micro-Bacterial taxonomy and virulence factors Flashcards by Amanda Beach

What are the colors for gram stain and explain why they stain that way

+ is blue/dark purple because the crystal violet gets trapped in the thick peptidoglycan wall
- is red/pink because does not retain crystal violet from shield LPS layer though the alcohol disrupts membrane and so the safrinin stains

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What catalyzes the stable cross linking of peptidoglycan and where is it located

transpeptidase in the inner cytoplasmic membrane

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What Tx inhibits transpeptidase

penicillin

also called penicillin binding protein

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What proteins are on the outer cell wall of gram +

teichoic acid, polysaccharides and other proteins

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what do we detect in serologic studies on surface of gram +

teichoic acid

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What are the layers of the gram - bacteria

cytoplasmic membrane
periplasmic space
peptidoglycan
LPS outer membrane

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what is in the periplasmic space of gram -

proteins and enzymes

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what lipoprotein is in the membrane of gram -

murein lipoprotein

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What are the 3 components of LPS

outer carbohydrate chains 1-50 oligosaccharides that differ organism to organism (O sepcific side chain or O Ag)
core polysaccharide in the center part that is water soluble
Lipid A on the inside of core polysaccharide

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What does Lipid A cause clinically? “endotoxin”

fever, diarrhea, and possibly septic shock

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how do gram - bacteria get nutrients if LPS is barrier

porin proteins

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What Antibiotics and chemicals break the peptidoglycan layer in gram +

penicillin and lysoyzmes

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What are the 6 classic gram + organisms

Staphcoccus
Streptococcus (enterococcus)
2 spore:
Bacillus Anthracis
Clostridium spp
non spore:
Corynebacterium
Listeria

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What are the gram neg cocci?

N gonorrhea
Morazella
both are diplococci

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What are the spirochetes?

gram neg
Treponema pallidum
Borrelia

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How do you stain mycobacterium

acid fast.

slightly gram + sometimes

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what type of microscope is needed to visualize spirochetes

dark field microscopy

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what are periplasmic flagella and what organisms have them

flagella that run under outer membrane sheath

in spirochetes

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Describe the membrane of mycoplasma

do not have cell wall. only simple cell membrane

neither gram + or -

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What are the enterics

E coli
Shigella
Salmonella
Yersinia
Klebsiella
Proteus
Enterobacter
Serratia
Vibrio
Campylobacter
Helicobacter
Pseudomonas
Bacteroides

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What are the pleomorphic bacteria

Chlamydia and Rickettsia

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Describe ribosomes of prokaryotes

70s subunits 50s and 30s

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why are erythromyocin and tetracycline great antibiotics

E- attacks 50s ribosomes

T- attacks 30s ribosomes

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What are the gram + obligate aerobes

nocardia

bacillus cereus

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What does catalase break down

H2O2

What does peroxidase break down

H2O2

What does superoxide dismutase break down

superoxide radicals

What are the gram- obligate aerobes

``` Neisseria Pseudomonas Bordetella Legionella Brucella ```

What are the Acid Fast obligate aerobes

mycobacterium and no cardia

what are the gram + facultative anaeriobes

``` staph bacillus anthracis corynebacterium listeria actinomyces ```

What are the gram - facultative anerobes

most gram - rods

what are the gram + microaerophils

enterococcus | strep

what are the gram - microaerophils

spirochetes and campylobacter

what are the gram + obligate anaerobes

clostridium

what are the gram - obligate anaerobes

bacteroides

what is the main difference of facultative anaerobes and microaerophils

facultative hace catalase and SOD, they also use O2 as acceptor in ETC microaerophils use fermentation, no ETC and no catalase, only SOD

what are chemoheterotrophs

use chemical and organic compounds for energy

What is the definition of obligate intracellular organism? give e.g.

cannot make ATP, use host for energy source | chlamydia and rickettsia

what spins the flagella on bacteria

the basal body that spans membranes

what is a polar flagellum vs peritirchous

polar is at one end only | peritrichous is all around the cell

What is the use of pili

adherence factors

what bacteria uses AA instead of sugar for its capsule

bacillus anthracis

What stains are used to visualize capsuled bacteria

india ink stain- crytptococcus fungus | quellung reaction Ab bind to capsule and the capsule will swell with water

what immune response can take care of sugar capsules around bacteria

opsonization

describe layer of endospores

``` cell membrane thick polypeptidoglycan mesh cell membrane wall of keratin like protein outer layer called exosporium ```

to best prevent the survival of endospores you must autoclave instruments for how long at what temp

15 min at 121 C

What is a biofilm

a wall of polysaccharides secreted by some bacteria to protect themselves

what is the best Tx against a biofilm on a prosthetic device

remove the device

What are the facultative intracell organism

