Management of Parapneumonic Pleural Effusions and Empyema

High-resolution CT findings in Streptococcus milleri pulmonary infection

AIM

To assess pulmonary high-resolution computed tomography (CT) findings in patients with acute Streptococcus milleri pulmonary infection.

MATERIALS AND METHODS

Sixty consecutive patients with acute S. milleri pneumonia who had undergone high-resolution CT chest examinations between January 2004 and March 2010 were retrospectively identified. Twenty-seven patients with concurrent infections were excluded. The final study group comprised 33 patients (25 men, 8 women; aged 20-88 years, mean 63.1 years) with S. milleri infection. The patients' clinical findings were assessed. Parenchymal abnormalities, enlarged lymph nodes, and pleural effusion were evaluated on high-resolution CT.

RESULTS

Underlying conditions included malignancy (n = 15), a smoking habit (n = 11), and diabetes mellitus (n = 8). CT images of all patients showed abnormal findings, including ground-glass opacity (n = 24), bronchial wall thickening (n = 23), consolidation (n = 17), and cavities (n = 7). Pleural effusion was found in 18 patients, and complex pleural effusions were found in seven patients.

CONCLUSION

Pulmonary infection caused by S. milleri was observed mostly in male patients with underlying conditions such as malignancy or a smoking habit. The CT findings in patients with S. milleri consisted mainly of ground-glass opacity, bronchial wall thickening, pleural effusions, and cavities.

Impact of antibiotic therapy on laboratory analysis of parapneumonic pleural fluid in children

OBJECTIVE

The therapeutic management of parapneumonic pleural effusions (PPE) is controversial in children. Decision-making often relies on parameters such as gross appearance of pleural fluid and on bacteriologic and biochemical analyses. Our goal was to describe the laboratory profile of PPE in children and to assess the influence of previous administration of antibacterial agents on culture and biochemical results.

PATIENTS AND METHODS

This was a prospective study including children (age, 1 month to 16 years) with a diagnosis of PPE. Two groups were evaluated: children with or without antibiotic treatment up to 48 hours before analysis of pleural fluid. Results were analyzed using the χ(2) or Mann-Whitney test (α = .05). Odds ratio and 95% confidence intervals (95% CIs) were calculated, with control of previous antibiotic therapy using multivariate logistic regression analysis, to determine the risk of empyema associated with specific biochemical parameters.

RESULTS

One hundred ten children were selected. Fifty percent had received antibiotics at least 48 hours before pleural fluid analysis. Differences were observed between the groups in terms of PPE gross appearance (P = .033) and identification of bacteriologic agent by culture or Gram stain (P = .023). Biochemical parameters (pH ≤7.1 and glucose ≤40 mg/dL) were associated with increased odds of receiving a more invasive treatment. For pH, the odds ratio was 9.614 (95% CI, 1.952-47.362; P = .005); and for glucose, 9.201 (95% CI, 1.333-63.496; P = .024).

CONCLUSIONS

Previous use of antibacterial agents affected the bacteriologic analysis of pleural fluid in this pediatric sample admitted for PPE. However, it did not interfere significantly with biochemical parameters of pleural fluid.

Pharmacokinetics of Linezolid and Ertapenem in experimental parapneumonic pleural effusion

Objective

To determine the extent of linezolid and ertapenem penetration into the empyemic fluid using a rabbit model of empyema.

Methods

An empyema was created via the intrapleural injection of Escherichia coli bacteria (ATCC 35218) into the pleural space of New Zealand white rabbits. After an empyema was verified by thoracocentesis, 24 hours post inoculation, linezolid (10 mg/kg) and ertapenem (60 mg/kg) were administered intravenously into 10 and 8 infected empyemic rabbits, respectively. Antibiotic levels were determined in samples of pleural fluid and blood serum, collected serially at 1, 2, 4, 6 and 8 hours, after administration each of the two antibiotics.

