Microbiology video 1

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what is the unique aspect of fungi that makes them succeptable to many antibiotics?: ergosterol
What is the normal flora found on our skin? nose? oropharynx? colon? Vagina?: Skin: Staphlococcus epidermidis

Nose: Staphlococcus Aureus

Oropharynx: Viridans Streptococci incl. Strep. mutans and Strep. Salivarius

Colon: Bacteroides (predominant organism)
Escherichia
Bifidobacterium

Vagina: Lactobacillus
What microorganisms make up the normal flora of the gingival crevices? (4): Aneerobes: Prevotella, fusobacterium, Streptococcus, and Actinomyces
What are the some adherence factors of both gram positive and negative bacteria?: Gram (-): pili/fimbriae - adherence to cell surfaces
Gram (+): teichoic acids - adherence to cell surfaces
Adhesins: colonizing factor aadhesins, pertussis toxin, and hemagglutinins.
IgA proteases: cleaved Fc portion may coat bacteria and bind them to cellular Fc receptors.
Which organisms secrete biofilms to attach to inert materials?: Staph. epidermidis, and strep. mutans
What is the numanic and organisms that have capsules?: Some Killers Have Pretty Nice Capsules

Streptococcus pneumoniae
Klebsiella pneumoniae
Haemophilus Influenzae
Pseudomonas Aeruginosa
Neisseria Meningitidis
Cryptococcus neoformans
What are two microorgaisms which are able to live within phagocytic cells? How do they do this?: M. tuberculosis (inhibits phagesome-lysosome fusion.
and
Listeria (escapes the phagosome into the cytoplams before phagosome-lysosomal fusion.
What organisms steal (chelate) and import iron?: siderophores
What is an invasin?: invade non-phagocytic cells, thus excaping the immune system.
What is the chemical in the gram negative organism that is toxic?: LPS, it is actually the LIPID A portion of the LPS that is toxic.
Usually endotoxin is not release until the gram negative organism dies. What is the one exception to this rule?: N. Meningitidis, which over-produces outer membrane fragments
What does this release of LPS cause, and what is each due to?: LPS activates macrophages which damages tissues.
bradykinin-induced vasodilation leads to SHOCK

activation of HAGEMAN FACTOR leads to COAGULATION (DIC)
What are exotoxins?: Very toxic released from living bacteria.
Can endotoxins or exotoxins be moeified to a toxoid?: Endotoxins cannot but exotoxins can be modified by chemicals or heat to produce a TOXOID that still is immunogenic, but no longer toxic and thus can be used as a vaccine.
How does an A-B toxin work?: The B part of the toxin attaches to the cell and allows the A part to enter the cell. The A part of the toxin is the toxic part (often an enzyme)
What are two examples of cytotoxins and: Cl. perfringens has the ALPHA TOXIN (enzyme) which is a lecithinase.

