Correlations between computed tomography findings and clinical manifestations of Streptococcus pneumoniae pneumonia

Imaging in pulmonary infections of immunocompetent adult patients

Pneumonia is a clinical syndrome characterised by fever, cough and alveolar infiltration of purulent fluid, caused by infection with a microbial pathogen. It can be caused by infections with bacteria, viruses or fungi, but a causative organism is identified in less than half of cases. The most common type of pneumonia is community-acquired pneumonia, which is caused by infections acquired outside the hospital. Current guidelines for pneumonia diagnosis require imaging to confirm the clinical suspicion of pneumonia. Thus, imaging plays an important role in both the diagnosis and management of pneumonia, with each modality having specific advantages and limitations. Chest radiographs are commonly used but have limitations in terms of sensitivity and specificity. Lung ultrasound shows high sensitivity and specificity. Computed tomography scans offer higher diagnostic accuracy but involve higher radiation doses. Radiological patterns, including lobar, lobular and interstitial pneumonia, provide valuable insights into causative pathogens and treatment decisions. Understanding these radiological patterns is crucial for accurate diagnosis. In this review, we will summarise the most important aspects pertaining to the role of imaging in pneumonia and will highlight the imaging characteristics of the most common causative organisms.

Case report: Streptococcus pneumoniae pneumonia characterized by diffuse centrilobular nodules in both lungs

Background

Streptococcus pneumoniae (S. pneumoniae) is the most common pathogen in community-acquired pneumonia (CAP) and takes the form of lobar pneumonia as typical computed tomography (CT) findings. Various patterns of radiological manifestation have also been reported in patients with S. pneumoniae pneumonia; however, the appearance of diffuse centrilobular nodules in both lungs is rarely reported.

Case presentation

We report the case of a patient with a history of chronic lymphocytic leukemia (CLL) for 9 years who presented with new-onset fever, cough, excess sputum, and shortness of breath for 1 week. He was given intravenous antibacterial (cephalosporin) treatment for 4 days, but his condition did not improve and dyspnea became more serious. The chest CT indicated diffuse centrilobular nodules in both lungs at admission. Patient's bronchoalveolar (BAL) fluid was sent for metagenomic next-generation sequencing, which only supported a diagnosis of S. pneumoniae infection. His condition improved gradually after antimicrobial treatment (moxifloxacin) and a follow-up CT showed that the diffuse centrilobular nodules in both lungs were absorbed completely.

Conclusion

This case highlights a rare CT presentation of S. pneumoniae pneumonia that should alert clinicians, so as to avoid taking unnecessary treatment measures.

Differential diagnosis between the coronavirus disease 2019 and Streptococcus pneumoniae pneumonia by thin-slice CT features

OBJECTIVE

The chest computed tomography (CT) features of coronavirus disease 2019 (COVID-19) and Streptococcus pneumoniae pneumonia (S. pneumoniae pneumonia) were compared to provide further evidence for the differential imaging diagnosis of patients with these two types of pneumonia.

METHODS

Clinical information and chest CT data of 149 COVID-19 patients between January 9, 2020 and March 15, 2020 and 97 patients with S. pneumoniae pneumonia between January 23, 2011 and March 18, 2020 in Zhongnan Hospital of Wuhan University were retrospectively analyzed. In addition, CT features were comparatively analyzed.

RESULTS

According to the chest CT images, the probability of lung segmental and lobar pneumonia in S. pneumoniae pneumonia was higher than that in COVID-19(P<0.001); the probabilities of ground-glass opacity (GGO), the "crazy paving" sign, and abnormally thickened interlobular septa in COVID-19 were higher than those in S. pneumoniae pneumonia(P = 0.005, P<0.001, P<0.001, respectively); and the probabilities of consolidation lesions, bronchial wall thickening, centrilobular nodules, and pleural effusion in S. pneumoniae pneumonia were higher than those in COVID-19 (P<0.001, P = 0.001, P = 0.003, P = 0.001, respectively).

CONCLUSION

The findings of GGO, the crazy paving sign, and abnormally thickened interlobular septa on chest CT were significantly higher in COVID-19 than S. pneumoniae pneumonia. The most important differential points on chest CT signs between COVID-19 and S. pneumoniae pneumonia were whether disease lesions were distributed in entire lung lobes and segments and whether the crazy paving sign, interlobular septal thickening, and consolidation lesions were found.