Results

Linezolid as well as ertapenem penetrate well into the empyemic pleural fluid, exhibiting a slower onset and decline compared to the corresponding blood serum levels. Equilibration between blood serum and pleural fluid compartments seems to occur at 1.5 hours for both linezolid and ertapenem, with peak pleural fluid levels (Cmax_pf of 2.02 ± 0.73 «mu»g/ml and Cmax_pf of 3.74 ± 1.39 «mu»g/ml, correspondingly) occurring 2 hours post antibiotics administration and decreasing very slowly thereafter. The serum concentrations for both antibiotics were significantly lower from the corresponding pleural fluid ones during the 8 hours collecting data, with the exception of samples collected at the 1^st hour (Cmax_serum of 2.1 ± 1.2 «mu»g/ml for linezolid and Cmax_serum of 6.26 ± 2.98 «mu»g/ml for ertapenem).

Conclusion

Pleural fluid levels of both antibiotics are inhibitory for common specified pathogens causing empyema.

Innate immune responses in murine pleural mesothelial cells: Toll-like receptor-2 dependent induction of beta-defensin-2 by staphylococcal peptidoglycan

The innate immune response is mediated in part by pattern recognition receptors including Toll-like receptors (TLRs). The pleural mesothelial cells (PMCs) that line the pleural surface are in direct contact with pleural fluid and accordingly carry the risk of exposure to infiltrating microorganisms or their components in an event of a complicated parapneumonic effusion. Here we show that murine primary PMCs constitutively express TLR-1 through TLR-9 and, upon activation with peptidoglycan (PGN), mouse PMC produce antimicrobial peptide beta-defensin-2 (mBD-2). Treatment of PMCs with staphylococcal PGN, a gram-positive bacterial cell wall component and a TLR-2 agonist, resulted in a significant increase in TLR-2 and mBD-2 expression. Silencing of TLR-2 expression by small interfering RNA led to the downregulation of PGN-induced mBD-2 expression, thereby establishing causal relationship between the activation of TLR-2 receptor and mBD-2 production. PMCs exposed to PGN showed increased p38 MAPK activity. In addition, PGN-induced mBD-2 expression was attenuated by SB203580, a p38 MAPK inhibitor, underlining the importance of p38 MAPK in mBD-2 induction. Inhibition of erk1/erk2 or phosphatidylinositol 3-kinase did not block PGN-induced mBD-2 expression in PMC. PGN-activated PMC-derived mBD-2 significantly killed Staphylococcus aureus, and mBD-2-neutralizing antibodies blunted this antimicrobial activity. Taken together, these data indicate that PMCs may contribute to host innate immune defense upon exposure to gram-positive bacteria or their products within the pleural space by upregulating TLR-2 and mBD-2 expression.

Pathology of the Pleura

The pleura and lung are intimately associated and share many pathologic conditions. Nevertheless, they represent two separate organs of different embryonic derivation and with different yet often symbiotic functions. In this article, the authors explore the pathologic manifestations of the many conditions that primarily or secondarily affect the pleura.

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.

Management of complicated parapneumonic effusions in children

Pneumonia with complicated parapneumonic effusion is a significant source of morbidity in children seen in our institution. This affords us the opportunity to evaluate new treatment options. In an effort to ensure that we provide quality care to these pediatric patients presenting with complicated parapneumonic effusions, we performed a retrospective review of patient records as well as our interventional radiology database. Fifty-eight patients were identified who were treated with intrapleural placement of pigtail catheters and administration of tPA. Successful drainage and resolution of 54 of the 58 effusions were achieved with percutaneous methods alone. There was no mortality or 30-day recurrence. Mean hospital stay was 9.1 days (range 5-21). On average, the chest catheter was removed on day 6 postplacement (range 1.5-20). tPA was administered intrapleurally, utilizing a standardized hospital protocol developed conjointly by Interventional Radiology and Thoracic Surgery. Patients were afebrile within 72 hours. In most patients, one catheter was placed. However, five patients had more than one catheter placed initially. Of the four patients that failed percutaneous tube therapy, three underwent video-assisted thoracic surgery (VATS) and one had open thoracotomy with decortication. The complication associated with this treatment was an average drop in hemoglobin of 2 g/mL. Based on our experience, tPA administered through a small-bore chest tube for drainage of complicated parapneumonic effusions has become our standard practice.

