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110 Cards in this Set
- Front
- Back
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What is LPS composed of?
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Outer O-antigen
Core polysaccharide Interior Lipid A, aka endotoxin |
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What Gram + bacteria has endotoxin?
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Listeria monocytogenes
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What are the mechanisms of tetracycline and erythromycin?
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Tetracycline - interrupts protein synthesis of 30S ribosome
Erythromycin - interrupts protein synthesis of 50S ribosome |
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Which two Gram + bacteria form spores?
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Bacillus and Clostridium
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What are examples of obligate intracellular organisms?
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Chlamydia and rickettsia
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What is the only bacterium that has a capsule made of amino acids?
What are other capsules made of? |
Bacillus anthracis
Sugar moieties - can be on both gram + and - |
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What are the facultative intracellular organisms?
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SLLYMFB
Salmonella Listeria Legionella Yersinia Mycobacterium Francisella Brucella |
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What are the effects of TNF?
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Release of IL-1 from macrophages and endothelial cells, which triggers release of other cytokines and prostaglandins. Vasodilation, hypotension, organ system dysfunction.
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What toxin is released by Clostridium tetani? What are its mechanism and effect?
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Tetanospasmin. H subunit binds to neuronal gangliosides. L subunit blocks inhibitory NTs (glycine, GABA) from Renshaw interneurons. Results in tetany.
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What toxin is released by Clostridium botulinum? What are its mechanism and effect?
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Botulinum toxin. Inhibits ACh release from motor neuron endplates NMJs. Flaccid paralysis w/respiration paralysis.
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What toxin is released by Vibrio cholerae? What are its mechanism and effect?
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Choleragen. Five B subunits -- bind to GM1 gangliosides on intestinal cell membranes.
Two A subunits - ADP ribosylation of GTP-binding protein --> activates adenylate cyclase, cAMP induces secretion of NaCl and inhibits reabsorption --> osmotic pull of fluid and electrolytes into lumen --> diarrhea |
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What bacteria release E. coli heat labile toxin? What is its mechanism?
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E. coli, Campylobacter jejuni, Bacillus cereus
Similar to choleragen |
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What bacteria release E. coli heat stabile toxin? What is its mechanism and effect?
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E. coli, Yersinia enterocolotica
Activated guanylate cyclase --> inhibits rebasorption of NaCl --> diarrhea |
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What bacteria (besides Shigella) release Shiga-like toxin? What are its mechanism and effect?
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Enterohemorrhagic E. coli, Enteroinvasive E. coli
Five B subunits -> bind intestinal cells A subunit -> inactivates 60S ribosome subunit, killing cells --> sloughing and poor absorption Bloody diarrhea, hemolytic-uremic syndrome |
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What are the effects of heat stable staph toxin and heat stable toxin from bacillus cereus?
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Diarrhea and vomiting that last less than 24 hours
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What toxin does Group A Strep pyogenes release? How does it work?
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Strep pyrogenic toxin. Activates cytokines
Scarlet fever |
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What toxin does Staph aureus produce? How does it work?
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Toxic Shock Syndrome toxin.
Activates cytokines (TSS - fever, rash, desquamation, diarrhea, hypotension) |
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What tissue invasive toxins are produced by Strep pyogenes?
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Hemolysins/streptolysin O and S - lyse RBCs
Streptokinase - activates plasminogen to lyse clots DNAases - hydrolyzes DNA Hyaluronidase - breaks down proteoglycans NADase - hydrolyzes NAD |
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What unique tissue invasive toxins does Staph aureus release?
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Lipase, penicillinase, staphylokinase
leukocidin (lysis WBCs), exfoliatin, factors that bind complement |
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What is the most important topxin released by Clostridium perfringens?
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Alpha toxin - lecithinase hydrolyzes lecithin in cell membranes--> cell death --> gas gangrene and tissue destruction
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What toxins are released by Bacillus anthracis?
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Anthrax toxin, which has three components
1) Protective antigen -allows entry of EF into cell 2) Edema factor - increased cAMP in macrophages and neutrophils, preventing phagocytosis 3) Lethal factor - kills macrophages |
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What toxin does corynebacterium release? Mechanism?
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Diphtheria toxin -
B subunit - binds to heart and neural tissue A subunit - ADP ribosylates EF2, inhibiting translation of human mRNA |
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What are the effects of diphtheria?
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Myocarditis, peripheral nerve palsies, CNS effects
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What are the toxins of Bordatella pertussis?
