Chapter 14 & 15 Flashcards Preview

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Flashcards in Chapter 14 & 15 Deck (98):
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pathology

the study of disease

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etiology

the cause of the disease

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transient microbiota

microbes present for days-years and then disappear

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normal microbiota

microbes in/on the body that don't cause disease

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antagonism

normal flora can prevent pathogens from causing disease
ex) E. Coli suppresses salmonella

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symbiosis

the normal flora and host live together

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commensalism

one organism benefits, the other is unaffected

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mutualism

both organisms benefit

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probiotics

live microbes applied to/ingested in the body

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parasitism

one organism benefits at the expense of the other

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opportunistic microorganisms

potentially pathogenic organisms that cause disease under special conditions (ex. immunocompromised persons)

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Koch's Postulates

1) same pathogen must be present in every case of the disease
2) pathogen must be isolated from the diseased host and grown in pure culture
3) pathogen from pure culture must cause the disease when inoculated into a heath animal
4) pathogen must be isolated from inoculated animal and must be shown to be the original organism

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syndrome

specific signs (measurable) and symptoms (observable changes) that cause a disease

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communicable

disease spreads directly or indirectly from one host to another (ex. flu, common cold)

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contagious

disease spreads easily from one person to another (ex. chicken pox)

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noncommunicable

disease caused by organism normally grown outside the body (ex. tetanus, botulism)

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incidence

number of new cases in the population

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prevalence

number of new cases + old cases in the population

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sporadic

in the population occasionally (ex. Typhoid Fever)

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endemic

constantly in the population (ex. histoplasmosis)

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epidemic

in the population for a short period of time (ex. flu Nov-March)

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Respiratory Syncytial Virus (RSV)

-RNA, enveloped
disease: pneumonia in infants
transmission: droplets, aerosoles
diagnosis: viral culture, nasal swab, serology, PCR
treatment: monoclonal antibiotics, supportive therapy

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pandemic

worldwide

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herd immunity

majority of the population is immune to a disease

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acute disease

rapid/sudden onset of syndrome (ex. strep throat)

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chronic disease

slow in development and long lasting (ex. hepatitis)

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latent disease

virus remains in the body with no syndrome

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local infection

pathogen is restricted to a small area of the body (ex. cavities, pimples)

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systemic infection

pathogen spreads through circulation to many sites (ex. candidiasis)

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focal infection

starts initially as a local infection, but circumstances cause the microbe to be carried to other sites systemically (ex. endocarditis)

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primary infection

the initial or acute infection (ex. cancer, AIDS)

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secondary infection

a second infection in a different location (usually) caused by a different microbe than the primary infection (ex. mucor, thrush)

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subclinical infection

no noticeable signs or symptoms (ex. polio, Hep A)

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predisposing factors

age, gender, genetic make-up

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incubation period

time interval between infection and first signs and symptoms

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prodromal period

time characterized by the first milds signs and symptoms

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period of illness

most signs and symptoms

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period of decline

signs and symptoms weaken

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period of convalescence

body returns to prediseased state

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causative agent

pathogen causing infection

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human reservoirs

carriers of the disease but show no signs or symptoms (ex. AIDS, gonorrhea)

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animal reservoirs

infections acquired by contact with animals (ex. Zoonoses - rabies, Lyme disease)

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Rhabdovirus

-RNA, enveloped
disease: Rabies
transmission: bite from infected animal
diagnosis: autopsy of saliva/brain tissue, viral culture
treatment: rabies immunoglobin plus vaccine
S+S: encephalitis, foaming at mouth, paralysis of throat

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portal of exit

route for pathogen to leave reservoir, same as portal of entry

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direct contact

touching, kissing, sexual

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indirect contact

drinking out of the same glass, dirty tissues, medical equipment, catheters

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droplet

coughing, sneezing, laughing

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vehicle

air, water, food, airborne, waterborne

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Hepatitis A

-RNA, enveloped
disease: Hep A
transmission: fecal-oral (contaminated waters)
diagnosis: serology for antibodies
treatment: immunoglobin
S+S: little liver damage, diarrhea, nausea

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Hepatitis E

-RNA, enveloped
disease: Hep E
transmission: fecal-oral (contaminated waters)
diagnosis: serology for antibodies, PCR for viral RNA
treatment: self-limiting
S+S: little liver damage, diarrhea, nausea

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vector

arthropod/insect that transmits the pathogen to host

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biological vector

pathogen multiplies in vector and bites host to transmit disease; active process (ex. malaria, Lyme disease)

