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Basic bacteriology Flashcards

1
Q

Bacterial structures

A

Petidoglycan, cell wall/membrane (gram pos), outer membrane (gram neg), plasma membrane, ribosome, periplasm, capsule pilus/fimbria, flagellum, spore, plasmic, glycocalyx

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2
Q

Petidoglycan

A

Rigid support, protects from osmotic P

- Sugar backbone, peptide side chains

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3
Q

Cell wall/membrane

A

Gram positives, major surface antigen

- Peptidoglycan for support, lipoteichoic acid induces TNF/IL-1

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4
Q

Outer membrane

A

Gram negatives, site of endotoxin (LPS), major surface antigen (O polysaccharide)
- Lipid A induces TNF/IL-1

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5
Q

Plasma membrane

A

Site of oxidation/transport enzymes

- Phospholipid bilayer

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6
Q

Ribosome

A

Protein synthesis

- 50S, 30S subunits

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7
Q

Periplasm

A

Gram neg; space btwn cytoplasmic membrnae and outer membrane

- Hydrolytic enzymes (B-lactamases)

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8
Q

Capsule

A

Protects from phagocytosis by macrophages/neutrophils

- Made of polysaccharide

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9
Q

Pilus/fimbria

A

Lets bacteria adhere to cell surface
(Conjugation = sex pilus btwn 2 bacteria)
- Glycoprotein

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10
Q

Flagellum

A

Motility

- Made of protein

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11
Q

Spore

A

Resistant to dehydration, heat, chemicals

- Keratin-like coat

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12
Q

Plasmid

A

Genes for abx resistance, enzymes, toxins

- DNA

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13
Q

Glycocalyx

A

Adherence to surfaces (foreign), i.e. indwelling catheters

- Polysaccharide

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14
Q

Unique structure of gram negative

A

Endotoxin/LPS and periplasm

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15
Q

Unique structure of gram positive

A

Lipoteichoic acid

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16
Q

Both gram neg/pos

A

Flagellum, pilus, capsule, peptidoglycan, cytoplasmic membrane

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17
Q

Bacterial taxonomy

A

Circular, rod, branching, pleomorphic, spiral no cell wall

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18
Q

Circular

A

Coccus

  • Gram +: staph, strep
  • Gram -: Neisseria
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19
Q

Rod

A

Bacillus

  • Gram +: Clostridium, corynebacterium, bacillus, listeria, mycobacterium (acid fast), gardernella
  • Gram -: most (enteric, respiratory, zoonotic)
20
Q

Branching filamentous

A

Gram +: Actinomyces nocardia

21
Q

Pleomorphic

A

Rickettsia, chlamydiae

22
Q

Spiral

A

Spirochetes

- Borelia, leptospira, treponema

23
Q

No cell wall

A

Mycoplasma - contain sterols, no cell wall

24
Q

Gram stain limitations

A

TMMLRC - these microbes may lack real color

- Treponema, mycobaceria, mycoplasma, legionella (silver stain), rickettsia, chlamydia