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Pertussis toxin (B subunit binds to cells, A activates G proteins to activated adenylate cyclase) - inhibits phagocytosis
Extracyotplasmic AC - impairs chemotaxis and phagocytosis Filamentous hemagglutinin - allows binding to ciliated epithelial cells Tracheal cytotoxin - damages repiratory epithelial cells |
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What are the toxins released by Clostridium difficile?
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Toxin A - causes fluid secretion and mucosal inflammation --> diarrhea
Toxin B - Cytotoxic to colonic epithelial cells Causes pseudomembranous enterocolitis (often associated with diarrhea) |
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What toxin is released by Pseudomonas aeruginosa?
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Pseudomonas exotoxin A - inhibits protein sythesis by inhibiting EF2 in liver
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What is the process of transformation in bacteria?
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Picking up naked DNA fragments and incorporating them into the genome.
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What is transduction?
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When a bacteriophage takes DNA from one bacterium to another (either generalized or specific)
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What is the major mechanism for the transfer of bacterial resisistance?
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Conjugation with a self-transmissable plasmid (F plasmid)
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How do you test for staph?
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Test for catalase by rubbing a wire loop across colony. If bubbles appear, it is positive for catalase (staph has catalase, strep doesn't)
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What is the major virulence factor for Group A Beta-Hemolytic Strep?
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M-protein. Inhibits activation of complement and prevents phagocytosis. Plasma cells develop antibodies to it, allowing opsonization.
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What antibiotic is typically used for skin infections?
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a penicillinase resistant penicllin like dicloxaciillin, which covers both group A strep and Staph aureus
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What antibiotic(s) are used for necrotizing fasciitis caused by Group A Strep?
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Penicillin G and clindamycin, which shuts down streptococcal metabolism
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What are the symptoms of rheumatic fever?
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a) Fever
b) Myocarditis c) Joint swelling d) Chorea e) Subcutaneous nodules f) Rash - erythema marginatum (Picture John Travolta in Rheumatic Fever) |
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Which delayed antibody-mediated diseases can result after strep infection of pharynx? Skin?
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Rheumatic fever - only pharynx
Acute post-strep GN - either skin OR pharynx |
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When is Group B strep infection common?
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Neonates (B for Baby)
Meningitis, pneumonia, sepsis |
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What organisms cause neonatal meningitis?
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E. coli, Listeria monocytogenes, Group B Strep
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Viridans strep -
what type of hemolytic? Where? Types of infections? |
Alpha --> produce green agar
Normal flora in nasopharynx, GI, gingival crevices Dental infections, endocarditis, abscesses |
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What is the most common cause of acute bacterial endocarditis? Subacute?
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Acute - staph from IV drugs
Subacute - strep viridans, group D |
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If Step. intermedius grows in a culture, what should you suspect?
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Abscess somewhere else in body
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What bacteria is strongly associated with colon cancer?
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S. bovis (Bovis in the Blood, Better Beware (Cancer in the Bowel))
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What is a major cause of bacterial pneumonia and meningitis in adults?
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Strep pneumoniae (Pneumococcus is to Parents what group B strep is to Babies)
Also causes otitis media in children |
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What is the major virulence factor of pneumococcus?
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Polysaccharide capsule, which prevents phagocytosis
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Which staphylococcus is coagulase positive?
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S. aureus
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What antibiotics are often used for Staph aureus?
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Methicilin and Nafcillin (they are penicillinase-resistant)
If resistant --> Vancomycin |
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What is the most common organism isolated from in-dwelling prosthetic devices?
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Staph epidermidis
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What staph commonly causes UTIs in women?
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Staph saprophyticus
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How are bacillus and clostridium differentiated?
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Bacillus is aerobic
Clostridium is anaerobic (likes it in the CLOSet) |
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What bacteria causes gas gangrene?
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Clostridium perfringens.
When necrotic skin is exposed to C. perfringens, it grows in anaerobic environment and damages tissue. Spongy, crepitus. |
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What antibiotics are used to kill C. difficile?
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Metronidazole and vancomycin (Metro and Van cruise down GI tract, not absorbed into blood)
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What are the non-spore-forming gram positive rods?
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Corynebacterium and Listeria
(Clostridium and Bacillus are spore-forming) |
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What is the mechanism of action for Corynebacterium diphtheriae?
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Colonizes pharynx with a pseudomembrane, releases exotoxin into bloodstream, attacks heart, CNS, PNS.
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What is the diagnostic procedure for diphtheria?
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TELL UR InTErn not to loaf around
(culture on potassium tellurite agar and Loeffler's coagulated blood serum) They will become gray or black in 24 hours on K-tellurite. Loeffler's will stain with methylene blue |
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What is the treatment for diphtheria?