``` Listeria Salmonella Yersinia Francisella Brucella Mycobacterium Legionella Nocardia Listen Sally Yer Friend Bruce Must Leave Now ```

exotosins are primarily secreted by gram + or -

+ usually thought E coli and V cholera do as well

What are examples of neurotoxins

botulinum and tetanus toxins

how to enterotoxins work

inhibit NaCl resorption, activate NaCl secretion or kill epithelial cells

What two manifestations do enterotoxins cause

infectious diarrhea | food poisoning

food poisoning lasts for how long

12-24 hours. diarrhea and vomiting

What are common culprits of food poisoning

S aureus | Baciilus cereus

What is the classification of pyrogenic exotoxin and give organisms that secrete these

stimulate release of cytokines that cause rash, fever and TSS S aureus St pyogenes

what are included as tissue invasive exotoxins

destroy DNA, collagen, fibrin, NAD RBC and WBC

What bacteria have the AB toxins

B antrahcis, C botulinum | C tetani, C diphtheriae and V cholera

what is bacteremia

bacteria in the blood

What is sepsis

bacteremia that causes systemic immune response to the infection

What is septic shock

dangerous drops in BP | organ dysfunction

What is the most famous endogenous mediator of sepsis

TNF of cachetin

What does tNF cause in sepsis

triggers release IL1

What happens to vascular system in septic shock

vasodilation | Inc BP and organ hypoperfusion

what happens to heart in septic shock

myocardial depression with dec CO and BP | organ hypoperfusion

what happens to kidneys in septic shock

acute renal failure dec urine output, volume overload accumulation of toxins

what happens to lungs in septic shock

ARDS hypoxia

what happens to liver in septic shock

hepatic failure from accumulation of metabolic toxins and hepatic encephalopathy

what happens to the brain in septic shock

encephalopathy | altered mental status

what happens to coagulation pathway in septic shock

DIC | clotting and bleeding

What is the mech of C. tetani

H (B) binds to neuronal gangliosides L (A) blocks release of inhibitor NT resulting in continuous motor activity

What is the mech of C. botulinum

inhibit Ach release from motor neuron endplates | resulting in flaccid paralysis

What is the mech of V cholera

5 B subunits bind GM1 gangliosides on intestinal cell membranes 2 A subunits carry out ADP ribosylation of GTP-binding protein activating cAMP results in increased intraluminal NaCl which pulls fluid into intestinal tract

What is the toxin of cholera

choleragen

what is the toxin of E coli, Campylobacter jejuni and B cereus

heat labile toxin

what toxin is common among E coli and Y enterocolitica

heat stabile toxin

what is the mech of shigella

5 B subunits binding GI epithelium | A subunit inhibit protein synthesis by inactivating 60s

What is characteristic of TSS

fever, rash, desquamation, diarrhea and hypotension

What are the tissue invasive toxins of strep pyogenes

``` hemolysins/Streptolysin O and S Streptokinase DNAases Hyaluronidase NADase ```

What are the tissue invasive toxins of Staph aureus

``` Lipases, penicillinase staphylokinase leukocidin exofiliatin factors that bind C' ```

What toxin is responsible for scalded skin syndrome in children

exfoliatin

What is the most lethal toxin of C perfringens

lecithinase which hydrolyzes membranes causing tissue destruction and gas gangrene

What are the 3 components of anthracis

edema factor lethal factor protective Ag

what is the mech of C diphth

``` B binds hear and neural tissue A: ADP ribosylates elongation factor EF2 inhibiting mRNA translation causes: myocarditis peripheral nerve palsies CNS effects ```

What is the mech of C difficile

toxin A causes fluid secretion and mucosal inflammation- diarrhea toxin B causes cytotoxic to colonic epithelial cells causes: pseudomembranous enterocolitis diarrhea bloody, fever, abdominal pain