microbiology midterm #2 Flashcards
what are the types of microbial control?
-sterilization
-disinfection
-sanitization
-antisepsis
-degerming
-asepsis
-biocide/germicide
-bacteriostasis
what is sterilization?
removal or destruction of ALL MOs
(ex cleaning surgical equipment)
what is disinfection?
treatment that kills or inhibits the growth of harmful MOs
(ex. cleaning a hospital room in between patients)
what is sanitization?
reduction of MOs to minimize transmission
(ex. food preparation areas or equipment)
what is antisepesis?
disinfection of live biological sample such as the skin or mucous membrane
(ex. showering before surgery)
what is degerming?
antisepsis that is localized into a small region of the body
(ex. cleaning the skin before a vaccination)
what is asepsis?
complete absense of bacterial contamination
what is biocide/germicide?
treatment that kills living MOs
what is bacteriostasis?
treatment that only halts or prevents growth of the bacteria (no bacteria death occurs)
what are the factors that influence microbial control?
-the death rate of the MO( MOs do not die immediately)
-alteration of rate (rate can be altered by environment, time the MO is exposed to treatment, and nature of the MO)
what are the three things a control agent can effect in the MO?
-plasma membrane
-proteins
-nucleic acids
how does a control agent effect the plasma membrane in an MO?
destruction of the plasma membranes permeability hampers the growth of the cell
how does a control agent effect the proteins in a MO?
control agent alters the shape of the protein via heat or chemicals to effect the cells function (denaturization)
how does a control agent effect the nucleic acids in a MO?
the control agents interfere with the bonds between atoms causing the prevention of proper protein function and formation
what are the 4 physical methods of MO control?
-heat
-filtration
-dessication
-radiation
how does heat control MOs?
heat denaturizes the proteins( alters the shape)
-moist heat and dry heat
how does filtration control MOs?
Physically seperates the MOs out of a smaple based on size (liquid or gas)
how does dessication control MOs?
removes the water from the MO that it needs for survival
what are the two types of radiation?
ionizing (xrays, gamma rays, electron beams)
non-ionizing (ultraviolet/UV)
how does ionizing radiation work?
-mutation of DNA
-sterilizes food, pharmaceuticals, and disposal of medical implements
-greater penetrating power
how does non-ionizing radiation work?
-mutation of DNA
-room sterilization (UVlamps)
-less penetrating power (only affects the skin)
what are the 5 modes of action?
1.inhibition of cell wall synthesis
2. inhibition of protein synthesis
3. inhibition of nucleic acid replication and transcription
4. injury to plasma membrane
5. inhibition of essential metabolite synthesis
what happens in the first mode of action?what kind of antibiotics are used?
inhibition of cell wall inhibition: without the cell wall the cell is not protected from environment and the osmotic pressure causes lysis
-penicillin
what happens in the second mode of action and what kind of antibiotics are used?
inhibition of protein synthesis: antibiotics alter the shape of the proteins
-streptomycin
-chloramphenical
-tetracycline
-erythromycin
what happens in the third mode of action and the antibiotics used?
inhibition of the plasma membrane: antibiotics alter the permeability of the membrane allowing essential nutrients out.
-amphotericin B
-Ketoconazole
what happens in the fourth mode of action and what antibiotics are used?
inhibition of nucleic acid synthesis: prevents the MO from reproducing and growing
-could cause side effects by effecting the hosts DNA/RNA
-quinolones (ciprofloxacin)
what is the fifth mode of action and what are the antibiotics used?
inhibit the synthesis of essential metabolites: prevent synthesis by competing for an enzyme in a metabolic pathway
-sulfonamides
what are the five mechanisms of drug resistance?