Current situation and need for prevention of invasive pneumococcal disease and pneumococcal pneumonia in 6- to 64-year-olds in Japan

We conducted a systematic review of the literature to evaluate the reported epidemiology and burden of invasive pneumococcal disease (IPD) and pneumococcal pneumonia (PP) among children and adults aged 6-64 years in Japan. Studies published from Japan between September 2009 and September 2019 and indexed in the MEDLINE/PubMed or ICHUSHI databases were evaluated. A majority of the studies reported overlapping age ranges, including children aged <6 years and adults aged >64 years. According to the national surveillance data, 19% of the IPD cases were patients aged 5-59 years, and an increasing trend in IPD cases was reported from 2013 to 2017. Comorbidities were consistent with those reported by the Advisory Committee on Immunization Practices. Deaths from IPD appeared to increase nearly 3-fold between 2013 and 2017. Overall, both 13-valent pneumococcal conjugate vaccine (PCV13) and 23-valent pneumococcal polysaccharide vaccine (PPSV23) coverage was higher for IPD compared with PP. All the serotypes known to be prominent in Japan were also identified as common serotypes (3, 6A, 19A: PCV13 serotypes; 12F: outbreak serotype; 15A, 35B: drug-resistant serotypes). This systematic literature review suggests a substantial burden of IPD and PP in Japanese children and adults aged 6-64 years. The burden of comorbidities, hospitalizations, and mortality was particularly high among adults. Concerted pneumococcal vaccination strategies may help to reduce the incidence and burden of IPD and PP in this large proportion of the Japanese population.

Relationship Between Clinical Features and Computed Tomographic Findings in Hospitalized Adult Patients With Community-Acquired Pneumonia

Background

Data on the relationship between the clinical and microbiological features of community-acquired pneumonia (CAP) and its computed tomography (CT) findings are limited. The aim of the present study was to investigate the clinic-microbiological features of patients with CAP presenting with ground-glass opacity (GGO) and centrilobular nodules or tree-in-bud pattern on CT images.

Methods

Patients with CAP who underwent a CT scan at presentation were retrospectively classified using CT findings into consolidation, GGO and bronchiolitis groups. These 3 groups were compared in terms of clinical parameters and microbiological data.

Results

A total of 40 patients (2.4%) were allocated to the bronchiolitis group and 46 (2.8%) to the GGO group. The most common pathogen in the bronchiolitis group was Mycoplasma pneumoniae, which was significantly more frequently isolated in this group. The bronchiolitis group was characterized by a higher percentage of cough, a lower percentage of chest pain and lower blood levels of inflammatory markers. Common pathogens in the GGO group were not significantly different from those in the other 2 groups. Unlike that observed in the consolidation group, complicated parapneumonic effusion or empyema was not observed in the bronchiolitis or GGO group. Outcome variables were similar in the 3 groups.

Conclusions

The bronchiolitis group was characterized by a higher frequency of M. pneumoniae and a less severe form of CAP. The GGO and consolidation groups was similar with respect to causative microorganisms and the clinical features of CAP. No patient in the bronchiolitis or GGO group exhibited complicated parapneumonic effusion or empyema.

Thoracic Imaging Features of Legionnaire's Disease

Imaging examinations are often performed in patients with Legionnaires' disease. The literature to date has documented that the imaging findings in this disorder are relatively nonspecific, and it is therefore difficult to prospectively differentiate legionella pneumonia from other forms of pneumonia, and from other noninfectious thoracic processes. Through a review of clinical cases and the literature, our objective is for the reader to gain a better understanding of the spectrum of radiographic manifestations of Legionnaires' disease.

Clinical Application of High-Resolution Computed Tomographic Imaging Features of Community-Acquired Pneumonia

Background

This article discusses the value of high-resolution computed tomography (HRCT) in the diagnosis and treatment of pulmonary infections. Lung infection caused by pathogens is an important cause of death. Traditional methods to treat lung infection involved empirical antibiotic therapy. Thin-slice CT scanning is widely used in the clinical setting, and HRCT scan can very clearly show alveolar and bronchiolar involvement of infection.

Material/Methods

In total, 178 patients with community-acquired pneumonia (CAP) were enrolled. All the patients underwent CT scan, qualified sputum, and blood samples for culture or immunological biochemical tests. CT imaging features, pathogenic bacteria, and treatment results were used for statistical analysis.

