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29 Cards in this Set
- Front
- Back
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What type of stain is used for bacteria that have a thick waxy cell wall?
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Ziehl Neelsen - Acid Fast Stain
stains acid fast bacteria, red Mycobacterium tuberulosis |
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Differentiate between gram+ and gram- stains
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G+ - thick peptidoglycan, stains blue-violet
G- - thing peptidoglycan, has an outer membrane (phospholipid bilayer), stains pink-red |
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What is the process to stain gram+ and gram-?
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add crystal violet - stains cell walls blue/purple
add gram's iodine - mordant (facilitates covalent bond) - makes it easier to wash out stain add alcohol - decolorizes - washes out stain - removes all color in thin layer (G-). add safranin - pink red - colors the cell walls. G+ still has blue/purple so it mixes with the pink red - remains blueish purple. G- has no color remaining so the addition of pink/red will color the G- pink/red |
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Differentiate the cell walls of G+ and G-
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G+ - thick peptidoglycan wall and techoic aicd
G- - thin peptidoglycan wall encased by an outer membrane; outer membrane contains lipopolysaccharide (LPS). A component of LPS is Lipid A (endotoxin). The outer membrane also has porins (determine what gets in and out) |
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What are the 2 bacteria's that are spores?
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Clostridium
Bacillus contain dipicolinic acid - dehydrates the cell - allowing it to survive for thousands of years |
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What is bad and good about encapsulated bacteria?
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most important - strep pneumo, N. meningitidis, H. influenzae
bad - capsules make it anti-phagocytic - can easily cause infection- difficult to kill good - the capsule allows us to make antibodies which make a vaccine possible |
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What does endotoxin (LPS) activate?
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in Gram-
activates macrophages - activating IL1 (fever), TNF, NO (decreased BP) activates complement (alt path) - C3a/C5a - increases histamine - decreased BP and exudation activates Hageman (F12, intrinsic clotting) - coagulation - consumption of clotting components - DIC |
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What is the process of increasing factor 12 to cause DIC?
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massive amounts of clots all over body
initially increases clotting like it's supposed to, but over time it keeps using up intrinsic clotting factors until they are used up the clots decrease tissue perfusion which causes tissue factor release starts bleeding in mucosal areas - decreased fibrinogen, increased PT and PTT d-dimer made when fibrin is degraded (FDP) - fibrin split products |
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What is exotoxin?
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polypeptide released by bacteria - different effects in different species
very antigenic because it IS a protein - body has most response to proteins - so we develop Ab to these therefore, deactivated version of the exotoxin (toxoid) is used as a vaccine Cornebacterium diphtheriae, Clostridium tetani, and Bordetella pertussis heat labile |
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What is the most potent exotoxin?
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Botulinum toxin
produced by Clostridium botulinum Blocks release of ACh at neuromuscular juntions Causes muscle paralysis (flaccid) constipation, then descending flaccid paralysis, flaccid paralysis of respiratory muscles |
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What is Toxic Shock Syndrome Toxin a super antigen?
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it binds to class 2 MHC proteins (HLA) directly without intracellular processing
Produced by Staph Aureus induces cytokines (IL1,2, etc) fever, rash, desquamation, diarrhea THEN HPoTN THEN shock |
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What is the MOA of cholera toxin?
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Produced by vibrio cholera - termed choleragen
Binds to gagliosides (glycolipd that lines the outer layer of the plasma membranes of most human cells) stimulates Gs protein - stimulates adenylate cyclase - overproduces cAMP - secretes chloride ions and water into bowel lumen - massive watery diarrhea (toxigenic - no inflammatory WBC in stool) |
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What is the MOA of pertussis toxin?
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produced by Bordetella pertussis
binds to ciliated resp tract epithelial cells and to lymphocytes - inhibits Gi protein - adenylate cyclase stimulated - overproduces cAMP results in: inhibition of chemokine receptors - lymphocytosis inhibition of ciliary movement - ciliated epithelial death - copious resp mucus |
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What are obligate aerobes? Obligate anaerobes?
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aerobes - must have plentiful O2 supply to survive - utilzed glycolysis, then Krebs, then the ETC - possess many enzymes for ROS removal
anaerobes - NO O2 requirement - rely on non-O2-dependent mechanisms for metabolis - fermentation and/or respiration that utilizes molecules other than O2 - cannot tolerate any O2 because have NO enzymes to remove ROS - die upon O2 exposure |
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What are facultative anaerobes?
