microbio -- microbe-human interactions

equilibrium

homeostasis==> everything is in balance —> lose it? disease

colonization

growth of microbes

anytime there are germs in the body

the immune system gets stronger

maturation of host defenses and development of the immunse system

disease caused by…

microbial damage to tissues and organs

normal resident microbiota/flora

microbes that engage in mutual or commensal associations —> what should be in an organism

off balance? disease

infection

microbes penetrate host defenses, enter sterile tissues, and multiply

pathogen

infectious agent

infectious disease

causes damage or disruption to tissues and organs

areas in contact with OUTSIDE environment harbor…

resident microbes —> ear, eyes, GIT, skin, upper resp tract,external genitalia

things that are microbe free

internal organs, tissues, and fluids

liver, kidney, lungs, brain, heart, bones, etc.

transients

microbes that occupt the body for only short periods

microbial antagonism

preventing overgrowth of harmful microbes

endogenous infections

normal flora is introduced to a site that was previously sterile

skin is the most ______ organ

large and accessible

two cutaneous populations - transients (influenced by hygeine) and residents (stable, predictable)

flora of GIT

vary depending on shifting conditions (e.g: oxygen, pH, etc.)

oral cavity, large intestine, and rectum harbor appreciable flora

STOMACH ACID —> harbors most microbes!

GI tube is exposed to outside environment

flora of mouth

most abundant, diverse, and unique flora

saliva - sterile until it enters the oral cavity

flora of large intestine (colon)

cecum and colon harbors many microbes per gram of feces

intestinal environment favors anaerobic bacteria

intestinal bacteria produces skatole and flatus

skatole

chemical that gives feces their stench

flatus

intestinal gas (flatulence)

flora of respiratory tract

oral streptococci —> first organisms to colonize

nose and throat = nasopharynx

tonsils and lower pharynx

genitourinary tract

females - vagina and opening of urethra

males - anterior urethra

changes in physiology influence the composition of the normal flora —> hormone changes (menstrual cycles, etc.)

what alters flora

broad spectrum antibiotics, dietary changes and disease

probiotics

introducing pure cultures of known microbes back into the body through injection or inoculation

development of an infection

1) portal entry (microbe enters organism via skin, GI tract, etc.)

2) attaching firmly (microbes have things like fimbriae, capsules, surface proteins, spikes, etc.)

3) surviving host defenses —> avoiding phagocytosis, death inside phagocyte, and immune system

4) damage and disease

5) exiting host —> resp tract, skin cells, blood, etc.

causes of damage and disease

direct damage - toxins, enzymes, lysis

indirect damage - host response is inappropriate and excessive

factors that weaken immunity

Old age

Genetic defects

Stress

Surgery

Drugs

Disease

Infections

OGSSDDI

true pathogens

capable of causing disease in healthy persons with normal immune defenses

influenza virus, covid, etc.

opportunistic pathogens

host’s defenses compromised, grow in part of the body that is not natural to them

virulence

strength

virulence factor

ability to create disease inside of us

exogenous agents

originate from source outside the body

true pathogen portal of entry

endogenous agents

already exist on or in the body

opportunistic pathway

possible portals of entry

skin, gastrointestinal tract, respiratory tract, urogenital tract (STDs, STIs), transplacentral (whatever mom has will go to baby via placenta)

pathogens that infect during pregnancy

STORCH

Syph

toxoplasmosis

other viruses (AIDS, hep B, chlamydia)

rubella

cytomagelo

herpres

infectious dose

minimum amount of microbes requires to get sick

number of microbes/infectous dose and virulence relationship

low ID = high virulence factor/strength

don’t need many microbes to get sick, meaning the microbe is strong

adhesion

microbes gain a stable foothold at the portal of entry —> binding between specific molecules on host and pathogen

e.g: fibrae, flagella, cilia, spikes, hooks, barbs

microbes invade ____ and evade defenses using their ______

host, virulence factor

types of virulence factor

antiphagocytic factors —> used to avoid phagocytosis

exoenzymes —> dissolve extracellular barriers and penetrate through or between cells

toxigenicity —> capacity to produce toxins at the site of multiplication

streptococcus produces _____ which are toxic to _____

leukocidins

white blood cells —> produces slime layer or capsule —> makes phagocytosis difficult

virulence factor

traits used to invade and establish themselves in the host —> determine the degree of tissue damage that occurs —> severity of disease

toxin

chemical products of microbes, plants, and animals, that have poisonous effects on other organisms

toxinoses

any disease, lesion caused by the action of a toxin

toxemia (“emia” = in blood)

toxin is spread by blood from the site of infection

intoxication

ingestion of toxins

2 types of bacterial toxins

endotoxin - not secreted, released after cell is damaged —> made of lipopolysaccharide, part of outer membrane of gram-negative cell walls

exotoxin - toxin molecule secreted by a living bacterial cell into the infected tissue —> strong specificity for a target cell

clinical infection stages

incubation period - time from initial contact with infectious agent to the appearance of first symptoms (several hours, years, etc.)