Incidence and etiologies of complicated parapneumonic effusions in children, 1996 to 2001

BACKGROUND

The incidence and causative organisms associated with complicated parapneumonic effusions in children with community-acquired pneumonia are likely to have changed during the past several years.

METHODS

Data regarding clinical and laboratory features were abstracted retrospectively from medical records of 76 subjects with complicated parapneumonic effusions at a tertiary children's hospital from 1996 through 2001. Incidence rates per 10 000 hospital discharges and per 1000 patients with nonviral pneumonia were calculated.

RESULTS

Etiologic organisms were Streptococcus pneumoniae (31 subjects), Staphylococcus aureus (7), Streptococcus pyogenes (5), Abiotrophia sp. (1) and no culture-confirmed agent (32). The annual incidence of complicated parapneumonic effusions per 10 000 discharges progressively increased from 4.5 in 1996 to 25.0 in 1999 (P = 0.0001), then declined to 10.1 in 2001 (P = 0.03). Similarly the incidence per 1000 cases of nonviral pneumonia increased from 2.9 in 1996 to 11.0 in 1999 (P = 0.003) and then declined to 4.8 in 2001 (P = 0.053). Whereas S. pneumoniae was the leading confirmed etiology in each year, the proportion of cases caused by Staphylococcus aureus increased from 6% in 1996 to 2000 (all of which were methicillin-susceptible) to 30% in 2001 (all methicillin-resistant; P = 0.04).

CONCLUSIONS

The incidence of complicated parapneumonic effusions in children with community-acquired pneumonia increased from 1996 to 1999 and then declined concomitant with the introduction of the pneumococcal conjugate vaccine. Although cases caused by S. pneumoniae have decreased, community onset methicillin-resistant Staphylococcus aureus has emerged as a cause of pneumonia with complicated effusions in children.

Empyema of lung associated with Streptococcus milleri infection

Empyema of the lung is a very serious illness which must be detected quickly and treated aggressively. We report an unusual case of empyema of the lung associated with a boating accident while the patient was fishing in a sea loch off the west coast of Scotland.

Decorticação pleural precoce no tratamento do empiema pleural complicado na criança

Os autores avaliam dez casos de empiema pleural tratados inicialmente pela drenagem pleural fechada e que tiveram evolução desfavorável e arrastada. Pacientes que evoluíram com septação do empiema, persistência de fístula broncopleural de alto débito ou de falta de expansão pulmonar após a drenagem pulmonar foram submetidos a estudo pela tomografia computadorizada e encaminhados para a decorticação pleural precoce como alternativa para o tratamento. Todos os pacientes tratados desta forma tiveram uma rápida melhora clínica, evoluindo com boa expansão pulmonar, recebendo alta hospitalar num prazo máximo de dez dias após a cirurgia. Concluem os autores que tal procedimento é seguro devendo ser considerado para o tratamento do empiema pleural de má evolução.

Pleural complications in the intensive care unit

In summary pleural complications in the ICU are common. Pneumothorax in a mechanically ventilated patient is a medical emergency that requires prompt diagnosis and therapy. Correct diagnosis and therapy of pleural effusions will assist in improving pulmonary physiology and outcome in the ICU patient.

Pyogenic lung infections

Pyogenic lung infections still occur despite the availability of effective antibiotics for the treatment of patients with acute bacterial pneumonia. Our understanding of the pathogenesis and management of these conditions has steadily improved over the past few decades, although some areas remain obscure. The effect of HIV infection on the incidence of pyogenic lung infections remains largely unknown, and large studies are required to evaluate this. Burkholderia (formerly Pseudomonas) cepacia strains are now recognized as important respiratory pathogens in patients with cystic fibrosis, and the high transmissibility of some strains, combined with their inherent multiple antibiotic resistance, are continuing causes for concern.

