microbiology final

pathogenicity

ability to cause disease

virulence factor

factors involved in pathogenicity, traits that allow an organism to cause disease

pathogens

organisms that cause disease

to cause disease, organisms need to:

be transmitted, attach, penetrate, multiply, evade host defense, damage, exit

pathogenesis

the process by which a disease develops in a host

signs

objective finding that a doctor can observe or measure

symptoms

subjective experience a patient reports

kochs postulates germ theory of disease

1.find the pathogen 2. grow the pathogen 3. infect a healthy host and reproduce the disease 4. re isolate the oathogen from new host

virulence factors definition (bacteria)

features that aid in causing disease, mostly enzymes

examples of virulence factors

adhesins, invasins, resistance to phagocytosis, spreading factor, localization factors

LD50

lethal dose of a toxin for 50% of the test population

ID50

infectious dose for 50% of the test population

five steps of infection

portal of entry, adherence, surviving host defenses, causing host damage, and exit host

portal of entry

how a pathogen enters the body: skin, GI, respiratory, urogenital, perenteral, or normal microbiota

adherence

how the pathogen sticks to the host: fimbriae and pili, glycocalyx, viral spike, specific proteins, Tissue Specific!!

surviving host defenses

how a pathogen survives the immune system: avoid phagocytosis and death by phagocyte, absence pf specific immunity

causing host damage

how the pathogen harms the host, either directly (toxins and enzymes) or indirectly (excessive host response)

exit host

how the pathogen leaves the hosts body: respiratory (coughing), feces, skin cells, blood, urogenital

coagulation (blood clotting)

coagulates fibrin to create blood clots, which protect against host defenses by allowing bacteria to hide

bacterial kinases

digest fibrin blood clots

damage to host cells

use host nutrients, direct cell damage (lysis), produce toxins, induce hypersensitive response

exotoxin

protein produced by the cells metabolism and is sent out

endotoxin

lipid A protein of LPS, part of a gram negative bacterias outer membrane

A-B toxins

class of bacterial exotoxins characterized by two distinct subunits: an active subunit (A) and a binding subunit (B)

B component

the binding subunit, binds to host cell receptors, facilitating the entry of the A subunit into the host cell

A component

the active subunit, exerts a toxic effect

botulism toxin

botox, prevents release of acetylcholine, causes flaccid paralysis

tetanus toxin

prevents muscle relaxation, causes rigid paralysis

superantigens

cause massive immune response, activates large portions of the immune system, includes toxic shock syndrome

membrane disrupting toxins

lyses host cells by making protein channels in the plasma membrane and disrupting the lipid bilayer

what causes superantigens to release intense immune response?

the release of cytokines from host cells

symptoms of superantigens

fever, nausea, vomiting, diarrhea, shock, and death

shock

drop in blood pressure resulting from increased permeability of blood capillaries and fluid loss

endotoxin characteristics

mostly gram positive, by products of growing cell, protein, doesnt cause fever, can be neutralized by antitoxins, small LD50

exotoxin

gram negative, on the outer membrane, lipid A, causes fever, is not neutralized by antitoxin, relatively large LD50

epidemiology is the study of

how diseases move and impact populations, focusing on patterns, transmissions, and characteristics of disease spread rather than individual cases

microbial antagonism

a competition between microbes

normal microbiota

protect the host by occupying niches where pathogens might be, producing acids, producing bacteriocins

how can probiotics antagonize opportunistic pathogens?

by directly competing with them for resources and binding sites, by producing antimicrobial substances that inhibit their growth, and by stimulating the host's immune system to fight off infection

symptom

a change in body function that is felt by a patient as a result of disease

sign

a change in a body that can be measured or observed as a result of disease

syndrome

specific group of signs and symptoms that accompany a disease

communicable disease

disease that us spread from one host to another

contagious disease

a disease that is easily spread from one host to another

noncommunicable disease

a disease that is not transmitted from one host to another, like heart disease and diabetes

incidence

number of newly reported cases

prevelance

total number of reported cases, old and new

incubation period

period of time with no symptoms

prodromal period

individual may show signs of symptoms

period of illness

period associated with the most severe symptoms during a disease

decline

period when symptoms begin to subside

convalescence

period in which the individual may still feel weak, but symptoms have largely ended, may still be contagious

