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110 Cards in this Set

  • Front
  • Back
What is LPS composed of?
Outer O-antigen
Core polysaccharide
Interior Lipid A, aka endotoxin
What Gram + bacteria has endotoxin?
Listeria monocytogenes
What are the mechanisms of tetracycline and erythromycin?
Tetracycline - interrupts protein synthesis of 30S ribosome
Erythromycin - interrupts protein synthesis of 50S ribosome
Which two Gram + bacteria form spores?
Bacillus and Clostridium
What are examples of obligate intracellular organisms?
Chlamydia and rickettsia
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 -
What are the facultative intracellular organisms?
What are the effects of TNF?
Release of IL-1 from macrophages and endothelial cells, which triggers release of other cytokines and prostaglandins. Vasodilation, hypotension, organ system dysfunction.
What toxin is released by Clostridium tetani? What are its mechanism and effect?
Tetanospasmin. H subunit binds to neuronal gangliosides. L subunit blocks inhibitory NTs (glycine, GABA) from Renshaw interneurons. Results in tetany.
What toxin is released by Clostridium botulinum? What are its mechanism and effect?
Botulinum toxin. Inhibits ACh release from motor neuron endplates NMJs. Flaccid paralysis w/respiration paralysis.
What toxin is released by Vibrio cholerae? What are its mechanism and effect?
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
What bacteria release E. coli heat labile toxin? What is its mechanism?
E. coli, Campylobacter jejuni, Bacillus cereus
Similar to choleragen
What bacteria release E. coli heat stabile toxin? What is its mechanism and effect?
E. coli, Yersinia enterocolotica
Activated guanylate cyclase --> inhibits rebasorption of NaCl --> diarrhea
What bacteria (besides Shigella) release Shiga-like toxin? What are its mechanism and effect?
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
What are the effects of heat stable staph toxin and heat stable toxin from bacillus cereus?
Diarrhea and vomiting that last less than 24 hours
What toxin does Group A Strep pyogenes release? How does it work?
Strep pyrogenic toxin. Activates cytokines
Scarlet fever
What toxin does Staph aureus produce? How does it work?
Toxic Shock Syndrome toxin.
Activates cytokines
(TSS - fever, rash, desquamation, diarrhea, hypotension)
What tissue invasive toxins are produced by Strep pyogenes?
Hemolysins/streptolysin O and S - lyse RBCs
Streptokinase - activates plasminogen to lyse clots
DNAases - hydrolyzes DNA
Hyaluronidase - breaks down proteoglycans
NADase - hydrolyzes NAD
What unique tissue invasive toxins does Staph aureus release?
Lipase, penicillinase, staphylokinase
leukocidin (lysis WBCs), exfoliatin, factors that bind complement
What is the most important topxin released by Clostridium perfringens?
Alpha toxin - lecithinase hydrolyzes lecithin in cell membranes--> cell death --> gas gangrene and tissue destruction
What toxins are released by Bacillus anthracis?
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
What toxin does corynebacterium release? Mechanism?
Diphtheria toxin -
B subunit - binds to heart and neural tissue
A subunit - ADP ribosylates EF2, inhibiting translation of human mRNA
What are the effects of diphtheria?
Myocarditis, peripheral nerve palsies, CNS effects
What are the toxins of Bordatella pertussis?
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
What are the toxins released by Clostridium difficile?
Toxin A - causes fluid secretion and mucosal inflammation --> diarrhea
Toxin B - Cytotoxic to colonic epithelial cells
Causes pseudomembranous enterocolitis (often associated with diarrhea)
What toxin is released by Pseudomonas aeruginosa?
Pseudomonas exotoxin A - inhibits protein sythesis by inhibiting EF2 in liver
What is the process of transformation in bacteria?
Picking up naked DNA fragments and incorporating them into the genome.
What is transduction?
When a bacteriophage takes DNA from one bacterium to another (either generalized or specific)
What is the major mechanism for the transfer of bacterial resisistance?
Conjugation with a self-transmissable plasmid (F plasmid)
How do you test for staph?
Test for catalase by rubbing a wire loop across colony. If bubbles appear, it is positive for catalase (staph has catalase, strep doesn't)
What is the major virulence factor for Group A Beta-Hemolytic Strep?
M-protein. Inhibits activation of complement and prevents phagocytosis. Plasma cells develop antibodies to it, allowing opsonization.
What antibiotic is typically used for skin infections?
a penicillinase resistant penicllin like dicloxaciillin, which covers both group A strep and Staph aureus
What antibiotic(s) are used for necrotizing fasciitis caused by Group A Strep?
