empyema narthananan

Empyema

Empyema

ByNarthanan Mathiselvan DM Pulmo Resident

Aims To evaluate patients with complicated pleural effusion

To know the current scientific evidence about the treatment of empyema

To discuss controversial questions in invasive management of empyema

IntroductionPleural space contains 0.3 mL/kg of fluid

Pleural fluid circulation- lymphatics deal with several 100 mLs of extra fluid/ 24 hrs

Pathogenesis

Am Rev Respir Dis 1962; 85: 935936.

PLEURAL EMPYEMA

Complicated paraneumonic effusionThoracic empyema

Uncomplicated paraneumonic effusionExudative biochemical characteristics

Usually sterile

Resolution with pneumonia

Paraneumonic pleural effusion

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Thoracic empyema

Uncomplicated paraneumonic effusion

Complicated paraneumonic effusion

Anaerobic use of glucosepHLysis of neutrophilsLDHRapid bacterial clearingCultures negativeDeposition of fibrinPleural loculationParaneumonic pleural effusion

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Uncomplicated paraneumonic effusionComplicated paraneumonic effusion

Thoracic empyemaParaneumonic pleural effusionBacterial organisms seen on Gram stain and/or aspiration of pus on thoracentesis

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DiagnosisThoracentesis

Thoracentesis is performed to guide futher management of the effusion and to provide fluid for culture and sensitivity studies. Pleural fluid characteristics remain the most reliable diagnostic test to guide the management and they are recommended to be checked in all patients with a pleural effusion >10 mm depth in association with a pneumonic illness or recent chest trauma or surgery and who have features of ongoing sepsis.

Imaging guidance should be used since this minimises risk of organ perforation and improves the recovery rate of pleural fluid.

Moreover, paraneumonic effusion should be sample if: -It is free-flowing but layers >25 mm on a lateral decubitus film or CT-It is loculated-It is associated with thickened parietal pleural on a contrast-enhance CT scan that is suggestive of empyema. -It is clearly delineated by ultrasound.9

DiagnosisPleural fluid analysis

Neutrophil proteaseCell lysis pH Glucose Proteins

LDH

In the infection of pleural space, neutrophil phagocytic activity, with protease production and cell wall lysis, leads to a fall in the pH of the pleural fluid, in the same way as glucose falls.

The increasing number of inflammatory cells within the pleural space lead to a rise in lactate dehydrogenase10

Pleural fluid analysis

Other biomarkersDiagnosisC-reactive proteinProcalcitoninSTREM-1, VEGF, IL-8

Eur Respir J 2009;34:1383-9Clin Biochem 2013;46:1484-8PCT>0.18: Senst 83%, Spec 81%

Many other biomarkers have been investigated for possible utility in distinguishing empyemasfrom uncomplicated pleural effusion but were found not to be more useful than the more traditional pleural chemistries. Serum procalcitonin levels up to 0.18 have been associated with a sensitivity of 83% and specificity of 81% for the effusion being infectious of bacterial etiology but there is no study to date that shows this biomarker has good sensitivity to indicate drainage.11

BacteriologyGram-positive bacteria

Anaerobic bacteriaMixed etiologyOther etiologies

In the same way as in community-acquired pneumonia, Streptococcus pneumoniae is the most frequent etiology agent of empyema in children and the second most frequ. It have been explored different molecular technicques comparing to conventional microbiological cultures increasing the rate of pneumonoccal identification in initial culture-negative pleural effusion.12

BacteriologyThorax 2010;65(suppl 2):ii41-ii53

S. milleriS. pneumoniaeS. intermedius

EnterobacteriaceaeEscherichia coli

Escherichia coliPs. aeruginosaKlebsiella spp.

Fusobacterium sppBacteroides sppPeptostreptococcus spp Mixed

25% MRSA10% MSSA

Patogens isolated differ between patients with community-acquired or hospital acquired pleural infection. In this way, in community-acquired empyema, Streptococcus spp account for aproximately 60% of the cases.Gram-negative organisms are less frequent and commonly culture in patients with comorbities.Anaerobes are the etiology agents in 12-34% of empyemas but anaerobes identification rises when molecular methods based on DNA amplification are used.