Results

In 77 patients with lobar consolidation, the rate of detection was 43.26% (77/178), and in 101 patients with lobular pneumonia it was 56.74% (101/178). In 51 patients, pathogenic bacteria were detected (28.65%, 51/178). Sixteen of 33 patients detected with bacteria had cavities (48.5%, 16/33) and 35 of 145 patients detected with bacteria had no cavities (24.1%, 35/145). The difference between the 2 groups was statistically significant (χ²=7.795, P=0.005). According to the pathogenic bacteria, 38 patients were cured (74.51%, 38/51), and according to the CT imaging features 81 patients were cured (71.05%, 81/114). No statistically significant difference was found between them (χ²=0.209, P=0.647).

Conclusions

Treatment effect of CAP based on HRCT findings is not inferior to treatment effect guided by microbial characterization.

The "Tree-in-Bud" Pattern on Chest CT: Radiologic and Microbiologic Correlation

BACKGROUND

Tree-in-bud (TIB) is a radiologic pattern seen on high-resolution chest CT reflecting bronchiolar mucoid impaction occasionally with additional involvement of adjacent alveoli. Its microbiologic significance has not been systematically evaluated.

OBJECTIVES

We aimed to establish the incidence of the TIB pattern as a proportion of all patients undergoing chest CT and to identify its etiology wherever possible.

METHODS

We included all patients with TIB pattern detected on chest CT in our institution from January 2007 to June 2012 and correlated this radiologic finding to the microbiologic etiology, which were available, for each patient.

RESULTS

During the study period, TIB pattern was described in 326 patients, which is 1.8% of all chest CTs. Of these, 220 (67.5%) patients had an infectious etiology and 34 (10.4%) had aspiration pneumonia. Other presumptive etiologies were in 13 (4%) lung malignancy, 31 (9.5%) other malignancies, 20 cases (6%) inconclusive etiology or incidental findings, and 8 (2.5%) had other inflammatory disorders. The relative incidence of the various organisms isolated reflected the overall incidence of these bacteria in community- or hospital-acquired populations independent of the TIB pattern. No correlation was found between distribution of TIB, the immune status, and the organism isolated.

CONCLUSIONS

TIB pattern reflects endobronchiolar inflammation due mainly but not exclusively to an infectious cause. The microbiologic etiology in patients with this finding is similar to that of the general population (community acquired versus hospital acquired).

A comparative study of thin-section CT findings between seasonal influenza virus pneumonia and Streptococcus pneumoniae pneumonia

OBJECTIVE

To compare the pulmonary thin-section CT findings in patients with seasonal influenza virus pneumonia with Streptococcus pneumoniae pneumonia.

METHODS

The study group included 30 patients (20 males and 10 females; age range, 20-91 years; mean age, 55.9 years) with seasonal influenza virus pneumonia and 71 patients (47 males and 24 females; age range, 27-92 years; mean age, 67.5 years) with S. pneumoniae pneumonia.

RESULTS

The proportion of community-acquired infection was significantly higher in patients with influenza virus pneumonia than with S. pneumoniae pneumonia (p = 0.001). CT findings of ground-glass attenuation (GGA) (p = 0.012) and crazy-paving appearance (p = 0.03) were significantly more frequent in patients with influenza virus pneumonia than with S. pneumoniae pneumonia. Conversely, consolidation (p < 0.001), mucoid impaction (p < 0.001), centrilobular nodules (p = 0.04) and pleural effusion (p = 0.003) were significantly more frequent in patients with S. pneumoniae pneumonia than in those with influenza virus pneumonia.

CONCLUSION

Pulmonary thin-section CT findings, such as consolidation and mucoid impaction may be useful in distinguishing between seasonal influenza virus pneumonia and S. pneumoniae pneumonia.

ADVANCES IN KNOWLEDGE

(1) Distinguishing seasonal influenza virus pneumonia with S. pneumoniae pneumonia is important. (2) The CT findings of GGA and crazy-paving appearance were more frequently found in patients with influenza virus pneumonia than in patients with S. pneumoniae pneumonia, whereas consolidation, mucoid impaction, centrilobular nodules and pleural effusion were more frequently found in patients with S. pneumoniae pneumonia.