Penicillin G and clindamycin, which shuts down streptococcal metabolism
What are the symptoms of rheumatic fever?
a) Fever
b) Myocarditis
c) Joint swelling
d) Chorea
e) Subcutaneous nodules
f) Rash - erythema marginatum
(Picture John Travolta in Rheumatic Fever)
Which delayed antibody-mediated diseases can result after strep infection of pharynx? Skin?
Rheumatic fever - only pharynx
Acute post-strep GN - either skin OR pharynx
When is Group B strep infection common?
Neonates (B for Baby)
Meningitis, pneumonia, sepsis
What organisms cause neonatal meningitis?
E. coli, Listeria monocytogenes, Group B Strep
Viridans strep -
what type of hemolytic?
Types of infections?
Alpha --> produce green agar
Normal flora in nasopharynx, GI, gingival crevices
Dental infections, endocarditis, abscesses
What is the most common cause of acute bacterial endocarditis? Subacute?
Acute - staph from IV drugs
Subacute - strep viridans, group D
If Step. intermedius grows in a culture, what should you suspect?
Abscess somewhere else in body
What bacteria is strongly associated with colon cancer?
S. bovis (Bovis in the Blood, Better Beware (Cancer in the Bowel))
What is a major cause of bacterial pneumonia and meningitis in adults?
Strep pneumoniae (Pneumococcus is to Parents what group B strep is to Babies)
Also causes otitis media in children
What is the major virulence factor of pneumococcus?
Polysaccharide capsule, which prevents phagocytosis
Which staphylococcus is coagulase positive?
S. aureus
What antibiotics are often used for Staph aureus?
Methicilin and Nafcillin (they are penicillinase-resistant)
If resistant --> Vancomycin
What is the most common organism isolated from in-dwelling prosthetic devices?
Staph epidermidis
What staph commonly causes UTIs in women?
Staph saprophyticus
How are bacillus and clostridium differentiated?
Bacillus is aerobic
Clostridium is anaerobic (likes it in the CLOSet)
What bacteria causes gas gangrene?
Clostridium perfringens.
When necrotic skin is exposed to C. perfringens, it grows in anaerobic environment and damages tissue. Spongy, crepitus.
What antibiotics are used to kill C. difficile?
Metronidazole and vancomycin (Metro and Van cruise down GI tract, not absorbed into blood)
What are the non-spore-forming gram positive rods?
Corynebacterium and Listeria

(Clostridium and Bacillus are spore-forming)
What is the mechanism of action for Corynebacterium diphtheriae?
Colonizes pharynx with a pseudomembrane, releases exotoxin into bloodstream, attacks heart, CNS, PNS.
What is the diagnostic procedure for diphtheria?
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
What is the treatment for diphtheria?
1) Antitoxin
2) Penicillin or erythromycin
3) DPT vaccine
What disease does Listeria monocytogenes cause?
Meningitis, usually in neonates (3rd behind E. coli and group B strep) and immunocompromised
Why does Listeria thrive in neonates and immunocompromised?
They can live in macrophages if they are not activated by cell-mediated immunity (facultative intracellular organisms)
What are the signs on lumbar puncture of a bacterial meningitis?
CSF has high number of neutrophils, protein, low glucose, and my reveal gram-positive rods)
What is the treatment for Listeria?
Ampicillin or trimethoprim-sulfamethoxazole
What are the only pathogenic gram-negative cocci?
Neisseria meningitidis and gonorrhoeae
What are the virulence factors of Neisseria meningitidis (meningococcus)?
1) Capsule - antiphagocytic
2) Endotoxin (LPS) - cause hemorrhage and sepsis --> petechiae
3) IgA1 protease
4) Can extract iron from transferrin
What are the cause and symptoms of Waterhouse-Friderichsen syndrome?
Fulminant meningococcemia. Meningococcus. Hemorrhage into adrenal glands, hypotension, tachycardia, petechiae, DIC, coma, death in 6-8 hours
What is Thayer-Martin VCN used for?
Culturing Neisseria in the absence of other organisms
(vanocmycin kills gram +, colistin kills gram neg except Neisseria, Nystatin kills fungus)
What is the treatment of disseminated meningococcemia?
Penicillin G or ceftriaxone
Close contacts - Rifampin
What is the treatment for neisseria gonorrhoeae?
Ceftriaxone, which also treats syphilis.
Which enteric bacteria ferment lactose?
E. coli and most enterobacteriaceae
(Shigella, Salmonella, and Pseudomonas don't)
What is the mechanism and symptoms of Enterotoxigenic E. coli?
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.
What is the mechanism and symptoms of enterohemorrhagic e. coli?
Pili, secrete Shiga-like toxin (verotoxin). Inhibits 60S ribosome --> cell death.
With what strain of E. coli is Hemolytic uremic syndrome associated? What is it?
Anemia, thrombocytopenia, renal failure. Found in hamburger meat.
What is the mechanism and symptoms of Enteroinvasive E. coli?
