Micro Exam 3 Flashcards
3 major factors leading to the significant decrease of infectious disease during the 20th century.
- greatly improved methods of sanitation/water treatment
- the discovery and use of vaccines
- the development and use of antimicrobial drugs and
antibiotics
antimicrobial drug
-Destroy the disease-causing organism without harming
the host cell
antibiotic
- natural product made by 1 microbe that inhibits or kills another microbe
Define what is meant by the term ‘spectrum of activity
- (specifity) specific group of organisms that agent is effective against
Narrow Spectrum:
-target very specific group
Broad Spectrum:
- target more than one group
Classify how ethambutol and isoniazid work
- Highly selective for Mycobacterium tuberculosis
- Inhibit the production and incorporation of mycolic acid
into the cell wall of Mycobacterium
Inhibition of the Cell Wall
Inhibition of cell wall synthesis
- penicillians
- cephelosporin
- bacitracin
- vancomycin
-isoniazid/ethambutol
Inhibition of protein synthesis
-aminoglycosides
-tetracycline
-erythromycin
-clindamycin
-chloramphenicol
Disruption of nucleic acid
-quinolones
-rifampin
Disruption of the plasma membrane
-polymyxins
-daptomycin
Inhibition of folic acid synthesis
-sulfonamides
-trimethoprim
Inhibition of fungal infections
- polyenes
-imidazoles
-echinocandins
-griseofulvin
Inhibition of protozoan infections
-synthesized quinolines
-metronidazole
Antihelminth drugs
-helminths: parasitic works
- flukes, tapeworms, roundworms
Antiviral drugs (modes of action)
- stop the penetration of the virus into the host cell
- stop the replication, transcription, and translation of viral genetic information
- stop the normal maturation of viral particles
Anti viral drugs that treat the flu
- Amantadine and rimantidine
- relenza and tamiflu
Anti viral drugs that treat herpes
-cyclovir drugs
Antiviral drugs that treat HIV a
-inhibit the entry of the virus
-inhibit conversion
-inhibit HIV protein processing, assembly, and release
Antibiotic resistance
Microbes no longer respond to antimicrobial drugs/antibiotics
Describe the 5 mechanisms by which an organism can become resistant to a drug/antibiotic.
- drug inactivation
- decreased permeability
- activation of drug pumps
4.change in drug binding site - use of alternate metabolic pathway
What are 3 major factors that play a role in the development of resistance?
- hospitals
- drug in animal feeds
- global transport
Identify possible interactions between the drug/antibiotic and the host.
Toxicity
-Liver/kidney: damage
-intestines: diarrhea
-heart: irregular heartbeat
-decreased blood count
-brain: seizures, dizzy, deaf, motor/sensory
-skin:photodermatitis
-teeth: discoloration
Identify possible interactions between the drug/antibiotic and the host.
Allergic reaction
-skin rash
-respitory inflammation
-anaphylaxis (rare)
Identify possible interactions between the drug/antibiotic and the host.
supression of the normal flora
-super infection
-diarrhea, fever, abdominal pain
Explain what the Kirby Bauer test is used for
- extremely standardized disk diffusion assay
- used to test susceptibility of pathogenic bacteria and fungi
how to do the kirby baur test in the lab.
- bacterial suspension in broth is made
- Mueller-Hilton agar swabbed
- antibiotic disk pressed onto surface of agar
- plat incubated overnight at 37 degrees
- Zones of inhibition: measured in mm
- sensitivity or resistance (standard table)
- results interpreted: sensitive, intermediate, resistant
Explain what the MIC test is used for
-tube dilution assay
-which antibiotic is most effective
how to do the MIC test in the lab.