In patients with hospital-acquired pleural infection, up to 50% present positive cultures for Staphylococcus aureus, where MRSA account for up to two-thirds of cases.Gram-negative isolation of E.coli, Pseudomonas aeruginosa and Klebsiella have been reported frequently associated with UCI patients.13

Bacteriology

Survival according etiologyAm J Respir Crit Care Med 2006;174:817-823

BacteriologyGram-positive, anaerobic, bacteriaStreptococcus milleri: The main etiological agent

Am J Respir Crit Care Med 1997;156:1508-14Frenquently associated with comorbiditiesMortality: 20%Anaerobes associated in 63%

Streptococcus milleri is part of Streptococcus viridans group that reprents a heterogeneous group of facultative anaerobic, gram positive cocci including Streptococcus intermedius, Streptococcus anginosus and Streptococcus constellatus. It is part of the normal flora of human oropharynx and it is rarely isolated in community-acquired pneumonia. On the other hand, it account for 30-50% of adults cases of community-acquired empyema and it is consider by most of the series, the main etiological agent of empyema. Patients infected by S. milleri have associated comorbities commonly, like underlying malignancy and diabetes mellitus. The empyema caused by S. milleri has a mortality of 20%.It have been describe a frequent coinfection with other anaerobic bacteria.15

Bacteriology

Serotypes: 1, 3, 19A, 17 and 7F

Relevant influence of PCV-7 in children and adultsClin Infect Dis:2006; 42:1135-40Gram-positive, aerobic, bacteriaStreptococcus pneumoniae: A common etiological agent

In the same way as in community-acquired pneumonia, Streptococcus pneumoniae is the most frequent etiology agent of empyema in children that reach, up to 50% in some pediatrical series, and the second most frequent etiology in adults. The main serotypes causing suppurative complications are serotype 1 and 3. The PCV-7 serotypes could have an important role in modifying the prevalence of serotypes and the incidence of empyema not only in children but in adults.

It have been explored different molecular technicques comparing to conventional microbiological cultures increasing the rate of pneumonoccal identification in initial culture-negative pleural effusion.

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Bacteriology

Causing empyema in 10-24%Older patients Underlying comorbities Tendency to cavitationMRSA not only in hospitalized patientsGram-positive, aerobic, bacteriaStaphylococcus aureusChest 2005;128:2732-8

Staphylococcus aureus casuses empyema in 10 to 24%. It is most often seen in older patients, especially with underlying medical comorbidities. Infection by MRSA often causes necrotizing pneumonia, lung abscess and empyema.Recent reports have comunicated not only MRSA infection in hospitalized patients but also in community-acquired pneumonia.17

Bacteriology

Anaerobic bacteria

Etiology in 36-76% of empyemas

Difficult culture and isolation

Predominant microorganisms: Fusobacterium nucleatum and Prevotella spp.

In the acidic and hypoxic enviromeno of the pleura, anaerobic bacteria find a place where their growth is facilitated.Clinically, anaerobic lung infection could result in an indolent way which permits pleural penetration of bacteria before antibiotics are instituted.On the other hand, anaerobic bacteria are difficult to isolate by culture of pleural fluid.Anaerobic bacteria have been culture in 36-76% of empyemas. The predominant microorganisms are Fusobacterium nucleatum and Prevotella spp.18

Bacteriology

Mixed etiology

Animal models suggest that infection with a mixed bacterial flora containing aerobes and anaerobes is more likely to produce an empyema than infection with a single microorganism.

The common combination is:

anaerobes + microaerophilic or aerobic streptococci (normal oral flora)

Animal models suggest that infection with a mixed bacterial flora containing aerobes and anaerobes is more likely to produce an empyema that infection with a single microorganism.The common combination is anaerobes with microaerophilic o aerobic streptococci, both are normal components of oral flora.19

Pleural Infections Rx general PrinciplesAccurate diagnosis Control sepsis: Suitable antibiotic therapy Drainage of infected material :Intercostal tube drainage Intrapleural adjunctive therapies Surgery

Complications of Empyema

Antibiotic treatmentTreatmentAntibiotics should be guided by bacterial cultures (when it is possible)

Use anaerobes coverage in all patients (except culture proven pneumoococcal infection)

Good pleural space penetration: penicillins, penicillins+beta-lactamase inhibitors, cephalosporines, metronidazol

Avoid aminoglycosides

Empirical hospital-acquired empyema treatment should include treatment for MRSA and anaerobic bacteria

Antibiotics are a very important part of the treatment of empyema. In a general way, antibiotics should be guide by bacterial cultures when it is possible.Antibiotics to cover anaerobic infection should be used in all patients except those with culture proven pneumococcal infection.

Many antibiotics, like penicillins, peni