STEP 1 Gram Positive Bacteria 3 Flashcards
Streptococcus agalactiae (GBS) gram, shape, catalase, coagulase, *hemolysis, resistance (differs from GAS)
Gram positive cocci
Catalase and coagulase negative
B-hemolysis
Bacitracin resistant
GBS colonizes (1)
GBS colonizes vagina
GBS diseases (3)? Which population primarily (think of its colonization location)?
Pneumonia, meningitis, and sepsis
Mainly in babies
GBS and pregnancy…screening and prophylaxis
Screen pregnant women at 35-37 weeks.
+ culture patients receive intrapartum PCN prophylaxis
Two main Enterococci bacteria
Enterococcus faecalis
Enterococcus faecium
Enterococci (group D strep) features
- location
- resistance
- infection causes (3)
- Normal colonic flora
- Penicillin G resistant
- Cause UTI, biliary tract infections, and subacute endocarditis
Streptococcus bovis (non-enterococcus strep):
- Colonizing location
- Causes which infections (2) in which patient population (1)
- Colonizes the gut
2. Causes bacteremia and subacute endocarditis in colon cancer patients
Enterococcus algorithm findings:
Gram and shape
hemolysis
growth in which medium (2)
Gram + cocci
Catalase -
Gamma hemolysis
Growth in bile and 6.5% NaCl
Non-enterococcus algorithm findings: gram stain and shape catalase hemolysis growth medium (compare to entercoccus)
Gram + cocci
Catalase -
Gamma hemolysis
Growth in bile, NOT in NaCl
Corynebacterium diphtheriae algorithm findings
Gram + BACILLI (ROD)
C. diphtheriae causes diphtheria via _____ encoded by _____
Causes diptheria via EXOTOXIN encoded by B-prophage
C. diphtheriae exotoxin inhibits ______ via _____ of _____
Inhibits PROTEIN SYNTHESIS via ADP-ribophosphorylation of EF-2
Symptoms of diphtheria (4)
- PSEUDOMEMBRANOUS PHARYNGITIS (gray-white plaques/membrane)
- lymphadenopathy
- myocarditis
- arrhythmias
Lab diagnosis of diphtheria (3)
- Algorithm findings
- Elek test for toxin
- Grows black colonies on cystine-tellurite
What kind of vaccine is the diphtheria vaccine?
Toxoid vaccine
ABCDEFG of diphtheria
ADP-ribophosphorylation B-prophage Corynebacterium Diphtheriae Elongation Factor 2 Granules
Spore-forming gram + bacteria found in soil (3)
Other spore formers (3)
Bacillus anthracis
Clostridium perfringens
C. tetani
B. cereus
C. botulinum
Coxiella burnetii
Lab algorithm findings of clostridia
Gram +
Spore-forming
Obligate anaerobic Bacilli
C. tetani produces ______, an exotoxin causing _____
C tetani causes TETANOSPASMIN, an exotoxin causing tetanu
How do the tetanus and botulinum toxins cause damage?
Both toxins are proteases that cleave releasing proteins for neurotransmitters
Which neurotransmitters does tetanus block? Which cells do the NTs come from?
GABA and glycine (both are inhibitory NTs)
Renshaw cells in spinal cord
Symptoms of tetanus (3)
Spastic paralysis
trismus (lockjaw)
risus sardonicus (grinning expression causes by spams of facial muscles)
How does C. botulinum cause damage?
Produces a preformed, heat-labile toxin that inhibits ACh release at the NMJ causing botulism
How do adults acquire botulism? Babies? which food is associated with babies and botulism
In adults, the disease is caused by ingestion of preformed TOXIN.
In babies, ingestion of SPORES in HONEY causes disease (floppy baby syndrome)
How does C. perfringens cause damage? Produces which toxin? symptoms (2)
Produces ALPHA toxin that causes MYCONECROSIS and HEMOLYSIS
What is the pathogenesis of the two C. diff toxins?
Toxin A, ENTEROTOXIN, binds to the brush border of the gut
Toxin B, CYTOTOXIN, causes cytoskeletal disruption via actin depolymerization–> pseudomembranous colitis –> diarrhea
Use of which antibiotics (2) is associated with C. diff diarrhea?
Ampicillin and clindamycin
How is C. diff detected?
Look for the toxins
Treatment for C. diff (2)
Metronidazole or oral vancomycin
Clostridium perfringens:
Name of the produced toxin? What is the cellular mechanism of this toxin
Produces ALPHA toxin (“lecithinase”)
It’s a phospholipase that cleaves the phospholipid bilayer of cells
