Prospective clinical and microbiological study of pleural effusions

Microbiological diagnosis of pleural infections: a comparative evaluation of a novel syndromic real-time PCR panel

Current microbial diagnostics for pleural infections are insufficient. Studies using 16S targeted next-generation sequencing report that only 10%-16% of bacteria present are cultured and that 50%-78% of pleural fluids containing relevant microbial DNA remain culture negative. As a rapid diagnostic alternative suitable for clinical laboratories, we wanted to explore a PCR-based approach. Based on the identification of key pathogens, we developed a syndromic PCR panel for community-acquired pleural infections (CAPIs). This was a pragmatic PCR panel, meaning that it was not designed for detecting all possibly involved bacterial species but for confirming the diagnosis of CAPI, and for detecting bacteria that might influence choice of antimicrobial treatment. We evaluated the PCR panel on 109 confirmed CAPIs previously characterized using culture and 16S targeted next-generation sequencing. The PCR secured the diagnosis of CAPI in 107/109 (98.2%) and detected all present pathogens in 69/109 (63.3%). Culture secured the diagnosis in 54/109 (49.5%) and detected all pathogens in 31/109 (28.4%). Corresponding results for 16S targeted next-generation sequencing were 109/109 (100%) and 98/109 (89.9%). For bacterial species included in the PCR panel, PCR had a sensitivity of 99.5% (184/185), culture of 21.6% (40/185), and 16S targeted next-generation sequencing of 92.4% (171/185). None of the bacterial species present not covered by the PCR panel were judged to impact antimicrobial therapy. A syndromic PCR panel represents a rapid and sensitive alternative to current diagnostic approaches for the microbiological diagnosis of CAPI.IMPORTANCEPleural empyema is a severe infection with high mortality and increasing incidence. Long hospital admissions and long courses of antimicrobial treatment drive healthcare and ecological costs. Current methods for microbiological diagnostics of pleural infections are inadequate. Recent studies using 16S targeted next-generation sequencing as a reference standard find culture to recover only 10%-16% of bacteria present and that 50%-78% of samples containing relevant bacterial DNA remain culture negative. To confirm the diagnosis of pleural infection and define optimal antimicrobial therapy while limiting unnecessary use of broad-spectrum antibiotics, there is a need for rapid and sensitive diagnostic approaches. PCR is a rapid method well suited for clinical laboratories. In this paper we show that a novel syndromic PCR panel can secure the diagnosis of pleural infection and detect all bacteria relevant for choice of antimicrobial treatment with a high sensitivity.

Expert Review on Nonsurgical Management of Parapneumonic Effusion: Advances, Controversies, and New Directions

Parapneumonic effusion and empyema are rising in incidence worldwide, particularly in association with comorbidities in an aging population. Also driving this change is the widespread uptake of pneumococcal vaccines, leading to the emergence of nonvaccine-type pneumococci and other bacteria. Early treatment with systemic antibiotics is essential but should be guided by local microbial guidelines and antimicrobial resistance patterns due to significant geographical variation. Thoracic ultrasound has emerged as a leading imaging technique in parapneumonic effusion, enabling physicians to characterize effusions, assess the underlying parenchyma, and safely guide pleural procedures. Drainage decisions remain based on longstanding criteria including the size of the effusion and fluid gram stain and biochemistry results. Small-bore chest drains appear to be as effective as large bore and are adequate for the delivery of intrapleural enzyme therapy (IET), which is now supported by a large body of evidence. The IET dosing regimen used in the UK Multicenter Sepsis Trial -2 has the most evidence available but data surrounding alternative dosing, concurrent and once-daily instillations, and novel fibrinolytic agents are promising. Prognostic scores used in pneumonia (e.g., CURB-65) tend to underestimate mortality in parapneumonic effusion/empyema. Scores specifically based on pleural infection have been developed but require validation in prospective cohorts.

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.

CT appearances of pleural infection: analysis of the Second Multi-centre Intra-pleural Sepsis Trial (MIST 2) cohort

AIM

To determine the prevalence of pleural abnormalities and describe the computed tomography (CT) features observed in a well-characterised population of patients with pleural infection.

