SCCC Microbiology Test 3 – Flashcards

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sterilization
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destruction of all forms of microbial life including spores (and viruses). Prions are not killed.
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disinfection
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destruction of all pathogenic microbes except spores
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antisepsis
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disinfection of living tissue
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sanitization
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lowering the number of microbes on a surface to a safe public health level
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-cide
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means kill
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-stat, -stasis
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"stop" growth. Growth may resume after agent is removed
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sepsis
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bacterial contamination (of blood) 
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asepsis
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a non-contaminated state
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antimicrobial treatments vary in the time they take to kill a microbe. Time depends on:
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-the number of microbes (Salmonella, need a lot; Shigella need a few)

-the environment - heat and an acid environmnt help kill microbes

-time of exposure - spores take longer to kill

-microbial characteristics - gram pos. organisms are easier to kill than gram neg because gram neg have very selective pores. Psuedomonas and Mycobacterium have a waxy cell wall (mycolic acid). Prions are very hard to kill - must be incinerated

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Actions (how microbes are killed)
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-damage the plasma membrane

-damage proteins and nucleic acids (heat & radiation)

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List of physical methods of microbial control
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-heat

-filtration

-low temperature

-high pressure

-dessication

-osmotic pressure

-radiation

 

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How does heat control microbes?
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It denatures enzymes
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thermal death point
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lowest temperature at which all the microorganism in a suspension will be killed in 10 minutes
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thermal death time
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minimal amount of time for all bacteria to be killed a given temperature
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decimal reduction time
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time, in minutes, for 90% of the bacteria to be killed at a given temperature
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List of moist heat techniques in microbial control
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autoclave

pasteurization

sterilization

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autoclave
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steam under pressure

121°C at 15 psi for 15 minutes

(may increase some factors to decrease others, ex increase temperature to decrease time)

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pasteurization - traditional
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30 minutes @ 60°C
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pasteurization - High Temp. Short-Time (HTST)
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15 min @ 72°C 

used for milk

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sterilization - ultra high temperature (UHT)
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can store milk unrefrigerated for a few months
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dry heat microbial control techniques
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-flaming

-hot air sterilization (oven)

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Filtration - High-efficiency Particulate Air (HEPA) filters
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-used in ORs and burn wards

membrane filters - the size of the pore dictates which organisms are retained

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Low temperature microbial control
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-Refrigeration is a bacteriostatic for most pathogens. Listeria is an exception

-Freezing can kill some bacteria, but can cause dormancy in others. They can be thawed and grow.

Freezing for 30 days at -5ºC will kill trichinella in pork.

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high pressure microbial control
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used for juices

spores resist pressure

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desiccation microbial control
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-removal of water

-many bacteria can survive lyophilization or freeze-drying

-Gonorrhea dies quickly out of the body

-TB can live much longer

-Viruses resist desiccation

-Endospores can live for many years

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osmotic pressure for microbial control
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-high sugar or salt concentration causes water to leave bacterial cells and they die

-molds resist osmotic pressure

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radiation for microbial control
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mutates DNA

-UV lights are used in hospitals

-microwaves do not destroy bacteria, the heat does

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Equivalent treatments
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If the temperature is increased, the length of time can be decreased to achieve the same number of microbes killed. For example, to kill endospores it might take 70 minutes at 115°C but only 7 minutes at the higher temperature of 125°C. 
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Phenol & phenolics
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Used in throat lozenges, pus, saliva
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Bispheols
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Used in antibacterial soap and nurseries
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Biguanides
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Used in surgical hand scrubs
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Halogens
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Iodine & chlorine. Used on skin, wounds, pools
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Alcohols
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used on intact skin
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Heavy metals
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silver - used in impregnated dressing for burns

zinc - mouthwash & dandruff shampoo

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Surface-active agents
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used on skin, mouthwash
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Chemical food preservatives
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sulfur dioxide - in wine

sodium nitrate in hot dogs, ham, sausage, bacon - excellent for preventing growth of Clostridium botulinum spores. May be carcinogenic, so levels have been reduced in foods.