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mechanical vector

pathogen carried on body part of vector; passive process (ex. shigella, salmonella)

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portal of entry

route for the pathogen to enter the host (ex. parenteral, break in skin, respiratory)

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Healthcare-Associated Infections (HAIs)

infections acquired in hospitals, nursing homes, surgical centers, and healthcare clinics

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HAIs result from

interactions of several factors including microbes in the hospital environment, the compromised host, and the chain of infection

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leading cause of HAIs

Clostridium difficile

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most susceptible to HAIs

patients with burns, surgical wounds, and suppressed immune systems

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HAIs are transmitted by

direct contact between staff and patients and between patients; fomites

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emerging infectious diseases (EMDs)

infections that have recently appeared within a population

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contributing factors to EMDs

evolution of new strains, misuse of antibiotics, changes in weather patterns, ecological disasters (war), modern transportation, animal control measures

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Methicillin-Resistant Staphylococcus aureus (MRSA)

causes bacteremia and pneumonia

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E. coli

causes hemorrhageic diarrhea and produces shiga-toxin

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Avain Influenza

causes bird flu, transmitted by infected birds to humans

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Swine Flu

causes swine flu, transited by infected pigs to humans

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Zika virus

transmitted by mosquitos

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epidemiology

the study of the transmission and frequency of disease

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modern epidemiology began because of

John Snow, Ignaz Semmelweis & Nightingale

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Center for Disease Control (CDC)

-provides data on incidence and prevalence
-main source of epidemiological information in USA
-publishes Mobility and Mortality Weekly Report

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Nationally Notifiable Infection Diseases

diseases for which physicians are required by law to report cases to the US Public Health Services

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pathogenicity

the ability to cause disease by overcoming the defenses of the host

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virulence

the extent/degree of pathogenicity

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parenteral route

direct inoculation of microorganisms into tissues by IVs, bites, injections

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ID50

infectious dose for 50% of the test population (mice)

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LD50

lethal dose for 50% of the test population

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preferred portal of entry

Salmonella Typhi - swallowed
S. pneumonia - inhaled

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multiple portals of entry

B. anthraces - inhalation, break in skin, GI tract
Plague - parenteral, inhalation, injection, bite

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adhesins (ligands)

spots on pathogen the bind specifically to complimentary surface receptors on the cells of certain host tissues; glycoproteins, lipoproteins

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diversity of adhesins

glycocalyx on S. mutans
fimbriae on E. coli
M protein on S. pyogenes

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capsules

have a virulence factor and are antiphagocytic

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cell wall components

M protein in S. pyogenes
mycolic acid in M. tuberculosis
outer membrane protein (Opa) in N. gonorrhoeae

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exoenzymes

extracellular enzymes produced by bacteria and are exerted outside of the cell

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coagulase

converts fibrinogen to fibrin (clot) which protects against phagocytosis (S. aureus)

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hemolysins

destroy RBC (S. aureus)

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leukocidins

destroy WBC (S. aureus)

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kinases

converts plasminogen to plasmin which breaks down fibrin (clots) (S. pyogenes)

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hyaluronidase

breaks down hyaluronic acid in connective tissue (S. pyogenes)

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collagenase

breaks down collagen (C. perfringens)

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IgA protease

breaks down antibiotics fighting against the bacteria (N. gonorrhoeae, N. meningitides)

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antigenic variation

escaping the host antibodies (flu)

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penetration into the host cell cytoskeleton

invasins rearrange host's acid to change the shape of the cell and then get in (salmonella)

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exotoxins

gram positives; destroy specific parts of the host cell by inhibiting certain metabolic functions (ex. A-B toxins, cytotoxins, neurotoxins, and entertoxins)

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endotoxins

gram negative cell walls (lipopolysaccharides); cause fever (pyrogenic response) by inducing the release of interleukin-1 from macrophages

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plasmids

small, circular, closed DNA molecules that are extrachromosomal and are capable of self-replication; encode for virulence factors such as enterotoxin, resistance factors to antibiotics, adhesins, coagulase, etc.

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lysogenic conversion

changes in the characteristic of the microbe due to prophage; pathogenic bacteria carry lysogenic phages that transmit exotoxins to nonpathogens

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cytophaic effects of viruses

visible effects that can lead to death or damage to the host cell

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examples of CPE

-stopping mitosis
-inclusion bodies
-syncytium
-induction of antigenic changes in host
-interferon production
-host cell transformation

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conenzyme

extracellular enzymes produced by bacteria