The role of serum procalcitonin in establishing the diagnosis and prognosis of pleural infection

Diagnosis and management of pleural infection

Pleural infection remains a medical challenge. Although closed tube drainage revolutionised treatment in the 19th century, pleural infection still poses a significant health burden with increasing incidence. Diagnosis presents challenges due to non-specific clinical presenting features. Imaging techniques such as chest radiographs, thoracic ultrasound and computed tomography scans aid diagnosis. Pleural fluid analysis, the gold standard, involves assessing gross appearance, biochemical markers and microbiology. Novel biomarkers such as suPAR (soluble urokinase plasminogen activator receptor) and PAI-1 (plasminogen activator inhibitor-1) show promise in diagnosis and prognosis, and microbiology demonstrates complex microbial diversity and is associated with outcomes. The management of pleural infection involves antibiotic therapy, chest drain insertion, intrapleural fibrinolytic therapy and surgery. Antibiotic therapy relies on empirical broad-spectrum antibiotics based on local policies, infection setting and resistance patterns. Chest drain insertion is the mainstay of management, and use of intrapleural fibrinolytics facilitates effective drainage. Surgical interventions such as video-assisted thoracoscopic surgery and decortication are considered in cases not responding to medical therapy. Risk stratification tools such as the RAPID (renal, age, purulence, infection source and dietary factors) score may help guide tailored management. The roles of other modalities such as local anaesthetic medical thoracoscopy and intrapleural antibiotics are debated. Ongoing research aims to improve outcomes by matching interventions with risk profile and to better understand the development of disease.

The clinical features and prognosis of fungal pleural infection: A case series and literature review

Fungal pleural infections are infrequent and insidious, for which there are neither large clinical studies nor targeted guidelines to provide standardized treatment options. We reported 4 cases of fungal pleural infection and reviewed the cases of fungal pleural infections in previous studies to provide a basis for the diagnosis and treatment of fungal pleural infections. There were 2 females and 2 males with a mean age of 58.5 years in our data. The average time from onset to diagnosis was 30.25 days. Risk factors most frequently included pulmonary diseases (n = 4) and malignancy (n = 1). Two patients underwent pleural biopsy through a thoracoscope, and no pathogens were detected. Pleural fluid culture was positive in 2 out of 3 cases. The diagnoses were "possible" (n = 1), "probable" (n = 1), and "proven" (n = 2). All patients received systemic antifungal therapy, and 3 received combined thoracic drainage. The outcomes were cured (n = 1), improved (n = 2) and lost to follow-up (n = 1). We reviewed 12 cases of fungal pleural infection in previous studies. The diagnosis was confirmed via culture in 7 cases and via biopsy in 8 cases. The pathogen was Aspergillus in 7 cases. After a combination of systemic antifungal (n = 12) and local treatment (n = 11), 10 patients improved and 2 patients died. Diagnosis of fungal pleural infection should incorporate risk factors, clinical presentation and fungal evidence, with pleural fluid culture being an important and feasible mean of confirming the diagnosis; and treatment should be based on systemic antifungal therapy supplemented by topical therapy.

Diagnostic value of soluble biomarkers for parapneumonic pleural effusion

Parapneumonic pleural effusion (PPE) is a common complication in patients with pneumonia. Timely and accurate diagnosis of PPE is of great value for its management. Measurement of biomarkers in circulating and pleural fluid have the advantages of easy accessibility, short turn-around time, objectiveness and low cost and thus have utility for PPE diagnosis and stratification. To date, many biomarkers have been reported to be of value for the management of PPE. Here, we review the values of pleural fluid and circulating biomarkers for the diagnosis and stratification PPE. The biomarkers discussed are C-reactive protein, procalcitonin, presepsin, soluble triggering receptor expressed on myeloid cells 1, lipopolysaccharide-binding protein, inflammatory markers, serum amyloid A, soluble urokinase plasminogen activator receptor, matrix metalloproteinases, pentraxin-3 and cell-free DNA. We found that none of the available biomarkers has adequate performance for diagnosing and stratifying PPE. Therefore, further work is needed to identify and validate novel biomarkers, and their combinations, for the management of PPE.