prodromal stage - vague feelings of discomfort - nonspecific complaints

period of invasion - multiplies at high levels, becomes well-established; more specific signs and symptoms

convalescent period - as person begins to respond to the infection, symptoms decline

localized infection

microbes enter and remain in confined, specific tissue

systemic infection

spreads to several sites and tissue fluids usually in the bloodstream (viral, bacterial, etc.)

focal infection

infectious agents break loose from local and begin to spread to other tissues

mixed infection

several microbes grow simultaneously at the infection site —> polymicrobial

primary infection

initial infection

secondary infection

another infection by a different microbe

patterns of infection

comes on rapidly, with severe but short-lived effects

chronic infections

progress and persist over a long period of time

inflammation

caused irritation

not infection

fever, pain, redness, warmth, swelling (edema)

signs of inflammation

edema, granulomas and abscesses - walled off collections of inflammatory cells and microbes, lymphadenitis —> swollen lymph nodes

signs of infection in the blood

circulating white blood cells —>

leukocytosis —> increase in white blood cells

leukopenia —> decrease in white blood cells —> e.g: cancer

septicemia —> microorganisms. are multiplying in the blood and present in large numbers

types of septicemia

bacteremia —> small numbers of bacteria present in blood not necessarily multiplying

viremia —> small number of viruses present not necessarily multiplying

asymptomatic infections

host doesn’t show any signs of disease

inapparent infection

so person doesn’t seek medical attention

portals of exit

how pathogens leave

respiratory —> mucus, sputum, nasal drainage, saliva, etc.

skin scales —

fecal exit

urogenital tract

removal of blood

recovery of host does not always mean…

microbe has been removed

latency, chronic carrer, sequelae

latency

after the initial symptoms in certain chronic diseases, microbe can periodically become active and produce a recurrent disease - person may or may not shed it during the latent stage

chronic carrier

person with. alatent infection who sheds the infectious agent

sequelae

long-term or permanent damage to tissues or organs

transmission of microbes

reservoir and source

reservoir

primary habitat of pathogen in the natural world

human or animal carrier, soil, water, plants

source

individual or object from which an infection is actually acquired

living reservoirs

carrier, asymptomatic carrier, passive carrier

carrier

individual who shelters a pathogen and spreads it to others —> may or may not have experienced disease due to the microbe

asymptomatic carrier

shows no symptoms

passive carrier

contaminated healthcare provider picks up pathogens and transfers them to other patients

asymptomatic carrier

shows no symptoms

incubation, convalescent carriers, chronic carrier

incubation carriers

spread the infectious agent during the intubation period

convalescent carriers

recuperating without symptoms

chronic carrier

individual who shelters the infectious agent for along period

vector

live animal that transmits an infectious agent from one host to another

majority = arthropods, like fleas and mosquitoes

biological vectors

actively participate in a pathogen’s life cycle

mechanical vectors

not necessary to the life cycle of an infectious agent and merely transports it without being infected

zoonosis

infection from an animal

communicable disease

transmitable disease from one host to another

HIGHLY - contagious

non communicable disease

agent doesn’t move from host to host

direct contact

physical contact or fine aerosol droplets

indirect contact

passes from infected host to intermediate conveyor and then to another host

vehicular transmission (non communicable diseases)

inanimate material (food water bio prodicts, etc)

airborne- aerosols

oral-fecal contamination

fomites

fomites

contaminated inanimate objects

nosocomial infections

diseases acquired during a hospital stay (surgery equipment, personnel, etc.)

epidemiology

study of frequency and distribution of disease and health-related factors in human pop.’s

frequency of disease cases based on

prevalence, incidence, mortality rate, morbidity rate

prevalence

total number of existing cases with respect to the entire population usually represented by. a percentage of the pop.

incidence

measures number of new cases over a certain time period, as compared with the general health pop

mortality rate

total number of deaths in a pop. due to a certain disease

morbidity rate

number of people afficted with. acertain disease

patterns of disease occurence include

endemic, sporadic , apidemic, pandemic

endemic

steady frequency over. aperiod of time in a particular geographic location

sporadic

occasional cases are reported at irregular intervals

epidemic

prevalence of disease is increasing beyond what is expected

pandemic

epidemic across continents