- serial dilutions of a particular antibiotic are made in microtiter plates: low concentration to high
- each well inoculated with bacterial suspension
- plate incubated at 37 degrees
- MIC determined: lowest concentration of antibiotic that inhibitis growth
Normal Flora
- microorganism normally found in a given habitat on our body consistenly
transient microorgansims
- organisms found on the body only for a brief period of time (hands/arms)
Define pathogen
organism capable of causing disease
infection
the invasion or colonization of the body by pathogenic organsims
invasiveness
the pathogens ability to penetrate a host and establish itself in the tissue
infectious disease
altered state of health caused by invasion of a pathogenic microorganism
sign vs symptom
- a sign is changes in the patient you can see and measure as a result (rash, swelling)
- a symptom is a change felt only by the patient as a result (pain, nausea)
Describe Mutualistic symbionts
Microbes and host both benefit
commensals
microbes benefit, host not affected
opportunist
microbes benefit, host is harmed
3 major interacting factors determining potential pathogen to infectious disease
- virulence of the organism
-number of organisms
-strength of the host immune response
6 major virulence factors:
- Body site
- adherence factors
-escape from body immune response
-direct invasion of the host cell
-siderophores
-toxin production
6 major virulence factors:
Body site
- All growth requirements must be met
-examples: nutrient availbility, pH, temp, oxygen requirements
6 major virulence factors:
Adherence Factors
- cell wall components
- fimbriae
- extracellular secretion
6 major virulence factors:
Escape from the bodys immune response
- antiphagocytic structures
- genetic changes
6 major virulence factors:
direct invasion
invades, multiplies, kill
6 major virulence factors:
Siderophores
aid organism to remain in host and be invasive (iron)
6 major virulence factos:
Toxin
- exotoxins
- endotoxins
Exotoxins
-secreted proteins
-cause disease-specific sign and symptom
-gene frequently located on a plasmid or a prophage
-antibodies are produced in response to exotoxins
- we immunize against exotoxins by using toxoid
-produced mainly by gram (+) bacteria, algae, fungi
endotoxins
- lipopolysaccharides
-released when the organism is destroyed
-produced the same signs and symptoms in the host
-antibodies are not produced in response to endotoxins - we do not immunize against endotoxins
-produced only by gram (-) bacteria
Pathology
the study of disease
3 major concerns of pathology
- etiology (what is causing the disease)
-pathogenesis (development of disease)
-the effects of the disease on the whole body
Identify the reservoirs of infectious disease
continual source of the infectious agent.
Identify the transmission routes for infectious disease
how the pathogen is spread
List the 5 major portals of entry into the body
- Respiratory tract
- Gastrointestinal tract
- Genitourinary Test
- Skin and Mucous Membranes
- Blood
Explain the 4 phases of infectious disease development
-incubation
-prodromal
-illness
-convalescence
incubation
- time interval between infection and appearance of first sign and symptoms
- length: organism, virulence, #s, immune resistance
prodromal period
short period of mild signs/symptoms
illness period
most acute: full blown disease; overt signs
convalescence period
recovery time: signs/symptoms subside
Categorization of infectious disease
-acute vs chronic
-local vs systemic
-primary vs secondary vs inapparent
acute vs chronic
acute:
disease develops rapidly
short duration
fever involved
chronic:
disease develops slow
long lasting symptoms
Local vs systemic infection
Local: infection limited to one area of the body
systemic: infection spread throughout the body (spread through blood)
Primary vs secondary vs inapparent
Primary: long term or permanent damage
secondary: opportunistic only after primary infection
inapparent: signs/symptoms absent
Define occurence of infectious disease: endemic
disease constantly present within a geographical area
Define occurence of infectious disease:
epidemic
sharp increase in the # of cases of a disease during a particular period of time
Define occurence of infectious disease:
sporadic
disease occurs occasionally in a random, unpredictable way
Define occurence of infectious disease:
prevalence
percentage of the population having a specific disease at any time
Define occurence of infectious disease:
incidence
percentage of the population that contracts a particular disease during a particular time
What is ‘epidemiology’?
study of…
-number of cases of a particular disease
-population affected
-when and where diseases occur
-the source and how they are transmitted
-control and prevention methods
what is meant by the term ‘emerging infectious disease’.
new or changing diseases that are increasing in the near future
what/where is CDC
center for disease control and prevention in Atlanta, GA
Nosocomial infection
aquired or developed during a hospital stay
Immune system
A multi-level network that provides complete protection against infection.
