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108 Cards in this Set
- Front
- Back
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Peptidoglycan
a. function b. chemical composition c. gram pos. vs. gram neg. |
a. rigid support, protects against osmotic pressure
b. sugar backbone, cross linked peptide side chains c. lots in gram positive, little in gram neg |
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Cell wall
a. function b. 2 components c. types of bact. |
a. major surface antigen
b. peptidoglycan (support), techoic acid (induces TNF and IL-1) c. gram positive |
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Outer membrane
a. what special structure is located here b. types of bact c. what induces immune response d. what is the antigen |
a. endotoxin (lipopolysaccharide), major surface antigen
b. gram neg c. Lipid A induces TNF and IL1 d. polysaccharide is the antigen |
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3 components of outer membrane on a gram negative bacteria
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O antigen = outer, antigenic determinant
Core polysaccharide Lipid A = reaches into membrane, causes fever, diarrhea, toxic shock |
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Structures unique to gram positive?
structures unique to gram negatives? |
techoic acid --> in cell wall, antigenic determinant, immune response
LPS --> in outer membrane, induces immune response |
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In treating gram negative bacteria, what types of antibiotics will not work and why?
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antibiotics aimed at the peptidoglycan layer (penicillin, lysozymes)
Outer membrane and periplasmic space protects peptidoglycan layer |
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How does penicillin work
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Interrupts transpeptidase from cross linking amino acid side chains in peptidoglycan
only works in gram pos. bacteria |
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Bacterial periplasm
a. what type of organisms b. what does it contain |
a. gram neg - space between cytoplasm and peptidoglycan
b. contains b-lactamases, hydrolytic enzymes |
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what is the role of the bacterial capsule
what is it made of what is one exception |
protect against phagocytosis
made of polysaccharides bacillus anthracis has D-glutamate-containing capsule |
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Bacterial pilus/fimbriae
a. made of b. 2 roles |
a. glycoprotein
b. adherance of bacteria to cell surface Sex pilus for attachment during conjugation |
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Role of flagellum in bact
made of |
motility
protein |
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Role of a spore in bact.
made of? |
resists dehydration, heat, chemicals
Keratin-like coat, dipicolinic acid |
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Role of plasmid
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DNA that contains variety of genes for antibiotic resistance, enzymes, and toxins
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What is a glycocalyx?
what equipment in the hospital is it notoriously associated with? made of? |
mediates adherance to surfaces, especially foreign (indwelling catheters)
polysaccharide |
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What are porins?
what type of bact |
allow passage of nutrients
only in outer membrane of gram negatives |
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6 gram positive bacteria that cause disease in humans
a. cocci b. rods - spore forming c. rods - non-spore |
a. streptococci (strips)
staphylococci (clusters) b. Bacillus, clostridium c. Corynebacterium, listeria |
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Bacteria with no cell wall
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mycoplasma
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mycobacteria
a. classification b. stain to use |
a. gram pos. rod
b. acid fast stain |
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Spirochete
a. type of cell wall b. how to visualize |
a. gram neg
b. darkfield microscopy |
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2 unique features of spirochetes
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1. outer phospholipid rich membrane w/few exposed proteins --> stealth
2. periplasmic flagella to spin and thrust |
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this organism has a cell wall with lots of mycolic acid, high lipid content
how does it stain |
mycobacteria
acid fast stain |
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Gram negative cocci
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Niesseria (diplococci)
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Filamentous gram pos. bacteria
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Nocardia
Actinomyces |
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Spiral bacteria - gram neg
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spirochetes
-treponema -borrelia -leptospira |
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pleomorphic gram neg bacteria
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Rickettsiae
Chlamydiae |
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Branching gram pos bact that stains weakly with acid fast
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Nocardia
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Pleomorphic gram neg. bacterial that stains with geimsa
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Chlamydia
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spiral bacterial that stains with geima
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spirochete- borrelia
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How do bacterial ribosomes differ from eukaryotic
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bacterial: 50s + 30s --> 70s
euk: 40s + 60s --> 80s |
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Erythromycin - where does it attack
Tetracycline - where does it attack |
50s ribosome
30s ribosome |
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6 organisms that do not gram stain well
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These Rascals May Microscopically Lack Color
-Treponema (too thin, use darkfield) -Rickettsia (intracellular) -Mycobacteria (high lipid content, use acid fast) -Mycoplasma (no cell wall) -Legionella (intracellular, use silver stain) -Chlamydia (intracellular, lacks muramic acid in cell wall, use Giemsa) |
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Which bacteria stain best with Giemsa
(4) |
Borrelia, Chlamydia, Plasmodium, Trypanosomes
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PAS
a. what does it stain b. what can it diagnose |
a. stains glycogen and mucopolysaccharides
b. Stain Tropheryma whippelii to diagnose whipple's disease |
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Patient complains of wt loss, joint pain, malabsorption symptoms
intestinal biopsy reveals PAS-positive macrophage inclusions dx? organism |
whipple's disease
tropheryma whippelii (actinomycete) |
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What can Ziehl Nielson stain find?