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use O2 when it's available, but will utilize other metabolic mechanisms when it's not available.
possess many enzymes for removal of ROS rely on fermentation when no O2 available LARGEST NUMBER OF BACTERIA |
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What is the difference in ETEC and EIEC?
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ETEC (Travelers) - secretes LT and ST - high chloride and water loss from enterocytes - severe watery diarrhea (rice water) - fecal oral contamination - does not arise until after at least 6 hours
EIEC - ingested and grows in the bowl (fecal oral) - invades enterocyte, initiating an immune mediated reaction - fever, WBC in stool, bloody diarrhea, leukocytosis |
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What is EHEC?
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hemorrhagic E.Coli - secretes Shiga-like toxin - causes death of enerocytes that line the bowel - inhibits enterocyte protein synthesis, cell death - bloody diarrhea, ab cramps
at least 6 hours feces of cattle, sheep, goats, and deer |
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What are the 3 pathogenic species of staph?
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aureus - skin infections, abscesses, food poisoning, scalded skin syndrome, toxic shock syndrome toxins, osteomyelitis
epidermidis - infection of prosthetic heart valves and hips saprophyticus - staghorn renal calculi, UTI |
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What is exfoliatin toxin responsible for?
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scalded skin syndrome
causes fere, bullae and a red macular rash - middle epidermis of the skin is cleaved - skin sloughs off along with loss of a lot of fluid - hair and nails may also slough off |
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What are the major strep pathogens?
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pneumo - otitis media, adult pnuemo, meningitis
agalactiae (group B) - sepsis or meningitis in neonate, potential contamination of the vulva and infant during delivery pyogenes (group A) - pharyngitis, tonsillitis, impetigo, scarlet fever, immunologic diseases such as in post-strep glomerulonephritis or ARF, necrotizing fasciitis, cellulitis/skin infections bovis (group D) - sub-acute infectious endocarditis; marker for colon cancer faecalis (group D) - UTI, endocarditis, cholecystitis, ascending cholangitis mutans (viridans) - subacute infectious endocarditis |
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What are the 3 possible Strep pyogenes (group A beta-hemolytic strep)?
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pyogenic - purulent lesions
toxigenic - multiple: high fever w HPoTN, necrotizing fasciitis, scarlet fever, tissue necrosis - all due to toxins the bacterium can elaborate immunologic diseases - 2 - rheumatic fevere with later rheumatic heart disease OR post-strep glomerulonephritis |
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Which Group A Beta-hemolytic strep toxin is responsible for the rash of scarlet fever?
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Erythrogenic toxin
a super antigen only produced by strep that is already infected by a type of bacteriophage scarlet fever - fever, rough/erythematous diffuse rash, strawberry tongue, focal strep infection |
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How can you check to see if a patient had a rheumatic fever recently?
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look for streptolysin O
proves that there may have been a strep pyogenes infection which could be rheumatic fever or post-streptococcal glomerulonephritis gives a chance to treat infection before it progresses |
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What causes meningococcus
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N. meningitidis
(+) IgA protease - encapsulated rich supply of LPS |
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What causes gonococcus?
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N. gonorrheae
(+) IgA protease not encapsulated (more easily phagocytosed but no protective Ab made) Abundant Pus made transmitted sexually or vertically during delivery |
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What are the medically important G+ rods?
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Spore-forming - Bacillus, Clostridium
Non-spore forming - Corynebacterium, Listeria |
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What are the 3 types of anthrax?
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Cutaneous - most common - at site of entry - painless ulcer with black crust eschar with massive edema locally - malignant pusutle
pulmonary - after inhaled, they germinate - dry cough, severe, dyspnea, fever, malaise - rapidly progressing to hemorrhagic mediastinitis - mediastinal widening on xray - death gastrointestinal - ingested and germinate - vomiting, ab pain, bloody diarrhea - shock, death DOC - if pen sensitive - Penicillin. Before labs back - cipro or doxy PLUS clindamycin and/or Rifampin |
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What is bacteria is characteristic of "chinese character" formation?
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Corynebacterium diphtheriae (also could be listeria monocytogenes - has a tumbling movement though)
produces diphtheria toxin - only if itself is infected with a bacteriophage causes diphtheria if it elaborates the toxin during infection pseudomembrane in throat, fever, myocarditis, paralysis (death) MUST CULTURE ON LOEFFLER'S TELLURIDE |
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What are the diseases of Clostridium species?
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obligate anaerobes:
tetanus - clostridium tetani botulism - c. botulinum gas gangrene - c. perfringens food poisoning - c. perfringens pseudomembranous colitis - c. diff |