four types of disease occurance

endemic, epidemic, sporadic, and pandemic

sporadic disease

disease that occurs occasionally in a population

endemic disease

disease constantly present in a population

epidemic disease

disease acquired by many hosts in a given area in a short time

pandemic disease

worldwide epidemic

acute disease

symptoms develop rapidly and usually only lasts for a short period

chronic disease

disease develops slowly and lasts a long time

subacute disease

symptoms between acute and chronic

latent disease

disease with a period of no symptoms when the causative agent is inactive

local infection

pathogens are limited to a small area of the body

systemic infection

an infection throughout the body

focal infection

systematic infection that began as a local infection

predisposing factors that make people more susceptible to disease

physiology, genetics, climate and weather, fatigue, age, lifestyle, chemotherapy, basically everything

reservoirs of infection

any place, person, animal, plant, soil, or substance where an infectious agent normally lives and multiplies

human reservoir

carriers of ongoing infections such as aids and gonorrhea, may have inapparent or latent diseases

animal reservior

play role in zoonotic diseases that can be transmitted to humans, includes rabies and lymes

nonliving reservoirs

environments or objects where pathogens can live and multiply, but are not living organisms, includes botulism and tetanus

modes of transmission of disease

direct, indirect, or droplet

direct transmission

requires close association between infected and susceptible host, sexually transmitted diseases like gonorrhea and HIV,

indirect transmission

disease spread by fomites, inanimate objects that transmit disease, such as a doorknob or a shared cup

droplet transmission

transmission via airborne droplets, such as mosquito, cough, or sneeze

vectors that spread disease

agents that carry and transmit disease-causing pathogens from one organism to another, such as mosquitos and fleas

mechanical transmission

the passive transfer of pathogens from an infected source to a susceptible host by a non infected vector who simply physically carries it

biological transmission

the process where a pathogen is transmitted from one host to another through a living organism, pathogen reproduces in vector

nosocomial infections

an infection acquired in a healthcare setting

biosafety level (BSL) 1

no containment, defined organisms, unlikely to cause disease

biosafety level (BSL) 2

containment, moderate risk, disease of varying severity, includes lymes and flu

biosafety level (BSL) 3

high containment, aerosol transmission, serious/potentially lethal disease, includes tuberculosis

biosafety level (BSL) 4

max containment, exotic, high risk agents, life threatening disease, includes ebola

immunology

the study of how the body distinguishes itself from everything else (central function)

host defense

relies on interrupting any of the following steps of infection: adherence, multiplication, evasion of host defense, or damage

components of immune response

innate immunity and adaptive immunity

innate immunity

first and second lines of defense, acts as a physical barrier and provides immune response, quick acting, includes mechanical, chemical, and immunological components

first line of defense

the physical barrier, includes skin, mucous membranes, and normal microbiota

second line of defense

the response, includes phagocytes, inflammation, fever, and antimicrobial substances

adaptive immunity

specific defense against certain antigen, develops by contact with that pathogen, acts as immune memory, based on the action of lymphocytes

trap, block, and washing in innate defense

mucous and mucous covered hairs trap pathogens, cilia and skin block pathogens, and saliva and other bodily secretions wash specific cavities

lymphatic system

drains interstitial fluids from tissue and filters it, settles in lymph nodes

types of lymphocytes

t cells (helper and cytotoxic), b cells, and natural killer cells

types of granulocytes

neutrophils, eosinophils, basophils, mast cells

neutrophils

phagocytic leukocytes, engulf and destroy things, effective against normal, small scale bacteria/invaders, release cytotoxic chemicals from granules

eosinophils

phagocytic, active with antigen-antibody complexes, combat allergies, parasites, and other inflammatory conditions

basophils

fight parasitic infections, contribute to producing allergic reactions, such as sneezing or runny nose, and regulating blood clotting

mast cell

release granules filled with chemicals that cause inflammation, like histamine, reside outside the bloodstream in the tissues

monocyte

type of white blood cell that circulate in the bloodstream, innate immune system, find and destroy germs and eliminate infected cells

macrophage

key cells in innate immune system, serve as the first line of defense against pathogens and cellular debris, phagocytic cells, engulf and digest foreign invaders and cellular waste

dendritic cell

hyper-mature macrophages, phagocytize but instead of killing, creates samples to present to specific immune system

megakaryocyte

polyploid cells found primarily in the bone marrow that play a crucial role in platelet production and hemostasis