Optimal diagnostic strategies for pleural diseases and identifying high-risk patients

INTRODUCTION

Pleural diseases encompass a broad range of conditions with diverse and heterogenous etiologies. Diagnostics in pleural diseases thus represents a challenging field with a wide array of available testing to distinguish between the numerous causes of pleural disease. Nonetheless, deploying best practice diagnostics in this area is essential in reducing both duration o the investigation pathway and symptom burden.

AREAS COVERED

This article critically appraises the optimal diagnostic strategies and pathway in patients with pleural disease, reviewing the latest evidence and key practice points in achieving a treatable diagnosis in patients with pleural disease. We also cover future and novel directions that are likely to influence pleural diagnostics in the near future. PubMed was searched for articles related to pleural diagnostics (search terms below), with the date ranges including June 2012 to June 2022.

EXPERT OPINION

No single test will ever be sufficient to provide a diagnosis in pleural conditions. The key to reducing procedure burden and duration to diagnosis lies in personalizing the investigation pathway to patients and deploying tests with the highest diagnostic yield early (such as pleural biopsy in infection and malignancy). Novel biomarkers may also allow earlier diagnostic precision in the near future.

Pleural fluid biochemical analysis: the past, present and future

Identifying the cause of pleural effusion is challenging for pulmonologists. Imaging, biopsy, microbiology and biochemical analyses are routinely used for diagnosing pleural effusion. Among these diagnostic tools, biochemical analyses are promising because they have the advantages of low cost, minimal invasiveness, observer independence and short turn-around time. Here, we reviewed the past, present and future of pleural fluid biochemical analysis. We reviewed the history of Light’s criteria and its modifications and the current status of biomarkers for heart failure, malignant pleural effusion, tuberculosis pleural effusion and parapneumonic pleural effusion. In addition, we anticipate the future of pleural fluid biochemical analysis, including the utility of machine learning, molecular diagnosis and high-throughput technologies. Clinical Chemistry and Laboratory Medicine (CCLM) should address the topic of pleural fluid biochemical analysis in the future to promote specific knowledge in the laboratory professional community.

Evaluation and management of pleural sepsis

Pleural sepsis stems from an infection within the pleural space typically from an underlying bacterial pneumonia leading to development of a parapneumonic effusion. This effusion is traditionally divided into uncomplicated, complicated, and empyema. Poor clinical outcomes and increased mortality can be associated with the development of parapneumonic effusions, reinforcing the importance of early recognition and diagnosis. Management necessitates a multimodal therapeutic strategy consisting of antimicrobials, catheter/tube thoracostomy, and at times, video-assisted thoracoscopic surgery.

Recent Insights into the Management of Pleural Infection

Pleural infection in adults has considerable morbidity and continues to be a life-threatening condition. The term “pleural infection” encompasses complicated parapneumonic effusions and primary pleural infections, and includes but is not limited to empyema, which refers to collection of pus in the pleural cavity. The incidence of pleural infection in adults has been continuously increasing over the past two decades, particularly in older adults, and most of such patients have comorbidities. Management of pleural infection requires prolonged duration of hospitalization (average 14 days). There are recognized differences in microbial etiology of pleural infection depending on whether the infection was acquired in the community or in a health-care setting. Anaerobic bacteria are acknowledged as a major cause of pleural infection, and thus anaerobic coverage in antibiotic regimens for pleural infection is mandatory. The key components of managing pleural infection are appropriate antimicrobial therapy and chest-tube drainage. In patients who fail medical therapy by manifesting persistent sepsis despite standard measures, surgical intervention to clear the infected space or intrapleural fibrinolytic therapy (in poor surgical candidates) are recommended. Recent studies have explored the role of early intrapleural fibrinolytics or first-line surgery, but due to considerable costs of such interventions and the lack of convincing evidence of improved outcomes with early use, early intervention cannot be recommended, and further evidence is awaited from ongoing studies. Other areas of research include the role of routine molecular testing of infected pleural fluid in improving the rate of identification of causative organisms. Other research topics include the benefit of such interventions as medical thoracoscopy, high-volume pleural irrigation with saline/antiseptic solution, and repeated thoracentesis (as opposed to chest-tube drainage) in reducing morbidity and improving outcomes of pleural infection. This review summarizes current knowledge and practice in managing pleural infection and future research directions.

