Etiology Midterm ETI 260

bacteria

prokaryotic, unicellular, patho+nonpatho

protists

eukaryotic, unicellular+multicellular, patho+nonpatho

fungi

eukaryotic, unicellular(yeast)+multicellular(mushrooms)

Helminths

eukaryotic, parasites

viruses

acellular, infect plant, animals, human (DNA or RNA never both)

prions

not cells, nonliving proteins

pathogen

the few microbes that cause infectious diseases

opportunistic pathogen

a microorganism that normally does not cause disease but can cause infection in individuals with weakened immune systems.

susceptible host

host that can develop disease

germ theory

the theory that microorganisms are the cause of many diseases, leading to advances in hygiene and treatment.

etiological agent

a pathogen or substance that causes disease or illness in a host.

koch’s postulates of disease

a set of criteria established by Robert Koch to identify the causative agent of a particular disease, including isolating the pathogen, cultivating it, and reproducing the disease in a healthy host.

morphology

the study of the form and structure of organisms, including their shape, size, and arrangement of cells.

toxonomy

the science of classifying organisms into groups based on shared characteristics and relationships.

prokaryotic species

share physical characteristics, 70% DNA similarity

symbiotic relationship

a close interaction between two different species that benefits at least one of the organisms involved.

biofilm

sticky communities of single or diverse microbial species

planktonic

free-floating bacteria, promotes bacteria growth

UTI

urinary tract infection, can affect any structure of urinary tract(kidneys, bladder, urethra, ureters)

uncomplicated UTI

a urinary tract infection that occurs in healthy individuals without any anatomical or functional abnormalities. (cystitis or pyelonephritis)

complicated UTI

urinary tract infection that can occur at any age or sex, usually structural abnormality, comorbidity of increase risk of infection or resistance to treatment

risk factors of UTI

sexual intercourse, history of UTI, recurrent UTI, new sex partners, antibiotic use, urinary tract abnormalities

etiology of bacterial UTI

most often cause cystitis or pyelonephritis, gram-negative bacteria is most common, E.Coli is most common non HAI cause, gram-negative klebsiella, gram-positive staphylococcus saprophyticus

urethritis

infection of urethra, acute or chronic colonize, can be caused by STIs such as chlamydia, gonorrhea, trichomoniasis, and herpes

cystitis

bladder infection, women=uncomplicated, men=complicated, symptoms: urgency, frequency, burning, pain

acute urethral syndrome

occurs in women, caused by abnormalities, trauma, or inflammation. symptoms: dysuria, and polyuria

asymptomatic bacteruria

absence of UTI symptoms, found when screening for something else

pyelonephritis

infection of kidney, symptoms: fever, chills, flank pain, nausea and vomiting

empiric therapy

medical treatment based off of experience, directed against anticipated disease

antimicrobial resistance

when bacteria builds resistance/ability to defend themselves against drugs, becomes harder to treat

evidence informed practice

evidence, experience, patient preference

host

targeted organism

true pathogen

does not require weakened host to cause disease

sporadic

cases of disease are isolated infections is specific populations

epidemic

widespread disease in specific region and time period

pandemic

epidemics spreads to numerous countries

emerging pathogens

newly identified agents that previously only caused sporadic cases

reemerging pathogens

infectious agents that was under control but is now resurfacing

zoonotic diseases

animals—>humans

noncommunicable

do not spread from person to person

communicable

human—>human

contagious

communicable disease that are easily spread from one host to the next

active infection

patient is symptomatic

signs

objective indicators of disease(measurable)

symptoms

sensed by patient, subjective, rather than measureable

latent infection

host is asymptomatic

acute diseases

rapid onset and progression

chronic disease

slower onset and progression

exogenous

came from outside of host, environment: contaminate food, soil, medical equipment; animals and humans

endogenous

came from inside the host, misplaced microbiota, disrupted microbiota+opportunistic pathogen= infection

direct contact

host somes into physical contact w/source of pathogen

vertical(direct contact)

specialized form of direct contact, mother to baby(utero, birth, breast feeding)