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acid fast organisms (mycobact, nocardia)
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What can india ink find?
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cryptococcus neoformans capsule
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what do you use to stain fungi or legionella
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silver stain
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3 enzymes common in obligate aerobes
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1. catalase - breaks down H2O2
2. peroxidase - breaks down H2O2 3. superoxide dismutase - breaks down oxygen radicals to form H2O2 |
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Media used for bacterial isolation
Chocolate agar with factor V (NAD) and X (hematin) |
H. influenzae
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Media used for bacterial isolation
What must you grow Niesseria on and why? |
VPN (Thayer Martin)
Vancomycin - to inhibit gram-pos Polymyxin - inhibits gram-neg Nystatin - inhibit fungi "to connect to Niesseria, use VPN client" |
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Media used for bacterial isolation
b. pertussis |
Bordet-genou (potato)
Bordet for BORDETella |
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Media used for bacterial isolation
c. diphtheria |
tellurite plate, Loffler's media
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Media used for bacterial isolation
M. tuberculosis |
Lowenstein-Jensen
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Media used for bacterial isolation
M. Pneumoniae |
Eaton's
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Media used for bacterial isolation
Lactose-fermenting enterics |
Pink colonies on MacConkey's
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Media used for bacterial isolation
E. coli |
eosin methylene blue agar - blue black with metallic sheen
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Media used for bacterial isolation
Legionella |
Charcoal yeast extract agar buffered with cysteine and Fe
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Media used for bacterial isolation
Fungi |
Sabouraud's agar
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Obligate aerobes
4 bacteria |
Nagging Pests Must Breathe
Nocardia Pseudomonas Mycobacterium tuberculosis (reactivation) Bacillus |
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Pseudomonas aeruginosa
a. how does it deal with oxygen b. 3 places to find it |
a. p. AERuginosa is AERobe
b. burn wounds, nosocomial pneumonia, pneumonia in CF patients |
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Obligate anaerobes
3 bacteria |
Anaerobes Can't Breath
Actinomyces Clostridium Baceroides |
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What enzymes do Actinomyces, Bacteroides, and Clostridium all lack
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lack catalase or superoxide dismutase --> obligate anaerobes
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where are obligate anaerobes
a. normal flora b. pathogenic |
a. GI tract
b. everywhere else |
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Actinomyces, Clostridium, and Bacteroides
a. smell b. culture c. what do they produce in tissue d. which antibiotics don't work |
anaerobic
a. foul smelling b. difficult to culture c. produce gas in tissue (CO2 and O2) d. aminOglycosides need Oxygen to enter cell, don't work |
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How do faculatative anaerobes get energy?
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These aerobic - have superoxide dismutase and catalase, use oxygen in ETC
ALSO have ability to use fermentation for energy |
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How do microaerophilic bacteria get energy
what enzyme do they have that allows them to tolerate a little oxygen |
fermentation (no ETC)
has superoxide dismutase (no catalase) |
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Obligate intracellular bact
Why must they be intracellular |
Rickettsie, Chlamydia (stay inside if it is Really Cold)
Can't make own ATP, must steal hosts |
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7 bact. that are facultatively intracellular
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Some Nasty Bugs May Live FacultativeLy
Salmonella Niesseria Brucella Mycobacterium Listeria Fraciscella Legionella |
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Bacterial Flagella
a. bact with polar flagellum b. bact with peritrichous flagella (2) c. bact w/o flagella |
a. v. cholera
b. e. coli, proteus c. shigella |
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How does a quellung test work?
