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Flashcards in Bacterial Structures Deck (34)
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1

Peptidoglycan function and chemical composition

-provides rigid support, protects against osmotic pressure
- made of sugar backbone with peptide side chains cross-linked by transpeptidase

2

Cell wall function and chemical composition

- major surface antigen
- peptidoglycan for support
- Lipoteichoic acid induces TNF and IL-1

3

Outer membrane function and chemical composition

present in gram negatives
- site of endotoxin (lipopolysaccharide [LPS])
- major surface antigen
- Lipid A induces TNF adn IL-1
- O polysaccharide is the antigen

4

Plasma membrane function and chemical composition

-site of oxidative and transport enzymes
- made of phospholipid bilayer

5

Ribosome function and chemical composition

- Protein synthesis
- Made of 50S and 30S subunits

6

Periplasm function and chemical composition

-space between cytoplasmic membrane and outer membrane in gram negative bacteria
- Contains many hydrolytic enzymes, including beta-lactamases

7

Pilus/fimbria function and chemical composition

-mediate adherence of bacteria to cell surface; sex pilus forms attachment between 2 bacteria during conjugation
- made of glycoprotein

8

flagellum function and chemical composition

- motility
- made of protein

9

Spore function and chemical composition

- resistant to dehydration, heat, and chemicals
- made of keratin-like coat; dipicolinic acid; peptidoglycan

10

Plasmid function and chemical composition

- contains variety of genes for antibiotic resistance, enzymes, and toxins
- comprised of DNA

11

Capsule function and chemical composition

-protects against phagocytosis
- comprised of organized, discrete polysaccharide layer (except Bacillus anthracis, which contains D-glutamate)

12

Glycocalyx function and chemical composition

- mediates adherence to surface, esp foreign surfaces (e.g. indwelling catheters)
- comprised of loose network of polysaccharides

13

characteristics unique to gram positive bacterial structure

lipoteichoic acid

14

features common to both gram positive and gram negative bacterial

Flagellum
Pilus
Capsule
cell wall
peptidoglycan
cytoplasmic membrane

15

features unique to gram negative bacterial structure

porin
endotoxin/LPS (outer membrane)
Periplasmic space (Beta lactamase location)

16

Bugs that don't gram stain well

-Treponema- too thin to be visualized
-Mycobacteria (high lipid content; mycolic acids in cell wall detected by carbolfuschin in acid-fast stain)
-Mycoplasma (no cell wall)
- Legionella pneumophilia (primarily intracellular)
- Rickettsia (intracellular parasite)
- Chlamydia (intracellular parsite; lacks classic peptidoglycan because of low muramic acid)

"These Microbes May Lack Real Color"

17

How to visualize Tremponemes

Not Gram stain -- too thin to be visualized
- Dark-field microscopy and fluorescent antibody staining

18

How to visualize Legionella

NOT Gram stain since primarily intracellular -- Silver stain

19

For what bugs is Giemsa stain used

Chlamydia, Borrelia, Rickettsia, Trypanosomes, Plasmodium

"Certain Bugs Really TRY my Patience"

20

for what bugs is PAS stain used

- Periodic acid-Schiff
- Stains glycogen, mucopolysaccharides; used to diagnose Whipple disease (Tropheryma whipplei)

"PASs the sugar"

21

For what bugs is Ziehl-Neelsen stain used

- Carbol fuscin
- Acid fast bacteria (Nocardia, Mycobacteria), protozoa (Cryptosporidium oocysts)

22

alternative to Ziehl Neelsen stain

auramine-rhodamine stain for screening--inexpensive, more sensitive but less specific

23

for what bugs is India ink used

detect Cryptococcus neoformans (mucicarmine can also be used to stain thick polysaccharide capsule red)

24

for what bugs is Silver stain used

Fungi (e.g. Pneumocystis), Legionella, Helicobacter pylori

25

Obligate Intracellular bugs

Rickettsia, CHlamydia, COxiella
- rely on host ATP
"Stay inside (cells) when it is Really CHilly and COld"

26

Facultative Intracellular bugs

Salmonella, Neisseria, Brucella, Mycobacterium, Listeria, Francisella, Legionella, Yersinia pestis

"Some Nasty Bugs May Live FacultativeLY"

27

Encapsulated Bacteria examples

Streptococcus pneumoniae, Haemophilus influenzae type B, Neisseria meningitidis, Escherichia coli, Salmonella, Klebsiella pneumoniae, Gropu B strep

"SHiNE SKis"

- capsules serve as antiphagocytic virulence factor
- Capsule + protein conjugate serves as antigen in vaccines

28

How does body deal with encapsulated bacteria

opsonized by spleen. Asplenics have decreased opsonizing ability and thus increased risk for severe infections

- give S. pneumo, H flu, N meningiditid vaccines

29

Encapsulated bacteria vaccines

some vaccines with polysaccharide capsule antigens are -conjugated to a carrier protein, enhancing immunogenicity by promoting T cell activation and subsequent class switching

- Polysaccharide antigen alone can't be presented to T cells

30

Conjugate vaccine examples

Examples
- Pneumococcal vaccine: PCV (pneumococcal conjugate vaccine, ie. Prevnar); PPSV (pneumococcal polysaccharide vaccine with no conjugated protein-- Pneumovax)
- H influenzae type B (conjugate vaccine)
- Meningococcal vaccine (conjugate)