General Flashcards
Which group of bacteria have thick peptidoglycan ?
Gram +
Gram - have a thin layer. Do not hold purple stain well since ethanol treatment destroys the outer membrane and leads to leaking of stain. (Outer membrane in LPS )
What is found in the thick peptidoglycan layer of gram +’s which leads to activation of TNF and IL-1 ?
Lipotechoic ACid
The outer membrane of gram - is made of LPS. List the constituents of LPS
O -antigen
Outer Core
Inner Core
Lipid A
Which part of LPS is the main antigen ?
O-antigen
What part of LPS is the major mediator of toxicity ? Why ?
Lipid A
Activates TNF and IL-1
What are the two constituents of the bacterial Ribosome ?
50s and 30s
What is the periplasm ? What is found in it ?
In gram - bacteria, it is the fluid between the cytoplasmic membrane and the outer membrane (LPS) . Beta- lactamases
What are most capsules made of ? What is the Exception ?
Polysacharides
B. anthracis : Poly D glutamate capsule
What are spores meant to be resistant to ?
Dehydration, Heat and Chemicals
What molecule make up plasmids ?
DNA
GLycocalyx help bacteria adhere to surfaces. What is it made of ?
Like most capsules, it is made of Polysaccharide.
These Rascals May Microscopically Lack Color
Treponema Rickettsiae Mycoplasma Mycobacterium Legionella Chlamydia
What test are used to diagnose Treponemal infections ?
Dark Field Microscopy
Immunofluorescence
What stain can be used for Mycobacterium (not mycoplasma)
Acid Fast
What stain can be used for Legionella ?
Silver ( BCYE is media for legionella)
Which class of bacteria contain sterols in their cell wall instead of peptidoglycan ?
Mycoplasma
Which class of bacteria contain mycolic acid in their cell wall instead of peptidoglycan ?
Mycobacterium
Giemsa Stain :Certain Bugs Really Try my Patience
Chlamydia Borrelia Rickettsia Trypanosomes (T.cruzi etc.) Plasmodium
What does the PAS stain bind to ? Which bug is indicated by this ?
Glyocogen
T. whippeli
Ziehl Nelson stain is another confirmatory for…
Acid Fast organisms ( Mycobacterium and Nocardia)
India Ink is used to look for what structure in bacteria ? What organism is often associated with this ?
CAPSULES (usually polysaccharide, not sure if it works for D-glutamate)
Cryptococcus neoformans
Name the bug cultured with Chocolate Agar with Factors V and X .
H. influenzae
V = NAD+ X = Hematin (Just in case they ask in a round about way)
Name the bugs cultured with Thayer-Martin (VNP)
N. meningitidis
N. gonorhoeae
What are the anti-microbials used in Thayer-Martin (VPN) and what organisms are they used to control for ?
Vancomycin ( G+’s)
Polymyxin ( G -‘s except Neisseria)
Nystatin (Fungi)
Bordet Genou Agar
Bortadella Pertussis
Tellurite (Loefflers)
C. dipterhia
Lowenstein Jensen
Mycobacterium
Eaton’s Agar
Mycoplasma pneumoniae
MacConkey’s with Pink colonies
MacConkeys is used for Gram -‘s
Lactose fermenting Enterics (G -‘s )
Fermentation leads to pink
Buffered Charcoal Yeast Extract
Legionella
Sabouraud Dextrose
Fungi (candida
Obligate Aerobes: Nagging Pets Must Breathe
Nocardia
Pseudomonas
M. tuberculosis (Acid Fast, Ziehl Nelson, Lowenstein Jenson)
Bacillus (anthracis etc)
Obligate Anaerobes: Cant Breathe Air
Clostridium (tetani, dificile, perfringens)
Bacteroides
Actinomyces
What drug class is ineffective agains Obligate Anaerobes ?
Aminoglycosides ( Think of the two O’s as oxygen) . Need 02 to be active .
Obligate intracellulars: Really Cold
Rickettsiae
Chlamydia
Stay inside when its cold ….
What do obligate anaerobes usually lack, making them susceptible to 02 damage ?
Catalase
Superoxide Dismutase.
Faculative Intracellulars :Some Nasty Bugs May Live FaculativeLY
Salmonella Neisseria Brucella Mycobacterium Listeria Legionella Yersinia
What test can be used to determine if bacteria is encapsulated ?
Quellung Reaction : Capsule swells when test is positive
Encapsulated Organisms: SHiNE SKiS (get it, like putting a capsule of wax on)
S. pneumoniae
H.infleunzae
Neisseria
E.coli
Salmonella
Klebsiella pneumoniae
Strep: Group B (Strep Agalactiae)
What is the purpose of capsules ?