25
Stains
Giemsa, PAS, Ziehl-Neelson (acid-fast), India ink (cryptococcus n), silver stain (fungi, legionella, H. pylori)
26
Obligate aerobes
Use O2-dependent system to make ATP * "Nagging Pests MustBreath" = Neisseria, pseudomonas, MycoBacteriumTB - Reactivation of TB in apices of lung (highest PO2) - P. aeruginosa - aerobe in burn wounds, diabetes, nosocomial/CF pneumonia
27
Obligate anaerobes
* "Anaerobes Can't Breathe Air" = Clostridium, Bacteriodes, Actinomyces - Lack catylase or SOD --> susceptible to superoxide damage - Nl in GI, abn everywhere else - Sx: Foul smelling, hard to culture, make gas in tissue - AminO2glycosides - ineffective bc need O2 to enter bacterial cell
28
Encapsulated bacteria
Strep pneumoniae, Hib, Neisseria meningitis, E. coli, Salmonella, Klebsiella, group B Strep (SHiNESKiS) - Capsules = antiphagocytic virulence factor (from macrophages/neutrophils) - Opsonized + cleared by spleen; asplenic pts are incr risk of infections from encapsulated bacteria * Give H. flu, S. pneumoniae, N. meningitis vaccines*
29
Catalase-positive organisms
Catalase degrades H2O2 before MPO can convert to bleach (ROS) - Chronic granulomatous disease = NADPH oxidase deficiency --> recurrent infections w/ these organisms *"PLACESS for your CATs" - pseudomonas, listeria, aspergillus, candida, E. coli, S. aureus, Serratia
30
Encapsulated bacteria vaccines
``` Conjugated vaccines - take polysaccharide capsule, present to/activate T cells --> class switching - Pneumococcal, HiB, meningococcal vaccines ```
31
Urease-positive bugs
"CHuck Norris hates weird PUNKSS" - cryptococcus, H. pylori, proteus, ureaplasma, nocardia, klebsiella, S. epidermidis, S. saphrophyticus (epidermidis/saphrophyticus = weird staph)
32
Pigment-producing bacteria
- Actinomyces israelii = yellow "sulfur" granules (filaments/bacteria) * Israel has yellow sand - S. aureus = yellow pigment * Aureus = gold - Pseudomonas aeruginosa = blue-green pigment * Aerugula = green - Serratia marcescens = red pigment * Red maraschino cherries
33
Bacterial virulence factors
Promote evasion of host immune system - Protein A - IgA protease - M protein
34
Protein A
Virulence factor, expressed by S. aureus | - Binds Fc region of IgG, prevents opsonization/phagocytosis
35
IgA protease
Virulence factor, enzyme cleaves IgA (which regulate mucosal penetration, esp respiratory) - SHiN = S. pneumoniae, HiB, Neisseria
36
M protein
Virulence factor, from Group A strep | - Prevents phagocytosis + complement activation
37
Exotoxin features
Some gram pos and gram negatives, secreted from cell, made of polypeptide - Genes in plasmid/bacteriophage - High toxicity --> induces antitoxicity (high-titer Abs) - Toxoids formed, used for vaccine - Not heat stable (destroyed at 60C, rapidly) Examples: tetanus, botulism, diptheria
38
Endotoxin features
Outer cell membrane of most gram negatives (cocci and rods) - Genes in bacterial chromosome - Not secreted from cell, made of LPS (structure of bacteria = toxin when lysed) - Induces TNF, IL-1, IL-6 --> causes fever, shock, DIC - No vaccines available (bc no toxoid formed) - Heat stable (100C for 1 hr) Example: meningococcemia, sepsis by gram neg rods
39
Endotoxin mechanism
Activates macrophages, complement, tissue factor Macrophages: - IL-1 = fever, TNF = fever/hypotension, NO = hypotension Complement: - C3a = hypotension, edema, C5a = neutrophil chemotaxis Tissue factor: coag cascade/DIC ENDOTOXIN - edema, NO, DIC/death, outer membrane(LPS), TNF-a, O-antigen, eXtremely heat stable, IL-1, Neutrophil chemotaxis
40
Bacterial genetics
Transformation, conjugation, transposition, transduction
41
Transformation
Take up naked DNA (cell lysis) from environment --> any DNA can by used - See in SHiN * Add DNAase to environment --> degrade naked DNA --> no transformation seen
42
Conjugation
F+ plasmid has genes for sex pilus/conjugation - Plasmid (dsDNA) = replicated/transferred through pilus of F+ - Chromosomal genes not transfered Hfr cell = F+ plasmid can be incorporated to bacterial chromosomal DNA - Replication of incorporated plasmid DNA can include flanking chromosomal DNA = plasmid + chromosomal genes transfered
43
Transposition
Segment of DNA that can jump from 1 location to another --> can transfer genes from plasmid to chromosome (or vice versa) - Can include chromosomal genes flanking --> incorporate into another bacterium
44
Transduction
Uses viral replication - Lytic = separate DNA w/in bacteria - Lysogenic = incorporated into host DNA * Generalized vs. specialized*
45
Generalized transduction
Generalized = packing event - Lytic phage (sep from host/bacterial DNA) infects bacterium --> cleaves bacterial DNA - Parts of bacteria can be packaged into viral capsid --> infects other bacterium, transfers genes btwn bacteria
46
Specialized transduction
Specialized = excision event - Lysogenic phage (in host/bacterial DNA) infects bacterium + viral DNA incorporates into bacterial chrom - Phage DNA excised + flanking bacterial genes excised/packaged --> infect other bacterium * ABCDE = shigA-like toxin, Botulinum toxin, Cholera toxin, Diptheria toxin, Erythrogenic toxin of strep pyogenes

Microbiology (7 decks)

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