A Case of Tuberculosis Misdiagnosed as Sarcoidosis and then Confirmed by NGS Testing.

BACKGROUND: Pulmonary tuberculosis (PTB) is an important infectious disease that threatens the health and life of human beings. In the diagnosis of PTB, imaging plays a dominant role, but due to the increasing drug resistance of Mycobacterium tuberculosis, atypical clinical manifestations, "different images with the same disease" or "different diseases with the same image" in chest imaging, and the low positivity rate of routine sputum bacteriology, which leads to a high rate of misdiagnosis of PTB. We report a case of pulmonary tuberculosis that was misdiagnosed on imaging. We report a case of pulmonary tuberculosis that resembled sarcoidosis on imaging and was negative for antacid staining on sputum smear and alveolar lavage fluid, and was later diagnosed by microbial next-generation sequencing (NGS). The case was initially misdiagnosed as sarcoidosis. METHODS: Alveolar lavage fluid NGS, chest CT, bronchoscopy. RESULTS: Chest CT showed multiple inflammatory lesions in both lungs, multiple nodular foci in both lungs, and multiple enlarged lymph nodes in the mediastinum and hilar region on both sides. Fiberoptic bronchoscopy was performed in the basal segment of the left lower lobe of the lungs to carry out bronchoalveolar lavage, and the lavage fluid was sent to the NGS test and returned the following results: Mycobacterium tuberculosis complex group detected in the number of sequences of 293. Based on the results of the NGS test, the diagnosis of pulmonary tuberculosis could be confirmed. CONCLUSIONS: The diagnosis of pulmonary tuberculosis cannot be easily excluded in patients with "different images with the same disease" or "different diseases with the same image" on chest imaging without the support of sputum positivity. The goal was to improve the alertness of medical personnel to the misdiagnosis of tuberculosis and the application of NGS technology.

CEA Negative Initial Diagnosis of HP Infection Finally Confirmed by Bronchoscopic Biopsy as Lung Adenocarcinoma.

BACKGROUND: Carcinoembryonic antigen (CEA) is a polysaccharide complex that is found in the human respiratory system. It is of significant use in disease surveillance of lung cancer; however, serum CEA can occasionally only offer little assistance. We present a case of recurring infection initially diagnosed as carcinoembryonic antigen-negative in a patient with a history of hypersensitivity pneumonitis infection, which finally led to the diagnosis of lung adenocarcinoma following percutaneous lung puncture. METHODS: Appropriate laboratory tests, chest CT, bronchoscopy, percutaneous lung puncture, and pathologic examination were performed to explore the cause of the disease. RESULTS: Because CEA was negative and a chest CT showed interstitial changes in both lungs with numerous hyperdense shadows, coupled with the patient's history of hypersensitivity pneumonitis, we initially believed that the infection was relapsing. However, a percutaneous lung puncture eventually revealed that the patient had lung adenocarcinoma. CONCLUSIONS: Vigilance needs to be increased in clinical work for patients with interstitial lung disease, low tumor markers such as CEA, and imaging suggestive of inflammatory progression, which in fact turns into lung cancer. When the treatment is ineffective after standardized application of hormone and anti-infection, lung tissue should be obtained for pathological examination in time to obtain pathological evidence.

Accidental Detection of Tuberculous Empyema at Health Check-Up.

BACKGROUND: Patients with tuberculous empyema (TE) can have a serious impact on lung function as their disease progresses, and, if left untreated, can cause damage to other parts of the body such as the thorax and spine, causing pain and inconvenience to the patient. Early diagnosis and the search for appropriate treatment are key to improving the survival rate of the disease. METHODS: We report a case of a young patient with an unexpected finding of right pleural effusion on physical examination, who was eventually diagnosed with TE using next-generation sequencing of pleural tissue. We analyzed the literature to improve clinicians' understanding of TE and how to properly diagnose and treat the disease. RESULTS: Laboratory results of the pleural effusion suggested a possible Mycobacterium tuberculosis infection, but pathogen-related tests were negative, and the diagnosis was eventually successfully confirmed by thoracoscopic pleural biopsy. CONCLUSIONS: The diagnosis of TE should be considered in young patients with pleural thickening of the empyema. Adenosine deaminase may provide diagnostic direction in patients with unexplained thorax abscess. Pleural biopsy, although an invasive procedure, is an essential diagnostic tool in some cases.

Positive Herpesvirus IgG Antibodies in Lung Cancer Patients Finally Proved as Drug-induced Pemphigus.