MATERIALS AND METHODS

A retrospective study of a subgroup of patients from the Second Multi-centre Intra-pleural Sepsis Trial (MIST 2) trial was carried out. Patients were diagnosed with pleural infection on robust clinical criteria. CT examinations were assessed by three observers independently for the presence of predefined features. Planned subgroup comparisons of patients with and without evidence of parenchymal infection were performed.

RESULTS

Eighty-one patients were included. Parietal pleural thickening and enhancement were seen in 98.7% of patients. Visceral pleural changes were observed in most, including several previously undescribed features. Consolidation was observed in 61.7% of patients and there was a significant association of parenchymal consolidation with CT evidence of small airways infection (p<0.001) and visceral pleural thickening and enhancement (p<0.05). Features of parenchymal infection were absent in one third of patients.

CONCLUSION

This study provides a comprehensive account of the parietal pleural, visceral pleural, and parenchymal changes of pleural infection on CT. Parenchymal infection is absent in a significant proportion of patients with pleural infection, suggesting that a pneumonic process may not be necessary for the development of pleural infection.

Routine Microbiologic Studies of Pleural Fluid Specimens in Cancer Patients

BACKGROUND

Patients who have pleural effusions typically undergo thoracentesis with examination of pleural fluid in their initial assessment. However, limited data are available on the diagnostic yield of pleural fluid bacterial cultures and fungal and acid-fast bacilli (AFB) smear and cultures in patients with cancer.

METHODS

We performed a retrospective cohort study of consecutive patients who had new onset pleural effusions and underwent an initial thoracentesis. The primary outcome was diagnostic yield of pleural fluid bacterial cultures and fungal and AFB smear and cultures.

RESULTS

Of 1637 patients, 1547 (94%) had evidence of active malignancy and 1359 (83%) had evidence of metastatic disease. Of the 1637 patients, 542 (33%) had high clinical suspicion of pneumonia within 14 days prior to thoracentesis. Only 14 patients (1.1%) had positive pleural fluid bacterial cultures, and only 6 of these positive cultures met the criteria for true pleural space infection.

CONCLUSIONS

The incidence of positive results from pleural fluid bacterial, fungal, and AFB in cancer populations is very low. Unless there is a suspicion for infection, microbiological analysis should be ordered selectively.

Emerging concepts in pleural infection

PURPOSE OF REVIEW

Pleural infection remains an important pulmonary disease, causing significant morbidity and mortality. There is a resurgence of disease burden despite introduction of antibiotics and pneumococcal vaccines. A revisit of the pathogenesis and update on intervention may improve the care of pleural infection.

RECENT FINDINGS

Recent studies have uncovered the prognostic implication of the presence of a pleural effusion in patients with pneumonia. Identifying where the bacteria lives may have diagnostic and therapeutic implications. Over-exaggerated pleural inflammation may underlie development of parapneumonic effusion as indirect evidence and a randomized study in children raised a role of corticosteroids in parapneumonic pleural effusions, but data are lacking for adults. Optimization of the delivery regimen of intrapleural fibrinolytic and deoxyribonuclease therapy is ongoing.

SUMMARY

The review aims to review the current practice and explore new directions of treatment on pleural infection.

Updates in Effusion Cytology

Effusion cytology plays multiple roles in the management of benign and malignant disease, from primary diagnosis to tissue allocation for ancillary diagnostic studies and biomarker testing of therapeutic targets. This article summarizes recent advances in pleural effusion cytology, with a focus on the practical application of immunohistochemical markers, cytogenetic techniques, flow cytometry, and molecular techniques for the diagnosis and management of primary and secondary neoplasms of the pleura.

Performance of the BacT/Alert Virtuo Microbial Detection System for the culture of sterile body fluids: prospective multicentre study

OBJECTIVES

Continuous monitoring blood culture systems are commonly used for sterile body fluid cultures. In this multicentre study, we evaluated the performance of the new-generation BacT/Alert Virtuo system compared to the BacT/Alert 3D and conventional culture for the recovery of microorganisms from sterile body fluids.