Evade phagocytosis
What encapsulated organisms do we routinely vaccinate against ?
Neisseria menigitidis
H. influenzae
S. pneumoniae
These are capsular conjugate (to protein) vaccine
Who is most at risk for infection with encapsulated organisms ?
Splenectomy Sickle Cell (have auto infarction of the spleen)
Catalase + : PLACESS for your Cats (catalase +’s)
Pseudomonas Listeria Aspergillus (Fungi) Candida (Fungi) E.coli S.aures (Staph in general are Catalase +) Serratia
What disease is associated with recurrent infection with Catalase + organisms ?
Chronic Granulomatous Disease
NADPH Oxidase is def leading to decreased H202 which Cat+ organisms can degrade to stop from being destroyed.
Why are Polysaccharide capsules conjugated to proteins in vaccines ?
TO promote T-Cell activation and class switching
W/O the protein only IgM would be made
Of the organisms we vaccinate for which one has a vaccine involving conjugated and unconjugated polysaccharide capsule \s ?
S. pneumoniae
Pneumovax : capsule only
Prevnar: Conjugated
Urease + : Chris Hagan PUNKSS
Cryptococcus H.pylori Proteus Ureaplasma Nocardia Klebsiella S. epi S. saprophyticus
Which organism produces Yellow ‘sulfur’ Granules ?
Actinomyces israelii (filaments of bacteria are yellow)
Israel uses yellow sulfur gas on the palestinians.
Honey(Gold)Crusts
S.aureus Aureus = gold … Au is chemical symbol for gold
Blue Green pigment
Pseudomonas aeruginosa (also , grape like odor)
Pigment caused by Serratia marcesesns
Red
mars is red .
Explain how Protein A increases virulence of bacteria (S.aureus)
Binds to the Fc portion of Ig leading to evasion of opsonization and phagocytosis
IgA protease, does as the name suggests and breaks down IgA. Which organisms express IgA protease ?
SHiN
S. pneumonia
Haemophilus Influenzae B
Neisseria
What organisms express M protein ?
Group A strep (Step Pyogenes)
Exotoxin is actively secreted from bacteria (both G+ and G-) . What class of molecule are most exotoxins ?
Polypeptides
Endotoxins are only found in what type of bacteria ?
Gram -
Endotoxin = LPS .. Not secreted, released when lysed )
Which is more fatal at low doses: Exotoxin or Endotoxin ?
Exotoxin (much more potent at low doses)
What are the main effects seen with LPS (endotoxin) release ?
Fever and SHOCK
As noted earlier, what does LPS induce to lead to fever and shock ?
TNF and IL-1
Which have we formed certain vaccines against: Exotoxins or Endotoxins ?
Exotoxins : Tetanus toxin, Diptheria Toxin, Botulism tonin etc.
Which is more heat stabile: Exotoxin or Endotoxin ?
Endotoxin: can last for an hour at 100 C
Exotoxins degrade rapidle at 60 C (Except S.aures toxin)
What is the mode of action for both Diptheria Toxin and Exotoxin A (Pseudomonas)
Inhibit Elongation Factor 2 (EF2)
Diptheria Presentation
Pharyngitis Grey pseudomembrane Serious lymphadenopathy (bull Neck)
Pseudomonas (Exotoxin A) presentation
Host cell death
Which organism produces Shiga-Like Toxin ?
E. coli O157:H7 (EHEC)
What is the mode of action for Shiga Toxin and Shiga Like Toxin ?
Inactivated 60S ribosome by removing adenine from rRNA, thus halting protein synthesis.
What is the main difference between Shigella (ST) and E.coli (SLT) in terms of clinical presentation ?
Both cause the release of cytokines –> HUS
Only Shigella will invade and cause dysentery. (E.coli does not do this)
Enterotoxigenic E.coli (ETEC) has two toxins, Heat Stabile (ST) and Heat Labile (LT). What 2nd messengers does each activate respectively ?
ST –> Activation cGMP (Stable on the Ground). Leads to decreased absorption of NaCl and H20 in the gut.
LT –> Activation of cAMP (Labile in the Air). Leads to Cl- secretion and H20 efflux
What two viral factors are associated with Bacillus antrhacis
Edema Factor (EF) –> increased cAMP and edema
Lethal Factor (LF).. leads to death via necrosis.
Vibrio Cholera produces a toxin which activates which G-proteins ?
