streptococcus pneumoniae animated Streptococcus pneumoniae infections

Streptococcus pneumoniae appearance

  • Gram-positive, lancet-shaped cocci. Usually they are seen as pairs of cocci (diplococci), but they may also occur singly and in short chains.
  • nonmotile
  • non-spore forming
  • pneumococcus has a polysaccharide capsule that acts as a virulence factor for the organism; more than 90 different serotypes are known, and these types differ in virulence.

Infections caused by Streptococcus pneumoniae bacteria

Streptococcus pneumoniae, or pneumococcus, can cause many types of illnesses. Some of these illnesses can be life-threatening. S. pneumoniae is one of the most common causes of bacterial meningitis in adults and young adults, along with Neisseria meningitidis, and is the leading cause of bacterial meningitis in adults in the USA. Some of these infections are considered “invasive.” Invasive disease means that germs invade parts of the body that are normally free from germs. For example, pneumococcal bacteria can invade the bloodstream, causing bacteremia, and the tissues and fluids surrounding the brain and spinal cord, causing meningitis. When this happens, disease is usually very severe, causing hospitalization or even death. As estimated by WHO in 2005 it killed about 1.6 million children every year worldwide with 0.7–1 million of them being under the age of five. The majority of these deaths were in developing countries.

  • Pneumonia
  • Meningitis
  • Bacteremia
  • Otitis media
  • Sinusitis

Deaths caused by Streptococcus pneumoniae (2004)

  • Worldwide incidence:
    14,500,000 [1]
  • Worldwide deaths:
    826,000 [2]

Streptococcus pneumoniae treatment
Should be always guided by in vitro susceptibility tests!!
Selection of appropriate antibiotics depends on diagnosis!!

  • penicillin
  • ampicillin
  • amoxicillin
  • cephalosporins I
  • cephalosporins II
Penicillin resistant:
  • cephalosporins III (e.g., cefotaxime, ceftriaxone)


  • vancomycin
  • chloramphenicol

Streptococcus pneumoniae vaccination




Textbook of bacteriology

Colony appearance

streptococcus pneumoniae morphology streptococcus pneumoniae cell morphology streptococcus pneumoniae Gram stain