o 7% salt in the medium inhibits the growth of most gram-positive and gram-negative bacteria
- differential for: mannitol fermentation
o phenol red pH indicator turns yellow in the presence of acid by-products of mannitol fermentation
o Staphylococcus aureus ferments mannitol
o S. aureus changes the color of the medium from pink to yellow due to acid by-products of mannitol fermentation
o Staphylococcus epidermidis grows on MSA, but does not ferment mannitol (media remains light pink in color & colonies are colorless
Selective Medium: culture medium that allows the growth of certain types of organisms, while inhibiting the growth of other organisms
- dyes in the medium (e.g.: methylene blue in EMB & crystal violet in MacConkey's) or high salt concentration in the medium (e.g.: 7% salt in MSA) inhibit the growth of unwanted microorganisms
Differential Medium: culture medium that allows one to distinguish between or among different microorganisms based on a difference in colony appearance (color, shape, or growth pattern) on the medium.
- dyes in the medium (e.g.: eosin/methylene blue in EMB) or pH indicators change the color of the medium as sugars in the medium (e.g.: lactose in EMB & MacConkey's and mannitol in MSA) are fermented to produce acid products
EMB (Eosin Methylene Blue) Agar
-
selective for: gram-negative bacteria
o growth of gram-positive bacteria (e.g.: Staphylococcus aureus in the image below) is inhibited by the eosin & methylene blue dyes in the media
- differential for: lactose fermentation
o gram-negative Enterobacteria Escherichia coli and Enterobacter aerogenes ferment lactose
o E. coli produces colonies with a characteristic green metallic sheen on EMB agar
o E. aerogenes produces pink colonies often with a central dark purple dot (fish eye colonies) on EMB agar
o gram-negative bacteria Proteus vulgaris and Salmonella typhimurium grow on EMB agar, but do not ferment lactose
Hemolysis with Blood Agar
- agar contains 5% sheep's blood
- differential for: hemolysis...particularly in streptococci
- based on the ability to break down hemoglobin or red blood cells, 3 groups of microorganisms can be described
o alpha-hemolysis: a green to light-brown halo is seen around the colonies; bacteria partially break down hemoglobin leaving a green pigment (biliverdin)
o beta-hemolysis: a clearing is seen around the colonies; bacteria produce a "beta-hemolysin" (streptolysin O or S), which lyses red blood cells in the medium
o gamma-hemolysis (no hemolysis): no hemolysis is observed; bacteria do not produce a hemolysin
Ixodes Tick (5 items)
1. Transmits Lyme Borrellia
2. Bloodmeals preferred source-rodents and small mammals
3. Duration of meal 5-7 days
4. Time between meals-months to years
5. Tick species-scapularis, pacificus
Borrelia species (3)
Burgdorferi
Afselii
Garinii
Pathology of Lyme Disease
Bulls eye rash
Arthritis
Bells Palsy
LYMErix (6 items)
1. Located on 54kb linear plasmid (B. bergdorferi has 12 linear and 9 circular plasmids) ospA and ospB are co-transcribed.
2. OspA and OspB are lipoproteins
3. OspA and OspB homologous to each other (53% overall sequence identity)
4. Neither share significant homology with any other available sequence.
5. Recombinant OspA is the immunogen of the Lymbe disease vaccine
6. FDA approval 1998-discontinued 2001.
Is OspA/OspB a midgut adhesin?( 5 quotes)
They are the major outer surface proteins expressed by Lyme borrelia in the Ixodes midgut
OspA synthesis in the tick is down-regulated duringthe bloodmeal.
Mammals infected by tick bite do not seroconvert to OspA.
OspA is a transmission-blocking Lyme disease vaccine.
Crystal structure predicts a bind pocket in C-terminal domain.
1. Cellular morphologies of bacteria are described as coccoid (round) and bacilliform (rod). Virus particles (virion) also have common shapes, two of which are;
B. Helical and Icosohedral
2. The nucleocapsid is best described as;
D. Lipid bilayer nucleus
C. Capsid and genome
3. Which best describes the virion size and nucleic acid content of picornaviruses?
A. RNA, very small (pico-rna)
4. Hepadnaviridae are a group of viruses that have a ________________________ genome and are associated with infection of the________________________.