METHODS

Peritoneal, cerebrospinal, pericardial, pleural and synovial fluids from adult patients submitted for culture were collected from three different centres. Specimens were inoculated into two bottles of the same bottle type (SA, SN, FA Plus or FN Plus) in equal volumes for simultaneous incubation in the Virtuo and 3D instruments. Each specimen was also Gram stained and seeded to solid media.

RESULTS

A total of 811 specimens were inoculated to 1257 bottle pairs. The Virtuo and 3D showed equivalent recovery of clinically significant microorganisms (127/155, 81.9%, vs. 126/155, 81.3%, respectively). Solid media cultures recovered fewer pathogens than either continuous monitoring system (95/155, 61.3%, p <0.001), including significantly fewer Enterobacteriaceae and enterococci. The Virtuo was significantly faster than the 3D in median time to detection of isolates from the same specimen (12.5 (range, 2.8-101.5) hours vs. 15.5 (range, 4.3-78.5) hours, p <0.001). Direct specimen Gram stain detected the eventual pathogen in 30 (26.1%) of 115 significant positive specimens.

CONCLUSIONS

The BacT/Alert Virtuo system was equivalent to the 3D system in organism recovery from sterile body fluid culture but showed faster detection of growth as a result of design enhancements.

Disseminated sporotrichosis in an immunocompetent patient

Sporothrix schenckii, the causative agent of sporotrichosis, is a relatively rare infection. Local infection usually occurs through direct inoculation of the organism through the skin; disseminated disease is rarely seen. This article describes a case of disseminated sporotrichosis in a middle-aged man without the commonly seen risk factors for dissemination.

Blood Culture Bottle and Standard Culture Bottle Methods for Detection of Bacterial Pathogens in Parapneumonic Pleural Effusion

Background:

Bacterial parapneumonic pleural effusions (PPEs) have high morbidity. The accurate identification of pathogens is vital for initiating the appropriate treatment. A previous study suggested that the use of blood culture bottles might improve the bacterial yield in PPEs.

Objectives:

The aim of this study was to compare the culture positivity rate by the blood culture bottles and the standard culture bottles in bacterial PPEs.

Patients and Methods:

Patients diagnosed with PPEs at the Khon Kaen Hospital, Khon Kaen, Thailand, which is an endemic area of melioidosis, were enrolled consecutively and prospectively. The study period was from June first, 2012 to December 31st, 2013. The inclusion criteria were adult patients aged > 18 years, with exudative, neutrophilic parapneumonic effusion. Of the pleural fluid samples, 5 mL from all the eligible patients were collected in both blood culture bottles and the standard culture bottles. Patient baseline characteristics, laboratory results, and culture results were collected and analyzed.

Results:

During the study period, 129 patients met the study criteria. The bacteria-positive rate of pleural fluid culture using the standard culture bottle was 14.0%, whereas the positive rate using blood culture bottles was 24.0% (P < 0.001).

Conclusions:

The blood culture bottle method is more effective than the standard culture bottle method for the detection of bacterial pathogens in PPE.

Predictors of prolonged stay in patients with community-acquired pneumonia and complicated parapneumonic effusion

BACKGROUND AND OBJECTIVE

Development of CPE in CAP is associated with prolonged hospital stay and it may increase the morbidity and mortality. We aimed to identify microbiological and clinical factors that predicate a prolonged hospital admission in patients treated with a tube thoracostomy to control CPE.

METHODS

This retrospective cohort included patients with CPE requiring chest tube drainage in a tertiary referral Korean hospital from 1 January 2004 to 30 July 2012. After dichotomous grouping according to the mean duration of hospital stay, clinical, laboratory and microbiological parameters were compared.