Management of Pleural Infection

Pleural infection is a millennia-spanning condition that has proved challenging to treat over many years. Fourteen percent of cases of pneumonia are reported to present with a pleural effusion on chest X-ray (CXR), which rises to 44% on ultrasound but many will resolve with prompt antibiotic therapy. To guide treatment, parapneumonic effusions have been separated into distinct categories according to their biochemical, microbiological and radiological characteristics. There is wide variation in causative organisms according to geographical location and healthcare setting. Positive cultures are only obtained in 56% of cases; therefore, empirical antibiotics should provide Gram-positive, Gram-negative and anaerobic cover whilst providing adequate pleural penetrance. With the advent of next-generation sequencing techniques, yields are expected to improve. Complicated parapneumonic effusions and empyema necessitate prompt tube thoracostomy. It is reported that 16-27% treated in this way will fail on this therapy and require some form of escalation. The now seminal Multi-centre Intrapleural Sepsis Trials (MIST) demonstrated the use of combination fibrinolysin and DNase as more effective in the treatment of empyema compared to either agent alone or placebo, and success rates of 90% are reported with this technique. The focus is now on dose adjustments according to the patient's specific 'fibrinolytic potential', in order to deliver personalised therapy. Surgery has remained a cornerstone in the management of pleural infection and is certainly required in late-stage manifestations of the disease. However, its role in early-stage disease and optimal patient selection is being re-explored. A number of adjunct and exploratory therapies are also discussed in this review, including the use of local anaesthetic thoracoscopy, indwelling pleural catheters, intrapleural antibiotics, pleural irrigation and steroid therapy.

Advances in pleural infection and malignancy

Pleural infection and malignancy are among the most common causes of pleural disease and form the mainstay of pleural practice. There has been significant research and increase in scientific understanding in these areas in the past decade. With regard to pleural infection, the rising incidence remains worrying. An increased awareness allowing earlier diagnosis, earlier escalation of therapy and the use of validated risk stratification measures may improve outcomes. In pleural malignancy, research has enabled clinicians to streamline patient pathways with focus on reducing time to diagnosis, definitive management of malignant pleural effusion and achieving these with the minimum number of pleural interventions. Trials comparing treatment modalities of malignant pleural effusion continue to highlight the importance of patient choice in clinical decision-making. This article aims to summarise some of the most recent literature informing current practice in these two areas.

Diagnostics in Pleural Disease

Pleural disease diagnostics represent a sprawling topic that has enjoyed a renaissance in recent years from humble beginnings. Whilst pleural patients are heterogeneous as a population and in the aetiology of the disease with which they present, we provide an overview of the typical diagnostic approach. Pleural fluid analysis is the cornerstone of the diagnostic pathway; however, it has many shortcomings. Strong cases have been made for more invasive upfront investigations, including image-guided biopsies or local anaesthetic thoracoscopy, in selected populations. Imaging can guide the diagnostic process as well as act as a vehicle to facilitate therapies, and this is never truer than with the recent advances in thoracic ultrasound.

Bronchial lavage under fiberoptic bronchoscopy in the treatment of severe pulmonary infection

Objective:

To investigate the clinical efficacy of bronchial lavage under fiberoptic bronchoscopy in the treatment of severe pulmonary infection.

Methods:

One hundred forty eight patients with severe pulmonary infection who were admitted to our hospital from October 2016 to December 2017 were included in this study. According to the random number table method, they were divided into a control group and an observation group with 79 patients each. The control group was given conventional treatment, while the observation group was given bronchoalveolar lavage with fiberoptic bronchoscopy on the basis of the treatment in the control group. The clinical efficacy of the two groups was compared, the duration of mechanical ventilation, antibiotic use and symptoms improvement of the two groups were recorded, and the respiratory mechanics parameters, serum procalcitonin (PCT) and transforming growth factor β (TGF-β) level were measured before and after treatment.