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1) Antitoxin
2) Penicillin or erythromycin 3) DPT vaccine |
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What disease does Listeria monocytogenes cause?
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Meningitis, usually in neonates (3rd behind E. coli and group B strep) and immunocompromised
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Why does Listeria thrive in neonates and immunocompromised?
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They can live in macrophages if they are not activated by cell-mediated immunity (facultative intracellular organisms)
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What are the signs on lumbar puncture of a bacterial meningitis?
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CSF has high number of neutrophils, protein, low glucose, and my reveal gram-positive rods)
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What is the treatment for Listeria?
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Ampicillin or trimethoprim-sulfamethoxazole
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What are the only pathogenic gram-negative cocci?
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Neisseria meningitidis and gonorrhoeae
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What are the virulence factors of Neisseria meningitidis (meningococcus)?
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1) Capsule - antiphagocytic
2) Endotoxin (LPS) - cause hemorrhage and sepsis --> petechiae 3) IgA1 protease 4) Can extract iron from transferrin |
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What are the cause and symptoms of Waterhouse-Friderichsen syndrome?
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Fulminant meningococcemia. Meningococcus. Hemorrhage into adrenal glands, hypotension, tachycardia, petechiae, DIC, coma, death in 6-8 hours
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What is Thayer-Martin VCN used for?
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Culturing Neisseria in the absence of other organisms
(vanocmycin kills gram +, colistin kills gram neg except Neisseria, Nystatin kills fungus) |
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What is the treatment of disseminated meningococcemia?
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Penicillin G or ceftriaxone
Close contacts - Rifampin |
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What is the treatment for neisseria gonorrhoeae?
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Ceftriaxone, which also treats syphilis.
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Which enteric bacteria ferment lactose?
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E. coli and most enterobacteriaceae
(Shigella, Salmonella, and Pseudomonas don't) |
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What is the mechanism and symptoms of Enterotoxigenic E. coli?
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Pili binds to epithelium, releases heat labile and stabile toxin (similar to cholera). Inhibit reabsoption of Na and Cl, stimulate secretion of Cl and HCO3, water follows. WATERY DIARRHEA.
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What is the mechanism and symptoms of enterohemorrhagic e. coli?
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Pili, secrete Shiga-like toxin (verotoxin). Inhibits 60S ribosome --> cell death.
BLOODY DIARRHEA, CRAMPS |
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With what strain of E. coli is Hemolytic uremic syndrome associated? What is it?
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0157:H7
Anemia, thrombocytopenia, renal failure. Found in hamburger meat. |
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What is the mechanism and symptoms of Enteroinvasive E. coli?
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Like Shigella. Virulence factor on plasmid. Invades epithelial cells, produces some shiga-like toxin. Host tries to get rid of bacterial --> immune reaction with fever, WBCs and blood in stool.
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How is Klebsiella manifested?
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Sepsis (2nd most common)
UTI with catheters Pneumonia (bloody sputum, cavities) |
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What special ability does Proteus mirabilis have?
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Urea splitting --> makes urine alkaline in UTI
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How can Shigella be differentiated from E. coli and Salmonella?
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Does not ferment lactose (E. coli does)
Does not produce H2S (Salmonella does) |
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Is Shigella part of the normal flora?
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NO
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What is the mechanism of Salmonella typhi?
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Invasion of regional lymph nodes allows seeding of multiple organ systems. Bacteria are phagocytosed, survive intracellularly
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What are the symptoms of typhoid fever?
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Fever, headache, abdominal pain over RLQ (mimicks appendicitis). Splenomegaly. Diarrhea. Rose spots on abdomen.
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What is the treatment for salmonella?
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Ciprofloxacin or ceftriaxone
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What populations are susceptible to Salmonella?
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Asplenic (can't clear opsonized bacteria), sickle cell (prone to osteomyelitis)
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What is the mechanism of virulence of Yersinia enterolitica?
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Invasion, regional lymph nodes, sepsis
Enterotoxin |
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How does choleragen work?
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B units bind to GM1 ganglioside on intestinal epithelial cell surface. A enters cell, activates G protein, stimulates adenylate cyclase --> cAMP --> secretion of Na and Cl, no reabsorption.
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What organism in sushi causes gastroenteritis?
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Vibrio parahaemolyticus
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How is campylobacter jejuni transmitted?
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Fecal-oral via contaminated water. Also unpasteurized milk.
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What disease does Campylobacter jejuni cause?
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Prodrome: fever, headache
Abdominal cramps, bloody loose diarrhea. Invades lining of small intestine, spreads systemically like Salmonella and Yersinia. |
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What are the characteristics of Pseudomonas aeruginosa?