BACKGROUND: Herpesvirus IgG antibody positivity can be a lifelong burden of disease replication and reinfection or recent viruses can be reactivated and play an important role in the diagnosis and monitoring of herpesvirus [1]. However, sometimes serum IgG antibody positivity is of limited help in determining the onset of disease. We reported a case of herpesvirus IgG antibody positive in a patient with lung cancer who was initially misdiagnosed as herpes simplex and later confirmed drug-induced pemphigus (DIP) by histological and immunofluorescence studies. METHODS: Appropriate laboratory tests, enzyme-linked immunosorbent assay (ELISA), immunofluorescence and histological tests were performed for diagnosis. RESULTS: In lung cancer patients who were positive for herpesvirus IgG antibodies, were initially misdiagnosed as herpes simplex and eventually confirmed by histological and immunofluorescence examinations as DIP. CONCLUSIONS: Positive herpesvirus IgG antibody is not a specific manifestation of herpesvirus infection. For patients with unexplained skin blisters, we should improve histological examinations as soon as possible to clarify the type of lesion.

Left Lung High-Density Shadow Combined with Elevated NSE Ultimately Confirmed as Pulmonary Aspergillosis.

BACKGROUND: Detection of serum neuron specific enolase (NSE) has high sensitivity and specificity in the diagnosis of lung cancer, especially small cell lung cancer, but sometimes serum NSE provides limited help. We report a case of high-density shadow of the left lung and elevated serum NSE which mimicked lung cancer. It was ultimately confirmed to be pulmonary aspergillosis (PA) by bronchoscopic alveolar lavage fluid (BALF) and next-generation sequencing (NGS). METHODS: Appropriate laboratory tests, chest computed tomography (CT) scan, bronchoscopic alveolar lavage fluid, and next-generation sequencing were used to explore latent causes. RESULTS: NSE level was elevated, chest CT scan showed high-density shadow of the left lung, bronchoscopy showed flesh-colored new organisms in the lower lobe of the left lung, BALF and NGS revealed the presence of Aspergillus. CONCLUSIONS: Elevated NSE is not a typical manifestation of lung cancer, and we should perform BALF and NGS early to determine whether there is infection with special pathogenic bacteria.

Elevated CEA Misdiagnosed as Lung Cancer Ultimately Confirmed Pulmonary Cryptococcosis.

BACKGROUND: Carcinoembryonic antigen (CEA) is a polysaccharide complex present in the human respiratory system, which can reflect the presence of tumors in the human body and has important value in the monitoring of lung cancer [1], but sometimes serum CEA provides limited help. We reported a case of multiple consolidation of the lungs with elevated serum CEA, initially misdiagnosed as lung cancer and eventually confirmed by bronchoscopic lung biopsy as pulmonary cryptococcosis (PC). METHODS: Appropriate laboratory examination, chest computed tomography (CT) scan, and bronchoscopy lung biopsy were used to explore the latent etiology. RESULTS: CEA level was elevated, chest CT scan showed multiple consolidation of the lungs, serum cryptococcal antigen was positive, and pathological findings on bronchoscopic lung biopsy confirmed pulmonary cryptococcosis. CONCLUSIONS: Elevated CEA is not typical of lung cancer. We should also consider the possibility of specific pathogenic infection. Bronchoscopic lung biopsy is the gold standard should be performed as soon as possible to identify the lesion.

Acute Eosinophilic Pneumonia Masquerading as a Lung Abscess.

BACKGROUND: Acute Eosinophilic Pneumonia (AEP) is a rare form of non-infectious pneumonia that is easily missed and misdiagnosed because of its atypical clinical symptoms and misleading laboratory and imaging studies. METHODS: By reporting a case of an initial diagnosis of lung abscess, which was treated with antibiotics and then CT suggesting that the lesion continued to worsen, it was eventually confirmed to be AEP by lung biopsy, A joint literature analysis was conducted to improve clinicians' understanding of the diagnosis and treatment of AEP. RESULTS: Initially, because of the atypical ancillary findings, we thought the disease was a lung abscess, which was eventually confirmed by pathology as AEP. CONCLUSIONS: The presence of AEP needs to be considered when various laboratory findings point to infectious dis-ease, but anti-infection is not effective. Diagnosis can be confirmed by bronchoalveolar lavage and lung tissue biopsy. Prompt treatment can provide rapid relief and reduce the risk of patient death.