Staphylococcus aureus also has an ALPHA TOXIN which inserts itself to into a cells membrane to form pores in the membrane
What does Cl. Perfringens cause?: gangrene
What is the toxin and how does it work? Corynebacterium diphtheriae?: Toxin is DIPHTHERIA TOXIN and it works by ADP RYBOSYL TRANSFERASE; WHICH INACTIVATES EF-2, thus stopping protein synthesis.
What is the toxin and how does it work? Pseudomonas aeruginosa?: Toxin is EXOTOSIN A and it works by ADP RYBOSYL TRANSFERASE; WHICH INACTIVATES EF-2, thus stopping protein synthesis
What are the primary targets for diphtheria toxin?: heart, nerves, and epithelium
What is the primary target for Exotoxin A and what organism secretes it?: Secreted by Pseudomonas aeruginosa, the primary target for exotoxin 2 is the LIVER.
What organism secretes Shiga toxin and what does it do?: Secreted by Shigella dysenteriae and it interferes with the 60S ribosomal subunit, thus inhibiting protein synthesis in eukaryotic cells.
What organism secretes Verotoxin and what is it's mechanism?: Secreted by Enterohemorrhagic E. Coli (EHEC). It interferes with the 60 S ribosomal subunit, thus inhibiting protein synthesis in eukaryotic cells.
What organism secretes Tetanus toxin and how does it work?: Clostribium tetani. Tetanus toxin blocks release of the inhibitory transmitters glycine and GABA, thus inhibiting neurotransmission in inhibitory synapses.
What organism secretes Botulinum toxin and how does it work?: Botulinum toxin is secreted by Clostridium botulinum. It blocks release of acetylcholine, thus inhibiting cholinergic synapses.
What organism secretes TSST-1 and how does it work?: TSST-1 is secreted by Staphylococcus aureus and is pyrogenic, decreases liver clearance of LPS, and is a superantigen...thus it produces fever, increased susceptibility to LPS, rash, shock, and capillary leakage.
Other than Pseudomonas aeruginosa, what is another organism that secretes Exotoxin A and how does it work?: Exotoxin A secreted by Streptococcus pyogenes. it has the exact same effects as TSST-1 secreted by staph. aureus (fever, increased LPS), but is also cardiotoxic.
What organism secretes Heat Labile toxin (LT) and how does it work?: LT is secreted by Entertoxic Escherichia coli. LT stimulates an adenylate cyclase by ADP ribosylation of GTP binding protein. This promotes secretion of fluid and electrolytes from intestinal epithelium.
What organism secretes cholera toxin and how does it work?: Cholera toxin secreted by Vibrio cholerae. It acts similar to the E. coli LT and thus results in a profuse, watery diarrhea.
What organism secretes Anthrax toxin?: Bacillus anthracis
What are the different proteins that make up the anthrax toxin?: EF= edema factor
LF= lethal factor
PA= protective antigen (B component for both EF and LF)
What is the effect of the anthrax toxin?: Decreases phagocytosis; causes edema, kills cells.
What is the organism that produces Pertussis toxin and how does it work?: Bordatella pertussis
Pertussis toxin ADP ribosylates Gi, which is the negative regulator of adenylate cyclase. This thus INCREASES cAMP
What are the effects of pertussis toxin?: Histamine sensitizing
Lymphocytosis promotion
Islet activation
What toxin is secreted by Clostridium perfringens and what does it do?: Alpha toxin is secreted. This Clostridium perfringens alpha toxin is a lecithinase that damages cell membranes.
What toxin is produced by Staphlococcus aureus and what does it do?: Staph. aureus secretes alpha toxin which intercalates forming pores, thus making the cell membrane leaky.
What type of paralysis does tetanus toxin produce?: Spastic paralysis due to inhibition of inhibitory synapses
What type of paralysis does botulinum toxin produce?: Flaccid paralysis due to inhibition of cholinergic synapses.
What is an important capsule of E. Coli and why is it important?: If E. Coli has the K1 capsule it is likely to cause neonatal meningitis.
What antibiotics work on the peptidoglycan layer?: penicillin and cephalosporins act on the peptidoglycan layers and split the peptidoglycan bonds, thus killing the organism.
What organism stain with the acid fast stain?: Mycobacterium and Nocardia (Nocardia is partially stained)
What organism is identified by it's numerous flagella.: Salmonella typhi
What is the M-protein?: M-protein of Strep pyogenes is a surface protein that is very important in it's virulence factor.
What is another name for the acid fast stain?: Ziehl-Neelsen Acid Fast Stain
What color is mycobactera in the ziehl-neelsen stain?: pink
What is the Auramine-Rhodamine Fluorescent Stain?: In the case of mycobacterium TB, because the acid fast stain takes some time to perform, the sputum goes thru the Rhodamine-Fluorescent Stain. If the organism is positive on the Auramine-Rhodamine stain then you will do a Acid Fast stain for confimation
What is the difference between bacteria and human ribosomes?: bacteria = 70S ribosomes
human = 80S ribosome

