Staphylococci and Neisseria Flashcards
(41 cards)
The Neisseria species is what type of bacteria?
Gram ( - ) diplococci (kidney-bean shaped)
What type of enzyme does this bacteria produce?
Oxidase
Where is this species found and is it pathogenic?
Many species found in normal flora of the oral cavity and is non-pathogenic.
What are 2 important pathogenic organisms in this species?
Neiserria meningitides and gonorrhoeae
How is Neiserria meningitides transmitted?
Through respiratory droplets (oral route).
What does Neiserria meningitides ferment?
Ferments glucose and maltose.
Where is Neiserria meningitides normally found?
In the human nasopharynx.
What are Neiserria meningitides’s virulence factors?
Pili, polysaccharide capsule (13 serogroups) which inhibits phagocytosis, endotoxin, IgA protease, which helps with adherence.
What are the clinical manifestations of this organism?
Meningitis (epidemic and sporadic) and Meningococcemia.
What is the treatment for Neiserria meningitides?
Penicillin (tifomycin in epidemic setting).
How can infection of Neiserria meningitides bacterium be prevented?
Capsular polysaccharide vaccine (A,B,C, W135) or Rifampin chemoprophylaxis in close contacts
Which strains of Neiserria meningitides are important for epidemics? Which strain causes sporadic but not epidemic outbreaks?
Strains A & C cause epidemics; Strain B causes sporadic settings.
For Facultative Gram (+) cocci, how do you determine if the bacterium is Streptococci or Staphylococci?
Catalase test:
(+) =bubbles, Staphylococci
(–) =no bubbles, Streptococci
What does Streptococci look like? Staphylococci?
Chains of cocci; Clusters of cocci
Which agar plate is more selective: Blood agar or Mannitol Salt agar?
Mannitol Salt agar, even though Staphylococci grows on most anything
Which test is used to determine if the organism is S. aureus or S. epidermidis?
Coagulase test:
aureus = (+)
epidermidis = (-)
How does the coagulase test work?
Coagulase is an enzyme that clots plasma, so if the final result is a jelly like clot it is (+) and if it is liquid it is (-).
Staphylococcus epidermidis is Gram ___ cocci grouped in ____, It is catalase ____ , coagulase ____
(+); clusters; (+), (-)
Where is normally located?
In the normal flora of the skin and mucous membranes.
What are Staphylococcus epidermidis’ clinical manifestations?
Becomes virulent when infections of IV catheters and prosthetic devices occur.
Staphylococcus aureus is Gram ___ cocci grouped in ____, It is catalase ____ , coagulase ____
(+); clusters; (+); (+)
What % of normal adults are nasal carriers? What % never colonize, intermittently colonize and persistently colonize?
10-40%; 20%; 50%; 30%
Which group of people has a higher carrier rate of S. aureus?
Nurses, physicians, and IV drug abusers (This is a Nosocomial pathogen).
What is the most common form of transmission and best way for prevention for S. aureus?
Person to person by hands; wash your hands!
