1. bacteria as pathogens

go through bacteria fcs ab gram pos and neg

yeah

HOW BACTERIA CAUSE DISEASE

• once pathogenic bacteria get into the body they cause symptoms of disease

• some cause them as a result of the way they invade and destroy host tissues

• most bacteria make people unwell through toxins they make as a by-product of their metabolism (chemical reactions)

• toxins may incapacitate whole host organisms or just its immune system

• toxins classed as endotoxins and exotoxins

ENDOTOXINS

• lipopolysaccharides (part of outer cell wall of Gram-neg bacteria)

• lipid part acts as toxin and polysaccharide stimulates an immune response

• have an effect around site of bacterial infection when some bacteria lyse

ENDOTOXINS- DISEASE

• symptoms usually fever, vomiting and diarrhoea (seen w/ strains of Salmonella and E.coli)

• diseases caused by endotoxins are often not fatal but symptoms they cause can lead to death

• antibiotics can kill these bacteria but this can lead to more endotoxins being released and symptoms worsening

EXOTOXINS

• soluble proteins produced and released into body by bacteria as they metabolise and reproduce in cells of host

• produced by both gram pos and neg bacteria but Staphylococcus aureus (pos) is named example in spec

• effects often more widespread and act at sites far away from infecting bacteria

EXOTOXINS- DISEASE

• many diff types causing specific damage

• some damage cell membranes causing cell breakdown or internal bleeding

• some act as competitive inhibitors to neurotransmitters

• others directly poison cells

HOST TISSUE INVASION

• invading host tissue and damaging cells is third way bacteria act as pathogens

• response of host organisms to this cell damage that causes symptoms of disease

• often, cell damage is also linked to production of exotoxins or presence of endotoxins in bacterial cell walls