indirect contact

pathogen spreads w/o direct physical contact

airborne(indirect)

pathogen enters respiratory route(respiratory droplets=cough or sneeze)

vehicle or fomite(indirect)

contaminated inanimate objects(doorknobs, needles, sheets, etc)

vector(indirect)

organisms that spread infectious diseases; biological: arthropods=mosquitoes and ticks; mechanical: spreads disease w/o being in host lifestyle(fly that goes into bathroom then kitchen)

stages of disease: incubation

time between infection and early symptoms

stages of disease: prodromal phase

early symptoms

stages of disease: acute phase

peak of disease

stages of disease: period of decline

replication is controlled and symptoms resolve

stages of disease: convalescent phase

patient recovers(pathogen can be kept latent); chronic carrier-may remain symptomatic for a long time; asymptomatic carrier-harbor pathogen w/o symptoms

host-microbe interactions

dynamic give+take between microbes and host(does not damage host)

tropism

preference of pathogen for specific host

pathogenecity

ability of a microbe to cause disease

virulence

degree or extent of disease that pathogen caused

attenuated

still infectious but weakened to the point they do not cause disease in immunocompromised host

toxigenic

microbe that makes toxins

toxins

molecules that in small amounts generate a range of adverse reactions in host(tissue damage and suppressed immune response)

infectious dose-50(ID50)

how many cells of virions are needed to infect 50% of susceptible hosts

endotoxins

lipid A region of LPS(lipopolysaccharide- in the outer membrane of gram-negative bacteria)

Lipid A

lipids and sugars that when activated can relase toxins

exotoxins

gram+ and gram- bacteria, toxic, soluble proteins that affect a wide range of cells

neurotoxins

affect nervous system

entertoxins

target GI tract

hepatotoxins

affect liver

nephrotoxins

affect kidneys

superantigens

overstimulate immune system to cause massive inflammation

portal of entry(5 steps to infection)

any site the pathogen uses to enter host(skin, eyes, respiratory, GI, urogenital)

adherence(5 steps to infection)

major class of virulence factors that bacteria, fungi, protists and viruses stick to host cells in specific or non-specific manners

invasion(5 steps to infection)

allows pathogen to invade host tissues(transferrin, siderophores, extracellular enzymes, and cytopathic effects)

immune evasion(5 steps to infection)

hiding- pathogen hides from immune system; intracellular pathogens-pathogens spend most time inside of cell; latency-ability of pathogen to quietly exist inside host; masking- pathogen coats itself w/host molecules; mimicry- emulating host molecules; variance-periodically altering surface molecules; interference of phagocytosis- pathogens avoid phagocytosis by making a capsules; immunosuppression- pathogen suppresses immune response by targeting immune system cells

transmission to new host(5 steps to infection)

exiting host, maintaining reservoir

binary fission

asexual cell division

plasma membrane

phospholipid bilayer, selectively permeable

peptidoglycan

mesh-like molecule includes proteins and sugars(thick in gram+ and thin in gram-)

outermembrane

makes it harder to kill w/antibioitcs(gram-negative cells only)

porin

protein channel on outer membrane(mutations to this can further restrict treatment)

mycoplasma bacteria

lack cell wall, but have sterol-enriched plasma membrane

Diffusion

exchanged between cells and their environment; facilitated- does not require energy but requires transport proteins; simple- does not require energy or protein channels(uncharged substances like CO2+O2)

osmosis

water moving across cell wall and plasma membrane; hyper tonic- more solute on outside of cell draws water out; hypotonic- more solute inside of cells pulls water in; isotonic-equal parts of solute in and out of cell

active transport

requires energy to transport specific substances through specfic channels

flagella

filament-like extracellular structures from protein flagellin(allows movement for bacteria cells)

chemotaxis

movement in repsonce to chemical stimulation

phototaxis

movement in response to light

aerotaxis

movement from oxygen levels

monotrichous

single flagella

lophotrichous

cluster of flagella on one end

amphitrichous

flagella on both ends of cell

peritrichous

flagella all over cell