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Antibiotics
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can be used externally & internally
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Aldehydes 
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used in biological specimens, vaccines, embalming
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Chemical sterilization 
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-ethylene oxide + CO2 used in closed chamber for sterilizing mattresses

-chlorine dioxide used to fumigate buildings infected w/anthrax

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Plasmas
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surgical instruments & hydrogen peroxide (H2O2) are placed in a chamber that is subject to an electromagnetic field. This forms an "excite gas" that forms free radicals which destroy microbes and their spores
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Supercritical fluids
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compressed CO2 at 45°C kills bacteria & spores

used on medical implants of bone, tendon & ligament

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Peroxygens 
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Hydrogen peroxide - intact skin (it is ineffective in open wounds because it is broken down by the catalase in red blood cells before it can act on bacteria)
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pathology
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the study of disease
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pathogenesis
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the manner in which a disease develops
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etiology
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the cause of disease
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infection
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when pathogenic organisms invade the body
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infection location
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an organism may be normal flora in one part of the body but pathogenic in another part of the body

an organism, E. coli, is normally found in the intestines, but can cause an infection if it invades the bladder

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cystitis
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bladder infection
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pyelonephritis
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kidney infection
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infection latency
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infection can be latent (inactive)

chicken pox and herpes virus can remain latent in nerve cells for years without causing disease

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disease
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a state where a part of the body is not functioning normally
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Normal Flora (microbiota) - general info
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-Babies are sterile

-Adults can have 1 x 1014 bacterial cells living in and on them, 10 times more than the number of cells we have!!


-"Normal" varies from person to person

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Where are normal flora present?
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-skin

-eyes (you will never get "normal eye flora" on an eye culture report, tears usually wash away bacteria)

-nose, throat, upper respiratory system

-lungs

-mouth

-intestines

-reproductive system in females

-stomach (sometimes)

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list of relationships between flora and host
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-antagonism

-symbiosis

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antagonism (definition)
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competition between normal flora and pathogens

ex. - E. coli produces proteins that inhibit the growth of Salmonella and Shigella

ex. - Acidophilis spp. lower the pH of the vagina to ~pH 4 so yeast cannot grow

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How do host flora make the environment unsuitable for pathogens?
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-competing for nutrients

-producing harmful substances

-affecting pH

-affecting oxygen availability

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What happens when host flora are reduced or removed from use of broad spectrum antibiotic therapy?
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-yeast (Candida) may colonize the mouth and vagina

-Clostridium difficil can infect the intestines (common nocosomial infection)

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symbiosis (definition)
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relationship where at least one organism depends on the other
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symbiosis - types
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-commensalism

-mutualism

-parasitism

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commensalism
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one benefits one is unaffected
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mutualism
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both benefit
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probiotic
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live bacteria that are ingested or applied that have a beneficial effect

ex - lactic acid bacteria in the intestine inhibit growth of pathogens

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prebiotic
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chemicals that promote the growth of probiotic bacteria
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parasitism
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one benefits, one is harmed
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opportunists
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take advantage!
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when do opportunists take advantage?
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-suitable location: bacteria in the intestine can cause infection when in the urinary tract or wounds

-immunosuppressed state: chemotherapy or AIDS. Organism normally present become pathogenic

-after broad spectrum antibiotics

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Examples of opportunistic organisms
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Pnemuocystis jirovecii - in AIDS.  Carriers have a potentially pathogenic organism as normal flora, when passed to another person it is a pathogen and causes pneumonia

Mycobacterium tuberculosis

Neisseria meningitidis (respiratory tract)

Strep. pneumoniae (throat)

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Etiology of Disease: Some diseases are caused by:
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A) some diseases are only caused by one organism (ex. syphilis-Trepanoma pallidum, leprosy-Mycobacterium leprae, tetanus - Clostridium tetani)

B) some dieases can be caused by many different organisms (pneumonia, UTIs, sepsin, meningitis)

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symptoms (definition)
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not apparent to an observer - aches, tiredness, nausea, pain
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signs (definition)
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can be observed or meaured - fever, swelling, discoloration, rash
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syndrome (definition)
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a group of signs and symptoms that point to a single disease
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communicable (definition)
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can spread from one host to another
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non-communicable (definition)
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cannot spread
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occurence of dissease: incidence
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the number of people who develop a disease in a particular time period
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occurence of disease: prevalence
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the number of people who develop a disease at a specified time. This takes into account old and new cases.
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severity & duration - list of types
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-acute

