What is the clinical significance of green sputum (mucopurulent sputum)?

From the Guidelines

Green sputum is a significant indicator of a bacterial respiratory infection, and its presence, especially when accompanied by other symptoms like fever, chest pain, or difficulty breathing, warrants prompt medical attention. The green color of the sputum is due to the presence of myeloperoxidase, an enzyme released by white blood cells fighting the infection 1. This is often seen in infections caused by bacteria such as Pseudomonas aeruginosa, Haemophilus influenzae, or Streptococcus pneumoniae.

Key Points to Consider:

• The presence of green sputum has been found to be 94.4% sensitive and 77.0% specific for the yield of a high bacterial load, indicating a significant bacterial infection 1.
• Patients with chronic conditions like cystic fibrosis, bronchiectasis, or COPD exacerbations may also produce green sputum, requiring specialized treatment approaches.
• Not all green sputum requires antibiotics, as viral infections can sometimes cause discolored sputum, emphasizing the need for proper evaluation by a healthcare provider for appropriate treatment.
• Antibiotics such as amoxicillin-clavulanate, azithromycin, or doxycycline may be prescribed depending on the suspected pathogen and the patient's medical history 1.

Management and Treatment:

• Patients presenting with green sputum, especially if accompanied by an increase in dyspnea, sputum volume, and sputum purulence, are likely to benefit from antibiotic therapy 1.
• The Anthonisen criteria, which classify patients based on the presence of certain symptoms, can help guide the decision to administer antibiotics in patients with COPD exacerbations 1.
• While waiting for medical care, patients should stay hydrated, rest, and consider using a humidifier to loosen secretions.

Important Considerations:

• The use of antibiotics should be guided by the severity of symptoms, the presence of bacterial infection indicators, and the patient's overall health status.
• Hospitalized patients with COPD exacerbations, particularly those with severe disease (FEV1 < 50%) or requiring mechanical ventilation, may benefit from antibiotics to prevent adverse outcomes and secondary infections 1.

From the Research

Clinical Significance of Green Sputum

The clinical significance of green sputum, also known as mucopurulent sputum, is a key indicator of bacterial infection in patients with acute exacerbations of chronic obstructive pulmonary disease (COPD) 2, 3.

• Green sputum is associated with a higher bacterial load and is often used as an indicator for antibiotic therapy 2.
• A study found that 84% of patients with purulent sputum had a positive bacterial culture, compared to 38% of patients with mucoid sputum 2.
• The presence of green sputum was 94.4% sensitive and 77.0% specific for the yield of a high bacterial load, indicating that it is a reliable marker for bacterial infection 2.
• Sputum purulence-guided antibiotic use has been shown to be effective in reducing unnecessary antibiotic use in patients with COPD 3, 4.

Relationship between Sputum Color and Bacterial Infection

The relationship between sputum color and bacterial infection is well established, with green or purulent sputum being a strong indicator of bacterial infection 2, 3.

• A study found that patients with purulent sputum had higher levels of C-reactive protein (CRP) and procalcitonin (PCT) than those with non-purulent sputum 3.
• The use of a sputum color chart to guide antibiotic use has been shown to be acceptable to both patients and healthcare professionals, but its impact on clinical practice is uncertain 4.

Management of Acute Exacerbations of COPD

The management of acute exacerbations of COPD often involves the use of antibiotics, but the decision to prescribe antibiotics should be guided by the presence of bacterial infection, as indicated by green or purulent sputum 5, 2, 3.

• A study found that a 3-day course of azithromycin was as effective as a 10-day course of amoxycillin-clavulanic acid in the treatment of acute lower respiratory tract infections, including COPD 6.
• The use of a sputum purulence-guided strategy for antibiotic treatment has been shown to be effective in reducing therapeutic failure and improving outcomes in patients with COPD 3.