Microbiology - Basic Bacteriology

zepowulu's version from 2016-03-15 18:29

Section 1

Question Answer
Peptidoglycangives support, protects against osmotic pressure, sugar backbone w/cross-linked peptide side chains
Cell wallonly in G+, major surface Ag, makes peptidoglycan for support, *Lipoteichoic acid induces TNF and IL1
outer membraneonly in G-, site of endotoxin (LPS), major surface Ag, lipid A induces TNF/IL1- polysaccharide is the Ag
Plasma membrane site of oxidative/transport enzymes, lipoprotein bilayer
Ribosome50s and 30s subunits
Periplasmbetween cytoplasmic membrane and outer membrane in G-, has hydrolytic enzymes, including B-lactamases
Capsuleprotects against phagocytosis, made of polysaccharide (except bacillus anthracis which has D-glutamate)
Pilus/fimbriamediate adherance of bacteria to cell surface, sex pilus forms during conjugation, made of glycoprotein
Sporeprovides resistance to dehydration, heat, and chemicals, has keratin-like coat, made of dipicolinic acid
Glycocalyxmediates adherence to surfaces, esp foreign surfaces (catheters), made of polysaccharide

Section 2

Question Answer
Circular Gram PositivesStaph and Strep
Circular Gram NegativesNeisseria
Branching filamentousActinomyces and nocardia (weakly acid fast)
Pleomorphic morphologyrickettsiae, chlamydiae
Spiral bacterialeptospira, borrelia (Giemsa), treponema
No cell wall bacteriamycoplasma (has sterols and no cell wall)
Mycolic acid bacteriamycobacteria, high lipid content
Gram Postive Rodsclostridium, corynebacterium, bacillus, listeria, mycobacterium (acid fast)
Gram Negative Rods: EntericsE coli, shigella, salmonella, yersinia, klebsiella, proteus, enterobacter, serratia, vibrio, campylobacter, helicobacter, pseudomonas, bacterioides
Gram Negative Rods: Respiratory bugsHaemophilus, Legionella, Bordetella
Gram Negative Rods: Zoonotic bugsFrancisella, Brucella, Pasteurella, Bartonella

Section 3

Question Answer
Gram Stain LimitationsThese Rascals May Microscopically Lack Color- Treponema (too thin), rickettsia (intracellular), myocbacteria (lots of lipid requires acid fast), mycoplasma (no wall), legionella (intracellular), chlamydia (intracelluar no muramic acid in wall)
Giemsa stainCertain Bugs Really Try my Patience
Chlamydia, Borrelia, Rickettsiae, Trypanosomes, Plasmodium
PAS (periodic acid-Schiff)Stains glycogen, mucopolysaccs- used to dx Whipple's disease (tropherymam whippelii)
Ziehl-Neelsenacid fast orgs (Nocardia, Mycobacterium)
India inkcryptococcus
Silver stainfungi (pneumocystis), legionella, helicobacter pylori
H flu culturechocolate agar w/factor V (NAD+) and X (hematin)
N. gonorrhoeae cultureThayer Martin media (VPN)- Vancomycin (no G+), polymyxin (no G-), Nystatin (no fungi)
B. pertussis culturepotato agar (Bordet-Gengou agar)
C. diphtheriae culturetellurite plate, Loffler's media
M. tuberculosis culturelowenstein-jensen agar
M. pneumoniae cultureeaton's agar
Legionella culturecharcoal yeast extract agar
Fungi culturesabouraud's agar
EMB agargrow E. coli on eosin-methylene blue and see blue/black colonies with green sheen
MacConkey's agargrow lactose fermenting enterics and see pink colonies from acid

