intro to microbiology final new stuff

Ways microbes can get into the body

skin, GI tract, upper respiratory tract, urogenital tract, placenta

portal specificity

most microbes have a preferred portal of entry

why are microbes attracted to humans as hosts?

nutrient rich, moist, stable pH, stable temp, lots of places to hang out

methods for microbes to get in through skin

breaks in skin, helminth digestive enzymes, insect vectors, needle injections

infectious dose

minimum number of microbes to cause disease

median infectious dose

number of microbes required to cause disease in 50% of inoculated animals

adhesion factors

used to bind receptor molecules on host cells to pathogens

types of adhesion factors

fimbriae, glycocalyx (biofilm), viral protein spikes, adhesive disks

how do cells avoid phagocytosis

capsules or coagulase

how do pathogens avoid host defenses?

avoid phagocytosis, camouflage, avoid immune cells by invading a cell

how do microbes damage host cells?

out-compete for nutrients, direct damage at entry site, toxins, disrupt immune response

siderophores

proteins that bind to iron and allow pathogens to out-compete host cells for iron

exotoxin

secreted proteins that target specific receptors on cells to cause damage

superantigens

trigger cytokine storm > toxic shock syndrome (S. aureus is an example)

endotoxin

consists of one lipopolysaccharide, only associated with Gram-negatives, general systemic effects

portals of exits

respiratory tract, GI tract, skin, urogenital tract, blood,

progress of an infection

getting in > adhesion > avoiding host defenses > disease caused by damage to host cell > disease transmission

exoenzymes

secreted enzymes that cause damage to host cells by breaking down tissues to allow deeper spread of bacteria

streptokinase

an exoenzyme that can cause flesh-eating disease. dissolves clots, so can also be used as a clot buster

pathology

study of disease

infection

successful invasion or colonization of a microbe within a host

microbial pathogenesis

the traits the microbe has that leads to the disease

normal microbiome

upper respiratory tract, GI tract, urogenical tract, skin

sterile body areas

nervous system, lower respiratory tract, cardiovascular ssytem

blood-brain barrier

endothelial cells, astrocytes, neurons

things that keep lower respiratory tract sterile

nasal hairs, mucous membranes, ciliary escalator, alveolar macrophages

holy trinity for nosocomial infections

microorganisms, compromised host, chain of transmission

incubation period

pathogens are multiplying but no signs or symptoms

prodromal period

pathogens still multiply, host begins to experience signs and symptoms and activation of immune system

period of illness

signs and symptoms of disease are most obvious and severe

period of convalescence

patient returns to normal functions

what does transmission of infection depend on?

the disease, pathogen, and mechanisms by which it develops and progresses

etiology

study of the causes of disease

etiologic agent

the pathogen or substance responsible for causing a particular disease

what is the purpose of Koch’s postulates

identify a microorganism as the cause of a specific infectious disease

reasons Koch’s postulates could not apply

opportunistic pathogens, varying immune system strengths, ethics for human exclusive diseases

epidemiology

science that studies when and where diseases occur and how they are transmitted

morbidity rate

number of people with the diesease/ number of all people

prevalence

number of people who are sick at a given time

incidence

number of new cases at a given time

mortality rate

number of deaths from a disease in a given population at a point in time

sporadic disease

occasionally without geographic concentration

endemic disease

constantly present in a population within a geographic region

common source spread

a single source for all infected

point source spread

common source for a short period of time

propagated spread

person to person, indirect or direct spread

3 types of reservoirs of infections

humans, animals, nonliving

passive carrier

not sick but can pick up and transmit disease

incubation carrier

active infection and spread to others during the incubation period

convalescent carrier

active infection and spread it to others during the convalescent periodc

chronic carriers

life-long infection and can spread disease throughout their life

asymptomatic

have an active infections but never show any signs or symptoms of disease

zoonosis

disease that occurs primarily in animals but can be transmitted to humans

two most common nonliving reservoirs

soil and water

fomite

a nonliving object that can transmit disease

mucociliary escalator

moves mucus away from lungs to stomach, coughed up, or sneezed out

intestinal tract lining

epithelial and mucus-secreting goblet cells

peristalsis

muscular contractions that help move mucus and other material through the GI tract

endothelia

epithelial cells that line the blood vessels, lymphatic vessels, and other tissues.

microbiome prevents pathogen attachment how

occupying binding sites and competing for nutrients

lysozyme

breaks down peptidoglycan

antimicrobial peptides

nonspecific antimicrobials secreted by skin, epithelial cells, immune cells

ion binding proteins

chemically bind and sequester iron, starves microbes

complement system

complement immune cells in destroying bacteria, connects innate and adaptive immunity

opsonization

sugar coating for phagocytic cell to come destroy it more easily

3 complement system mechanisms

opsonization, initiate inflammation, promot cytolysis

cytokines

proteins that are communication signals between cells

3 types of phagocyte white blood cells

neutrophils, dendritic cells, monocytes/macrophages

inflammatory response

vasodilation, redness, heat, increased BV permeability, swelling, pain, loss of function

diapedesis

when phagocytes squeeze between endothelial cells that line BV walls and into tissue during inflammation response

phases of phagocytosis

chemotaxis, adherence, ingestion, formation of a phagosome, formation of a phagolysosome, digestion, discharge

pyrogens

chemical that cause the hypothalamus to turn up the body temp by releasing prostaglandins.

humoral immunity

B cells release antibodies to fight pathogens in the blood

cell-mediated immunity

T-cells destroy cells that have been infected with pathogens inside them

epitope

portion of antigens that antibodies and T-cells can recognize and attach to

IgG

most abundant, can cross placenta

IgM

must stay in blood, not tissue. first in primary response

IgA

mucous membranes, dimer

IgD

b-cell receptor

IgE

allergic reactions

agglutination

cross-linking pathogens by antibodies, creating large aggregates, IgM

antibody titer

amount of a specific antibody to a specific epitope in the blood

inactivated vaccine

dead or inactive organism with heat or chemicals or radiation

attenuated vaccine

microbe is alive but reduced virulence

sub-unit vaccine

uses only a part of the microbe like its DNA or viral capsid

toxoid

toxin that has been inactivated by chemical treatment or mutations

anti-toxin

antibodies from another host/animal, purified, and administered to a patient who already has the disease

allergic reaction

secondary immune response to an allergen

hypersensitivity

unnecessary response/overreaction of the immune system

autoimmune disorder/disease

immune system recognizes its own tissues as foreign and attacks them.

type I

IgE, regular allergies

Type II

IgG and IgM, antibodiy-mediated cytotoxic, blood transfusions

Type III

IgG, immune complex formation, rheumatoid arthritis

Type IV

T-cell mediated cytotoxic, delayed. contact dermatitis, graft rejection

isohemagglutinins

naturally occuring IgM antibodies in plasma that can cross react with blood group antigens not present on one’s own RBCs.

allograft

person to person graft

isograft

identical twin graft

autograft

self tissue graft

xenograft

animal to human graft

Graft vs Host disease

transplanted tissue is capable of producing immune cells, recognizes the host as foreign and starts rejecting host cells, T-cells attack host cells