Acute Heart Failure due to Pulmonary Aspergillus Fumigatus and Cryptococcus Neoformans Infection Associated with COVID-19.

BACKGROUND: Current studies have reported that it is rare for the coronavirus disease 2019 (COVID-19) to be combined with two fungal infections and that COVID-19 can be combined with multiple cardiovascular complications, both of which can complicate the condition and increase the risk of death. METHODS: We report a case of COVID-19 in which Aspergillus fumigatus and Cryptococcus neoformans were detected by sputum targeted next-generation sequencing (tNGS) and cardiac monitoring during treatment revealed cardiovascular complications. RESULTS: We consider that this patient's fungal infection was associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and the application of corticosteroids. In addition, cardiovascular complications were associated with an inflammatory response and increased sympathetic stimulation due to SARS-CoV-2 infection. CONCLUSIONS: The presence of COVID-19-associated fungal infections cannot be excluded when multiple risk factors for fungal infections are present in patients with COVID-19 and the condition is rapidly deteriorating. Effective long-term monitoring of cardiac function during the patient's hospitalization is necessary to reduce morbidity and mortality.

Positive PPD Test and TB-Ab Misdiagnosed as Tuberculosis Finally Proved as Sarcoidosis by Thoracoscopy: a Case Report.

BACKGROUND: Tuberculosis (TB) is a common infectious disease in developing countries. Tuberculosis and sarcoidosis are difficult to differentiate. We report a case of a patient who was initially misdiagnosed as tuberculosis due to positive tuberculin test (PPD test) and tuberculosis antibody (TB-Ab), which was eventually proven as sarcoidosis by thoracoscopy. METHODS: Appropriate laboratory tests are carried out and a chest CT scan, bronchoscopy, thoracoscopic pathological biopsy were done. RESULTS: Serum sedimentation was increased and tuberculosis antibody was positive. The chest CT scan showed multiple pulmonary nodules in both lungs. The bronchoscopy demonstrated no abnormality. Thoracoscopic pathology showed noncaseating granulomas and acid-fast staining was negative. CONCLUSIONS: When a patient has multiple pulmonary nodules and lymphadenopathy without obvious tuberculosis poisoning symptoms, physicians should pay attention to tuberculosis, sarcoidosis, and lung cancer. Pathology is crucial for the ultimate diagnosis.

Connective Tissue Disease-Associated Pulmonary Interstitial Fibrosis with Mycobacterium Paraintracellulare Infection: a Case Report.

BACKGROUND: Infectious pulmonary diseases caused by nontuberculous mycobacteria (NTM) are becoming more common in clinical work, and early detection of the bacterium and its early identification are prerequisites for accurate treatment. METHODS: By reporting a case of confirmed NTM infection in a patient with connective tissue disease-associated interstitial lung fibrosis, a joint literature analysis was performed to improve clinicians' understanding of NTM and the clinical application of targeted next-generation sequencing (tNGS). RESULTS: Chest CT suggested a partially enlarged cavitary lesion in the upper lobe of the right lung, combined with positive sputum antacid staining, and sputum tNGS was sent to confirm the final diagnosis of Mycobacterium paraintracellulare infection. CONCLUSIONS: The successful application of tNGS helps in the rapid diagnosis of NTM infection. It also reminds medical practitioners to consider the presence of NTM infection in advance in the presence of many NTM infection factors, combined with imaging manifestations.

Organizing Pneumonia Secondary to Infection with Coxiella Burnetii: a Case Report.

BACKGROUND: Organizing pneumonia is a non-specific inflammatory response to various types of damage to the lungs. It is usually considered bacterial pneumonia that has not been absorbed for more than 4 weeks, accompanied by granulomas and fibrosis. Lung lesions in patients with organizing pneumonia are usually irreversible and the prognosis is relatively poor. Coxiella burnetii can cause Q fever. Acute Q fever usually presents as a self-limiting febrile illness with a good prognosis, but there are few cases of coexisting organizing pneumonia. We report a case of organizing pneumonia secondary to Coxiella burnetii infection. METHODS: Percutaneous lung biopsy, Next-generation sequencing (NGS). RESULTS: Percutaneous lung biopsy showed the existence of organizing pneumonia, and external examination of NGS showed the existence of Coxiella burnetii infection. After symptomatic treatment with azithromycin and glucocorticoids, the patient improved and was discharged from the hospital. CONCLUSIONS: For lesions with obvious heterogeneous enhancement on chest CT imaging, percutaneous lung biopsy or bronchoscopy should be performed promptly to obtain pathological tissue, and NGS should be used for definite diagnosis if necessary.