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Shows if a bacteria is encapsulated
Give anticapsular antibodies; if capsule is present, it will swell "Quellung = Swellung" |
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6 bact with an antiphagocytic capsule
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Some Killers Have Nice Shiny Bodies
Strep pneumo Klebsiella pneumo Haemophilus influenza B Neisseria meningitides Salmonella group B strep |
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how does the strep pneumo vaccine work
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vaccine contains antigens from the 23 most common types of capsules
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Vaccines with polysaccharide capsule antigens --> what does it need to work
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Protein conjugated to antigen to promote T cell activation and class switching
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What is the result of a polysaccharide antigen vaccine without a conjugated protein
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only IgM antibodies would be produced, would not be recognized by T cells
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3 examples of polysaccharide capsular antigen vaccines
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pneumovax
H. influenza type B Meningococcal |
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4 urease-positive bact
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Particular Kinds Have Urease
Proteus Klebsiella H. pylori Ureaplasma |
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Bacteria that produces yellow "sulfur" granules in pus
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Actinomyces israelii
"israel has yellow sand" |
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Pigment producing bacteria
which bacteria produce the following pigments a. yellow b. blue-green c. red |
a. S. aureus (aureus = gold in latin!)
b. p. aeruginosa (AERUGula is green) c. Serratia marcescens (think red maraschino cherries!) |
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Bacterial virulence factors
which bact has protein A, what does it do |
s. aureus
binds Fc region of Ig, prevents opsonization and phagocytosis |
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Bacterial virulence factors
4 bact that secrete IgA protease What does it allow them to do |
SHiN
S. Pneumoniae H. influenza type b Neisseria cleaves IgA, allows these organisms to colonize respiratory mucosa |
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Bacterial virulence factors
What is the M protein and what organisms has it |
helps prevent phagocytosis
group A strep |
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Exotoxin vs. endotoxin
a. chemical makeup b. location of genes |
a. Exo = polypeptide
Endo = LPS b. Exo = plasmid/bacteriophage Endo = bact. chromosome |
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Exotoxin vs. endotoxin
a. toxicity b. antigenicity c. vaccines d. heat stability |
a. Exo = highly fatal
Endo = low fatality b. Exo = induces high titer antibodies (antitoxins) Endo = poorly antigenic c. Exo = toxoid vaccine Endo = no vaccine d. Exo = destroyed at 60 (except staph enterotoxin) Endo = stable at 100C for 1 hr |
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The only gram positive with an endotoxin
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listeria
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Type of exotoxin
Which 2 bact produce neurotoxins |
tetanus
botulinum |
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Vibrio cholera
E. coli C. jejuni Shigella dysenteriae How do these cause osmotic diarrhea |
Local invasion of bacteria --> constant release of enterotoxin
diarrhea continues until bact is stopped (immune or antibiotics or death or patient!) |
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Patient had diarrhea and vomiting for 24 hours after eating some old food
2 possible bacteria pathogenesis |
S. aureus, bacillus
pre-formed enterotoxin in food |
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Patient has rash, fever, toxic shock syndrome
2 possible infections type of toxin |
Staph aureus, Streptococcus pyogenes (group A)
pyrogenic toxin |
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Bacillus anthracis
Clostridium botulinum Clostridium tetani Conrynebacterium diphtheriae Vibrio cholera |
AB exotoxin
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Most important endogenous mediator of sepsis
What does it do |
TNF
trigers IL-1 from macrophages and endothelial cells --> release of other cytokines and prostaglandins |
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4 bacteria that produce exotoxins that increase cAMP levels? how do they work?