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Obligate aerobic, non-lactose fermenting, gram negative rod. Produces green and blue fluorescent pigments. Sweet grape-like scent.
Only prevalent in immunocompromised patients. |
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What are the virulence factors of Pseudomonas aeruginosa?
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Exotoxin A (like diphtheria) - stops protein synthesis.
Some also possess capsule, aids in adhesion. |
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What are some important Pseudomonas infections?
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Pneumonia, osteomyelitis, burn-wound infections, sepsis, UTI and pyelonephritis, endocarditis, malignant external otitis, corneal infections
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What are complications caused by Bacterioides fragilis?
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Usually low virulence, but when it gets loose in peritoneal cavity, it causes abscesses.
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What antibiotics are used to prevent bacterioides fragilis infection?
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Clindamycin, metronidazole, chloramphenicol.
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Which polysaccharide capsule type of H. influenzae is associated most with invasive disease in children?
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Type B
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What are manifestations of H. influenzae infection?
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Meningitis, acute epiglottitis, septic arthritis, sepsis
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What antibiotics can be used for H. influenzae?
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3rd generation cephalosporins (cefotaxime, ceftriaxone)
Ampicillin or amoxacillin for less serious infections |
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What does H. ducreyi cause?
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STD chancroid (painful genital ulcer, painful unilateral swollen inguinal lymph nodes)
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What is the differential for H. ducreyi?
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1) Syphilis (painless ulcer, bilateral nodes, non-suppurative
2) Herpes (start as blisters, painful, systemic myalgias, fevers) 3) Lymphogranuloma venereum (chlamydia trachomatis) - painless, develope slowly |
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How is H. ducreyi chancroid treated?
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Erythromycin, trimethoprim/sulfamethoxazole
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How is the diagnosis of Gardnerella vaginalis made?
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Presence of clue cells (vaginal epithelium with pleomorphic bacilli inside) in vaginal discharge
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How is Gardnerella treated?
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Metronidazole (also covers co-infecting anaerobes)
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What exotoxins are produced by Bordatella pertussis?
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1) Pertussis toxin --> increased cAMP --> histamine sensitization, increased insulin synthesis, lymphocyte production and inhibition of phagocytosis
2) Extracytoplasmic adenylate cyclase --> impaired chemotaxis and generation of H2O2 and superoxide by WBCs 3) Filamentous hemagglutinin (FHA) - pili rod attaches to ciliated epithelial cells 4) Tracheal cytotoxin (destroys ciliated epithelial cells --> impaired clearance --> cough) |
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What is the treatment for Whooping cough?
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Erythromycin in early stages
Also supportive (O2, suctioning of secretions) |
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What is the treatment of Legionnaire's disease?
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Erythromycin (possesses beta-lactamase, so it's resistant to penicillin)
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What features are common to yersinia, francisella, and brucella?
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1) gram-negative rods
2) Zoonotic diseases 3) Very virulent - penetrate any body area 4) Facultative intracellular organisms, leave delayed hypersensitivity (indurated skin at site of insertion) 5) Treat with an aminoglycoside (gentamicin or streptomycin) or doxycycline given for a long time |
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What organism causes bubonic plague?
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Yersinia pestis
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What disease is common in meat-packers, veterinarians, farmers, and travelers who consume dairy products in Mexico.
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Brucellosis
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What organism most often infects cat or dog bites?
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Pasteurella multocida
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What antibiotic do you treat Chlamydia with?
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Erythromycin (eyedrops given to newborns) or tetracycline
(no peptidoglycan layer, which is target of penicillin) |
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Where does chlamydia trachomatis infect?
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eyes and genitals
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How does Rickettsia differ from Chlamydia?
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1) Rickettsia requires arthropod vector
2) Rickettsia replicates in cytoplasm, Chlamydia in endosomes 3) Rickettsia likes endothelial cells (Chlamydia likes columnar epithelial) 4) Rickettsia causes rashes, high fevers, headaches |
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What is a diagnostic test for rickettsia?
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Weil-Felix test, which uses antigens from Proteus vulgaris that cross react with Rickettsia --> agglutinatelatex beads
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What are the manifestations of Rocky Mountain Spotted Fever?
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Fever, conjunctival redness, headache, rash on wrists, ankles, soles, and palms, spreads to trunk
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What organism cause RMSF?
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Rickettsia rickettsii
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What is responsible for epidemic typhus? Endemic?
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Epi: Rickettsia prowazekii
End: Rickettsia typhi |
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What is the skin pattern for the rash of epidemic typhus?
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Small pink macules on upper trunk, cover entire body but spare palms, soles, and face
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