Results:

The duration of mechanical ventilation, antibiotic use, respiratory failure correction, body temperature decline and white blood cell recovery in the observation group were significantly shorter than those in the control group (P<0.05). The total efficacy of the observation group was significantly higher than that of the control group (92.4% vs. 74.7%). The respiratory mechanics parameters of the two groups after treatment were higher than those before treatment (P<0.05) and the increase of the observation group was more obvious than that of the control group (P<0.05). The serum PCT and TGF-β levels of the two groups after treatment were lower than those before treatment (P<0.05), and the decrease level in the observation group was more obvious (P<0.05).

Conclusion:

Bronchial lavage under fiberoptic bronchoscopy can improve the clinical efficacy, accelerate the improvement of clinical symptoms and respiratory mechanics parameters, significantly reduce the PCT and TGF-β levels, and promote the rapid recovery of patients in the treatment of severe pulmonary infection.

Advances in pleural effusion diagnostics

Introduction: Pleural effusion is a common clinical problem. Yet, in a significant proportion of patients (~20%), the cause of pleural effusion remains unknown. Understanding the diagnostic value of pleural fluid tests is crucial for the development of accurate diagnostic models.Areas covered: This paper provides an overview of latest advances in the diagnosis of pleural effusion based on the best evidence available.Expert opinion: For pleural fluid tests to have a good diagnostic value, it is necessary that data obtained from clinical history, physical examination, and radiological studies are correctly interpreted. Thoracentesis and pleural biopsy should always be performed under image guidance to improve its diagnostic sensitivity and prevent complications. Nucleic acid amplification tests, pleural tissue cultures, and collection of pleural fluid in blood culture bottles improve the diagnostic yield of pleural fluid cultures. Although undiagnosed pleural effusions generally have a favorable prognosis, follow-up is recommended to prevent the development of a malignant pleural effusion.

Improvement of cell counting method for Neubauer counting chamber

Background

We compared the cell counting accuracy of the conventional method and the improved method by using Neubauer counting chamber.

Methods

In the improved method, all the border cells were counted and then divided by two; while, in the conventional method, only border cells on the two boundaries (top and left) were counted.

Results

About 55.814% of the samples showed more accurate results by improved counting method, about 38.372% had more accurate results by conventional counting method, and about 5.814% were counted with similar counting error by both methods. The improved method had significantly smaller counting error than conventional method (P < .05). The distribution ratio of the border cells was an independent factor for counting accuracy (P < .05).

Conclusion

Together, the improved counting method can reduce the counting error of the Neubauer counting chamber to some extent, assess the distributing uniformity of border cells, and help to eliminate the samples with large differences in distribution.

Pleural infection: a closer look at the etiopathogenesis, microbiology and role of antibiotics

INTRODUCTION

Pleural infection is a condition that continues to pose a significant challenge to respiratory physicians. We hypothesize that the main barriers to progress include limited understanding of the etiopathogenesis, microbiology,and role of antibiotics in the pleural space. Areas covered: PubMed was searched for articles related to adult pleural infection using the terms 'pleural infection', 'empyema' and 'parapneumonic'. The search focused on relevant literature within the last 10 years, with any older citations used only to display context or lack of progress. Tuberculous pleural infection was excluded. We chose to give specific attention to the etiopathogenesis of pleural infection, including recent advances in diagnostics and biomarkers. We discuss our understanding of the pleural microbiome and rationalize the current use of antibiotics in treating this condition. Expert commentary: Understanding of key events in the development of this condition remains limited. The microbiology is unique compared to the lung, and highly variable. Higher culture yields from pleural biopsy may add new insights into the etiopathogenesis. There is little evidence into achievable effective antibiotic concentration within the pleura. Research into issues including the relevance of biofilm formation and significance of pleural thickening is necessary for treatment progress.

Diagnosis of infectious pleural effusion using predictive models based on pleural fluid biomarkers

INTRODUCTION:

Diagnosis of pleural infection (PI) may be challenging. The purpose of this paper is to develop and validate a clinical prediction model for the diagnosis of PI based on pleural fluid (PF) biomarkers.