Gs is activated irreversibly leading to Cl- efflux, H20 follows.
“Rice Water Stools”
What G-protein does Pertussis toxin act on leading to its effects ?
Inactivates Gi inadvertently leading to increased Gs activation.
Stops effective Phagocytosis of bortadella
Whoops on inspriation, coughs on expiration.
What is the mode of action of both Tetanus Toxin and Botulinum toxin ?
Cleaves SNARE protein , inhibiting NT release
What NT is inhibited from release by Tetanus Toxin ?
The inhibitory NT GABA and Glycine . Since GABA/Glycine are not released in the interneurons of the spinal cord, muscle remains tonic
What NT is inhibited from release by Botulinum toxin ?
ACh (stimulatory to muscles). Without ACh release, flaccid paralysis occurs
(Floppy Baby Syndrome, honey )
What toxin is produced by Clostridium perfringens and what is its MOA ?
Alpha Toxin
Phospholipase thate degrades tissue and cells membranes
Manifestations of Clostridium perfringens
Gas Gangrene (due to degradation of Phospholipid C)
Hemolysis (double zone on blood agar)
What is the MOA of Streptolysin O, the exotoxin of Strep. pyogenes
Degrades Cell membranes
(lyses RBC) . Anti-Streptolysin O Ab’s are used to diagnose S.pyogenes infection in Rheumatic Fever (even though this is really due to M-Protein)
What is the super-antigen associated with S.aureus ?
TSST-1 (Toxic Shock Syndrome Toxin)
What is the MOA of TSST-1 ?
Brings MHCII and TCR in close proximity leading to incredible IFN-y and IL-2 release –> Shock
What other toxins are associated with S.aureus besides TSST-1 /
Exofoliative Exotoxing (Scalded Skin Syndrome) Enterotoxin (Food poisoning, potato salad fool).
What symptoms are associated to with Toxic Shock ?
Fever, Rash, Shock
What is the mode of action of Strep pyogenes’ Exotoxin A
Brings MHCII and TCR in close proximity leading to incredible IFN-y and IL-2 release –> Shock (Same as TSST-1)
What are the three main effects seen with ENDOTOXIN (Lipid A) release ?
Activated macrophages
Activates Complement
Activates Tissue Factor
When activated by Lipid A, what will Macrophages Release ?
TNF: Fever, Hypotension (ICAM activation)
IL-1: Fever (ICAM activation)
Nitric Oxide: Hypotension
When activated by Lipid A, what complement particles are created that important in sepsis ?
C3a: Hypotension, Edema, Anaphylaxis
C5a: Neutrophil Chemotaxis, Anaphylaxis.
When activated by Lipid A, tissue factor lead to what sequelae ?
DIC
ENDOTOXIN
Edema Nitric Oxide DIC/DEATH Outer membrane (LPS) TNFa O - O antigen Xtremely heat stabile IL-1 Neutrophils
Lag phase
metabolic activity w/o growh
Log phase
exponential growth
Stationary phase
nutrient delpletion slows growth
Transformation
Ability to take up DNA from the environment and integrate it into genome.
What bacteria are especially adept at transformation ?
S. pneumoniae
H. infuenzae
Neisseria
SHiN ! Also, have IgA protease and are all encapsulated. So, that’s cool.
F+/F- conjugation
Stricly, this is conjugation involving the genes needed for pilus and conjugation on a plasmid.
F+ cells pass the F+ plasmid to F-. Allows F- to become F+ and pass plasmid to another F- cell.
Hfr+
Hfr: F+ plasmid becomes integrated into the bacterial chromosome. When plasmid is replicated from chromosome DNA, segments of DNA surrounding it may also become transcribed –> increased gene sharing between F+ and F- cells.
Transposition
DNA that Jumps from one position to another on the genome.
Transduction (Generalized)
Phage with DNA material infects the cell, and Phage DNA is incorporated into cell DNA
(In earlier Phage infection, a cells DNA may have been lysed and put into phage DNA so that upon subsequent infection, that cells DNA is also passed to new cell)
The lysis portion is totally needed for this to be considered Generalized
Transduction (Specialized)
The Phage DNA is specifically put into the host cell DNA. It is also specifically excised and may take host DNA with it in the absence of genome lysis)
What are the 5 main toxins that are packaged in Lysogenic Phages
Shiga-Like Toxin (E.coli) Botulinum Toxin Cholera Diptheria Erythrogenic Toxin (S.pyogenes)
ABCDE (A is from shiGa-like toxin)