RESULTS

The final analysis included 158 patients with CPE. The majority were male (130, 85.0%), and the mean age was 62.8 years. The mean duration of hospital stay was 17.7 (±10.2) days. The mean duration of chest tube drainage was 9.6 (±6.7) days. Streptococcus viridans (48.4%) was the most common pathogen. Intrapleural fibrinolysis was performed in 85 (53.8%); additional tube insertion was needed in 40 (25.3%) patients. In the multivariate analysis after adjusting for covariates, a prolonged hospital stay was associated with fever (aOR: 3.42, P = 0.02), lower PaO2 (aOR: 4.89, P = 0.007) and haemoglobin (aOR: 4.90, P = 0.003) levels, and an increased blood neutrophil fraction (aOR: 3.83, P = 0.01) on admission as well as the identification of microbes in CPE (aOR: 4.14, P = 0.03), and ineffective pleural drainage (aOR: 3.28, P = 0.03).

CONCLUSIONS

This study suggests that physicians should note the clinical symptoms and laboratory findings of severe infection and effectiveness of pleural drainage to predicate which patients with a CAP needing thoracostomy for CPE will have a prolonged hospital stay.

Pleural Disorders

This chapter provides an overview of both benign and malignant pleural disorders, starting with the relevant anatomy and physiology. The focus is on the management of pneumothoraces and pleural effusions—conditions that are commonly encountered on a general thoracic surgery service. The pleural cavity is lined by parietal and visceral pleura, which are smooth membranes that are continuous with one another at the hilum and pulmonary ligaments. Parietal Pleura: innermost chest wall layer, divided into cervical, costal, mediastinal and diaphragmatic pleura.

Treatment of complicated pleural effusions in 2013

The incidence of pleural infection seems to be increasing worldwide. Despite continued advances in the management of this condition, morbidity and mortality have essentially remained static over the past decade. This article summarizes the current evidence and opinions on the epidemiology, etiology, and management of complicated pleural effusions caused by infection, including empyema. Although many parallels may be drawn between children and adults in such cases, most trials, guidelines, and series regard pediatric patient groups and those more than 18 years of age as separate entities. This review focuses mainly on the treatment of adult disease.

Systematic use of universal 16S rRNA gene polymerase chain reaction (PCR) and sequencing for processing pleural effusions improves conventional culture techniques

Conventional culture of pleural fluid samples frequently provides false-negative results. Universal polymerase chain reaction (PCR) of the 16S ribosomal ribonucleic acid (rRNA) gene (16S PCR) has proven useful in the diagnosis of various bacterial infections. We conducted a prospective study to assess the value of 16S PCR in the etiologic diagnosis of pleural effusion. All pleural fluid samples received for culture were also studied using 16S PCR. Positive samples were sequenced for identification. Clinical records and conventional culture results were analyzed to classify pleural fluid samples as infected or not infected. We studied 723 samples. We excluded 188 samples because they were obtained from a long-term chest tube, there was a diagnosis of mycobacterial infection, or there were insufficient data to classify the episode. Finally, 535 pleural fluid samples were analyzed. According to our criteria, 82 (15.3%) were infected and 453 (84.7%) were not infected. In the infected samples, 16S PCR was positive in 67 samples (81.7%) while conventional culture was positive in 45 (54.9%). There were 4 false positives with 16S PCR (0.9%) and 12 with culture (2.6%). The values for the etiologic diagnosis of bacterial pleural effusion of conventional culture compared with 16S PCR were as follows: sensitivity, 54.9%/81.7%; specificity, 97.4%/99.1%; positive predictive value, 76.3%/94.4%; negative predictive value, 92.6%/96.8%; and accuracy, 90.8%/96.5%.When compared with conventional culture, 16S PCR plus sequencing substantially improves the etiologic diagnosis of infectious pleural effusion. In our opinion, this technique should be added to the routine diagnostic armamentarium of clinical microbiology laboratories.

Diagnosis of community-acquired pneumonia in adults

Community-acquired pneumonia (CAP) is a common presentation to both primary and secondary care, representing approximately 5% of the acute medical intake in the UK. Treatment is often based on an empirical approach, using broad-spectrum antibiotic regimens, with which the majority of patients will achieve clinical cure. However, in cases of severe CAP, initial treatment failure or severe comorbidity, a more rigorous diagnostic approach is required. This review assesses the evidence base behind the common diagnostic methods for CAP, and presents the case for a rapid and accurate microbiological and radiological diagnosis in improving management and outcomes of this common condition.