D. DNA, liver (hepa dna)
5. From a single cell, bacteria multiply (binary fission) resulting in a population of clones on the surface of an agar plate termed a ‘colony’. Analogously, a single virion can infect a single host cell on the surface of a culture plate containing living tissue or cells. Subsequent infection and lysis of neighboring cells results in a clearing termed a ______________________.
A. lysozone B. virolony C. plaque D. hemozone
C. Plaque I think
6. The ___________________________ assay is a method used to quantify the number of virion in a particular sample, wherein serial dilutions of the sample are mixed with RBC’s in microtiter plates, and ‘button’ results are visible by eye.
A. hemagglutination--find out for sure!
7. _____________________ is the term used to describe the process where enveloped virion are released from the host cell.
C. Budding
8. Presence of virion in the _________________ is termed viremia.\
A. Blood
9. Reverse transcriptase is an enzyme that converts ____________ into ____________ , a necessity for the retroviridae such as HIV.
B. RNA to DNA
10. Positive-strand RNA viruses possess a genome that is just like eukaryotic ______________, enabling instantaneous synthesis of proteins required for self replication.
A. rRNA
B. mRNA
C. tRNA
D. gDNA
I think it's mRNA
12. The acquired immune response plays a mayor role in viral infections. true or false
True?
12. Initial binding of virus particle to host cell is most commonly referred to as ______________________.
D. Adherence
14. Quantification of virus can be achieved by hemagglutination, plaque formation, and real time PCR. True or False
True.
14. The 3 terms used to describe outcomes of a viral infection are acute, chronic, and _____________.
C. Latent
16. The most effective cellular immune response to viral infection is accomplished by;
A. Natural Killer cells
B. Dendritic cells
C. Macrophages
D. PMN’s
I think it's A. Natural Kill
What is Epidemiology?
the study of where and when diseases occur and how they are transmitted
What is Infection?
the penetration of the host defenses and colonization by a pathogen
What is Disease?
a state of unhealth, the loss of homeostasis, or the presence of signs and symptoms
What is an example of a disease NOT caused by a microorganism?
diabetes
What are some words to describe how common or widespread a disease is?
sporadic, endemic, epidemic, and pandemic
What is Sporadic?
disease occurs infrequently
What is Endemic?
the disease is constantly present
What is Epidemic?
a sudden increase in the incidence of a disease over the normally expected amount of time
What is Pandemic?
epidemic on more than one continent
What's the difference in an outbreak and an epidemic?
They are the same to an epidemiologist, they both indicate a sudden increase in number of cases
What is a Reservoir?
where the microbe normally lives
What can a reservoir be for a disease?
a continuous source of the pathogen or infection
Where are most reservoirs for human pathogens?
the human
What are some other pathogen reservoirs?
animals, soil, water, enviromental
How can transmission happen from person-to-person?
direct, indirect, or aerosols
How does Indirect Transmission occur?
when a pathogen is temporarily transferred to an object by one person and picked up by a second person when they handle the same object
What are objects that transfer pathogens called? What are some examples?
What is Aerosol Transmission? What are some examples?
when pathogens travel on tiny droplets (aerosols) of fluid from person to person - when we talk, cough, or sneeze
What are vectors?
arthropods that transport pathogens from one host to another
What are some common biting vectors?
fleas, ticks, mosquitoes
What are some regular vectors and how do they transmit?
Flies and Roaches - spread them as they crawl around carrying pathogens on their surface
What are diseases called that occur primarily in animals but can be transmitted to humans?
zoonotic diseases
What three factors attribute the high risk of contracting infections during hospital visits?
pathogens in the hospital environment, presence of compromised hosts, and a chain on transmission
What are some ways pathogens work their way into hospitals?
people often come to the hospital carrying pathogens, and sanitation efforts leave behind resistant microbes with little competition
What is the most common type of nosocomial infection? What is the second most common?
urinary tract infection - surgical site infection
What usually causes urinary tract infections? How?
use of catheters - they carry microbes into the urinary tract if it's contaminated or it prevents normal flush of urine and microbes in tract multiply
How do surgical incisions cause nosocomial infections?
expose normally protected tissues to microbes in the environment
What are the most common causes of nosocomial infections?
gram-positive cocci, gram-negative rods
What gram-positive cocci causes nosocomial infections?
Staphylococcus
What gram-negative rods cause nosocomial infections?
E. coli, Psuedomonas
What causes intestinal infections?
