Gram Positive Algorithm Flashcards
1
Q
Staph Aureus (catalase +, coagulase +)
A
- beta hemolytic
- cocci in clusters
- Protein A–inhibits complement activation
- commonly in nose
- pneumonia after flu
- TSST-1
- rapid onset food poisoning (old mayo)–enterotoxin that is heat stable and not destroyed by cooking
- forms fibrin clot around self (Abscess forming)
2
Q
Staph epidermis
A
- adherent biofilms to prosthetic devices and catheters
- contaminates blood cultures
- novobiocin sensitive
3
Q
Staph Saprophyticus
A
- Novobiocin resistant
- UTI (young women)–most common though is Ecoli
- urease +
4
Q
Strep Pneumoniae (lancet shaped, diplococci)
A
- MOPS (lobar pneumonia)
- encapsulated
- IgA protease
- Optochin sensitive
- “rusty sputum”
- sepsis in sickle cell anemia
- alpha hemolytic
5
Q
Viridans Group Strep
A
- Alpha hemolytic
- Optochin resistant
- normal flora of oropharynx
- Sub acute bacterial endocarditis (S. Sanguinis)
- Sanguinis–dextrans (binds fibrin platelet aggregates on damaged heart valves)
6
Q
Strep Pyogenes (group A strep)
A
- Beta hemolytic, bacitracin sensitive
- Rheumatic fever —bc of M proteins (after pharyngitis)
- ASO titer–Streptolysin O (degrades cell membrane)
- JONES criteria-rheumatic fever
- Scarlet fever
7
Q
Strep Agalactiae (group B strep)
A
- Bacitracin resistant
- mainly in babies (pneumonia, meningitis)
- CAMP factor (hippurate test)
8
Q
Enterococci (group D strep)
A
- normal colonic flora
- Pen G resistant
- UTI
- subacute endocarditis (following GI/GU procedures)
- grow in 6.5% NaCl
9
Q
Strep Bovis
A
- Subacute endocarditis in colon cancer patients
2. Bacteremia with strep bovis, look for colon cancer
10
Q
Cornyebacteria Diptheriae
A
- Black Colonies on Cystine tellurite agar
- Diptheria toxin (encoded by a B prophage, ADP ribosylation of EF2–proteins cant grow on ribosome)
- Pseudomembranous pharyngitis
- gram pos rods, metachromatic granules
- elek test: toxin
11
Q
What are the spore forming gram positive bacteria? and what is a spore?
A
spore–metabolically inactive, resistant to heat and chemicals
Dipicolinic acid in their core
Anthrax, clostridium perfringens, Cl. tetani, (in soil)
C. Botulinum, B. cereus, Coxiella burnetti
12
Q
Clostridium Tetani
A
- tetanus toxin ( stops release of GABA and glycine)–from Renshaw cells in spinal cord
- spastic paralysis
- sardonic smile
- lockjaw
13
Q
C. Botulinum
A
- botulin toxin (stops release of AcH), preformed heat labile
- flaccid paralysis
- Floppy baby syndrome (spores in honey)
14
Q
C. Perfringens
A
- gas gangrene
- Alpha toxin–lecithinase, –> myonecrosis
- infection in wounds (military)
- double zone of B hemolysis
15
Q
C. Difficile
A
- Toxin A–enterotoxin–binds brush border of intestine
- Toxin B– cytoskeleton disruption( via actin depolymerization)
- Pseudomembranous colitis –> diarrhea
- Secondary to antibiotic use ( clindamycin or ampicillin)
TX; metrinidazole, oral vanc, fecal transplant
16
Q
Bacillus Anthracis
A
- Spore forming rod
- Polypeptide capsule (D-glutamate) –only bacterium all other polysaccharide?
- Anthrax toxin (mimics AC)
- Cutaneous anthrax– ulcer with black eschar(painless)
- Pulmonary Anthrax- widened mediastinum on CXR, pulmonary hemorrhage and mediastinitis.
Woolsorters’ dz–inhaled from contaminated wool
17
Q
B. Cereus
A
- Rice
- spores survive cooking (germinate in warm environment)
- Emetic type–Cereulide (preformed toxin)–N/V within 5 hrs
- Diarrheal type– watery, nonbloody diarrhea (8-18hrs)
18
Q
Listeria
A
- Unpasteurized dairy products, deli meats, raw veggies
- Motile at cold temps (4), non motile at 37 ‘tumbling motility at cold temps’
- LPS (only gram positive with LPS)
- Intracellular (requires T cell mediated action)
- Listeriolysin O (activated at acidic envrinments, pokes holes in lysosomes and allows organism to escape)
- vaginal transmission (neonatal meningitis)
19
Q
Actinomyces
A
- Normal oral flora (anaerobe)
- facial/oral abscesses
- “sulfur” granules –yellow
- branching
20
Q
Nocardia
A
- Acid fast (aerobe)
- branching
- Found in soil
- Urease +
- Pulmonary infections in IC
- Skin infections in immunocompetent
21
Q
TB (mycobacterium)
a. high lipid content (no gram stain)
b. Lowenstein jensen agar (takes 2-4 weeks)
c.
A
- acid fast (Ziehl Neelsen stain–carbolfuchsin)
- granuloma
- Cord factor–inhibits macrophage maturation and induces TNF a release (granulomas)
- Sulfatides–inhibit phagosome-lysosome fusion inhibit killing of mycobacteria
TB survive in alveolar macrophages
22
Q
Leprosy
A
- Mycobacterium Leprae
- likes cool temps
- glove and stocking pattern (superficial nerves)
- Armadillos
- Lepramatous– communicable, low Th2 response, diffusely over skin
- Tuberculoid– high Th1 response, few hairless skin plaques
