pathogenesis of bacterial infection Flashcards
normal flora ( microbiomes as good bugs commensals and microbiota ) are in or on our body and they —— diseases as most of them are —–
- may cause infection if:
1. —- from usual location
2. —– breached
3. host is —-
- don’t cause diseases
- non-pathogenic
- escape
- barrier
- immunospression
—– bacteria has increased ability to invade or damage the host
—- able to cause a disease bc of their presence within the host
these bacteria can live along normal flora without causing any disease in host aka —-
the genetic/biochemical/structural features of pathogens that enable it or enhances the ability to produce disease is known as —-
- virulent bacteria
- primary pathogens
- colonised
- virulent factors
1.opportunitic bacteria have —- intrinsic virulence which usually don’t cause infections in non immunocompromised patients
2. they may cause serious infections in situations as :
- low
- immunocompromised and forge in body
1.why does infection occur ( steps )
2. how pathogens are transmitted
-the organism is virulent –> the size of the inoculum —-> the portal of entry —> survival in the host —> the state of the host
- get in –> attach to cells —> invade immune system —> cause damage to host cells —> get out and spread further
the 5 types of entry :
1. —– as salmonella in food poisoning
2. ——– as tucerculosrosis
3. ——— staphylococcus aurous
4. —— chalamydia
5. —— group b strepcoccous
- ingestion
- inhalation of droplets of aerosols
- penetration/inoculation
- sexual
- vertical
—- of the bacteria to host cell is required to establish a stable population of bacteria within the host and prevents bacterial clearance from mechanical host defences
- adhesion
adhesion occurs through —– mediated process called —- by which they are small bacterial protein ligands which recognise specific receptors on host cells
- receptor / ligand
- adhesins
—– formation protectrs the bacteria and makes eradication difficult with our the removal of prosthesis
- biofilm
to facilitate invasions pathogens can employ biochemical virulence factors called —– these can be:
- invasins
1. proteins
2. damaged host cells and facilitate spread and invasion
3. hylauronidase , kinase , and collagenase
-the presence of bacteria in the host induces — responses to attempt bacterial eradication
-to ensure ongoing survival bacteria have developed numerous mechanisms to prevent immune mediated clearance which are:
- immune
1. prevents phagocytosis which is the ingestion go bacteria by phagocyte immune wbc as neutrophils
2. survival within the phagocytes
3. immune cell destruction
-inhibition of phagocytosis is done by — which is composed of polysarchide which sits outside the cell membrane
- pathogens associated w meningitis and penunomia as: neisseria meningitides , streptococcus penunomia , hemolphilus influenza )
- capsule
survival within phagocytes:
- they escape the —- aka listeria monocytogene
- prevents —— fusion aka mycobacterium tuberculosis
- survival within —– aka staphylococcus aureus
- phagosome
- phagosome / lysozyme fusion
- phagolysosome
some bacteria are able to produce —- that directly target immune cells or prevent their function such as:
1. —- pore forming enzyme which targets phagocytes ( canton - Valentin leucodicin of staphylococcus aureus )
2. —- pore forming enzyme produced by streptococci
3. —- produced by s. aureus , converts fibrongigen to fibrin which promotes clotting , coats bacteria in fibrin which acts as a barrier to immune cells ( can be tested in the lab to help identify S. auerous )
-enzymes
- leucocidins
- streptolysins
- coagulase
bacterial enzymes damage — cells as well as being important in —- evasion. this is done by:
- host cells
- immune
1. invasins
2. toxins
2. superantigens
—- are compounds/chemicals which are toxic to host cells by directly harming host tissue or by interacting with immune cells. the two types are:
- toxins
- endotoxins and exotoxins