Clostridium difficile
What are some symptoms of an intestinal infection?
diarrhea to death
When are fungal infections caused?
after antibiotic theraphy (when antibiotics kill bacteria and leave fungi without any competition for nutrients, which result in overgrowth of fungi)
What is the germ theory of disease?
many diseases are caused by microbes
In order to cause disease a microbe must follow what steps?
must be capable of causing disease, must be transmitted to the host and have a route of entry, host must be susceptible
How is virulence measured?
the severity of the disease the pathogen causes
What are virulence factors?
traits of a pathogen that contribute to its ability to cause disease
What are some virulence factors?
Attachment, Toxins, Evading immune system
What is an example of Attachment when talking about Virulence Factors?
E. Coli and Neisseria gonorrhoeae require fimbriae to attach to the cell of the urinary tract, Streptococcus pnuemoniae requires a capsule to stick to cells of the respiratory tract
What is an example of evading the immune system when talking about virulence factors?
flagella allows cells to move away from immune cells - the mycolic acid in the cell walls of mycobacteria is resistant to many chemicals immune defenses
What is ID50?
infectious dose for 50% of the population
Highly pathogenic species have what kind of ID50?
low (low numbers of cells)
How are respiratory illnesses contracted?
through airborne transmission (the air we breathe)
What is the most common portal of entry? The second most common?
respiratory tract - gastrointestinal tract
What are some portals of entry?
Mucous membranes, Skin, Parenteral route
When skin is damaged, the portal of entry is called what?
Parenteral route
What are some examples of disease by Parenteral route?
What are commonly used to attach to surfaces, including host cells?
fimbriae and capsules
What are biofilms formed?
if cells produce enough capsule slime
What is biofilm?
a thick layer of slime inhabited by numerous slime-producing and non-slime-producing cells
What is an example of a biofilm?
slime on spoiled food or slime that develops on dirty dishes soaking in the sink
What do biofilms do for cells?
has a protective effect on cells
What are exotoxins?
toxins that are released from the cell - always proteins
What are the genes that code for exotoxins?
on plasmids
What are endotoxins? Example?
held in or on the cell and are released only when the cell dies or breaks apart - lipopolysaccharide in the outer membrane of gram-negative bacteria
What is the biologically active component of LPS?
lipid A
What do endotoxins caused in low amounts? High amounts?
fever and chills - shock and death
How does LPS cause fever? 6 items
1) phagocytes engulf and digest gram-negative cells
2) digestion breaks the cells apart which releases the LPS
3) LPS stimulates the phagocyte to produce IL-1 (interleukin-1)
4) IL-1 travels through the bloodstream and stimulates the hypothalamus to produce prostaglandins
5) prostoglandins stimulate the hypothalamus to re-set the body temperature to a higher level
6) fever develops and continues as lonas as the level of prostaglandins remains high in the hypothalamus
How do aspirin, acetaminophen, and inbuprofen reduce fever?
block the production of prostaglandins
What is shock?
life-threatening drop in blood pressure
What happens if blood pressure drops too low?
blood flow to various organs decreases or even stops, which results in organ failure followed by death if the condition isn't corrected
What is septic shock caused by?
the presence of bacteria in the blood and the complex toxic condition that occurs as a result
What is the complex toxic condition that can result from having bacteria in the blood?
sepsis
What are the symptoms of sepsis cause of?
chemicals our immune system produce during the fight against the bacteria in the blood
How does LPS cause septic shock? 6 items
1) phagocytes engulf and digest the gram-negative bacteria
2) digestion breaks the cells apart which releases the LPS
3) LPS stimulates the phagocyte to produce TNF (tumor necrosis factor)
4) a series of events initiated by TNF results in damage to capillaries
5) the damaged capillaries leak excessive fluid from the circulatory ystem
6) the loss of fluid caues blood pressure to drop
How can you raise blood pressure?
fluid replacement and epinephrine
How does epinephrine raise blood pressure?
causes blood vessels to constrict
What two major branches can the immune system be divided into?
the innate immune system and the adaptive immune system
When are the components of the innate immun system functional?
at birth or soon after
When are the components of the adaptive immune system functional?
as we are exposed to more microbes throughout our lives
What are some physical microbe barriers?
skin, mucous membranes, ciliary escalator, peristalsis, fluid flow in various locations
What is skin a physical barrier?
the major protein of skin is keratin, few microbes produce enzymes that can break down keratin so as long as the skin is not damaged microbes can't go through it
How are mucous membranes physical barriers?
