micro-Bacterial taxonomy and virulence factors Flashcards
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
What catalyzes the stable cross linking of peptidoglycan and where is it located
transpeptidase in the inner cytoplasmic membrane
What Tx inhibits transpeptidase
penicillin
also called penicillin binding protein
What proteins are on the outer cell wall of gram +
teichoic acid, polysaccharides and other proteins
what do we detect in serologic studies on surface of gram +
teichoic acid
What are the layers of the gram - bacteria
cytoplasmic membrane
periplasmic space
peptidoglycan
LPS outer membrane
what is in the periplasmic space of gram -
proteins and enzymes
what lipoprotein is in the membrane of gram -
murein lipoprotein
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
What does Lipid A cause clinically? “endotoxin”
fever, diarrhea, and possibly septic shock
how do gram - bacteria get nutrients if LPS is barrier
porin proteins
What Antibiotics and chemicals break the peptidoglycan layer in gram +
penicillin and lysoyzmes
What are the 6 classic gram + organisms
Staphcoccus Streptococcus (enterococcus) 2 spore: Bacillus Anthracis Clostridium spp non spore: Corynebacterium Listeria
What are the gram neg cocci?
N gonorrhea
Morazella
both are diplococci
What are the spirochetes?
gram neg
Treponema pallidum
Borrelia
How do you stain mycobacterium
acid fast.
slightly gram + sometimes
what type of microscope is needed to visualize spirochetes
dark field microscopy
what are periplasmic flagella and what organisms have them
flagella that run under outer membrane sheath
in spirochetes
Describe the membrane of mycoplasma
do not have cell wall. only simple cell membrane
neither gram + or -
What are the enterics
E coli Shigella Salmonella Yersinia Klebsiella Proteus Enterobacter Serratia Vibrio Campylobacter Helicobacter Pseudomonas Bacteroides
What are the pleomorphic bacteria
Chlamydia and Rickettsia
Describe ribosomes of prokaryotes
70s subunits 50s and 30s
why are erythromyocin and tetracycline great antibiotics
E- attacks 50s ribosomes
T- attacks 30s ribosomes
What are the gram + obligate aerobes
nocardia
bacillus cereus
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