Streptococcus milleri pulmonary disease: a review and clinical description of 25 patients

BACKGROUND

Streptococcus milleri is increasingly being recognised as an important pulmonary pathogen which may lead to the development of empyema or lung abscess. Although several small series have been reported, the clinical and laboratory features have yet to be fully characterised.

METHODS

Twenty five cases were identified and the clinical and laboratory data from case records were analysed.

RESULTS

There were 16 empyemas, five lung abscesses, and four with both lung abscess and empyema. The mean age of the patients was 61 years (range 36-89) and 84% were men. The most common symptoms at presentation were shortness of breath, chest pain, cough, and weight loss; only 36% had a fever. Four of the nine patients with lung abscess required a diagnostic lobectomy because of suspected malignancy. Predisposing factors were present in 80% of patients and included the following: pneumonia, periodontal disease, excess alcohol intake, previous thoracic surgical procedures, and malignancy. Laboratory features of S milleri infection were leucocytosis, neutrophilia, anaemia, abnormal liver function tests, and hypoalbuminaemia. In the group with empyema five patients had a pneumothorax on initial presentation and pleural loculation occurred in 10 of these patients. The median stay in hospital was 34 days (range 11-88). Six patients died, five of whom had significant underlying illnesses.

CONCLUSIONS

Pulmonary infection with S milleri may result in considerable morbidity and mortality, and is characterised by a strong male predominance, non-specific symptoms (often without toxicity), the presence of predisposing factors, pleural loculation, pneumothorax, and a protracted stay in hospital.

Non surgical treatment of empyema thoracis with intrapleural streptokinase in a patient with AIDS

After unsuccessful treatment with intercostal tube drainage and antibiotics intrapleural streptokinase was used to treat successfully an empyema in a man with AIDS and advanced cutaneous Kaposi's sarcoma who was unfit for surgical decortication. The role of this technique in the management of HIV positive patients with empyema is discussed.

Penetration of intravenous and oral ciprofloxacin into sterile and empyemic human pleural fluid

OBJECTIVE

To compare the penetration of oral and intravenously administered ciprofloxacin into infected (empyemic) and noninfected (sterile) human pleural fluid.

DESIGN

Eleven men and 5 women (aged 29-76) were consecutively selected from adult patients referred to the respiratory unit for pleural effusion. In this open-label, prospective trial, 13 patients with sterile pleural effusions were nonrandomly assigned to receive either ciprofloxacin 200 mg (single intravenous dose), 750 mg (single oral dose), or 750 mg (two oral doses per day for 3 days); 3 patients with infected pleural effusions received 750 mg oral doses for 10 days. Simultaneous pleural fluid and venous blood specimens were drawn over 5 hours after single dose or when steady-state was attained, and ciprofloxacin concentrations were measured by HPLC.

RESULTS

Pleural fluid concentrations of ciprofloxacin equaled plasma concentrations 1.5 hours after 200 mg was given intravenously and the pleural/plasma ratio remained > or = 0.9 for 4 hours. After a single 750-mg oral dose, pleural ciprofloxacin concentrations rose from 0 to 1.4 micrograms/mL over 5 hours with the highest pleural fluid/plasma ratio (0.7) at 5 hours. Average steady-state ciprofloxacin concentrations in sterile pleural fluid after 750 mg administered twice daily for 3 days, ranged between 1.1 and 1.8 micrograms/mL with ratios between 0.3 and 0.9 over 4 hours. In empyemic pleural fluid at the same dosage, average steady-state ciprofloxacin concentrations ranged between 1.9 and 3.4 micrograms/mL with ratios between 1.0 and 2.0 over 5 hours.

CONCLUSIONS

Oral ciprofloxacin penetrates into sterile and empyemic pleural fluid with concentrations 30-90 percent and 100-200 percent of plasma concentrations, respectively.