-chronic

-latent

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severity & duration - acute (definition)
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develops rapidly
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severity & duration - chronic (definition)
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develops slowly and lasts

ex. TB, Hep B

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severity & duration - latent (definition)
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symptoms disappear and resurface later

ex. malaria, herpes, checkenpox

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extent of involvement - list of types
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-local

-systemic

-septicemia

-primary infection

-secondary infection

-subclinical

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extent of involvement - local (definition)
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in one area

ex. boil, MRSA

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extent of involvement - systemic (definition)
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spread throughout the body

ex. chickenpox

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extent of involvement - septicemia (definition)
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infection of the blood
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extent of involvement - septicemia (types)
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-bacteremia - bacterial infection in blood

-toxemia - toxins in blood (ex. Strep. pyogenes, E. coli O157:H7, tetanus, botulism)

-viremia - viral infection in blood

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extent of involvement - primary infection (definition)
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first infective organism, ex AIDS
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extent of involvement - secondary infection (definition)
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opportunist sets in when the body is weak

ex. Pneumocystis jirovecii

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extent of involvement - subclinical (definition)
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no noticable illness, very mild
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predisposing factors (definition)
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makes one person more susceptible than others
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list of predisposing factors
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genetics

gender

nutrition

age

preexisting illness

chemotherapy

environment - humidity

stress

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development of disease:

stage - time - signs & symptoms

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incubation - time varies - no symptoms

prodromal - short duration - mild symptoms

illness - time varies - all signs and symptoms

decline - 1 day to several days - symptom decrease

convalescense - can last for years - carriers

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spread of infection - reservoirs - list
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humans

animals (zoonoses)

soil

water

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spread of infection - reservoirs - humans (examples)
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colds, Hep. A (fecal-oral), Hep. B (blood-blood)
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spread of infection - reservoirs - animals (examples)
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Pasturella multocida - cat bites

Rabies - mammals

Malaria - mosquitoes

Tularemia -hamsters

Tapeworms

Leprosy - armadillos

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spread of infection - reservoirs - soil (examples)
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tetanus

Necator americanus (hookworm)

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spread of infection - reservoirs - water (examples)
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cholera
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Disease transmission - list
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-contact

-vehicles

-vectors

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Disease transmission - contact - definition
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touching someone or something that they touched
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fomite
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any inanimate object capable of carrying infectious disease and transmitting them from one person to another
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Disease transmission - vehicles
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blood, IV fluid, water
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Disease transmission - vectors - definition
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animals that carrry pathogens from one host to another

ex. hoof & mouth disease

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Disease transmission - vectors - types
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-mechanical - insect carry disease on wings or feet

-biological - arthopod bites an infected animal, draws blood. Organism matures. Arthopod bites an uninfected animal and transmit the disease or defecate in open wound

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nosocomial infection - general info
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-kill 20,000/yr in the US

-affect 5 - 15% of all hospitalizations

-many bacteria in hospitals are drug resistant

-compromised hosts - broken skin or weak immune systems

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nosocomial infection - vehicles
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hospital personnel

ventilation systems

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Common nosocomial infections
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Pseudomonas

Staph. aureus-MRSA

Clostridium difficil

Enterococcus-multiple drug resistants strains

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3 most common sites for nosocomial infections
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-urinary tract

-surgical sites

-lower respiratory infections

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control of nosocomial infections
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-handwashing!!!

-alcohol based hand sanitizers not effective agains noroviruses which cause gastroenteritis

-sterile technique

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causes of new diseases
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-genetic recombination

-evolution ex. Vibrio cholera O139

-widespread use of antibiotics

-global warming - expanding range of reservoirs

-transportation

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epidemiology
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when and where disease occur and how they are transmitted
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descriptive epidemiology
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retrospective, look back and examine people, place, time disease occured
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analytical epidemiology
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attempts to find the cause

compare 2 populations, 1 group with diease and 1 without disease

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case reporting
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nationally notifiable infectious diseases that must be reported to local, state, and federal health agencies
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mechanisms of pathogenicity - intro
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some pathogens directly damage our tissue. Others produce waste products that cause disease
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portals of entry - list
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-mucous membranes

