This test is primarily performed to:

• Diagnose Respiratory Infections: Identify the causative agent of conditions like pneumonia, bronchitis, tuberculosis (TB), fungal infections, and other respiratory tract infections.
• Monitor Treatment: Assess the effectiveness of antibiotic or antifungal treatments.
• Identify Pathogens: Determine the specific type of bacteria, fungi, or other microorganisms present in the respiratory tract.
• Determine Antibiotic Susceptibility: Perform culture and sensitivity testing to find out which antibiotics will be most effective against the identified pathogens.
• Detect Abnormal Cells: In some cases, it can help detect cancer cells, though this is less common than other diagnostic methods.

Sputum is typically collected by:

• Deep Cough: The patient is asked to take several deep breaths, hold their breath for a few seconds, and then cough deeply to bring up sputum from the lungs, not just saliva from the mouth. This is often done in the morning before eating or drinking, as sputum tends to accumulate overnight.
• Induced Sputum: If a patient cannot produce a sample naturally, they may be asked to inhale a sterile saline solution mist, which helps to loosen secretions and induce coughing.
• Bronchoscopy: In some cases, if other methods are unsuccessful, a sample may be collected during a bronchoscopy procedure, where a thin, flexible tube is inserted into the airways.

The sample is collected in a sterile, wide-mouthed container.

Once collected, the sputum sample undergoes several analyses in the laboratory:

• Gross Examination: The lab technician observes the sputum's color, consistency (e.g., watery, thick, purulent), and volume. Certain appearances can suggest specific conditions (e.g., rusty sputum in pneumococcal pneumonia, green sputum in bacterial infections).
• Microscopic Examination:
  • Gram Stain: A common stain used to classify bacteria into Gram-positive or Gram-negative groups and observe their shapes (e.g., rods, cocci). This can provide rapid preliminary information about the type of infection.
  • Acid-Fast Stain (Ziehl-Neelsen stain): Used specifically to detect acid-fast bacilli, such as Mycobacterium tuberculosis, the bacterium that causes tuberculosis.
  • Direct Microscopy: Examination for white blood cells (indicating inflammation), red blood cells, epithelial cells, fungi, or parasites.
• Culture and Sensitivity (C&S):
  • Culture: The sample is placed on special agar plates to allow bacteria or fungi to grow. This helps identify the specific microorganism causing the infection.
  • Sensitivity: Once the organism is identified, various antibiotics are tested against it to determine which ones are effective in inhibiting its growth. This guides appropriate treatment.
• Molecular Tests (e.g., PCR): These tests detect the genetic material of specific pathogens (like TB, certain viruses) and can provide rapid and highly sensitive results.

The results of a sputum examination help healthcare providers diagnose and manage respiratory conditions:

• Presence of Bacteria or Fungi: Indicates a bacterial or fungal infection.
• Positive Acid-Fast Bacilli (AFB) Stain or Culture: Strongly suggests tuberculosis.
• High Number of White Blood Cells: Points to an inflammatory or infectious process.
• Presence of Specific Cells (e.g., atypical cells): May indicate cancer, though further investigation is required.
• Negative Results: May mean no infection or that the infection is viral or located elsewhere.