2 Gram-Positive Bacteria Flashcards
PID
What are identifying characteristics of Streptococcus pneumoniae (by staining and microscopy or microbiology lab tests)?
Gram positive diplococci, alpha-hemolytic, sensitive to optochin (autolytic compound), and produce a large polysaccharide capsule
What can cause a patient’s fever to break on day 4 of an infection?
Presence of IgM antibodies
What bacterium is the most common cause of meningitis (called green-cap meningitis)?
Streptococcus pneumoniae
What causes the green color in green-cap meningitis?
The green color is due to the oxidation state of iron in damaged tissues. This iron comes from the myeloperoxidase (MPO) reaction with tissues.
All Gram-positive bacteria capsules are made of polysaccharides, except:
What kind of capsule does this bacterium have?
Bacillus anthracis - poly D-glutamic acid capsule
T/F
Antibodies to the capsule will be protective against a Gram positive bacterium.
False. Capsules may or may not be immunogenic, and antibodies against the capsules may or may not be protective.
In the case presentation, what were the symptoms seen with the 17-year-old male infected with Streptococcus pneumoniae?
- Suddenly developed shaking chills
- Violent cough with blood-tinged sputum
- Significant chest pain
- High fever (104)
What other DNA may a Gram positive bacterium have besides a haploid chromosome?
Episomes (plasmids & bacteriophages), transposons, and pathogenicity islands (a few virulence factor genes that likely used to be bacteriophage or transposon)
What is the purpose of a capsule?
It is often negatively charged to repel the negatively charged surface of phagocytic host cells, &/or it mimics self.
What is the dominant virulence factor of Streptococcus pneumoniae?
Capsule
What are the components of a Gram positive cell wall?
Lipotechoic/techoic acid
No outer membrane
Thick peptidoglycan
*75% cross-bridged peptidoglycan
*Some have O-acetylationWhat is the significance of O-acetylated peptidoglycan?
Highly inflammatory!
Difficult for humans to degrade
Collects in joints and causes arthritis (from inflammation)
What are fimbriae?
Proteins, techoic acids, or lipotechoic acids that create a fuzz layer on the surface of bacteria. They are important for adhesion to host tissues &/or antiphagocytic activity &/or facilitation of nutrient uptake
1) What are flagellae?
2) What types are there?
1) Polymers of flagellin proteins. Motor made up of a ring structure, a curved hook, and the filament.
2) Peritrichous - flagella surrounding the bacterium
Polar flagella - flagella on the ends
T/F
Pathogenic cocci have flagella.
False.
Pathogenic cocci do NOT have flagella
What are spores?
They are inert structures that are heat and dryness resistant and form when environmental conditions are hostile. When favorable conditions return, they regenerate into vegetative cells. Spore coats contain dipicolonic acid (derivative of lysine) and Ca2+
What bacteria form spores?
Bacillus (aerobic) and Clostridium (anaerobic)
What are protoplasts?
The structure generated when G+ bacteria are treated with enzymes to remove the cell wall. (A cell wall cannot be regenerated)
What are poly-beta-hydroxyl-butyric acid granules?
Energy storage granules that are seen in some bacteria upon staining
What do spores look like in stained preparation?
Clostridium tetani spores - tennis racquet appearance (rod with round end and clear zone in middle of rounding)
Bacillus spores - clear zone in rod (spore does not take up dye well)
What bacteria have O-acetylated peptidoglycan?
Mainly streptococci and Neisseria
- Rheumatic fever (arthritis, carditis, neurologic autoimmune disease) - Post-gonococcal arthritis
What are examples of fimbrae in specific bacteria staph a. and strep pyogenes?
Streptococcus pyogenes - M protein
Staphylococcus aureus - ribitol teichoic acid
What organism is a gram + diplococcus, alpha hemolytic, and optician sensitive?
Streptococcus pneumonia
Which bacteria has a hyaluronic acid capsule?
Streptococcus pyogenes