-skin

-parenteral

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portals of entry - mucous membranes - list
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respiratory tract

GI tract

genitourniary tract

conjuctiva

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portals of entry - skin - info
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unbroken skin usually cannot be penetrated

exceptions - Necator americanus (hookworm), fungi - grow in the skin (keratin)

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portals of entry - parenteral - list
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puncture wounds, injections, bites, cuts, surgical wounds
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preferred portal of entry
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most bugs only cause disease when they enter through this portal

ex. Strep. : resp tract, causes disease; GI tract, no disease

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virulence
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depends on number of organisms infected with. must have sufficeint # to cause disease
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ID50
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Infectious Dose - number of bus needed to cause disease in 50% of the population

ex. Anthrax:

skin-ID50=10-50 spores

respiratory-ID50=10,000 spores

GI-ID50=1/2 million spores

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Toxin Potency - LD50
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Lethal Dose

botulism toxin LD50=0.03 ng/kg

staph LD50=1400 ng/kg

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adherence
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surface molecules are called adhesins or ligands

usually glycoproteins or lipoproteins that attach to receptors on host cells

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adherence example - Strep. mutans
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Strep. mutans - on teeth

S. mutans converts glucose to dextran

dextran becomes bugs glycocalyx 

Actinomyces uses fimbrae to attach to S. mutans glycocalyx

This forms plaque on our teeth

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Penetration of host defenses - list
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capsules

cell walls

enzymes

antigenic variation

penetration into the host cell cytoskeleton

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Penetration of host defenses - capsules
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inhibit ability of phgocytosis

found on: Streptococcus pneumoniae, Klebsiella pneumoniae, Haemophilis influenzae, Yersinia pestis

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Penetration of host defenses - cell walls
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Strep. pyogenes makes M protein that helps attachment and avoid phagocytes

Neisseria gonorrhoeae has protein called Opa to attach, invade, and grow inside WBC. Opa attaches to CD4-lymphocyte, it prevents production of "memory cells" (lifelong immunity where we "remember" antigens we were exposed to)

Mycobacterium have waxy cell wall (mycolic acid) to resist phagocytosis

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Penetration of host defenses - enzymes - list
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coagulase

streptokinase

hyaluronidase

collagenase

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Penetration of host defenses - enzymes - coagulase
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Staph makes coagulase

coagulase causes the formation of fibrin clots which wall off the infection

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Penetration of host defenses - enzymes - streptokinase
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Strep. pyogenes (Group A Strep) makes streptokinase which breaks clots and helps infection spread

streptokinase is given to heart attack and stroke victims to prevent formation of clots.

Blood vessels get plaque made of cholesterol, fat, fibrin, and calcium. Platelets stick to plaque and initiate clot formation which contains fibrin. Streptokinase helps break up fibrin. (now TPA (tissue plasminogen activator) is used)

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Penetration of host defenses - enzymes - hyaluronidase
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made by Strep. and Clostridium

hyaluronidase digests hyaluronic acids

hyaluronic acids holds cells together

hyaluronidase destroys tissue to help infection spread

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Penetration of host defenses - enzymes - collagenase
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Clostridium makes collagenase

collagenase destroys collagen, destroys tissue, & keeps antibiotics away (destroys blood vessels through which antibiotics travel to reach infection)

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Penetration of host defenses - antigens
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antigens trigger antibody production - proteins, sugars, nucleic acids

Antigenic variation - some pathogens can change surface antigens and our antibodies no longer recognize them

ex. Influenza, AIDS, Neisseria

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Penetration of host defenses - invasins
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Invasins - the pathogen's surface proteins disrupt the cytoskeleton of the host cell (actin ; myacin - contractile proteins) and cause it to be engulfed

ex. Neisseria

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Damage to host cells - list
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-using host nutrients

-directly damaging tissue

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Damage to host cells - using host nutrients
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Bacteria require iron. They secrete siderophores - proteins that bind free iron. Some bacteria have receptors for hemoblobin. They take in and use its iron. Lyse RBCs.
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siderophores
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bacterial proteins that bind free iron
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Damage to host cells - direct damage to tissue
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Bacteria directly damage tissue by infecting, growing, and reproducing in our cells. Ex. E. coli, Shigella, Salmonella, Neisseria gonorrhoeae
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Portal of entry - list of diseases - respiratory tract
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1.      Pneumonia – Streptococcus pneumoniae