1st line of defense
- physical barriers
-chemical barriers
-genetic barriers
State the major factors which make the skin an unsuitable environment for most microbes.
- dry
-salty
-acidic
What is the mucous membrane
Epithelial layer which secretes mucus
where is the mucous membrane lined
-respiratory
-urinary
-gastrointestinal
-reproductive
Chemical barriers:
-sebaceous gland
-meibomian gland
-lysozyme
-sweat
-hydrochloric acid
sebaceous gland found in
skin
meibomian gland found in
eye lid
lysozyme found in
body secretion
hydrochloric acid found in
stomach
what is meant by a ‘genetic barrier’ and how a genetic barrier can protect a host against a specific pathogen.
Natural barrier created because a given pathogen is specific for a given host
2nd line of defense
- phagocytosis
-inflammation
-fever
-interferons
-complement system
what is the main WBC involved in second line of defense ?
Phagocyte
what is a phagocyte
scavenger WBCs that engulf and destroy particulate matter
compare/contrast neutrophils and macrophages
Neutrophils respond first then macrophages (phagocytic cell)
Four steps of Phagocytosis
- chemotaxis
- adherence
- ingestion
- digestion
what is chemotaxis
WBC moves toward microbes
what is adherence
close contact between WBC and microbe
ingestion
microbe is internalized by WBC
Digestion
microbes are digested, lysosomes fuse with phagosome membrane
what does PAMP and PRR stand for?
PAMP= pathogen associated molecular patterns
PRR= pattern recohnition receptors
what do PAMP and PRRs do ?
PRRs: are WBC receptors that binds to PAMPS
PAMPS: signal molecules shared by many microbes
what are the four hallmarks of inflammation
-heat
-redness
-swelling
-pain
process of inflammation
-tissue damage
-chemicals released
-chemotatic factors
-tissue repair
define fever
an abnormally elevated body temperature
benefit of fever in immune response
- inhibits multiplication of heat sensitive microbes
- impedes nutrition of bacteria by decreasing the availability of iron
- speeds up production of blood cells
what is an interferon
small protein produced naturally by certain white blood cells and tissue cells
Describe what the complement cascade is and the end result of this process.
complex system of 26 blood protein which work together to destroy bacteria, viruses, and parasites.
End result: forms membrane attack complex, leading to lysis and destruction of pathogen
what are the major cell types in the third line of defense?
- Antigen presenting cells: macrophages and dendritic cells
-Lymphocytes
-Natural killer cell
where do B cells originate and what are the cell surface receptors?
originate: bone marrow
cell surface receptors: immunoglobulin molecules
where do T cells originate and what are the cell surface receptors?
originate: bone marrow
cell surface receptors: thymus gland
define MHC-1
present on all nucleated cells of the body
define MHC-II
present on macrophages and B cells
What are the two branches of the specific immune response?
