Micro 1 - Bacteria

gsafsaf's version from 2015-05-22 17:54

Bacteria Basics

Question Answer
Induces IL-1, IL 6, TNF-alphaG+ Lipoteichoic acid
Induces IL-1 and TNF-alpha onlyG- Outer Membrane (LPS endotoxin)
Responsible for septic shockG- LPS endotoxin
Contain beta lactamaseG- Periplasmic space
Structures unique to G+Outer membrane (LPS endotoxin),Periplasmic space,Porin
Facilitates conjugationPilus (Sex pilus, or F pilus)
Bacterial ribosomes? 50S and 30S
Transferred during conjugation? Plasmid
Loose network of polysachharidesGlycocalyx biofilm
Organized network of polysaccharidesGlycocalyx capsule
Takes up naked DNA Transformation
How does transformation work?When a cell is lysed, its DNA fragments float around and can be incorporated into living bacteria
What bacteria can transform?S. pneumo, H. influenza (type b), Neisseria [SHiN]
Plasmids transferred via sex pilusConjugation, mediated by the bacterial penis
Transfer of DNA segments via excision and reintegrationTransPosition: Transposons jump
Flanking chromosomal DNA is found in?Transposons
DNA transfer mediated by viruses?TransDuction: part of lysed bacterial DNA gets incorporated into viral capsid
Provides support in cell wallPeptidoglycan
Unique to Gram positives?Cross-linked peptidoglycan layer, lipoteichoic acid

Bacterial Stains

Question Answer
GiemsaChlamydia, Borrelia, Rickettsia, trypanosomes, Plasmodium, Histoplasma
PASGlycogen: T. whipplei
Ziehl-Neelson[carbol fuschin]: Acid fast (Nocardia, Mycobacteria) and Protozoa (Cryptosporidium)
India inkCryptococcus neoformans
Silver stainFungi (PCP), Legionella, Helicobacter pylori
No cell wall, sterolsMycoplasma
Mycolic acid, lipid richMycoBacteria
Which organisms don't gram stain?Mycoplasma, Mycobacterium, Treponema, Rickettsia, Legionella
Which bacteria are encapsulated ?S. pneumo, Pseudomonas, N. meningiditis, Klebsiella, H. influenza, Salmonella, E. Coli, gBs
[Some Pretty Nasty Killers Have Shiny, Encapsulated Bodies]

Bacterial Cultures

Question Answer
Degrades H2O2 into H2O and bubbles of O2Catalase test
Catalase+ organisms Nocardia, Pseudomonas, Listeria, Aspergillus, Candida, E. coli, Staphylococci, Serratia [Cats Need PLACESS to hide]
Which population is susceptible to Catalase + Organisms?Chronic granulomatous disease (NADPH oxidase deficiency)
No NADPH: Can't convert H2O2 to ROS
Cat+ organisms gobble up the H2O2
CoagulaseCoagulates blood
Allows binding to fibrin and fibrinogen (easier phagocytosis)
Cocci in clustersStaph
Cocci in pairs and chainsStrep
Partial hemolysisAlpha hemolysis (green): S. Pneumonia and S. Viridans
G+ DiplococciS. Pneumonia
No hemolysisGamma hemolytic: Enterococcus
G+ RodsClostridium
G+ Branching filamentsActinomyces (not acid fast) and Nocardia (acid fast)
Gold pigmentS. aureus
Yellow pigmentActinomyces Israelii
Green-blue pigmentPseudomonas
Red pigmentSerratia marcecens

Bacterial Endotoxins

Question Answer
Where are endotoxins found?Outer membrane of gram negatives (LPS)
3 main targets of endotoxins(1) Macrophages (2) Complement (3) Tissue factor
What inflammatory mediators are activated by Macrophages?IL-1, IL-6
TNF-alphaCell death > Fever, hypotension, Cachexia
How does Complement induce endoctoxin damage?C3a and C3b
C3aHypotension and Edema
C5aNeutrophil Chemotaxis
Tissue factorActivates Coagulation Cascade >> DIC

Bacterial Exotoxins

Question Answer
Inactivates EF-2C. Diptheriae, Pseudomonas
Gray pseudomembranous pharyngitis and bull neckC. Diptheriae (EF-2)
Which organ systems are particularly vulnerable to EF-2?Heart, and nerve cells
Exotoxin APseudomonas
Causes host cell deathPseudomonas: Exotoxin A
Mechanism of shiga toxin?Inactivates 60S ribosome by removing adenine from rRNA
Removes adenine from rRNA on 60S ribosomeShigella (ST) and EHEC 0157:H7 (SLT)
Inhibit protein synthesisInactivate EF-2: Diptheria and Pseudomonas
Inactivate 60S ribosomal subunit: Shigella (ST) and EHEC 0157:H7 (SLT)
Hemolytic anemia
Acute renal failure
HUS: Shigella and EHEC 0157:H7
Dysentary from GI mucosal damageShigella (ST)
What is the difference between Shigella (ST) and EHEC (SLT)?EHEC does not invade host cells
Stimulates cAMP in gut >> Cl- secretion in gutETEC and Cholera
Overactivates cGMP in gut >> Decrease resorption of NaClHeat Stable ETEC (ST)
Mimics adenylyl cyclase enzyme to increase cAMPBacillus anthracis
What are the components of anthrax toxin?Edema toxin (adenylyl cyclase), Lethal factor, Protective antigen
Black escharEdema toxin is AC >> stimulates cAMP
Watery diarrheaETEC (LT, ST), Vibrio cholera
"pseudoappendicitis"Yersinia enterolytica stimulates cGMP
Exotoxin of whooping cough?Pertussis toxin: Disables Gi to increase cAMP
Cleave SNARE proteinsClostridium tetani and botulinum.
What does SNARE usually do?Allows NT release. Inhibits NT when cleaved.
Exotoxin causing spastic paralysis?Tetanospasmin: Cleaves SNARE to prevent release of GABA and glycine (inhibitory neurotransmitters) so that nerves are firing unopposed
Exotoxin causing descending flaccid paralysis?Botulinum: Cleaves SNARE to inhibit ACh release at the NMJ
Exotoxin causing gas gangrene and double zone hemolysis?C.perfringens: Alpha toxin
Alpha toxin?Phospholipase degrades tissue and cell membranes [C. Perfringens]
How do superantigens cause shock?Bind MHII and T cells simultaneously (crosslink) >> Polyclonal T cell expansion >> Uncontrolled cytokine release
Binds to MHCII and TCR to cause release of IL-1, IL-2, IFN-gamma and TNF alphaStaph aureus: TSST-1, S. pyogenes: Exotoxin A
Scalded skin syndromeS. Aureus Exfoliative toxin
Oxygen Stable toxinGAS: Streptolysin S
Oxygen LabileGAS: streptolysin O
Destroys leukocytesS. aureus: Leukocidin toxin
Diarrhea 2-6 hours after eating mayo (eggs, dairy, potato salad)S. aureus enterotoxin (pre-formed, heat stable)

Other Bacterial Virulence Factors

Question Answer
IgA ProteaseS. pneumo, H. influenza