Section 4

Question Answer
Obligate aerobesNagging Pests Must Breathe- nocardia, pseudomonas, mycobacterium, bacillus
Obligate anaerobesCan't Breathe Air- Clostridium, bacteroides, actinomyceS. s- no catalase and/or superoxide dismutase-->susceptible to oxidative damage, foul smelling and hard to culture, make gas in tissue (CO2/H2)
Obligate intracellularrickettsia, chlamydia
Facultative intracellularSome Nasty Bugs May Live FacultativeLY- Salmonella, neisseria, brucella, mycobacterium, listeria, francisella, legionella, yersinia
Urease + bugsCH PUNKSS
Cryptococcus, H. pylori, Proteus, Ureaplasma, Nocardia, Klebsiella, S. epidermidis, S. saprophyticus
Pigment producing bacteriaactinomyces israelli (yellow sulfur), S. aureus (yellow), Pseudomonas aeruginosa (blue green), Serratia (red)
Protein AS. aureus, binds Fc region of Ig, prevents opsonization and phagocytosis
IgA proteaseenzyme that cleaves IgA, secreted by S pneumo, H. flu, and Neisseria (SHiN)
M proteinhelps prevent phago (group A strep)

Section 5

Question Answer
Positive quellung rxnif encapsulated bug is present capsule swells when anticapsular antisera are added
Encapsulated bacteria+ quellung, SHiNE SKiS
Step Pneumo, H. influenza type B, Neisseria meningitidis, E. coli, Salmonella, Klebsiella pneumoniae, group B Strep
Capsules have virulence vactor, SHiN makes IgA protease, cause meningititis, and take up DNA from environment

'' Some Killers Have Nice Shiny Capsule +E.coli ""
Exotoxin sourcesome G+ and G-
Endotoxin sourceouter cell membrane of most G- bacteria and Listeria
Exotoxin and Endotxin secreted from cellexo is secreted from cell, endo is not
Chemistry of exotoxin and endotoxinexo made of polypeptdes, endo made of LPS
Location of genes for exo and endotoxinsexo is plasmid/bacteriophage, endo is bacterial chromosome
Toxicity of exo vs endotoxinshigher for exo (1microgram)
Clinical effects of endotoxin and mode of actionfever and shock, production of TNF and IL1
Antigenicity of exo vs endotoxinexo has high titer antibodes called antitoxins, endotoxin is poorly antigenic
Vaccine use of exo or endotoxinstoxoids used as vaccines for exotoxins, no vaccines from endotoxins
Heat stability for exo vs endotoxinsexo destroyed at 60deg, endotoxins stable at 100 for 1 hr
Diseases with exotoxinstetanus, botulism, diphtheria
Diseases with endotoxinsmeningococcemia, sepsis by G- rods

