Streptococcus pneumoniae
Why in News?
Researchers have taken a massive step toward developing a universal pneumococcal vaccine capable of covering all 100+ known serotypes of the bacteria, bypassing the costly and complex limits of current subset-only vaccines.
Core Characteristics
- Streptococcus pneumoniae (pneumococcus) is a Gram-positive, lancet-shaped diplococcus, occurring in pairs or short chains.
- It is a facultative anaerobe and produces alpha-hemolysis, forming a greenish zone on blood agar.
- It is catalase-negative, optochin-sensitive, and bile-soluble, which are important laboratory identification features.
- Its polysaccharide capsule is the major virulence factor because it prevents phagocytosis.
- More than 100 serotypes have been identified based on capsule variations.
Transmission & Habitat
- The bacterium commonly colonizes the human nasopharynx without causing disease.
- It spreads mainly through respiratory droplets and close contact.
- Asymptomatic carriage is particularly common among children.
Diseases Caused
- Pneumococcal infections include non-invasive diseases such as otitis media, sinusitis, and conjunctivitis.
- More serious invasive pneumococcal diseases (IPD) occur when bacteria enter normally sterile body sites, causing pneumonia, meningitis, bacteraemia, and sepsis.
Risk Factors
- Children below 5 years, older adults, and people with conditions such as diabetes, chronic heart disease, asthma, and COPD are at increased risk.
- Individuals with asplenia are especially vulnerable to encapsulated bacteria.
Prevention & Treatment
- Vaccination is the most effective preventive measure. Pneumococcal conjugate vaccines (PCV13, PCV15, PCV20) and PPSV23 provide protection for different populations.
- Treatment involves appropriate antibiotics, guided by antimicrobial susceptibility testing because of growing antimicrobial resistance (AMR).