- blocking entry
- inactivation by enzymes
- alteration of target molecules
- efflux of antibiotics
how does the first mechanism of drug resistance work and what is an example of a resistance?
prevention of entry: the Mo has some sort of protective structure preventing the antibiotic from reaching its target molecule
-gram-negative bacteria
how does the second mechanism of drug resistance work and what is an example of a resistance?
inactivation of enzymes: The MO produces an enzyme that destroys or deactivates the antibiotic
-penicillin resistance
how does the third mechanism of drug resistance work and what is an example of a resistance?
alteration of target molecule:change in shape of the effected protein or structure prevents the antibiotic from reaching its target molecule
-staphylococcus aureus
how does the fourth mechanism of drug resistance work and an example of a resistance?
efflux of antibiotic: MO expels antibiotic from the cell so it can’t bind
-can occur with all types of antibiotics
how do you properly use antibiotics?
-take antibiotics as prescribed
-do not skip doses
-do not save antibiotics
-do not take antibiotics prescribed for someone else
-all drugs have side effects
what kind of bacteria causes tuberculosis?
mycobacterium tuberculosis
what is pathogenicity?
the ability of an MO to overcome a hosts defences and cause a disease
what is virulence?
a measure of pathogenicity of an MO, the higher the virulence the higher the ability to cause disease
what are the 3 major portals of entry?
-mucous membrane
-skin
-parenteral route
explain the mucous membrane portal of entry?
-respiratory: MO enter by being breathed in
-gastrointestinal: MOs that are ingested
-genitourinary tract: STIs
what are the most common MOs that spread via respiratory tract?
-influenza
-bordetella pertuttis (whooping cough)
-streptococcus pneumoniae
-mycobacterium tuberculosis
what are the most common MOs that are spread via gastrointestinal tract?
-shigella spp.
-salmonella enterica
-S.typhi
what Mos are most commonly spread via genitourinary tract?
-neisseria gonorrheae
-chlamydia trachomatis
-HIV
explain the skin portal of entry?
the skin is normally impermeable to MOs but Mos can enter through the eyes, hair follicles, and sweat glands
-some can enter through the skin, such as fungi and hookworms
explain the parenteral portal of entry?
when the Mo enters through a wound in the skin
how does S.typhi cause disease?
only when swallowed
how does streptococci spp. cause disease?
only through inhalation
what does infectious dose mean and what does ID50 mean?
infectious does is the dose high enough to infect half the population which is ID50
what does lethal does and LD50 mean?
lethal dose is the dose sufficient to kill half the population which is LD50
what are the three side effects when a host’s cells are damaged by bacterial pathogens?
1.use of hosts cells nutrients (MOs use metabolites before the host cell can)
2. direct damage (MOs grow so large in number that the host cells burst causing lysis)
3.toxins
what are the two different types of toxins?
-endotoxins
-exotoxins
explain exotoxins
-mostly produced by gram-positive cells
-synthesized during bacterial metabolism
-secreted during MO growth or upon cell lysis
-highly toxic
what are some examples of exotoxins?
-clostridium botulinum
-staphylococcus food poisoning
explain endotoxins
-part of the outer membrane of gram-negative cells
-released when bacteria die
-can be triggered when antibiotics kill bacteria
what is the immune system?
important defense system against infection in the body (5% of body weight)
where are immune cells formed?
bone marrow and thymus
what are the peripheral lymphoid organs?and what do they do?
remove and destroy antigens in the lymph and blood
-tonsils
-lymph nodes
-spleen
-intestinal lymphoid tissues
what are the central lymphoid organs and what do they do?
site if maturation of immune cells
-thymus
-bone marrow
what is the innate defense system?
constitutes first and second lines of defense
what are the first lines of defense?
external body membranes:
mucous membranes and skins epidermis
what are the second lines of defense?
internal defenses after the first line has been broken:
-phagocyte
-NKC
-antimicrobial proteins
-fever
what are Natural Killer cells?
cells that kill by inducing apoptosis in cancer cells and infected cells
explain how fever helps immunity?
fever causes liver and spleen to sequester zinc and iron which are vital for MOs
increases metabolic rate which increases rate of healing in the body from the MO
what is adaptive immunity?
specific, systematic, and has a memory
what are the two branches in the adaptive immune system?
-humoral and cellular immunity
what does the humoral branch do?
-humoral branch has extracellular targets
-antibodies produced by B cells circulate freely in bodily fluids
-temporarily binds to target and inactivates
-marks for destruction
what does the cellular immunity branch do?