- Humoral Response
-Cell mediated response
what is humoral response
production of antibodies
what are the specific cell types
- macrophages
- t helper 2 cells
- B cells
- plasma cells
define antigen
Any foreign molecule which can trigger a specific immune response
antibody
Glycoprotein produced and secreted by activated WBCs in response to a specific antigen in the body
epitope
the tips of the Y, 3d pockets which binds to a very specific site on the antigen
hapten
if too small to elicit an immune response
what are the five classes of antibodies
-IgM
-IgG
-IgA
-IgD
-IgE
IgM
-5 to 10 percent antibodies
-largest Ig
-first Ig to increase in antigen response
-lysis of gram - bacteria
-M: macroglobulin
IgG
-primary secondary response
-only class that crosses placental barrier
-eliminates gram - and gram +
-80 percent of total Igs
-neutralization of viruses and toxins
IgE
-0.002 %
-responsible for allergic reactions
-Fc portion bound tightly to basophils and mast cells
-desensitization programs
IgA
-1st line of defense
-monomer form: serum
-diner form: mucus secretions
-respiratory, genitoruinary, intestinal, and breast milk
-1-15%
steps in T cell dependent pathway
-protein based
-APC-TH2 Cells- B cells- plasma cells - antibodies
steps in T cell independent pathway
-simple carbs
-B cells-plasma cells-antibodies
what is amnestic response
rapid production of antibody following second contact with antigen
what cells are responsible for amnesties response
memory cells
primary response to antigen
primary response to antigen
a
occurs directly after exposure
IgM responds first then IgG
secondary response to antigen
- antigen exposed to body for the second time
- me rory cells produced that allow body to respond quickly and effectively
- IgG primary response and increases significantly
6 roles of antibodies
-activation of compliment
-inflammation
-cytotoxicity
-neutralization
-opsonization
-agglutination
benefits of live vaccines
- grow in host
-stimulate antibody production for longer period of time
-stimulate numeral and cell mediated response
-induce production of IgA
clonal selection theory
when foreign antigen enters body, only lymphocytes having receptors specific for that antigen will be activated to proliferate
cell mediated response
- cell-cell contact leading to destruction of infected/abnormal cells
- defends against bacteria, viruses, protozoa, worms, cancer cells
Specific cells involved in cell mediated
- Macrophages
-T helper 1 cells - cyto t cells
-natural killer cells
process of cell mediated response
- APC engulf, process, and display antigen fragments in MHC-2
- TH1 cells recognize MHC2/Ag and bind
- in response to cytokines: TH1 cells activated
- Activated TH1 cells produce additional cytokines which activate macrophages and T cytotoxic cells
define cytokine
secreted proteins of the immune system that have an affect on other cells
process of T cytotoxic cell lysis
- T cells recognize specific antigen in context on MHC1
- granules within cell move to point of contact between 2 cells and fuse with membrane
- potent cytolytic enzymes cause lysis of target cells
- Tc cells released unharmed to seek out another target cell
T cytotoxic cells and natural killer cells
- both derived from bone marrow and target and lyse cells
- NKC do not recognize Ag/MHC-1
- important in killing malignant cells and antibody released cells
active immunity
- person exposed to antigen, antibody created, memory forms
- long term protection
passive immunity
- preformed antibodies
- immediate protection
short term
Natural active
immune response produced antibodies
artificial active
antigen exposure through vaccine
immune response produces antibodies
natural passive
antibodies pass from mother to fetus
artificial passive
anti-serum containing preformed antibodies
define vaccine
provides active acquired immunity to infectious disease
Name the categories of vaccines
- Killed bacteria or viruses
- Living, attenuated bacteria or viruses
- Toxoids/capsular material of bacteria
- Recombinant DNA technology (genetic engineering)
- Conjugated vaccines
benefits of live vaccines
- grow in host
- stimulate antibody production for longer period of time
- stimulate numeral and cell mediated response
- induce production of IgA
why do some vaccine require boosters
to ensure an effective secondary response
What is an ‘adjuvant’, and why do some vaccines require an adjuvant?
compound that enhances the immune response and it retains antigen at the injection site
normal flora and role
- organism found on consistent basis in specific body areas
- compete with and control pathogens
body parts with normal flora
- skin
- eyes
- nasal cavity, middle ear, auditory tube, pharynx (highly colonized)
- mouth, esophagus (highly colonized)
- large intestines(extreme numbers)
- external urethra
- reproductive tracts
sterile body parts
- larynx, trachea, lungs, bronchus
- stomach
- small intestines
- kidneys, ureters, urinary bladder
- blood and tissues
things to know about normal flora
- what is normal flora for one person may not be normal flora for another
- what is normal flora on one body part may not be normal flora on another
- gram (+) bacteria
What is ‘conjunctivitis’?
inflammation of the conjuctiva “pink eye”
what is the ciliary escalator and how does it work
- mucus traps organisms and particles
-the cilia moves them up and out
