From the Guidelines
Common cocci seen in sputum samples include Streptococcus pneumoniae, Staphylococcus aureus, and Moraxella catarrhalis, with Streptococcus pneumoniae being the most common bacterial cause of community-acquired pneumonia. These organisms can be identified through Gram staining, which helps distinguish between pathogenic bacteria and normal oral flora.
- Streptococcus pneumoniae appears as lancet-shaped diplococci and is often associated with community-acquired pneumonia 1.
- Staphylococcus aureus presents as grape-like clusters of cocci and is frequently found in patients with healthcare-associated pneumonia or post-influenza bacterial pneumonia 1.
- Moraxella catarrhalis appears as kidney bean-shaped diplococci and is commonly seen in patients with chronic obstructive pulmonary disease (COPD) exacerbations 1. Other cocci that may be observed in sputum samples include Streptococcus pyogenes (Group A Streptococcus) in chain formations and Enterococcus species. When examining sputum samples, it's essential to distinguish between pathogenic bacteria and normal oral flora, which may include non-pathogenic streptococci, to ensure accurate diagnosis and treatment. Gram staining is a valuable tool in identifying these organisms, with gram-positive cocci (Streptococcus, Staphylococcus) staining purple and gram-negative cocci (Moraxella) staining pink 1.
From the Research
Common Cocci in Sputum Samples
The common cocci that can be seen in a sputum sample include:
Characteristics of These Cocci
These bacteria are known to cause community-acquired pneumonia (CAP) and have distinct metabolic responses 4.
- Streptococcus pneumoniae is a leading cause of acute CAP 2
- Staphylococcus aureus, particularly methicillin-resistant S. aureus (MRSA), is also a significant cause of CAP and can lead to severe clinical outcomes 3
Diagnosis and Treatment
The diagnosis of gram-positive pneumonia, including infections caused by these cocci, remains less than satisfactory, and drug resistance is a serious therapeutic problem 5.