Bugs with Exotoxins

Question Answer
Bugs that inhibit protein synthesisPECS
P. aeruginosa
Enterohemorrhagic E. coli (EHEC) incl. 0157:H7 strain
C. diphtheriae
Shigella spp.
Bugs that increase fluid secretionEnterotoxigenic E. coli (ETEC)
Bacillus anthracis
Vibrio cholerae
Bugs that inhibits phagocytic abilityBordetella pertussis
Bugs that inhibit release of neurotransmitterClostridium tetani
Clostridium botulinum
C. diphtheriae toxin and mechanismDiphtheria toxin
Inactivate elongation factor (EF-2)
P. aeruginosa toxin and mechanismExotoxin A
Inactivate elongation factor (EF-2)
Shigella spp. toxin and mechanismShiga toxin (ST)
Inactivate 60S ribosome by removing adenine from rRNA
Enterohemorrhagic E.coli (EHEC) toxin and mechanismShiga-like toxin (SLT)
Inactivate 60S ribosome by removing adenine from rRNA
Enterotoxigenic E.coli (ETEC) toxin and mechanismLabile in the Air(heat labile toxin (LT): ↑cAMP → ↑ Cl secretion in gut and H20 efflux
Stable on the Ground (Heat-stable toxin (ST): ↑cGMP → ↓ resorption of NaCl and H20 in gut
Bacillus anthracis toxin and mechanismEdema factor
Mimics the adenylate cyclase enzyme (↑ cAMP)
Vibrio cholerae toxin and mechanismCholera toxin
Overactivates adenylate cyclase by permanently activating Gs → ↑ Cl secretion in gut and H20 efflux
Bordetella pertussis toxin and mechanismPertussis toxin
↑ cAMP by disabling Gi, impairing phagocytosis to permit survival of microbe
C. tetani toxin and mechanismTetanospasmin
Cleave SNARE protein required for neurotransmitter release
C. botulinum toxin and mechanismBotulinum toxin
Cleave SNARE protein required for neurotransmitter release
Bugs that lyse cell membranesC. perfringens
Strep. pyogenes
Bugs with superantigens causing shockStaph a.
Strep. pyogenes
C. perfringens toxin and mechanismAlpha toxin
Phospholipase that degrades tissue and cell membranes
Strep. pyogenes toxin and mechanism (lyse cell membranes)Streptolysin O
Protein that degrades cell membrane
Staph aureus toxin and mechanismToxic shock syndrome toxin (TSST-1)
Bring MHC II and TCR in proximity to outside of antigen binding site to cause overwhelming release of IFN-gamma and IL-2 → shock
Strep. pyogenes toxin and mechanism (causes shock)Exotoxin A
Bring MHC II and TCR in proximity to outside of antigen binding site to cause overwhelming release of IFN-gamma and IL-2 → shock
cAMP inducersvibrio cholerae (permanently activates Gs-->rice water diarrhea), pertussis (disables Gi permanently-->whooping cough), E.coli (ETEC- heat labile toxin), bacillus anthracis (edema factor is an adenylate cyclase to increase cAMP)
Which toxins act via ADP ribosylation to permanently activate endogenous adenylate cyclase?Ecoli, pertussis, cholera (anthrax edema factor is an adenylate cyclase in itself)
ADP ribosylating A-B toxinsinterfere with host cell function, B (binding) component binds to receptor on surface of host cell-->endocytosis, A (active) component then attaches an ADP-ribosyl to host cell protein altering protein function

Section 7

Question Answer
EndotoxinEdema via C3a
Nitric oxide - Hypotension/shock
Outer membrane - LPS in G(-) outer membrane (Listeria is only G+ with endotoxin)
TNF-a - hemorrhagic tissue necrosis
eXtremely heat stable
IL-1 - fever
Neutrophil chemotaxis via C5a
Bacterial growth curvelag phase (metabolic activity), log (rapid cell division), stationary (nutrient depletion slows growth, spores form in some), bacterial death phase due to inc. waste products and nutrient depletion
Transformationtake up DNA from environment (competence),many bacteria can have this but specifially SHiN: Spneumo, Hflu, Neisseria
Conjugation F+ x F-F+ plasmid has genes for conjugation, otherwise they are F-, plasmid replicated/transferred thru pilus from F+ cell, plasmid DNA only (no chromosomal genes)
Conjugation F- x HfrF+ plasmid can be incl. into bacterial xsomal DNA termed Hfr cell, transfer of plasmid AND xsomal genes
Generalized transduction"packaging event", lytic phage infects bacteri-->cleavage of bacterial DNA and synth of viral proteins-->part of bacteria xsomal DNA can be put into viral capsid
Specialized transduction"excision event", lysogenic phage infects bacterium-->viral DNA into bacterial xsome, when phage DNA is excised flanking bacterial genes may be excised also, DNA into phage viral capsid and can infect another bacterium
Transpositionsegment of DNA can jump from 1 location to another, transfer genes from plasmid to xsome and vice versa, when excision happens some flanking xsomal DNA can be incoporated into plasmi and transferred to other bacterium
Lysogeny, specialized transductionABCDE, shigA-like toxin, botulinum toxin, cholera toxin, diphtheria toxin, erythrogenic toxin of S. pyogenes