Pulmonary Tuberculosis with Elevated CEA and Positive PET-CT.

BACKGROUND: Pulmonary tuberculosis presenting as solitary pulmonary nodules in imaging is sometimes difficult to differentiate from lung cancer and is more likely to be misdiagnosed when accompanied by elevated CEA and positive PET-CT findings. METHODS: By reporting a case of misdiagnosed lung cancer, which was confirmed to be pulmonary tuberculosis by lung biopsy, a joint literature analysis was performed to raise clinicians' awareness of isolated nodules in the lung. RESULTS: With a series of ancillary tests, we initially considered the nodule to be malignant, and the lung biopsy pathology eventually confirmed pulmonary tuberculosis. CONCLUSIONS: When chest imaging suggests the presence of malignant features in solitary pulmonary nodules, invasive procedures can be performed appropriately to clarify the nature of the lesion. The diagnosis cannot be made blindly to ensure that no incorrect diagnosis is made nor wrong treatment given.

Organizing Pneumonia with NGS False-Positive Imaging Resembling Tuberculosis: a Case Report.

BACKGROUND: Organizing pneumonia (OP) is a pathologic concept characterized by the formation of granulation tissue from fibroblasts, myofibroblasts, collagen, and fibrotic exudate in the respiratory fine bronchi, alveolar ducts, and alveoli. The clinical imaging of mechanized pneumonia is variable, and histopathological examination is required to clarify the nature of the lesion when imaging is atypical. We report a case of OP with imaging resem-blance to pulmonary tuberculosis and false-positive next-generation sequencing (NGS), which was first misdiag-nosed as pulmonary tuberculosis. METHODS: Appropriate laboratory tests, alveolar lavage fluid NGS, chest CT, bronchoscopy, percutaneous lung puncture, pathology. RESULTS: Chest CT showed a nodular high-density shadow in the lower lobe of the right lung. According to the chest CT, bronchoalveolar lavage was performed in the dorsal segment of the right lower lobe of the lung. NGS of lavage fluid: the sequence number of Moraxella osseae was 1,423; the sequence number of Prevotella melanogaster was 1,129. Based on lung histopathology, fibrous emboli and necrotic material were seen in the alveolar lumen, and the final diagnosis of the OP was confirmed. CONCLUSIONS: It should be noted that physicians should not blindly believe the NGS result report. When the diagnosis is not clear and anti-infection treatment is ineffective, lung tissue should be obtained promptly for pathological examination to obtain pathological evidence to differentiate from misdiagnosed diseases.

Mycobacterium Tuberculosis Infection in AECOPD Combined with Pulmonary Embolism: a Case Report.

BACKGROUND: Mycobacterium tuberculosis belongs to the group of mycobacteria, most of which can cause a delayed hypersensitivity reaction in the body and is a bacterium that causes tuberculosis. Mycobacterium tuberculosis infection often presents with symptoms of tuberculosis toxicity and rarely with respiratory distress. At the same time, chest imaging often shows an ill-defined solid shadow in the apical and posterior segments of the upper lobe and, less frequently, in the dorsal segment of the lower lobe, and less frequently a diffuse nodular shadow. We report a case of AECOPD combined with pulmonary embolism infected with Mycobacterium tuberculosis. METHODS: Bronchoscopy, Next-generation sequencing (NGS). RESULTS: Antacid staining of bronchoalveolar lavage fluid suggested that a small amount of Mycobacterium antacid was visible. NGS was sent for examination and it suggested the presence of Mycobacterium tuberculosis with a sequence number of 5 (reference range ≥ 0). Treatment such as bronchodilation and antituberculosis was given. CONCLUSIONS: In patients with dyspnea, it is crucial to find the causative agent and to promptly improve relevant examinations such as pulmonary arteriography and bronchoscopy, and if necessary, to make a definitive diagnosis by NGS.

T-SPOT.TB Negative and Diagnosed as Interstitial Pulmonary Tuberculosis by NGS: a Case Report and Literature Review.

