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Microbiology > Basic bacteriology > Flashcards

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
Q

Stains

A

Giemsa, PAS, Ziehl-Neelson (acid-fast), India ink (cryptococcus n), silver stain (fungi, legionella, H. pylori)

26
Q

Obligate aerobes

A

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
Q

Obligate anaerobes

A
  • “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
Q

Encapsulated bacteria

A

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
Q

Catalase-positive organisms

A

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
Q

Encapsulated bacteria vaccines

A 
Conjugated vaccines - take polysaccharide capsule, present to/activate T cells --> class switching
- Pneumococcal, HiB, meningococcal vaccines
31
Q

Urease-positive bugs

A

“CHuck Norris hates weird PUNKSS” - cryptococcus, H. pylori, proteus, ureaplasma, nocardia, klebsiella, S. epidermidis, S. saphrophyticus (epidermidis/saphrophyticus = weird staph)

32
Q

Pigment-producing bacteria

A
  • 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
Q

Bacterial virulence factors

A

Promote evasion of host immune system

  • Protein A
  • IgA protease
  • M protein
34
Q

Protein A

A

Virulence factor, expressed by S. aureus

- Binds Fc region of IgG, prevents opsonization/phagocytosis

35
Q

IgA protease

A

Virulence factor, enzyme cleaves IgA (which regulate mucosal penetration, esp respiratory)
- SHiN = S. pneumoniae, HiB, Neisseria

36
Q

M protein

A

Virulence factor, from Group A strep

- Prevents phagocytosis + complement activation

37
Q

Exotoxin features

A

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
Q

Endotoxin features

A

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
Q

Endotoxin mechanism

A

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
Q

Bacterial genetics

A

Transformation, conjugation, transposition, transduction

41
Q

Transformation

A

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
Q

Conjugation

A

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
Q

Transposition

A

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
Q

Transduction

A

Uses viral replication

  • Lytic = separate DNA w/in bacteria
  • Lysogenic = incorporated into host DNA
  • Generalized vs. specialized*
45
Q

Generalized transduction

A

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
Q

Specialized transduction

A

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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