they line the respiratory, digestive, and genitourinary tracts, the membranes trap invading cells and prevent contact with host cells
How is the ciliary escalator a physical barrier?
the cilia on the cells in the respiratory tract move mucus (and microbes trapped in it) out of the lungs and into the throat
How is peristalsis a physical barrier?
rhythmic contractions that move materials along the digestive tract
How is fluid flow a physical barrier?
fluids flowing across the surfaces of the mouth (saliva), urinary tract (urine), and eyes (tears) rinse away microbes
What are some chemical microbe barriers?
low pH, lysozyme, digestive enzymes, and transferrins
How is low pH a chemical barrier?
the pH of the skin is often around 3-5, which is low enough to inhibit microorganisms, the pH of the stomach is about 2, and the pH of the vagina is very low
How is lysozyme a chemical barrier?
an enzyme produced in tears, sweat, and saliva that breaks down peptidoglycan and ruining that peptidoglycan layer make the cell vulnerable to damage and death
How are digestive enzymes chemical barriers?
enzymes in our saliva, stomach, small intestine, and pancreas break down the carbohydrates, proteins, and lipids in bacterial cells as easily as the food we eat
How are transferrins chemical barriers?
iron-binding proteins in the blood, saliva, milk, and tears work by preventing iron from floating free in our fluids which prevent nutrients for microbes
If transferrins take away iron in body fluids, how do some microbes get nutrients in our body?
they produce their own iron-binding proteis called siderophores that help them grab available iron
What are included in transient microbiota?
bacteria we pick up and drop off during the day when we come into contact with dust and other things
Where is the vast majority of our normal microbiota?
in the colon
What do our normal microbiota contribute to?
innate immune system
How do our normal microbiota contribute to our innate immune system?
crowd out pathogens and produce acids
Where is E. coli commonly found?
colon
What is the most common microbiota of the skin?
Staphylococcus epidermidis
What are other common microbiota of the skin?
Propionibacterium acnes
Brevibacterium linens
What is Propionibacterium acnes?
major contributor to the acidity of the skin
What is Brevibacterium linens?
major contributor to foot and body oder due to sulfer compounds it produces (methanethiol)
What are probiotics?
live microbes consumed for a benficial effect
What are some microbiota that are considered probiotics?
lactobacillus (Lactobacillus acidophilus or Bifidobacterium - colon)
What does consuming probiotics ensure?
a good population of normal microbiota will always be present in the intestinal tract
What do leukocytes include?
neutrophils, basophils, eosinophils, monocytes, natural killer cells, B cells, and T cells
What is the most common leukocyte?
neutrophils
What are the major functions of neutrophils?
phagocytic, first responder
What do basophils contain?
histamine
What do basophils play a role in?
allergic and inflammatory responses
What do eosinophils defend against?
helminths
What do monocytes differentiate into?
macrophages (which are phagocytic)
What do natural killer cells do?
attack infected cells
What are neutrophils also known as?
PMNs (polymorphonuclear leukocytes)
Basophils are important in what? Why?
anaphylactic shock - they histamine they release when stimulated cause capillaries to expand and become leaky all over the body - the loss of fluid from the blood is shock (anaphylactic bc of the things that enter the blood)
Where are mast cells located?
they live under skin and mucous membranes
What do mast cells contain? What do mast cells cause?
vesicles of histamine - basic allergic reactions that affect they eyes and respiratory passages where their histamine cause a more local reaction that involves redness and swelling
Are mast cells leukocytes? Why?
No, they don't live in the blood
How do eosinophils kill helminths?
releasing toxins and reactive oxygen species (like peroxide)
Monocytes are inactive, but how do they work?
they leave the circulatory system when stimulated and mature into macrophages
What do monocytes do at sites of infection?
they come second (after neutrophils) and act as clean up crew
Where do wandering macrophages exist?
they wander through our tissues and respond to infection where they find it
What are Kupffer cells?
macrophages found in blood vessels of the liver where they kill bacteria that flow by
What are microglial cells?
macrophages found in the central nervous system (spinal cord, brain) where they migrate around and kill bacteria they find
Where are alveolar macrophages found?
passageways and alveoli of the lungs where they digest bacteria or particles that enter
How do natural killer cells kill the cells?
they release perforin and granzymes - the perforin creates pores in the cell membrane which allows granzymes to enter then stimulate cell suicide
What is cell suicide called scientifically?