BACKGROUND: Tuberculosis is an airborne infectious disease with multiple morphologic changes on chest imaging. Tuberculosis-specific enzyme-linked immunospot assay (T-SPOT.TB) is widely used in the diagnosis of tuberculosis. Clinically, pulmonary tuberculosis with T-SPOT.TB negative and interstitial changes is very rare. METHODS: T-SPOT.TB, pathogenetic testing, chest CT scan, next-generation sequencing (NGS). RESULTS: Laboratory tests showed negative T-SPOT.TB and sputum antacid staining, chest CT showed interstitial fibrosis and multiple high-density shadows in both lungs, and sputum NGS showed Mycobacterium tuberculosis infection. CONCLUSIONS: Negative T-SPOT.TB and interstitial lung changes do not exclude Mycobacterium tuberculosis infection. NGS has a high specificity in the detection of pathogens in infectious diseases, especially in complex, mixed infectious diseases.

Rare Co-Infection of the Lungs with EBV and Pneumocystis Carinii in a Patient with Kidney Cancer: a Case Report.

BACKGROUND: Epstein-Barr virus (EBV) is the primary agent of infectious mononucleosis, lymphoma, and naso-pharyngeal carcinoma, but rarely involves the lungs. Pneumocystis carinii is commonly found in patients with HIV infection and is not pathogenic when the host is healthy, but opportunistic infections can occur when the body is immunocompromised, causing pneumocystis pneumonia (PCP). It is rare for both diseases to occur in the lungs of the same patient. METHODS: Next-generation sequencing (NGS), laboratory examination, chest CT scan, electronic bronchoscopy, and pathogenetic examination were used in this study. RESULTS: Laboratory tests showed (1-3)-ß-D-glucan of 889.47 pg/mL, negative human immunodeficiency virus (HIV) antibody, and negative Aspergillus immunological test. Chest CT showed multiple high-density shadows in both lungs, and EBV infection combined with Pneumocystis carinii pneumonia was confirmed by bronchoscopic biopsy and NGS examination. CONCLUSIONS: Elevated serum (1-3)-ß-D-glucan is not a specific index for infectious diseases. Bronchoscopy and the NGS has high specificity in pathogen detection of infectious diseases.

D-Dimer and Procalcitonin Improve the Sensitivity of BAP-65 Score in Predicting AECOPD Patients Admission to ICU.

BACKGROUND: The study aimed at investigating the effectiveness of the BAP-65 score combined with D-dimer and procalcitonin (PCT) in predicting admission of acute exacerbation chronic obstructive pulmonary disease (AECOPD) patients to the intensive care unit (ICU). METHODS: We conducted a retrospective study. We analyzed data from 369 patients over the age of 40 years ad-mitted to our hospital with AECOPD. All patients received blood routine measurements and BAP-65 score calculation on admission. Receiver operating characteristic curves (ROC) were used to assess the sensitivity and specificity of D-dimer, PCT, and BAP-65 scores and combined metrics in predicting the risk of admissions to the ICU of AECOPD patients. RESULTS: We found that the percentage of patients with AECOPD admitted to the ICU was 32.25% (119/369). The area under the curve (AUC) of D-dimer, PCT, and BAP-65 score in individually predicting the probability of entering the ICU of AECOPD patients were 0.74 (95% CI 0.68 - 0.80), 0.83 (95% CI 0.78 - 0.88), and 0.72 (95% CI 0.66 - 0.79), respectively. The sensitivities of D-dimer, PCT, and BAP-65 score were 0.51, 0.65, and 0.52, respectively. The specificities of D-dimer, PCT, and BAP-65 score were 0.90, 0.91, and 0.92, respectively. The AUC of D-dimer and PCT combined with BAP-65 score was 0.90 (95% CI 0.86 - 0.94), the sensitivity and specificity were 0.90 and 0.80, respectively. CONCLUSIONS: D-dimer and procalcitonin improve the sensitivity of the BAP-65 score in predicting the probability of AECOPD patients entering the ICU while having a good specificity.

Nomogram Prediction Model of the Severity of CAP Patients Based on Blood Indicators.

