BIOC2306 Bacterial Disease

3 types of bacteria

pathogenic

conditionally pathogenic/opportunistic

nonpathogenic

koch’s postulates

MO present in every case of disease

must be isolated from diseased host and grown in pure culture

disease reproduced when MO innoculated into healthy suseptible host

MO must be recoverable from experimentally infected host and is identical to causative agent

role of normal flora/microbiome in body

provides colonisation resistance

has many conditional pathogens

a major source of disease

types of infection

endogenous and exogenous

types of exogenous routes of infections

resp route, fecal-oral, veneral spread, vector mediated

define zoonosis

infectious disease transmitted from animal to human (opp = reverse zoonosis)

may or may not cause disease in animal host

Tuberculosis

primarily an infection of the lungs

latent and active infection

granuloma formation, nectrosis and fibrosis

MDR and XDR TB (multi and extensively)

bacterial pneumonia

02 transport thru alveoli compromised

leakage of bact into bloodstream

is there synergy between viral and bacterial disease

yes, can often coincide

why are HIV patients more likely to die of TB

latent infections more likely to become active

define exotoxin mediated disease

either ingestion of preformed toxin (botulism) or toxin prod during infection (cholera)

worst symptoms of cholera infection

rapid dehydration

electrolyte imbalance

mechanism of action of cholera toxin/choleragen

A (active) subunit = toxin, B (binding) subunit = delivery portion

B binds GM1 ganglioside receptor on enterocytes (ep cells) receptor mediated endocytosis, to golgi, to ER, A subunit transloc into cyto.

stim adenylate cyclase to gen cAMP to pi PKA to pi channels to open to secrete ions into lumen, follow by water movement

most common cause of septic shock

enterotoxin like lipopolysaccharide, cause multiple organ failure. (via stim rel of pro-inflam cytokines by macrophages)

how prev bact disease

disinfect/sterilise

aseptic technique

decolonisation and prophylactic antibacterials (preventative)

vaccination

treatment of bact diseases

antibac chemotherapy

antitoxin

other (surgery, electrolyte replacement…)