Exam 1 Lecture 9 Flashcards
True or False: Streptococcus is a genus of gram-negative coccus. Most tend to be in chains. Some tend to be in pairs (end to end diplocci), bullet-shaped, lancet-shaped
False. Streptococcus is a genus of GRAM-POSITIVE bacteria
Do streptococci have catalase?
No
Most streptococci are ________ _______, meaning that they can grow anaerobically and aerobically
facultative anaerobes
True or False: Streptococci do not use oxygen in their metabolism
True
Name 2 types of streptococci that are α-hemolytic
- Viridans streptococci
2. Streptococcus pneumoniae
How can we tell if bacteria is α-hemolytic on a blood agar plate?
It will form greenish discoloration where the colony grows
Name 2 types of streptococci that are β-hemolytic
- Group A streptococcus
2. Streptococcus pyogenes
How can we tell if bacteria is β-hemolytic on a blood agar plate?
The bacteria will completely lyse the red blood cells around or under the colony. The area appears light yellow or clear
Name an example of streptococci that do not fit in the category of α-hemolysis or β-hemolysis
Streptococcus bovis
S. pneumoniae can cause a range of diseases. List what those diseases are (5 things)
- ear infection
- sinusitis
- pneumonia
- blood infections (bacteremia)
- meningitis
True or False: Cracking upon auscultation is commonly seen in patients with pneumococcal pneumonia
True
Who are people most at risk for severe symptoms of Pneumococcal disease? (2 things)
- Smokers
2. People w/ asthma or other respiratory issues
What does pneumococcal disease often follow?
Respiratory infections like influenza
__________ is the most common cause of bacteremia, meningitis, and middle ear infections in children.
Pneumococcus
What is bacteremia and what groups of people is it most dangerous for?
- Bacteremia is a type of invasive pneumococcal disease that infects the bloodstream.
- Children under 5 and the elderly
Why can bacteremia be dangerous?
It can lead to sepsis and possibly septic shock, which can lead to death
How is transient bacteremia different?
Bacteria can get in the blood and grow and divide, but in a healthy individual, the immune system is able to overcome it
True or False: Bacteremia is more severe than meningitis
False. Meningitis is much more severe.
What is meningitis?
Inflammation of the meninges (the protecting lining surrounding the brain & spinal cord)
True or False: S. pneumoniae are Gram-positive cocci that tend to be in pairs
True
Over time, the initial round + glistening S. pneumoniae colonies flatten. This is due to a compound known as _____.
autolysin
How many diff serotypes does S. pneumoniae have?
98
Name one major virulence factor of S. pneumoniae
polysaccharide capsule
What leads to the various serotypes of S. pneumoniae?
Variations in the capsule composition, which has to do w/ variable expression of glycosyltransferase and other sugar-dependent synthesis genes
True or False: S. pneumoniae is not naturally competent for genetic transformation
False
In 2-3 year olds, 60% can be carriers of S. pneumoniae. Where does S. pneumoniae colonize?
The mucosal surfaces lining the nasopharynx
Increased production of _____ can lead to increased transmission.
mucus
How does S. pneumoniae spread? (3 things)
Direct contact, respiratory droplets, some evidence for fomite transmission
What is the role of the capsule? (3 things)
- Crucial in colonization by preventing entrapment in mucus
- Expression undergoes phase variation between thick and thin capsule
- Required for invasion (prevents opsonization, inhibits complement)
Name a second major virulence factor
Pneumolysin
Monomers of pneumolysin bind to _______, then it oligomerizes and forms a _____ that consists of 50 monomers. The formation of the _____ causes cell to lyse and eventually die.
cholesterol, pore, pore
What is the role of Ply? (4 things)
- Increases mucus production by inducing inflammation, thus increasing transmission
- Damages mucociliary escalator by inhibiting cilia beating
- Recruitment of host inflammatory cells
- Forms pores in host cells
What does Ply specifically form pores in?
Alveolar epithelium
What is the quickest way to detect the presence of S. pneumoniae?
Urine antigen test
What does the urine antigen test detect that is common to all serotypes of S. pneumoniae?
C polysaccharide antigen
True or False: the urine antigen test is more sensitive than culture and Gram stain
True
What’s a downside to the urine antigen test?
No info on antibiotic susceptibility (b/c we don’t know the serotype)
What are 2 characteristics used to ID S. pneumoniae in vitro?
- Optochin-sensitive
2. Bile-solube
The colonies of S. pneumoniae dissolve when ______ ______ is added. Thus this indicates that the colony is bile solube.
Sodium deoxycholate
True or False: There is 1 vaccine currently available for S. pneumoniae
False. There are two - PPSV23 and 13vPCV)
Which vaccine is recommend for infants AND adults?
The conjugate vaccine
The polyvalent pneumococcal polysaccharide vaccine contains _______ from the capsule of ___ different serotypes. It is intended for adults over 65, but not children.
polysaccharides, 23
How many serotypes does the conjugated vaccine cover?
13
What is the treatment for S. pneumoniae?
It depends on the strain. If it’s penS, then use PenG or amoxicillin.
If it’s penR, increase the dose of use cephalosporins, fluoroquinolones.
If S. pneumoniae is not confirmed by lab, a ______ may be given. If the patient is resistant, use _______/
macrolide
fluoroquinolone
Viridans strep. is a gram-positive that comes in ____ and has _____ _____. They are _ hemolytic.
pairs, short chains
alpha
Where does S. mutans colonize?
The oral cavity
What does S. mutans contribute to?
Cavities
S. mutans uses _____ to to produce ________, which allows it to synthesize ________ ___________ by using _______________.
sucrose
glucans
extracellular polysaccharides
glucosyltransferases
Use of sucrose to produce glucans allows S. mutants to attach better to ______ and ______ _____.
enamel
heart valves
When may transient bacteremia occur?
flossing, teeth brushing, dental procedures
True or False: endocarditis is especially a risk when the individual has injured or inflamed heart valves
True
Where is S. anginosus commonly found?
oral cavity, GI
What does S. anginosus smell like?
butter, butterscotch!
What is unique about the pathogenicity of S. anginosus?
It tends to lead to abscess formation
