pathogenesis Flashcards
pathogenesis
1) the mechanism by which microorganisms cause disease
where does crystal violet bind
1) peptidoglycan
why stain bacteria
1 )to see them
2) distinguish + from -
which type have a pentaglycine bridge in their peptidoglycan
1) +
if transpeptidases bind penicillin what does this imply
1) enzyme that links the peptides in peptidoglycan will be inactivated
where do peptides bind on the glycans
1)
murein
1) is another name for peptidoglycan
which bacteria have teichoic acid and lipoteichoic acid
1) gram +
what kind of phospholipids are found in the cytoplasmic membrane of bacteria
1) dipalmitoylphosphatidylcholine in our lungs
2) Phosphatidylethanol?
why type of secretion systems inject exotoxins into other cells
1) type III and IV
what diseases do p gingivalis and aeruginosa cause
1) periodontitis
2) cystic fibrosis
why is there a lag phase in bacterial growth
1) allow bacteria to adapt to environment
stationary phase
1) reproducing at same rate as death
endospores
1) can survive in tough environment
which pathogenic bacteria form endospores
1) clostridium species
- tetani, etc
how was semi conservative replication discovered
1) labeled and unlabeled DNA
transcriptional regulation in bacteria
1) discovered by French people - Jacques Moneau?
endemic
1) constantly present at a low levell
epidemic
1) infection occurs much more frequently than usual
pandemic
1) worldwide distribution
cause disease by 2 mechanisms
1) invasion and inflammation
2) toxin production
- exotoxin
- endotoxin - LPS of cell wall in gram - bacteria cause fever and shock
symptoms of shock
1) low BP
2) high or low temp
3) cool, pale arms
4) rapid heart rate
5) shortness of breath
septic shock
1) broad spectrum anitboitic
2) then narrow spectrum
3) vasopressors
4) corticosteroids and insulin
aspects of infection control
1) symptomatic
2) subclinical
- unapparent
3) latent
- stable
chronic carrier
1) organisms continue to grow in the host with or without symptoms
2) salmonella typhi (survive and multiple in gall bladder)
- thyphoid mary
lytic infection
cells lyse and release virions
persistent infections
few virions
latent infections
genome remains in the host cell
transforming infection
infected cell becomes cancerous
- ex. HPV, and epstein barr virus
viral cytopathology
1) inhibit cellular protein or DNA
2) altering structure of cell membrane
3) syncytium formation (cell cell fusion)
4) most recent development regarding RSV
- inclusion (proteins the cell is producing for virus)
virulence factors
1) invade
2) adhere or colonize
3) avoid or subvert defenses
4) multiply
opportunistic
1) certain bacteria like mycobacterium avium or fungi (c. albicans) cause disease only in immunocompromised individuals
2) HIV AIDS
3) malignancies
4) immunosuppressive therapy
transmission
1) most infections are exogenous
- m. tuberculosis
2) others are endogenous
- e. coli
transmission
1) respiratory tract
- influenza
- measles
- tb
2) gastrointestinal
- vibrio cholerae
- norovirus
- giardia
3) skin
4) congenital-transplacental
- rubella
5) zoonoses
- rabies, avian influenza
6) skin, blood, genitals
attachment to host surfaces
1) specialized structures or produce substances that facilitate attachment to the surface of cells or prostheses
- ex dentures, heart valves, catheters
2) viruses bind specific receptors of host cells
- ex HIV binds CD4 molecule on T helper
- coronavirus binds ACE2 on lung epithelial cells
pili
1) fimbriae
- e. coli attachment to surface of urinary tract
2) teichoic acids in the outer layer of gram + attach to mucosal cells
biofilms
1) major source of agents that cause tooth decay
2) produce matrix proteins that prevent antibiotic attak
3) biofilm grows and organisms attack other sites
4) polysaccharide matrix that is self produced
5) biofilm asossiated organsims differ from planktonic
biofilms can form on
2) living tissue
2) indwelling medical devices
4) water lines
collagenase and hyaluronase
1) degrade collagen and hyaluronic acid
coagulase
1) fibrin clot to prevent immune system from reaching it
leukocidins
1) destroy neutrophils macrophages
- AA
streptolysin
1) streptococcus pyogenes
Panton valentine leukocidin
s. aures
1) cause destruction of host cell by lysosome leakage
leukotoxin of AA
1) apoptosis in lymphocytes
2) caspase 1 in macrophages => IL-1
pyogenic
1) pus producing
2) neutrophils predominate
2) common bacteria
- staph aureus
- strep pyogenes
- strep pneumoniae
pustular impetigo
1) pus producing inflammation caused by staph aureus
granulomatous
1) macrophages and t cells
2) mycobacterium tuberculosis
- cell-mediate immune responses causes granuloma and tubercle formation
- lysing of tubercles cause reactivation
interferon alpha and cytokines
1) flu like symptoms (fever, headache, malaise)
cell mediated immunity
1) measles and mumps
immune complex formation
1) hep B interacts with antibodys
- forms antigen antiviral antibody complex
- activates complement and tissue damage
hemorrhagic disease
1) yellow fever and dengue
2) excessive immune activation on 2nd exposure
lipopolysaccharides
1) released when bacteria dies
2) lipid A portion has endotoxic activity
3) can activate macrophages
- secrete TNF and cause fever
4) lipopolysaccharides and platelets
- disseminated coagulation
exotoxins
1) polypeptides (proteins) genes are located on plasmids or lysogenic bacterial viruses (phages)
2) two subunits
- A (active has inhibitory activity
- B (binds to specific surface receptor)
exotoxins are among the most toxic substances known
1) neutralize with acid, heat, or formaldehyde
( toxoids)
2) exotoxins are strong immunogens and induce synthesis of protective antibodies (antitoxins)
neurotoxin
1) tetanus toxin
shiga 1 and shiga 2
1) toxins from shigella dystenteriaee
enteric syndromes
1) cholera toxin
2) vibrio cholerae
superantigens
1) toxic shock syndrome of staph aureus
2) staphylococcal enterotoxins
3) activate large numbers of T cells to release interleukins
- cytokine storm
4) IL-1, IL-2, and TNF cause life threatening immune response
mechanism for escaping host defense
1) TB can secrete things that prevent release of lysosomes
2) stays in there and multiples
capsule
1) most important
biofilms
1) prevent binding of antibody and complement to bacteria
antigenic variation
1) expressing different proteins so immune system is confused
inactivation of antibody or complement
1) s. pyogenes degrades C5a
2) IgA protease degrades IgA on mucosal surfaces
iron transport in bacteria
1) siderophores
- need iron for ribonucleotide reductase and bacterial cell replication
- complex iron for uptake
