CH14 2

Incubation period

Varies from person to person and infection to infection

Time that lapses from exposure to first set of signs

Potentially contagious

Exposure

When the microorganisms gain entry

Prodromal period

Weak presentation of symptoms (begin to feel off or like you are getting sick)

Short period

Potentially contagious

Period of illness

Infection load dramatically load

Severe/very strong symptoms (either u get better or u die)

Potentially contagious

Period of decline

start to feel bettter

Prone to opportunistic organism + 2nd infection

Still potentially contagious

Convalescence

Still weak to due microorganisms still present

Feel way better

Still prone to secondary infection + still potentially contagious

When are you contagious?

all the stages of infectious disease

As long as there are organisms in your systems you have the potential to be contagious

Disease related capability

Pathogenicity

Virulence

Pathogenicity

How good is the organism at being a pathogen?

Can very front of not at all (like normal flora)

Virulence

The more virulence the better it is at being a pathogen

LD50

Lethal dose 50

Quantitative measurement of virulence

When dose does it kill 50% → lower that is the more dangerous and strong it is

Virulence factors

Capsules

Specialized cell walls

Enzymes

Capsules

Protect against phagocytosis

Specialized cell walls

Like mycobacterium with myolic acid layer making them stronger or can have specific proteins like streptococcus pyogenese → has M protein → protects from phagocytosis

Enzymes

Leukocidins

Hemolysis

Coagulase/Kinase

Hyalurondiase/collagenase

Leukocidins

Kills WBC

Hemolysis

Breaks down RBC → even during coagulation to form clots → allows bacteria to spread more

Coagulate/Kinase

Bacteria gets in → builds clot around itself due to coagulase → protects from immune response → multiples in clot → kinase bursts the clot → bacteria released

Hyaluronidase/Collagenase

Enable bacteria to reach deeper tissue

Bacteria reach tightly together epithelial cell surface → produces hyalurondiase (breaks down the “glue” aka hyaluronic acid of cells) and collagenase (breaks down collagen aka structural protein) - created entryway → bacteria invade into deeper tissues

Pathogenicity

Ability of a microbe to cause disease

virulence

The degree of pathogenicity (the more virulence the more pathogenic)

Likelihood of Disease

Portal of Entry (Route of Entry)

Vulnerability of host

Infective/Inoculating Dose

Adhesion/Adherence of organism to entry route

Virulence of Organism

Vulnerability of Host

Is the host immunocompromised? Stressed? Older? Has antibodies already to fight

A lot can change whether an organism can cause infection in a person

Portal of Entry

The way in

Respiratory

Skin entry (natural openings or parental aka puncture or break in the skin)

Ocular

GI

Reproductive

Urinary

Placental Transfer

Infective/Inoculating Dose

number of microbes that got in (more gives a higher chance of getting sick)

Ability for Adherence

Can it stick and create residency?

fimbriae and capsule help (certain organism have better fimbriae for certain portals of entr)

Virulence of Disease

Lower LD50→ the higher the virulence then the lower the inoculating dose is needed to cause disease

Damage to Host

Direct Damage or Toxins (Exo/Endotoxin)

Direct Damage to Host

Like pimples (bacterial infection)

Exotoxins

Produced and released by living microbial cells

Toxicity potency varies

(Cell is producing exotoxins and then they leave the cell → cause localized infection (use antibiotic to kill cell) AND travels → in blood stream (toxemia) (try and treat with antitoxin)

As long as cell is still alive, it can produce exotoxins

Examples of Exotoxins

Diphtheria

Eryhtrogenic

Botulinum

Tetanus

Choleragen

Staphylococcal

Diphtheria

Produced by Corynebacterium diphtheria

Classified as cytotoxin (destroys cell) → very strong and can cause organs to shut down

Infection in throat (upper respiratory system)

Have an antitoxin for it

Rare to see due to vaccine (DPT vaccine)

Would usually do blood culture for toxin to confirm diagnosis but the pseudomembrane in throat is a good enough indicator

Erythrogenic

Low toxicity

Causes red pigmentation → symptoms are red rash, red throat and strawberry tongue (with bumps)

Streptococcus pyogènes (strep) → some strains can release the toxin which causes these symptoms (scarlet fever)

Botulinum

Produced by clostridium botulinum

Neurotoxin (nervous system) → blocks release of acetylcholine → muscles can NOT contract → diaphragm gets paralyzed which causes respiratory failure

Most toxic exotixin

Used in many things like Botox, migraine treatment, hyperhydrosis

Tetanus

Produced by clostridium tetani

Neurotoxin blocks inhibitory neurotransmitter → both muscles are contracting (stronger one will win which is what causes lock jaw)

Usually gotten through a break in the skin (infection of wound aka localized and lock jaw (everywhere else)

Choleragen

Produced by vibrio cholerae (presents as GI)

Transmitted through containmentrd water or seafood (from water)

Rapid loss of fluids and electrolytes → rice water stool

Actions of cholera toxin in intestinal epithealial cells

1. Cholera toxin binds to membrane of epithelial cells -

2. Portion of toxin enters cell

3. activâtes Cyclades

4. cAMP is synthesized

5. cAMP stimulates cell to secret Cl-, Na+ and other electrolytes

6. Water will follow

Staphylococcal Toxin

S. Aureus produces (some strains and there are different kinds of toxins)

SSS (scalded skin syndrome)

TSS (Toxic Shock Syndrome)

Enterotoxin (GI toxin)

S.S.S

Scalded skin syndrome

Staph infection in body → produces toxin that causes red patches of epidermis to slough off (due to exfoliative toxin)

Treated with antibiotics and IV fluids → usually leaves no lasting damage

T.S.S

Toxic shock syndrome

Literally going into shock (fever, weird rash on palm of hand or sole of foot, chest pain, drops in BP, unresponsiveness)

Usually caused by tampons (s.aurues in vaginal canal but certain fibers can allow it to take over normal flora → produces toxin)

Enterotoxin

True food poisoning

Ingesting the toxin (due to s. Aureus being in the food and producing the toxin)

4-6 hours to feel symptoms like vomiting or diarrhea→ usually gone within 24 hours

Endotoxins

Component of gram negative cell wall (lipopolysaccharides)

Released upon cell death

Potency of toxicity is identical (but generally lower)

Cumulative impact tho