial blood gas analysis revealed a pH of 7.438, PCO2 of 40.1 mmHg, PO2 of 118 mmHg, HCO3- of 26.8 mmol/L, BE (base excess) of 2.7 mmol/L, and lactate levels of 2.0 mmol/L. The patient was discharged from the bed with a ventilator, for exercise. Although the infection-related indicators of the patient improved and her general condition was stable, the patient still had a fever with a peak body temperature of 38.4  C. This occurred mainly in the afternoon and evening and was accompanied by sweating. Further, the CRP was still as high at 90.5 mg/L. Abdominal, pelvic, and gynecological ultrasonography revealed no obvious abnormalities. The examination indices of bacteria, fungi, TB, viruses, specific pathogenic bacteria, and factors related to non-infectious fever were all normal (Table 1), and no pathogenic bacteria were found. However, the patient failed to leave ventilator support. Re-examination of chest CT revealed multiple nodules in the upper lobes of both the lungs and multiple patchy high-density shadows with uneven density in both the lungs (Figure 1C and D). The chest CT showed no improvement on October 16. Combined together, the patient's pathogenesis, relevant examination, and treatment process led us to believe that she had no infectious diseases. Therefore, we sent the alveolar lavage fluid for an mNGS test. The mNGS results showed that only three sequences of the M. tuberculosis complex group were present; moreover, the Xpert results were positive for M. tuberculosis but negative for rifampicin resistance. Combined with the symptoms and signs of the patient, a diagnosis of pulmonary TB was established, and hematogenous disseminated pulmonary TB was considered. Accordingly, the administration of moxifloxacin, meropenem, and linezolid was stopped. Isoniazid, rifampicin, pyrazinamide, and ethambutol were administered as anti-TB therapy. Re-examination of chest radiographs on October 25 revealed extensive exudation in both the lungs, with small nodules visible, particularly in the lower lobes of both the lungs (Figure 2B). On October 28, the patient was referred to a specialized TB hospital for treatment. M. tuberculosis culture results were positive. Quadruple anti-TB therapy and ventilator assistance were continued. One month after being transferred from our hospital, the patient died of multiple organ failure.