2.      Tuberculosis – Mycobacterium tuberculosis

3.      Whooping cough – Bordetella pertussis

4.      Influenza – Influenzavirus

5.      Measles (rubeola) – Measles virus (Morbillivirus)

6.      German measles – Rubella virus (Rubivirus)

7.      Infectious mononucleosis – Epstein-Barr virus (Lymphocrptovirus)

8.      Chickenpox – Varicella-zoster virus (Varicellovirus)

9.      Histoplasmosis  - Histoplasma capsulatum


10. Cold - Rhinovirus

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Portal of entry - list of diseases - gastrointestinal tract
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1.      Shigellosis (bacillary dysentery) – Shigella spp.

2.      Brucellosis (undulant fever) – Brucella spp.

3.      Cholera – Vibrio cholera

4.      Salmonellosis – Salmonella enterica

5.      Typhoid fever – Salmonella typhi

6.      Hepatitis A – Hepatitis A virus (Hepatovirus)

7.      Mumps – Mumps virus (Rubulavirus)

8.      Trichinellosis – Trichenella spiralis

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Portal of entry - list of diseases - genitourinary tract
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1.      Gonorrhea – Neisseria gonnorrhoeae

2.      Syphilis – Treponema pallidum

3.      Nongonococcal urethritis - Chlamydia trachomatis

4.      Herpes virus – Herpes simplex virus type 2

5.      AIDS – HIV

6.      Candidiasis – Candida albicans


7. Genital warts - HPV

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Portal of entry - list of diseases - parenteral route
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1.      Gas gangrene – Clostridium perfringens

2.      Tetanus -  Clostridium tetani

3.      Rocky Mountain spotted fever – Rickettsia rickettsii

4.      Hepatitis B – Hepatitis B virus (Hepadnavirus)

5.      Rabies – Rabies virus (Lyssavirus)

6.      Malaria – Plasmodium spp.


7. AIDS - HIV

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Effects of bacterial toxins
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1.      fever

2.      cardiovascular disturbances

3.      diarrhea

4.      shock

5.      inhibition of protein synthesis

6.      destruction of blood cells and blood vessels

7.      spasms disrupting the nervous system

8.      damage of eukaryotic cell membranes

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Exotoxin & Effects - Corynebacterium diphtheriae
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Diphtheria toxin    

Inhibits protein synthesis in eukaryotic cells, especially nerve, heart, and kidney cells

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Exotoxin & Effects - Streptococcus pyogenes
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Erythrogenic toxins          

Damages the plasma membranes of blood capillaries under the skin and produce a red skin rash. Ex. Scarlet fever

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Exotoxin & Effects - Clostridium botulinum
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Botulinum toxin     

Prevents transmission of impulses from nerve cell to muscle and causes paralysis where muscle tone is lacking

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Exotoxin & Effects - Clostridium tetani 

 

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Tetanus toxin

(tetanospasmin)                              

Blocks the nerve relaxation pathway causing uncontrollable muscle contractions, such as “lockjaw”

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Exotoxin & Effects - Vibrio cholera        

 

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Cholera toxin          

Causes cells to secrete large amounts of fluids and electrolytes resulting in severe diarrhea 

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Exotoxin & Effects - Staphylococcus aureus
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Staphylococcal enterotoxin    

Produces a superantigen that causes cells to secrete large amounts of fluids and electrolytes resulting in severe diarrhea. Toxic shock syndrome is caused by secretion of fluids and electrolytes from capillaries that decrease blood volume and lowers blood pressure

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Where are inclusion bodies found and what are they made of?
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Inclusion bodies are granules found in the cytoplasm or nucleus of some infected cells. The granules are sometimes viral parts such as nucleic acids or proteins in the process of being assembled into a virion.
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What are inclusion bodies called when found in a rabid animal’s brain tissue?
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They are called Negri bodies.
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What are interferons? 
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Interferons are a class of antiviral proteins.
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Which types of cells make interferons?
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Interferons are produced by lymphocytes and macrophages after viral stimulation.
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What is the effect of interferon?  
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 It interferes with viral multiplication and protects neighboring unaffected cells from viral infection.
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