prokaryote
- bacteria
- small unicellular organisms
- all proteins begin with a special amino acid, formylmethionine
eukaryote
- fungi, plant cells, protozoa, metozoa, human cells
- all proteins begin with the amino acid methionine
bacterial motility
flagella, axial filament
attachment and conjugation between bacteria
pili/fimbriae
1. attachment to cells/tissues
2. to some extent can pull bacteria along the surface of cells so motility
3. sex pilus (transfer of plasmid)
bacterial capsule or glycoclyx
function: evasion from white blood cells
peptidoglycan
lattice structure like a mesh
lipopolysaccharide
outer membrane, only g-
- lipid a: endotoxin anchors in bacterial outer membrane
- polysaccharide: o antigen projects outward from the cell
teichoic and lipoteichoic acids
only gram +
- attached to peptidoglycan layer, project outwards and cause cells to have a negative charge
plasma membrane: human vs. fungi cells
- human cell plasma membrane contains cholesterol
- fungi cells plasma membrane contains ergosterol
endospores
- resting cells
- genetic material within a
hard coat - resistant to heat
- drying
- UV radiation
- chemicals
(function for bacteria is survival) - produced by clostridium and bacillus
Clostridium difficile
- A major cause of nosocomial infection globally
- Anaerobic Gram + rod that produces endospores
What kind of organism is C. difficile?
- Strict anaerobe, Gram-positive bacillus, spore forming
- fecal-oral transmission
spores are not living
spores not inactivated by antibiotics, alcohols, or alcohol based hand cleansers
Virulence factors and Pathogenicity of C. difficile
- Spores are ingested, not affected by stomach acid and
germinate in the intestine after contact with bile acids - Exotoxins made by vegetative bacteria damage intestinal mucosa, kill cells and cause epithelium to leak leading to watery diarrhea
C. difficile endotoxins
- TcdA
- TcdB
CDT- C difficile binary toxin
C. difficile syndromes
- dehydration
- diseases are:
AAD (antibiotic associated diarrhea) - AAC (antibiotic associated colitis)
- CDAD (Clostridium difficile associated diarrhea)
- PMC (pseudomembranous colitis)
- Toxic megacolon (gangrene of intestines)
- Death
children under 2 with C. difficile
never have symptomatic
C. difficile infection but they may harbour the bacterium
conventional treatment of C. difficile
antibiotics
- nonconventional treatment of C. difficile
- probiotics
- fecal implants
bacteria not stained by grams stain
- Mycobacterium sp i.e. M. tuberculosis (causes TB)
(cell wall has peptidoglycan but large amounts of mycolic acid which prevent stain penetration) - Mycoplasma sp i.e. M. pneumoniae (causes pneumonia)
(no cell wall and no peptidoglycan; contains large amounts of sterols)
