WHAT IS IT?
Streptococcus pneumoniae (often called “strep pneumo”) is a lancet-shaped, gram-positive diplococci bacteria.
Alpha hemolytic: form green area of hemolysis on blood agar (due to incomplete/partial hemolysis)
Optochin sensitive: bacteria will not grow in the presence of optochin.
Catalase negative: bubbles will not be observed when hydrogen peroxide is added to a colony of the bacteria.
Encapsulated: this bacteria is not thought to be virulent without its capsule. The Quellung reaction can detect the presence of the polysaccharide antigen.
IgA protease: this bacterium releases this enzyme that cleaves the IgA immunoglobulin. Helps colonize respiratory mucosa.
Infections can be community acquired
CNS: meningitis (this pathogen is the most common cause of meningitis)
HEENT: Otitis media, sinusitis (most common cause of these both), conjunctivitis
Respiratory: lobar pneumonia (most common cause), bronchopneumonia
Penicillin G, V are commonly used as first line treatments for infection with this pathogen. Cephalasporins can also be used.
Chloramphenicol is a bacteriostatic antibiotic that blocks peptidyltransferase at 50S ribosomal subunit.
Telithromycin is a macrolide that has improved activity against S. pneumoniae
Antimetabolites—Trimethoprim/Sulfamethoxazole can also be used to treat infection with this pathogen.
Two types of vaccinations are available for this microbe.
1.) 23 varient pneumococcal polisaccaride vaccine (PPSv23, Pneumovax):
- Recommended for all adults > 65
- Not immunogenic for children < 2 years of age
- Covers more variants
- Antibody levels decide over 5 years
- Unconjugated vaccine
2.) 13 varient pneumococcal conjugate vaccine (PCV13, Prevnar)
- Polysaccharide antigen conjugated to a nontoxic diphtheria protein: boosts immune response through T cell recruitment.
- Covers less variants.
OTHER HY FACTS
Transformation (uptake of environmental DNA) is common with this bacteria.
Associated with (as far as the step exam is concerned):
- Rusty sputum
- Sepsis in sickle cell disease
- Splenectomy (which predisposes to infection with this pathogen, and other capsulated bacteria).
- Decreased B-cells are associated with infection with this pathogen.
Influenza patients are at risk for super-infection from this pathogen.
Multiple myeloma patients are at increased risk of infection with S. pneumoniae
Cystic fibrosis patients are predisposed to getting pneumonia from this pathogen.
ARCHIVE OF STANDARDIZED EXAM QUESTIONS
This archive compiles standardized exam questions that relate to this topic.
Page Updated: 05.17.2016