A systematic approach to the investigation and diagnosis of a unilateral pleural effusion

Fluid in the pleural space is a common sequela of a wide range of diseases which may be pulmonary, pleural or extrapulmonary. As the differential diagnosis is wide, a systematic approach to investigation and diagnosis is recommended. This review highlights the important features and recommendations for the investigation of a unilateral pleural effusion, a common condition encountered by the general physician. The aim of this study was to assist with a speedy diagnosis of the underlying pathology, using appropriate investigative techniques, while minimising the use of invasive procedures.

Clinical background of cases showing a positive culture of pleural effusion at Shin-Kokura Hospital over a period of 5 years

We investigated the clinical background of patients at Shin-Kokura Hospital who showed a positive culture of pleural effusion during the period from January 1998 through December 2002. Microorganism cultures of the pleural effusions of 127 patients were performed in this 5-year period. Seventeen patients showed a positive microorganism culture from a pleural effusion, and 12 of these patients (70.6%) were 60 years old or more. Ten patients were diagnosed with thoracic empyema. Thirteen patients had an underlying disease such as malignancy (5 cases), diabetes mellitus (4 cases), etc. A purulent effusion and a high concentration of lactic dehydrogenase (LDH) in the pleural fluid were more frequently recognized in the positive-culture group. A total of 21 strains of microorganism were isolated from the 17 patients, including 10 strains of Gram-positive cocci, 6 strains of Gram-negative bacilli, 3 strains of anaerobes, 1 strain of mycobacterium (Mycobacterium tuberculosis), and 1 strain of fungus. Susceptibility to antimicrobial agents was generally good for most of the microorganisms isolated. Of the 17 patients, chest-tube drainage was performed in 13, and 6 needed a surgical operation. Twelve patients improved, but 5 died. In this study, thoracic empyema accounted for 58.8% of the 17 cases with a positive culture of pleural effusion. Of the 10 thoracic empyema patients, 5 patients needed surgical treatment in spite of adequate antimicrobial treatment and chest-tube drainage. Our data indicate that thoracic empyema is still difficult to treat, and thus adequate and rapid treatment is needed for any pleural infection.

The Approach to the Patient with a Parapneumonic Effusion

Parapneumonic effusion is a common clinical problem, and those that go on to develop pleural infection have high morbidity and mortality. The process of pleural infection evolution involves changes in pleural physiology that are increasingly being elucidated and understood. The microbiology of pleural infection has changed over recent years, with clear differences emerging between hospital- and community-acquired infections. Using biochemical surrogates of infection, chest drainage can be undertaken rationally for those who do not respond to antibiotics alone. Recent data suggest that fibrinolytics do not influence outcomes in pleural infection. The optimal type and timing of surgery remain controversial.

Routine use of pleural fluid cultures. Are they indicated? Limited yield, minimal impact on treatment decisions

In pleural infection, it has been recommended that Gram stain and cultures should be obtained on a routine basis. However, this recommendation has not been tested prospectively. We evaluated the yield of microbiological studies in 259 patients with parapneumonic pleural effusion. Microbiological studies were positive on the pleural fluid of 50 patients (19.3%). In 48 of the 50 patients with positive microbiological results (96%), the need for pleural drainage was correctly predicted by pleural fluid parameters. There were no differences in hospital stay (9.5+/-2.5 days versus 9.9+/-3.2 days, P=0.68) or in mortality (2 deaths in each group, P=0.58) between the group of patients in which antibiotic treatment was changed according to microbiological results and the group of patients in which it is not. In conclusion, this study demonstrates that, at least in our institution, routine microbial investigation of pleural fluid adds very little to the standard management of parapneumonic effusions.

Diagnosis and Management of Infectious Pleural Effusion

Pleural infection remains a common illness, with a high morbidity and mortality. The development of frank empyema from a simple exudative pleural effusion is a result of biochemical changes within the pleural space in response to bacterial invasion. These changes can be used in the diagnosis of pleural infection and used to predict which patients will require intercostal drainage for resolution of infection. Recent large trials in empyema have further advanced our knowledge of microbiologic patterns, informing important decisions about empiric antibacterial therapy. Diagnosis of pleural infection relies on high clinical suspicion in association with clinical features, radiology, and pleural fluid characteristics. Treatment of pleural infection is based upon accurate and often empiric choice of antibacterial agents, intercostal drainage in certain contexts, and appropriate surgical referral. Intrapleural thrombolytic therapy is not currently recommended for the treatment of pleural infection, on the basis of evidence from the largest randomized trial in empyema to date.