-cellular immunity has cellular targets
-T cell lymphocytes directly kill target cells
-also indirectly releases chemicals that activate the inflammatory response or activate other lymphocytes or macrophages
what is the active humoral immune response?
occurs when B cells encounter antigens, produce specific antibodies against them and memory cells which remain in body
what are the two types of active humoral immunity?
- naturally acquired: formed in response to actual bacteria or infectious virus
2.artificially acquired: formed in response to vaccine
what is the passive humoral immunity response?
-occurs when ready made antibodies are introduced in the body
what are the two types of the passive humoral immune response?
1.naturally acquired: antibodies pass from mother to fetus
2.artificially acquired:injection of antibodies
what are antigens?
-substances that can mobilize adaptive defenses and provoke an immune response
-targets of all adaptive immune responses
-recognizes as intruders
-can be complete or incomplete
what are immunodeficiencies?
congenital or acquired conditions that impair function or production of immune cells or molecules
how does HIV affect the body?
-cripples immune cell system by interfering with activity of helper T cells
what is a vaccine?
a product that when introduced into the body produces immunity from a disease. can be administered through injection, mouth, or nasal route
what is vaccination?
the process of stimulating the bodies immune system to protect against infectious diseases
what is immunization?
the process where a person is protected or immune from an infectious disease
what happens to the immune system when a vaccine is administered?
-deliberate exposure to the antigen results in production of memory B and T lymphocytes against specific targets
what is the purpose of a vaccine?
to prevent or reduce the acute clinical manifestation of the infection
what are the 5 different types of vaccine?
- live vaccine
- inactivated vaccine
- toxoids
- subunits or conjugates vaccine
- mRNA vaccine
how should vaccines be stored?
refrigerated within the temps of 2-8 degrees celsius depending on the vaccine
what is epidemiology?
study of disease progression within a population
who are the two founders of epidemiology?
John snow and Florence nightingale
what is meant by epidemiology should be descriptive?
should acquire all data about the disease being examined
what is meant by epidemiology should be analytic?
-use case control(compare groups with or without disease to determine causes or other factors
-identify a cohort
what is meant by epidemiology should be experimental?
-should use hypothesis testing to discover how the disease spreads, factors influencing its spread, and how it can be treated
what is a notifiable disease?
infections that must be reported to a public health body if found (ex. covid)
what is mortality?
deaths caused by notifiable diseases
what is morbidity?
incidence of specific notifiable disease
what are the steps involved in Koch’s postulates?
1.microorganisms are isolated from a dead animal
2a. the microorganisms are grown in pure culture
2b. the microorganism is identified
3. the microorganisms are injected into a live lab animal
4. disease reproduces in live lab animal
5a. microorganism are isolated from the animal and grown in pure culture
5b. microorganisms are identified
compare communicable and non-communicable diseases and give examples
communicable: the disease can be passed from host to host (chicken pox, measles, herpes, typhoid fever)
non-communication:host can not pass the disease to others
(clostridium tetani, cryptococcus gattii, naegleria fowleri)
what does an incidence occurrence mean?
new infections
what does a prevalence occurrence mean?
new and existing infections(more relevant for long term infections)
what does a sporadic frequency mean? and an example
only shows up occasionally (ex.typhoid fever in the US)
what does an endemic frequency mean? and an example
always present in a particular environment (malaria in mexico)
what does an epidemic frequency mean? and an example
many new infections in an area over a short period of time (frequently influenza)
what does a pandemic frequency mean? and an example
epidemic disease at a global scale (covid)
what does an acute severity mean? and an example
develops and resolves quickly (influenza)
what does chronic/persistent severity mean? and an example
slower development and longer lasting, continues or reoccurs ( mono, tuberculosis, Hep B)
what does latent severity mean? and an example
inactive period before producing symptoms (shingles)
what are local infections and some examples?
limited to a small area of the body (ex. boils, acne, pimples)
what are systemic/generalized infections and some examples?
infections throughout the body, typically spread by blood or lymph (ex.measles)
what is a primary infection?
initial infection
what is a secondary infection?
a infection caused by a initial infection