BACKGROUND: Community-acquired pneumonia (CAP) is a common cause of hospitalization, characterized by high mortality, morbidity, and cost and has serious human health implications. Various scoring criteria have been used to predict the severity of pneumonia, including the CURB-65 score, Pneumonia Severity Index (PSI) score, and Severe Community-Acquired Pneumonia (SCAP) score. However, these scoring criteria have shortcomings such as low sensitivity, cumbersome clinical application, and limited application. This study aimed to construct a nomogram model to predict the severity of CAP patients by blood indicators. METHODS: This is a retrospective study. Patients with CAP were enrolled and then tested by routine blood, coagulation series, biochemical and inflammatory indicators, and general information such as imaging findings and disease history of the patients were recorded. The main observation was the progression of the patients' disease. Univariate analysis and binary logistic regression analysis were used to explore the independent risk factors for the severity of CAP patients, followed by plotting a nomogram to obtain the prediction model and constructing calibration curves to assess the authenticity and accuracy of the prediction model. Finally, the sensitivity, specificity, and other evaluation indexes were calculated by the receiver operating characteristic curve (ROC) to evaluate the clinical application value of the nomogram prediction model. RESULTS: Univariate analysis and binary logistic regression analysis of 277 hospitalized patients yielded platelet to lymphocyte ratio (PLR) and serum amyloid A (SAA) as independent risk factors for the severity of CAP patients. The AUC of the nomogram model for PLR and SAA was 0.889 (95% CI 0.845 - 0.932). The sensitivity was 77.3%, and the specificity was 85.3%, which had an excellent predictive value. CONCLUSIONS: The nomogram model based on PLR and SAA to predict the severity of CAP patients has a high specificity and sensitivity.

Non-Tuberculous Mycobacteria with Enlarged Mediastinal Lymph Node by Next Generation Sequencing: Case Report.

BACKGROUND: A young patient characterized by rapid enlargement of mediastinal lymph nodes was diagnosed as non-tuberculous mycobacterial pulmonary disease (NTM-PD) by bronchoalveolar lavage fluid Next Generation Sequencing (NGS). METHODS: Laboratory examination, Chest CT scan, electronic bronchoscopy, and endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) were performed to diagnose non-tuberculous mycobacterium pulmonary disease. RESULTS: Detection of bird-intracellular mycobacterium complex in bronchoalveolar lavage fluid by NGS. Chest CT scan showed multiple enlarged lymph nodes in mediastinum. 4R region TBNA: chronic granulomatous inflammation, positive bacilli were found by acid-fast staining. After the anti-NTM treatment, the symptoms of the patients were relieved. CONCLUSIONS: When the patient shows mediastinal lymph node enlargement of unknown cause, NTM-PD can be considered and NGS can be used to assist in the diagnosis.

Procalcitonin (PCT) Improves the Accuracy and Sensitivity of CURB-65 Score in Predicting CAP Patients Admission to ICU.

BACKGROUND: The CURB-65 scoring system is a simple tool for assessment and prognosis prediction for community-acquired pneumonia (CAP) patients. However, the variations in the performance of CURB-65 in young and elderly patients, underestimation, or overestimation of the severity have often been reported. It is worth noting that the application of biomarkers is helpful for improving the accuracy of the scoring system. In recent years, more and more reports and studies paid attention to procalcitonin (PCT) in respiratory infectious diseases, and its clinical value has attracted increasing attention. The study aimed at investigating the effectiveness of the CURB-65 score combined with PCT in predicting admission of CAP patients to intensive care units (ICU). METHODS: We conducted a retrospective study. We analyzed data from 520 non-immune individuals over the age of 18 in this study. All patients received blood indicators measurement and CURB-65 score calculation on admission. The primary outcome used to assess the probability of a CAP patient was who would get a bed in general ward or ICU. Receiver operating characteristic curves (ROC) were used to evaluate the sensitivity and specificity of the CURB-65 model and PCT combined CURB-65 augmented model in predicting the main outcomes. RESULTS: After analyzing the data from 520 patients, we found that the probability of entering the ICU was 22.1% (115/520). The AUC of Combination 1 (PCT&CURB-65 scores), Combination 2 (WBC&CURB-65 scores), Combination 3 (hs-CRP&CURB-65 scores) and Combination 4 (D-dimer&CURB-65 scores) for predicting CAP patients entering the ICU was 0.92 (95% CI 0.88 - 0.95), 0.91 (95% CI 0.87 - 0.94), 0.89 (95% CI 0.85 - 0.92), and 0.90 (95% CI 0.87 - 0.94), respectively, with statistically significant differences (p = 0.00); the sensitivities were 0.83, 0.82, 0.77 and 0.77, respectively, and the specificities were 0.92, 0.84, 0.90 and 0.91, respectively. PCT was superior to other indexes to improve the sensitivity and specificity of the CURB-65 score. CONCLUSIONS: Procalcitonin improves the accuracy and sensitivity of the CURB-65 score in predicting the probability of CAP patients entering the ICU, and PCT was superior to other indexes to improve the sensitivity and specificity of the CURB-65 score.