Assistant Professor Narongwit Nakwan

Pulmonologist, Division of Pulmonology, Department of Medicine,
Hat Yai Medical Education Center, Hat Yai Hospital, Hat Yai, Songkhla,
Thailand

Bacterial pleural empyema, a severe and potentially life-threatening infection of the pleural space, poses significant challenges to clinicians.¹ Characterised by the accumulation of pus within the pleural cavity, this condition demands timely and appropriate treatment to minimise complications and improve patient outcomes.¹ Antibiotic therapy plays a pivotal role in management by eradicating the infectious pathogens responsible for the condition.^1-3 However, the optimal approach to antibiotic treatment remains the subject of ongoing research and clinical investigation.

Assistant Professor Narongwit Nakwan from Thailand discusses the factors that influence treatment decisions and current strategies for optimising antibiotic therapy in the management of bacterial pleural empyema.

Q1: What are the most common bacterial genera responsible for causing pleural empyema, and how does the choice of antibiotics differ based on the causative agent?

Bacterial genera typically responsible for causing pleural empyema include Streptococcus pneumoniae and Staphylococcus aureus, which fall under the category of aerobic Gram-positive cultures.⁴ Klebsiella, Pseudomonas, and Haemophilus species are also implicated as causative agents and are Gram-negative cultures.⁵ Certain cases of empyema involve anaerobic organisms such as Bacteroides and Peptostreptococcus species, especially in patients with conditions like aspiration pneumonia, neurological diseases, oropharyngeal-oesophageal disorder, chronic alcoholism, dental caries or bedridden individuals.

Although culture remains the gold standard for identifying these bacteria species, the results frequently reveal little information. Notably, in Thailand, these cultures frequently show no growth and obtaining anaerobic cultures poses a challenge, particularly in public hospitals. Therefore, antibiotics should encompass a broad spectrum of coverage to effectively target the wide range of potential causative organisms that are suitable to the clinical setting.³

Q2: Are there any specific guidelines or recommendations for the antibiotic treatment of known or suspected bacterial pleural empyema? How do these guidelines inform your treatment decisions?

The first recommendation is that pleural empyema requires close coordination between pulmonologists, infectious disease specialists and cardiovascular-thoracic doctors. Evidence-based recommendations for the antibiotic treatment of known or suspected bacterial pleural empyema are outlined by the British Thoracic Society (BTS) in their 2010 guidelines for the Management of Pleural Infection in Adults and a more recent 2023 version known as the ‘BTS Guideline for Pleural Disease’.^3,6 According to these guidelines, all patients should receive antibiotics targeted to the bacterial profile of modern pleural infection. The BTS guidelines further recommend that patients should receive antibiotics that cover potential anaerobic infections in all cases except for those patients with culture-proven pneumococcal infection. It is also crucial to consider local antibiotic policies and resistance patterns when selecting the appropriate antibiotics for treatment.

Notably, the development of empyema is often associated with the progression of pneumonia.⁷ Therefore, initial antibiotic choice, following a diagnosis of pneumonia, plays a critical role in controlling the infection and halting the transformation into pleural infection.

Q3: Have there been any recent advancements in antibiotic treatment strategies for bacterial pleural empyema that have improved clinical outcomes, such as modifying the duration, type or route of antibiotic therapy?

Surgical drainage remains the primary management option for pleural empyema because it is a late form of pleural infection. However, antibiotics also play a significant role in treatment, particularly intravenous antibiotics, which should be selected based on the results of pleural fluid or blood culture and antibiotic sensitivity testing.

It is important to note that approximately 50% of pleural fluid samples may not yield positive culture results from pleural fluid sampling, making empirical antibiotic selection critical.⁸ In such cases, broad-spectrum antibiotics must be considered, taking into consideration local epidemiology and antibiogram data.⁸ Antibiotics that exhibit good penetration into the pleural space, such as fluoroquinolones and beta-lactams, are often the preferred options for effective treatment.⁹ The recommended duration of treatment is typically 4–6 weeks, based on clinical and radiological responses.⁹ Monitoring clinical subjective and objective responses to any treatment is crucial for determining the appropriate duration of antibiotic treatment to minimise the risk of antibiotic resistance.

Following observation of clinical and biochemical improvement, switching a patient to an oral form of the antibiotic would be suggested for outpatient management, lasting for 2–4 weeks.⁹ During this oral phase, it is crucial to ensure that the selected antibiotic continues to work against the causative bacteria, especially anaerobes, with good penetration into the pleural space.

Q4: What is the role of anti-anaerobic antibiotics in the treatment of known and suspected empyema?

Given that anaerobic infections may be implicated in cases of bacterial pneumonia and pleural empyema, it is essential to administer antibiotics that provide coverage against anaerobic organisms in all patients diagnosed with pleural empyema to ensure comprehensive and targeted therapy.

Q5: Based on available evidence and your experience, are there any specific patient populations or clinical scenarios where the duration of antibiotic therapy or the use of anti-anaerobic antibiotics becomes particularly important for achieving favourable treatment outcomes?

Based on available evidence and clinical experience, patients with a history of unconscious conditions such as stroke and alcoholism¹¹, oropharyngeal disorders such as Guillain–Barré syndrome (GBS) and myasthenia gravis, poor oral hygiene¹² and oesophageal muscular disorders such as achalasia and gastroesophageal reflux disease (GERD)¹¹, are at higher risk for pleural empyema. Considering the potential for anaerobic infection is important for such patients. In addition, when mixed organisms are identified in sputum or pleural fluid sampling, this serves as another important indicator for clinicians to consider the use of anti-anaerobic antibiotics in the treatment of pleural infection.

In my experience, the typical duration for bacterial pleural empyema treatment ranges from 6–8 weeks. After the intravenous phase, transitioning to oral antibiotics in an outpatient setting is favourable. Sitafloxacin, a promising new-generation quinolone, is my preferred choice of broad-spectrum antibacterial agent in its oral form, owing to its efficacy against both Gram-positive and Gram-negative bacteria, including anaerobic bacteria. In addition, sitafloxacin demonstrates good penetration into the alveolar epithelial lining fluid in the lung, making it effective for the treatment of pneumonia.¹³ In my clinical practice, a daily dose of 200 mg of sitafloxacin is an appropriate regimen for treating bacterial pleural empyema.

References

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