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cAMP
c = cholera (vibrio cholera) - activates Gs A = b. Anthracis - includes bacterial adenylate cyclase (edema factor) M = Monteczuma's revenge (e. coli enterotoxin) - heat labile ETEC P = bordatella Pertussis - tunrs off Gi |
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2 functions of bordatella pertussis toxin
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1. disables Gi --> induces cAMP --> whooping cough
2. promotes lymphocytosis by inhibiting chemokine receptors |
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What is a superantigen
stimulates the release of which cytokines? |
binds directly to MHCII and T cell receptor simulataneously --> activates T cells --> stimulates release of IFN-g and IL-2
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3 exotoxins of S. aureus
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1. TSST-1 superantigen --> toxic shock
2. Enterotoxin --> food poisoning 3. exfoliatin --> scalded skin syndrome |
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exotoxins of strep pyogenes
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1. pyogenic toxin --> pharyngitis, cellulitis, impetigo
2. toxigenic - scarlet fever, toxiv shock syndrome 3. immunogenic - rheumatic fever, acute glomerulonephritis |
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ADP ribosylating toxins
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C. diphteriae
V. cholerae E. coli |
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Toxin of corynebacterium diphteriae
function? |
ADP ribosylates (inactivates) EF2 --> pharyngitis and pseudmembrane in throat
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Toxin of v. cholerae
function? |
ADP ribosylation of G protein --> Stimulates AC --> stimulates cAMP --> pump Cl into gut, limit Na reabsorption --> rice water diarrhea
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2 toxins of e.coli
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1. heat labile - stimulates AC --> watery diarrhea
2. heat stable - stimulates Guanylate cyclase --> watery diarrhea "Labile like Air, Stable like Ground" |
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how does bordatella pertussis toxin work
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inhibits Gi --> increases cAMP --> whooping cough
Inhibits chemokine receptor --> lymphocytosis |
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How does C. perfringens toxin work
what do you see on blood agar |
alpha toxin - lecithinase that acts as a phospholipase that cleaves cell membranes --> gas gangrene
see double zone of hemolysis |
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bacterial toxin that causes lockjaw
how does it work |
c. tetani toxin
blocks GABA and glycine NT release (inhibitory NTs) |
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bacterial toxin that causes anticholnergic symptoms and CNS paralysis (cranial nerves)
where are spores found |
C. botulinum
spores in honey (floppy baby), canned food |
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how does bacillus anthracis toxin work
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has edema factor, an endogenous adenylate cyclase
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how does shiga toxin work
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cleaves host rRNA (60s ribosome), enhances cytokine release --> HUS
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How does S. pyogenes toxin work
What do you detect to diagnose rheumatic fever |
Streptolysin O = hemolysin
Streptolysin exotoxin is an antigen for ASO antibody |
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endotoxin
heat labile or stable |
heat stable
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endotoxin activates what three things? (mediate shock)
What do these things activate? |
macrophages
-IL-1 (fever) -TNF (fever, hemorrhagic tissue necrosis) -NO (hypotension) Alternative complement pathway -c3a (hypotension, edema) -c5a (PMN chemotaxis) Hageman factor -coagulation cascade --> DIC |
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4 phases of bacterial growth
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1. lag = metabolic activity w/o division
2. log = rapid cell division 3. stationary = nutrient depletion slows growth, spore formation in some bact Death = nutrient depletion, buildup of waste products --> death |
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What is the process of transformation?
What are 3 bacteria that do this well? |
Competent bacteria can take up DNA from the envirnoment
SHiN (same group that has IgA protease) -Strep Pneumo -H. Infuenza B -Neisseria |
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Strep Pneumo
H. Influenza B Neisseria 2 properties common to this group |
1. IgA protease
2. competent bacteria that readily undergo transformation SHiN group |
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What is the process of generalized transduction?
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Lytic phage infects a bacterium, leading to cleavage of bacterial DNA
This bacterial DNA may be packaged inside newly produced viral phage, which can go infect other bacteria |
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What is the process of specialized transduction
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when a temperate phage infects a bacteria, it incorporates the viral DNA into the bacterial DNA, creating a prophage
The lysogenic phage can be reactivated, and the prophage DNA can be cleaved Error in cleavage can result in parts of the bacterial DNA being included in the prophage, packaged in a capsid, and sent of in a new phage |
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What is an F plasmid
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Self-transmissable plasmid in bacteria
Circular ds DNA that encodes for proteins necessary to carry out process of conjugation (sex pilus gene) |
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What happens in F+ x F- conjugation
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F+ plasmid encodes for sex pilus
Sex pilus penetrates F- bacteria one strand F plasmid DNA moves into F- bacteria so that each bacteria has one strand, serves as a template to remake other strand Both bacteria end up with ds F plasmids (both are F+) |
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What is an Hfr x F- conjugation
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F+ plasmid incorporated into bacterial chromosomal DNA (Hfr cell)
Replication of incorporated plasma DNA may include flanking chromosomal DNA --> transfer of plasmid and chromosomal genes |
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What is transposition
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Segment of DNA that can jump from one location to another --> transfers genes of plasmid to chromosome and back
When excision occurs, flanking DNA may be included -> incorporated into plasmid --> transferred to new bacteria |
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Genes for the following 5 bacterial toxins are encoded in a lysogenic phage
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A = shigA-like toxin
B = Botulinum toxin C = Cholera toxin D - Diphtheria toxin e. Erythrogenic toxin of Strep pyogenes |
