Lecture 9 practice exam

• Constitute largest group of human bacterial pathogens • Due in part to lipid A (found when TRL 4 is activate) in the bacterial cell wall • Triggers fever, vasodilation, inflammation, shock

• Intestinal microbiota of most animals and humans • Ubiquitous in water, soil, and decaying vegetation • Enteric bacteria are the most common Gramnegative pathogens of humans

Physiology • G- Motile bacilli and coccobacilli (just cause its gram stained does not mean we know its species) • ferment glucose • Grow best in aerobic environments • Species distinguished based on: • biochemical properties • motility\ • colony characteristics

Pathogenesis • Membrane components • Protein and polysaccharide capsular antigens • Used to distinguish among strains and species • Numerous virulence factors

Uses secretion for proteins that could phagocytes it out.

The deposit type 3 toxins (exotoxins) inside the cell.

toxins are shot right into the cells to kill or live inside cells.

Pathogens use adhesion to stick to cells to transfer type 3 secretions.

Out of the human body, they don't have a capsule. within-host they use capsules as a virulence factor to infect humans.

Plasmid within bacteria contain genetic information to infect host.

Iron-binding proteins within DNA

MacConkey Agar are made of bio salts and are found in bile salts.

Gram-positive dies Gram-negative salts grow in MacConkey and have a reddish-purple color.

Salt agar turns yellow.

Lab test within the intestinal tracts

Turn because it ferments lactose

Positive for lactose and gas

Positive lactose and negative gas

red color are both negative neither lactose nor gas

Aerobic or facultatively anaerobic • Gram-negative • rod-shaped bacteria that ferment lactose to form gas in lactose broth

Both compete for nutrition in the environment (Host)

Both create a siderophore unique to it.

iron binds to the siderophore

once bonded they act as complex

Both will bind to the siderophore of one another and bind to iron.

Iron is released into cells and gets into the blood.

The two must compete for iron within the blood.

the more siderophore the more bacteria can grow within host.

Escherichia coli

•Most common of the coliforms

•E. coli antigens used to identify particular strains (variation of the gene)

•Flagella (E.coli can be identified by its flagella)

•O-antigen

different enzymes will add different carbons

Virulent strains may have genes for:

•fimbriae

•adhesins

•Exotoxins

•Often dependent on TTSS

Type 3 secretion injects a toxin into the cell

(bacteria cells) secretion enter cells

•Pathogenic strains have virulence plasmids

•Have genes for fimbriae, adhesins, and exotoxins

•diarrhea, cramps, nausea, and vomiting

•Often mediated by enterotoxins (depending on the strain)

•Major cause of pediatric diarrhea in developing countries

produces enterotoxins damage the microtubule forms biofilms (produces microvilli which help us absorb nutrients)

aggravate the cells

Adherent invasive E. coli (AIEC)

M cells are present in absence of microvilli.

M. cell identifies any possible infections from viruses

E.coli takes advantage of M.cells by adhering to them to get through tissue

replicating of

forms biofilms

(take advantage of damaged microvilli and invade macrophages. the macrophages use Toll-like receptors to clear out infections. Though the process is beneficial to the body, nonetheless in this process tissues are damaged)

intracellular pathogens that penetrate the intestinal epithelium through M cells to gain access to the submucosa.