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.
How is Klebsiella manifested?
Sepsis (2nd most common)
UTI with catheters
Pneumonia (bloody sputum, cavities)
What special ability does Proteus mirabilis have?
Urea splitting --> makes urine alkaline in UTI
How can Shigella be differentiated from E. coli and Salmonella?
Does not ferment lactose (E. coli does)
Does not produce H2S (Salmonella does)
Is Shigella part of the normal flora?
What is the mechanism of Salmonella typhi?
Invasion of regional lymph nodes allows seeding of multiple organ systems. Bacteria are phagocytosed, survive intracellularly
What are the symptoms of typhoid fever?
Fever, headache, abdominal pain over RLQ (mimicks appendicitis). Splenomegaly. Diarrhea. Rose spots on abdomen.
What is the treatment for salmonella?
Ciprofloxacin or ceftriaxone
What populations are susceptible to Salmonella?
Asplenic (can't clear opsonized bacteria), sickle cell (prone to osteomyelitis)
What is the mechanism of virulence of Yersinia enterolitica?
Invasion, regional lymph nodes, sepsis
How does choleragen work?
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.
What organism in sushi causes gastroenteritis?
Vibrio parahaemolyticus
How is campylobacter jejuni transmitted?
Fecal-oral via contaminated water. Also unpasteurized milk.
What disease does Campylobacter jejuni cause?
Prodrome: fever, headache
Abdominal cramps, bloody loose diarrhea. Invades lining of small intestine, spreads systemically like Salmonella and Yersinia.
What are the characteristics of Pseudomonas aeruginosa?
Obligate aerobic, non-lactose fermenting, gram negative rod. Produces green and blue fluorescent pigments. Sweet grape-like scent.

Only prevalent in immunocompromised patients.
What are the virulence factors of Pseudomonas aeruginosa?
Exotoxin A (like diphtheria) - stops protein synthesis.
Some also possess capsule, aids in adhesion.
What are some important Pseudomonas infections?
Pneumonia, osteomyelitis, burn-wound infections, sepsis, UTI and pyelonephritis, endocarditis, malignant external otitis, corneal infections
What are complications caused by Bacterioides fragilis?
Usually low virulence, but when it gets loose in peritoneal cavity, it causes abscesses.
What antibiotics are used to prevent bacterioides fragilis infection?
Clindamycin, metronidazole, chloramphenicol.
Which polysaccharide capsule type of H. influenzae is associated most with invasive disease in children?
Type B
What are manifestations of H. influenzae infection?
Meningitis, acute epiglottitis, septic arthritis, sepsis
What antibiotics can be used for H. influenzae?
3rd generation cephalosporins (cefotaxime, ceftriaxone)
Ampicillin or amoxacillin for less serious infections
What does H. ducreyi cause?
STD chancroid (painful genital ulcer, painful unilateral swollen inguinal lymph nodes)
What is the differential for H. ducreyi?
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
How is H. ducreyi chancroid treated?
Erythromycin, trimethoprim/sulfamethoxazole
How is the diagnosis of Gardnerella vaginalis made?
Presence of clue cells (vaginal epithelium with pleomorphic bacilli inside) in vaginal discharge
How is Gardnerella treated?
Metronidazole (also covers co-infecting anaerobes)
What exotoxins are produced by Bordatella pertussis?
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)
What is the treatment for Whooping cough?
Erythromycin in early stages
Also supportive (O2, suctioning of secretions)
What is the treatment of Legionnaire's disease?
Erythromycin (possesses beta-lactamase, so it's resistant to penicillin)
What features are common to yersinia, francisella, and brucella?
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
What organism causes bubonic plague?
Yersinia pestis
What disease is common in meat-packers, veterinarians, farmers, and travelers who consume dairy products in Mexico.
What organism most often infects cat or dog bites?
Pasteurella multocida
What antibiotic do you treat Chlamydia with?
Erythromycin (eyedrops given to newborns) or tetracycline
(no peptidoglycan layer, which is target of penicillin)
Where does chlamydia trachomatis infect?
eyes and genitals
How does Rickettsia differ from Chlamydia?
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
What is a diagnostic test for rickettsia?
Weil-Felix test, which uses antigens from Proteus vulgaris that cross react with Rickettsia --> agglutinatelatex beads
What are the manifestations of Rocky Mountain Spotted Fever?
Fever, conjunctival redness, headache, rash on wrists, ankles, soles, and palms, spreads to trunk
What organism cause RMSF?
Rickettsia rickettsii
What is responsible for epidemic typhus? Endemic?
Epi: Rickettsia prowazekii
End: Rickettsia typhi
What is the skin pattern for the rash of epidemic typhus?
Small pink macules on upper trunk, cover entire body but spare palms, soles, and face