Bacterial Structures Flashcards by k k

Peptidoglycan function and chemical composition

provides rigid support, protects against osmotic pressure

- made of sugar backbone with peptide side chains cross-linked by transpeptidase

How well did you know this?

Not at all

Perfectly

Cell wall function and chemical composition

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

How well did you know this?

Not at all

Perfectly

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

How well did you know this?

Not at all

Perfectly

Plasma membrane function and chemical composition

site of oxidative and transport enzymes

- made of phospholipid bilayer

How well did you know this?

Not at all

Perfectly

Ribosome function and chemical composition

Protein synthesis

- Made of 50S and 30S subunits

How well did you know this?

Not at all

Perfectly

Periplasm function and chemical composition

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

How well did you know this?

Not at all

Perfectly

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

How well did you know this?

Not at all

Perfectly

flagellum function and chemical composition

motility

- made of protein

How well did you know this?

Not at all

Perfectly

Spore function and chemical composition

resistant to dehydration, heat, and chemicals

- made of keratin-like coat; dipicolinic acid; peptidoglycan

How well did you know this?

Not at all

Perfectly

Plasmid function and chemical composition

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

How well did you know this?

Not at all

Perfectly

Capsule function and chemical composition

protects against phagocytosis

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

How well did you know this?

Not at all

Perfectly

Glycocalyx function and chemical composition

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

How well did you know this?

Not at all

Perfectly

characteristics unique to gram positive bacterial structure

lipoteichoic acid

How well did you know this?

Not at all

Perfectly

features common to both gram positive and gram negative bacterial

Flagellum
Pilus
Capsule
cell wall
peptidoglycan
cytoplasmic membrane

How well did you know this?

Not at all

Perfectly

features unique to gram negative bacterial structure

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

How well did you know this?

Not at all

Perfectly

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”

How to visualize Tremponemes

Not Gram stain – too thin to be visualized

- Dark-field microscopy and fluorescent antibody staining

How to visualize Legionella

NOT Gram stain since primarily intracellular – Silver stain

For what bugs is Giemsa stain used

Chlamydia, Borrelia, Rickettsia, Trypanosomes, Plasmodium

“Certain Bugs Really TRY my Patience”

for what bugs is PAS stain used

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

“PASs the sugar”

For what bugs is Ziehl-Neelsen stain used

Carbol fuscin

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

alternative to Ziehl Neelsen stain

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

for what bugs is India ink used

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

for what bugs is Silver stain used

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

Obligate Intracellular bugs

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

Facultative Intracellular bugs

Salmonella, Neisseria, Brucella, Mycobacterium, Listeria, Francisella, Legionella, Yersinia pestis "Some Nasty Bugs May Live FacultativeLY"

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

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

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

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)

Urease positive organisms

``` Cryptococcus H. pylori Proteus Ureaplasma Nocardia Klebsiella S. epidermidis S. saprophyticus ``` "CHuck Norriss hates PUNKSS"

Catalase positive organisms

Nocardia, Pseudomonas, Listeria, Aspergillus, Candida, E. coli, Staphylococci, Serratia "Cats Need PLACESS to hide"

Catalase function

- degrades H2O2 into H2O and bubbles of O2 before it can be converted to microbicidal products by enzyme myeloperoxidase - Ppl with chronic granulomatous disease (NADPH oxidase deficient) have recurrent infections with catalase + organisms

Pigment producing organisms

- Actinomyces israelii = yellow "sulfur" granules composed of filaments of bacteria - S. aureus = yellow/Gold (AU- Gold) - Pseudomonas aeruginosa= blue-green pigment - Serratia marcescens = red pigment (think red maraschino cherries)