pathophysiology, chapter 8 (infectious processes)

prevalence

the number of people who have a certain disease in one year

incidence

the number of people who develop a new infection/disease in a year

incidence rate

the number of new cases within a given population

pathogen

a disease producing organism

must have a portal exit and mode of transmission from the reservoir to a susceptible victim

what are the routes of direct transmission?

body fluids (droplets)

animal bites

soil

placental transfer

what are the routes of indirect transmission?

vehicle-borne

vector-borne

airborne

what is the most effective way to break the chain of transmission?

hand washing

what are some biochemical barriers to infection in humans?

lysozymes in most secretions

sebaceous gland secretions

acidic environment of stomach

resident flora in gut and vagina

vaginal secretions

prostatic and testicular secretions

what are some mechanical barriers to infection in humans?

skin

mucus

cilia lining the trachea

skin

what are some risk factors to make a person more susceptible to infection?

malnutrition

age (very young and very old)

chronic illness

immunosuppression

stress

what is the most cost-effective method of altering pathogen susceptibility?

vaccines/immunizations

resident flora

microorganisms that live on or in the host without causing disease

benefit the host by inhibiting the growth of nonresident microorganisms

* may become pathogenic if the host's immune system is compromised

virulence

a microorganism's ability to cause severe disease and cause harm to the host

toxin

a lipopolysaccharide produced by bacteria

cause a strong immune response in the host

exotoxin

excreted by a living cell, with high concentrations in liquid

endotoxin

integral part of the cell wall which is released upon cell death, and sometimes during cell growth

bacterial enzymes

help microorganisms to spread or invade tissues by breaking down mucus membranes

ex: coagulase, hyaluronidase, cytolysins

antiphaocytic factors

prevents microorganism from being phagocytized

ex: coating or biofilm

endospore

allows microorganism to survive under harsh environmental conditions

what are 4 mechanisms that allow a microorganism to resist drugs?

1. produce enzymes that inactivate the drug

2. create a modified target that is no longer susceptible to the antibiotic

3. prevent entry of the drug into the cell

4. actively pump out the drug

bacteria

single-celled organisms that have no internal organelles

gram-positive bacteria

dark purple under a microscope

thick peptidoglycan cell wall

gram-negative bacteria

appear pink under a microscope

think peptidoglycan

acid-fast bacteria

resist staining (once stained, resist decoloration)

virus

smallest known infective agents

3 parts:

protein shell (capsid)

DNA or RNA

protective envelope

retrovirus

contain enzyme reverse transcriptase

converts their RNA into DNA to be incorporated into the host's DNA

mycoses

infection caused by fungi

superficial fungi

only occurs on superficial, dead, keratinized tissue

does not invade the tissue

causes inflammation

subcutaneous fungi

introduced into subcutaneous tissue during trauma

leads to ulcers and abscesses

systemic fungi

caused by inhalation of dust that contains fungus (usually soil)

compromises the host's immune system

protozoa

single-celled animal parasites

helminthes

roundworms and flatworms (parasites)

arthropods

invertebrate animals with jointed appendages (parasites)

ex: lice, fleas

commonly infect the skin and GI tract