METHODS:

A prospective study was conducted on pleural effusion. Logistic regression was used to estimate the likelihood of having PI. Two models were built using PF biomarkers. The power of discrimination (area under the curve) and calibration of the two models were evaluated.

RESULTS:

The sample was composed of 706 pleural effusion (248 malignant; 28 tuberculous; 177 infectious; 48 miscellaneous exudates; and 212 transudates). Areas under the curve for Model 1 (leukocytes, percentage of neutrophils, and C-reactive protein) and Model 2 (the same markers plus interleukin-6 [IL-6]) were 0.896 and 0.909, respectively (not significant differences). However, both models showed higher capacity of discrimination than their biomarkers when used separately (P < 0.001 for all). Rates of correct classification for Models 1 and 2 were 88.2% (623/706: 160/177 [90.4%] with infectious pleural effusion [IPE] and 463/529 [87.5%] with non-IPE) and 89.2% (630/706: 153/177 [86.4%] of IPE and 477/529 [90.2%] of non-IPE), respectively.

CONCLUSIONS:

The two predictive models developed for IPE showed a good diagnostic performance, superior to that of any of the markers when used separately. Although IL-6 contributes a slight greater capacity of discrimination to the model that includes it, its routine determination does not seem justified.

Diagnostic performance of C-reactive protein for parapneumonic pleural effusion: a meta-analysis

Background

Parapneumonic pleural effusion (PPE) refers to effusion secondary to lung infection, the accurate diagnosis of which remains a clinical challenge. Many studies have suggested that the C-reactive protein (CRP) may be useful for diagnosing PPE, but the results have varied. This study aimed to summarize the overall diagnostic ability of serum/pleural CRP for PPE through a meta-analysis.

Methods

Eligible studies were searched for within PubMed, EMBASE, and other databases up to March 1, 2018. The main diagnostic indexes, sensitivity, specificity, positive likelihood ratio/negative likelihood ratio (PLR/NLR), and diagnostic odds ratio (DOR), were then pooled from the individual studies. The summary receiver operating characteristic curves and area under the curve (AUC) were used to summarize the overall test performance.

Results

Eighteen publications were included in this meta-analysis. Summary estimates of the diagnostic performance of pleural CRP for PPE were as follows: sensitivity, 0.80; specificity, 0.82; PLR, 4.51; NLR, 0.25; DOR, 18.26; and AUC, 0.88. The AUC of serum CRP in diagnosing PPE was 0.79. The diagnostic indexes for pleural CRP in differentiating complicated PPE (CPPE) from uncomplicated PPE were as follows: sensitivity, 0.65; specificity, 0.85; PLR, 4.26; NLR, 0.41; DOR, 10.38; and AUC, 0.83. There was no evidence of publication bias.

Conclusions

Both serum and pleural CRP help to diagnose PPE but with moderate diagnostic ability. Pleural CRP measurements also can aid in differentiating CPPE from uncomplicated PPE. However, the results of the CRP assay should be interpreted with additional biomarker tests.

Recent developments in the management of pleural infection: A comprehensive review

OBJECTIVES

Pleural infection is a condition commonly encountered by the respiratory physician. This review aims to provide the reader with an update on the most recent data regarding the epidemiology, microbiology, and the management of pleural infection.

DATA SOURCE

Medline was searched for articles related to pleural infection using the terms "pleural infection," "empyema," and "parapneumonic." The search was limited to the years 1997-2017. Only human studies and reports in English were included.

RESULTS

A rise in the incidence of pleural infection is seen worldwide. Despite the improvement in healthcare practices, the mortality from pleural infection remains high. The role of oral microflora in the etiology of pleural infection is firmly established. A concise review of the recent insights on the pathogenesis of pleural infections is presented. A particular focus is made on the role of tPA, DNAse and similar substances and their interaction with inflammatory cells and how this affects the pathogenesis and treatment of pleural infection.

CONCLUSION

Pleural infection is a common disease with significant morbidity and mortality, as well as a considerable economic burden. The role of medical management is expanding thanks to the widespread use of newer treatments.