Mechanisms of Infectious Disease, chap. 14 Flashcards
Mutualism
both the host and the microorganism benefit.
humming bird and plant
Parasitic
Only the infecting organism benefits
Typically the host does not die
“infectious” means the host sustains injury or pathological damage
Virulence
disease producing potential
Pathogen
very virulent microorganisms. Rarely found in the absence of disease
Saprophyte
Environmental organisms that feed off of dead/decaying material (maggots). Usually fungi
Harmless to humans, but can be opportnistic organisms if host immune system is compromised
Commensal Flora
Gut flora.
Over 300 diff species if bacteria live in the large intest
bacterial and fungi live on our skin
mouth and pharynx contain many bacteria
vagina contains acid-producing bacteria
Prions
Agent of Infection
Abnormally shaped proteins that cause normal proteins to change their shape and this become new prions. Proteins that attack other proteins and turn them into self
Doesnt reproduce. turns others into self
cause neurodegenerating disease of the CNS
Ex. Creutzfeld- Jacob diseasesome
Viruses are:
> small with no organized cell structure
incapable or replicating outside a living cell
Protein coat surrounded by a nucleic acid core
some have lipoprotein envelope, which is why we can treat some but not others
it inserts genome into host cells DNA, ten uses cells energy from other living cells to replicate.
Grouped by: size, composition, replication,transmission, resulting disease, envelope, double/single strand DNA/RNA
Latent Virus
Enter cell and insert genome, remain dormant until stimulated. Wait until defenses and low
Ex. herpes virus and shingles
Oncogenic Virus
Can transform host cell to malignant cells during replication
Ex. HPV, Epstein-Barr, Hep B
Influenza Viruses
H1N1, H3N2
Retrovirus group
Unique replication
Ex. HIV/AIDS
Enterovirus
Single strand RNA virus
Common: saliva, mucous, stool
Ex. Poliomyelitis
Bacteria are:
Small simple structure– cytoplasm covering that is susceptible to antibacterials
Can live independently, but uses organisms nutrients
Contains both DNA and RNA
Flagella and Pili
Bacteria:
Streptococci
Diplococci
Staphylococci
Strep- divide into chains
Diplo- divide into pairs
Staph- divide into clusters
Bacteria biofilm
structured community of bacteria
bacteria spores
group waiting for stimulation to replicate
bacteria aerobic
rqrs O2
bacteria anaerobic
hates too much O2
bacteria facilitatively anaerobic
can adapt to O2 rich environments. More adaptable and stronger
Gram +/gram -
stain red/blue
bacteria 3:
- acid-fast bacilli
do not stain
bacteria 3:
- Spirocets
Helical, long bacteria
bacteria 3:
- Mycoplasma
Little bit stronger
Stronger than normal bacteria
resistant to some antibiotics
Rickettsiaceae
Organisms that have both viral and bacterial characteristics:
*Not a bacteria or virus
carried by fleas, ticks, lice
need host nutrients and cell ATP byproducts
Ex. Rocky mountain spotted fever, typhoid fever
Chlamydiaceae
Organisms that have both viral and bacterial characteristics:
STI
Ocular infection in newborns
Respiratory infections
Fungi:
Only a few cause serious disease
rqr temp
Parasites 3:
- Protozoa
Unicellular Animals
Transmission:
> host-to-host (sexual)
> Arthropod vector (lice, tick, fleas)
> Contaminated water
Ex. Malaria, dysentery (inflam of intestine causing diarrhea with blood)
Parasites 3:
- Helminths
Wormlike
Roundworms, tapeworms, flukes
Any body organ (or numerous)
Ex. intestinal parasite
Transmission:
> ingested in fertilized ova
> Penetration through skin. (arthropod vector). Getting bitten by tick
Parasites 3:
- Anthropod
Ticks, mosquitoes, flies, mites, scabies, lice, fleas
Transmission:
> clothing/bedding/combs/brushes
Ex. Bubonic plague (fleas, rats: are vector bc they carry the disease) Epidemic typhus (lice)
Infections Portal of Entry
- Penetration- primary, accidental, medical
- Direct contact- Tissue/secretions, congenital
- Ingestion- must survive pH, enzymes, peristalsis, normal flora
- Inhalation- must survive mucous, cilia, coughing, antibodies, phagocytes
Sources of infectious disease refers to:
location, host, object, or substance from which the infectious agent was acquired (who, what, where, when)
- Endogenous source- have it inside you. opportunistic normal flora
- Exogenous source- get it from outside the body.
» human, fomite (something that carries infectious organism), animal, arthropods (bug), inhalation - Nomocomial- hosp acquired
- Community acquired
Mechanisms of disease production
Virulence Factors:
- Toxins
Substances that alter or destroy normal cells
a) Exotoxins- are proteins released from bacteria during growth. Inhibit cellular synthesis
b) Endotoxins- are lipopolysaccharides from cell wall of Gram negative bacteria
- - Induced cytokines, leukocytes, T-Lymphocytes
- -results in increased cap permeability
- -less potent than exotoxins
Mechanisms of disease production
Virulence Factors:
- Adhesion factors:
help infective organisms stick to the body
Mechanisms of disease production
Virulence Factors:
- Evasive Factors:
able to evade host immune system
Ex. H. Pylori
Mechanisms of disease production
Virulence Factors:
- Invasive factors:
products produced by infectious agents to help it move across barriers (ex. cell walls)
Disease course:
Stages of any disease
- Incubation: beginning process
- -influenced by? portal of entry?, dose, health of host - Prodronal: initial symptoms
- Acute: maximum impact of the disease
- Convalescent: when you start to get better
Chronic infections have a different course!!!
Infection Diagnosis: 3
- Culture- propagation of microorganisms outside the body with artificial growth media
- Serology- study of serum
- - measure serum antibodies in the diseased host
- -antibody titer (antibody level) can diagnose the disease.
- - not as accurate as culture - DNA/RNA sequencing
- - can recognize what the above cant
Treatments:
Antibacterials (antibiotics)
–not all antibiotics are effective against pathogenic bacteria
- Bactericidal- lethal to bacteria.
- -produced by other microorganisms as a byproduct of metabolism. - Bacteriostatic- prevent bacteria from replicating. Does not kill the bacteria, it stops it from replicating.
- -can give meds that will stop the bacteria from growing and give the body a chance to fight it
- -Ex. Tetracycline, sulpha - Broad Spectrum- G- and G+ bacilli. WE give these when we are not sure which type of bacteria it is.
Treatment:
Antibiotics kill bacteria by affecting:
- cell wall synthesis
- Protein synthesis
- Nucleic acid synthesis
- Bacterial Metabolism
Treatment:
Bacteria fight antibiotics back by:
- inactivating antibiotics by creating enzymes
- changing antibiotic binding site
- using different metabolic pathways
- changing their walls to keep antibiotics out
Treatment:
Antiviral agents block:
- Virus’s DNA/RNA synthesis (replication)
- binding to cell
- production of protein coat
Treatment:
Antifungal agents:
Target cell wall as substances are different than normal body cell wall
Treatment:
Surgical interventions
- Drain- tubing
- Debridement
- Removal- ex. Appendectomy/amputation
- REplacement- heart valve