Factors Influencing Length of Hospital Stay in Patients with Bacterial Pleural Effusion

BACKGROUND

Factors influencing length of hospital stay have been poorly analyzed in parapneumonic pleural effusions (PPE).

OBJECTIVES

The aim of this work is to identify the variables that determine increased hospital stay in patients with infectious pleural effusion (PE).

PATIENTS AND METHODS

We analyzed 112 patients with PE: empyema, complicated parapneumonic and non-complicated parapneumonic. Epidemiologic, biochemical, therapeutic and radiological variables were analyzed. Correlations with hospital stay were studied using the Student's t test, analysis of variance, Mann-Whitney U-test and linear regression model.

RESULTS

Among the 112 patients studied, there were 32 empyema, 50 complicated and 30 non-complicated parapneumonic cases. The median of length stay for all patients was 17 days. Longer hospitalization was required in patients with empyemic PE (p = 0.015), patients with underlying diseases (p = 0.003), those needing pleural drainage (p = 0.005) or decortication (p = 0.043) and those presenting unfavorable radiological outcome after treatment (p = 0.02). Biochemical parameters associated with longer hospital stay were elevated pleural fluid polymorphonuclear elastase (p = 0.001, r = 0.307) and lactate dehydrogenase (p = 0.001, r = 0.312). After linear regression analysis, only underlying disease, pleural drainage and pleural fluid polymorphonuclear elastase values remained in the model, explaining 23.1% of the variability of days of hospitalization.

CONCLUSIONS

The patients with PPE and empyema who required longer hospitalization were those with purulent fluid, underlying disease, surgical drainage and/or decortication, with unfavorable radiological outcome and higher pleural fluid levels of lactate dehydrogenase and polymorphonuclear elastase.

Low Yield of Microbiologic Studies on Pleural Fluid Specimens

BACKGROUND

It is generally recommended that pleural fluid samples from pleural effusions of unknown cause be cultured for bacteria, mycobacteria, and fungi. However, the utility of this practice has been not been adequately assessed.

DESIGN

Retrospective review.

SETTING

Tertiary care, referral medical center.

PATIENTS

Five hundred twenty-five patients undergoing diagnostic thoracentesis at Mayo Medical Center, Rochester, MN, over a 12-month period from July 1, 2001, to June 30, 2002.

INTERVENTIONS

None.

MEASUREMENTS AND RESULTS

Among 525 patients undergoing diagnostic thoracenteses, 476 patients (91%) had one or more cultures performed on their pleural fluid specimens. Thirty-nine positive results (3.0% of 1,320 cultures) occurred in 35 of these 476 patients (7.4%). After excluding likely contaminants, true pathogens were identified in only 19 of 1,320 pleural fluid cultures (1.4%) belonging to 15 patients (3.2% of those who had cultures performed on their pleural fluid specimen). These positive results included 2.3% of aerobic bacterial, 1.2% of anaerobic bacterial, 1.4% of fungal, and 0% of mycobacterial cultures. Microbiologic smears performed on these pleural fluid samples included 357 Gram stains, 109 fungal smears (potassium hydroxide), and 232 acid-fast smears with positive yields of 2.5%, 0%, and 0%, respectively. These positive findings represented 1.3% of all smears performed. Of the specimens obtained from outpatient thoracenteses, only one had a true-positive result (0.8%). Only 1.1% (four specimens) of the cultures performed on free-flowing effusions demonstrated true pathogens; three of these four specimens grew fungi.

CONCLUSIONS

The positive yield of microbiologic smears and cultures on pleural fluid specimens is low, particularly in the outpatient setting and in patients with free-flowing effusions. Microbiologic testing of pleural fluid specimens should be ordered more selectively.