and thus it is a major mechanism of antibiotic action
What organisms produce endospores?: Baccillus genus and Clostridium genus
what does differential media do and what is a good example of a differential media?: Diff. media helps to differentiate one organism from another. A good example of this is blood agur.
What does blood agur help you differentiate?: Blood agur helps you differentiate alpha, beta, and gamma Streptcocci.
What is the differential medium for Corynebacterium?: Tellurite agar where the corynebacterium turn black.
What is the differential medium for Enteric bacteria and what is the significance of this medium?: MacConkeys agar allows gram negative organisms to grow but not gram positive. Thus it is a selective media, but at the same time it diferentiates lactose from non-lactose fermenters. Lactose fermenters show up as pik colonies.
What is a good example of a lactose fermenter?: E. Coli
What is a good example of a non-lactose fermenter?: Salmonella Typhi
What media is used to differentiate Vibrio cholerae?: TCBS (thiosulfate citrate bile salts sucrose agar)
What medium is selective for mycobacterium?: Lowenstein-Jensen medium
What agar is used for Neisseria? Which is usually used: Chocolate agar and Thayer-Martin medium.

The Thayer-Martin medium is usually used because it is selective for Neisseria. It is basically a chololate agar with antibiotics to inhibit the growth of normal flora.
What is an important test for the identification of neisseria gonnorrhea?: oxidate test
What are three good examples of obligate aerobes?: mycobacterium TB
pseudomonas
bacillus
What are the three major obligate anaerobes?: actinomyces

bacteriodes

clostridium
Aerobically or anaerobically, how are most bacteria classified?: Facultative anaerobes
What is the mneumonic for the organisms that require cysteine to grow?: The four sister Ells and the Cysteine chapel.

Flancisella, Brucella, Legionella, and Pasteurella
What is hte mneumonic for remembering the three obligate anaerobes?: ABCs of anaerobiosis = Actinomyces, Bacteroides, and Clostridium
What are the microareophilic organisms and what does each cause?: Campylobacter and helicobacter

Camplobacter causes gastroenteritis

Helicobacter causes gastric and duodenal ulcers
What is included in the DTP vaccine?: Diphtheria: diphtheria toxoid

Tetanus: tetanus toxoid

Pertussis: killed Bordetella pertussisis cells
When is the DTP vaccine given?: 2 months, 4 months, 6 months, 18 months, and 5 years old
What is the vaccine with the new pertussis called and what is the difference?: The new vacccine is DTaP. The a stands for a cellular b/c it is no longer the dead organism in the vaccine...it is some cellular components. it contains the capsule, toxoid, and hemagluttinin fimbrie
What is the HIB vaccine and what does it contain?: Haemophilus influenzae type b
It is an H. influenzae capsular polysaccharide conjugated to protein
When is the HIB vaccine given and what disease has it helped significantly?: It is given at 2, 4, 6, 18 months and 5 years old and it has helped neonates fight meningitis.
Who should get the spreptococcus pneumoniae vacine and what is it composed of?: elderly people should get the spreptococcus pneumoniae vaccine and it is composed of capsular polysaccharides of 23 different Pneumoncoccus strains.
Why shouold the spreptococcus pneumoniae vaccine be given to people who lack a spleen?: The spleen is the major organ that clears capsular proteins.
What does the neisseria meningitidis vaccine contain.: Four capsular polysaccharides: Y, W-135, C, and A.

These are the four different types of capsules
Who should the salmonella typhi vaccine be given to and what does it contain?: it should be given to travelers to endemic typhoid areas and it is composed of attenuated bacterium
What is the new salmonella typhi vaccine called?: ty21
What is the vaccine for TB?: BCG = Bacille Calmette Guerin (BCG)
What is the BCG vaccine composed of?: Attenuated (living) strain of Mycobacterium bovis
What is the bacillus anthracis vaccine composed of and who is it used on?: composed of a supernatant of partially purified proteins and it is used for military and people around cows and wool a lot.

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