The management of pleural space infections

Pleural infection is responsible for significant morbidity and mortality worldwide, and its clinical management is challenging. The diagnosis of empyema and tuberculous pleurisy may be difficult, and these conditions may be confused with other causes of exudative pleural effusions. Complicated parapneumonic effusion or empyema may present with 'atypical' clinical features; delays in diagnosis are common and may contribute to the high mortality of these infections. Pleural aspiration is the key diagnostic step; pleural fluid that is purulent or that has a pH < 7.2, or organisms on Gram stain or culture, is an indication for formal intercostal drainage. In order to achieve a definitive diagnosis of tuberculous pleurisy, Mycobacterium tuberculosis must be isolated in the culture of pleural fluid, pleural tissue or sputum; demonstration of granulomas in pleural tissue is also suggestive of tuberculosis. The use of pleural fluid biochemical markers, such as adenosine deaminase, in the diagnosis of tuberculous pleurisy varies among clinicians; the diagnostic value of such markers is affected by the background prevalence of tuberculosis and the likelihood of an alternative diagnosis. Uncertainties also remain regarding the treatment of pleural infection. Treatment of complicated parapneumonic effusion and empyema involves prolonged courses of antibiotics and attention to the patient's nutritional state. The role of intrapleural fibrinolytics and the optimal timing of surgical intervention are unknown. The lack of clear predictors of clinical outcome in empyema contributes to the difficulty in treating this condition. The pharmacological treatment of tuberculous pleurisy is the same as for pulmonary tuberculosis; the precise role of steroids in the treatment of tuberculous pleurisy remains uncertain.

Recent advances in parapneumonic effusion and empyema

PURPOSE OF REVIEW

Complicated parapneumonic effusion and empyema continue to account for significant morbidity and mortality, and uncertainties remain regarding their optimal management. This review describes recent advances in this field, as well as areas for future research.

RECENT FINDINGS

Recent advances have addressed the pathogenesis, bacteriology, and treatment of pleural infection. Key areas for research in the development of empyema include the interplay between inflammatory and coagulation cascades and development of fibrosis within the pleural space. The varied bacteriology of empyema has been more clearly defined, and in particular the differences between community- and hospital-acquired infection highlighted. Studies of treatment have focused particularly on the roles of intrapleural fibrinolytics and surgery.

SUMMARY

Increased understanding of the pathogenesis of empyema may ultimately yield novel therapeutic targets. Comprehensive descriptions of the bacteriology of empyema aids antibiotic choice, and the use of intrapleural DNase shows promise in facilitating drainage of infected pleural fluid. Uncertainties remain, such as the role of intrapleural fibrinolytics and the optimal timing of surgical intervention.

Rapid diagnosis of infectious pleural effusions by use of reagent strips

Reagent strips have not yet been tested for use in the diagnosis of infectious pleural effusions. A reagent strip was used to evaluate 82 patients with pleural effusions: 20 patients had transudative effusions, 35 had infectious exudative effusions (empyema in 14 and parapneumonic effusion in 21), and 27 had noninfectious exudative effusions. Pleural fluid protein, as evaluated by the reagent strip, proved accurate for the detection of exudative effusions (sensitivity, 93.1%; specificity, 50%; positive predictive value, 84.3%; negative predictive value, 71.5%; odds ratio [OR], 6.77; and 95% confidence interval [CI], 1.87-24). The reagent strip leukocyte esterase test effectively detected infectious exudative effusions (sensitivity, 42.8%; specificity, 91.3%; positive predictive value, 88.2%; negative predictive value, 51.2%; OR, 4.46; and 95% CI, 1.2-16.4). Pleural pH was significantly predicted by the reagent strip but was of no assistance in categorization of exudative effusions as infectious or noninfectious. Compared with physical, laboratory, and microbiological data, the reagent strip was as accurate for estimation of percentages of infectious and noninfectious exudative effusions. Thus, reagent strips may be a rapid, easy-to-use, and inexpensive technique for discriminating transudative from exudative pleural effusions and for categorizing exudative pleural effusions as infectious or noninfectious.