apoptosis
Natural killer cells do not kill microbes inside the host cell, but instead do what?
kill the host cell and then phagocytes (neutrophils and macrophages) kill any bacteria/viruses released
Any chemical that stimulates or regulates immune cells.
cytokines
How does most communication in the cell occur?
chemicals (cytokines)
The ingestion of microbes or particles by an immune cell.
phagocytosis
What are the three steps to killing microbes by phagocytosis?
phagocytosis, fusion of the vesicle with a lysozome, and digestion
Describe the step of phagocytosis.
initial ingestion of an invader, after the microbe is contained in a vesicle inside the cell
Describe the step of fusion.
the vesicle merges with a lysozome (another vesicle filled with digestive enzymes)
Describe the step of digestion.
various digestive enzymes begin breaking down all parts of the microbe (proteins, lipids, DNA, carbs) and other enzymes produce acids, hypochlorite, and an oxidative burst
What is an oxidative burst?
the sudden production of various toxic forms of oxygen (ROS) - cause numerous undesirable reactions and interfere with all cell functions
What are the interferons alpha-INF and beta-INF produced by?
virus-infected cells
How do interferons work to prevent infection?
the stimulate neighboring cells antiviral proteins (hopefully before it becomes infected), these proteins prevent viral biosynthesis and limit the spread of infection
How are interferons used medically?
therapeutically in combination with other drugs to treat chronic viral infections and some types of cancer
What is complement?
a set of proteins found in the blood, when damage or inflammation occur they enter the affected area and activate
How do complement proteins work?
form pores in the cell membrane of invading cells, resulting of the death of the invader
When does fever occur?
when the level of prostaglandins increase in the hypothalamus, which causes the hypothalamus to reset the body temp to a higher temp
What is the increase in prostaglandins usually caused by?
infection
What does higher body temp do to us?
increases our metabolism and effectiveness of immune cells (the high temp does not kill pathogens)
What are the four classic symptoms of inflammation? What is a fifth that may occur?
heat
redness
swelling
pus
pain
What is the inflammatory response?
injury causes mast cells to release histamine, prostaglandins, and other materials
histamine increases vasodilation, vascular permeability, and phagocyte chemtaxis
damage, sweeling, and prostaglandins all stimulate pain nerves
What is vasodilation?
expansion of the blood vessels
What does vasodilation do?
increases blood flow to the area which results in heat and redness
What does increased permeability do for blood vessels during inflammation?
allows fluids, phagocytes, complement, and antibodies to escape from capillaries - the accumulation of these fluids causes swelling
How is pus formed?
phagocytes flowing in the bloodstream sense histamine and other cytokines and they migrate to the damaged area
What do lymph nodes contain?
numerous lymphocytes that detect invaders that flow by in the lymph fluid
How do lymph nodes become swollen?
they fill up with large numbers of reproducing lymphocytes during infection
What are Helper T Cells called?
CD4 cells
What is CD4?
a molecule on the surface of helper t cell's that is important to their function
What are Helper T Cell's?
ringleaders of the immune system, they stimulate and regulate oher immune cells with the cytokines they release
What are helper t cell's activited by?
antigens displayed on the surface of other immune cells, once stimulated they release cytokines that stimulate the immune cell
What are every B cell coated with?
antibodies - each are identical and grab the same antigen
What are events are required for the stimulation of B cells?
initial stimulation by an antigen and then stimulation by a helper t cell
What do most B cells turn into? What do the rest turn into?
plasma cells, memory cells
What do plasma cells do?
release large quantities of antibodies, all of which are identical and bind to the antigen that stimulated its production
What do memory cells do?
they wait and multipy and release antibodies when we become infected again with the same pathogen, these cells help us react more quickly the second time
The first time we are exposed to an antigen, how long does it take to produce antibodies?
days
What is the first type of antibody produced during an infection? What does large amounts of this antibody indicate?
IgM - first stages of infection
What is produced after IgM?
IgG
When a second exposure occurs what are IgM and IgG amounts in the body?
they are both produced but IgG are much higher
What is the purpose of vaccinating individuals?
to mimic the initial infection of a pathogen and stimulate the adaptive immune response (without causing sickness) so that the immune system can respond faster and stronger when exposed to the actual pathogen
What are antibodies?
proteins produced by plasma cells in response to an antigen and able to bind to the antigen
What is another term for antibody?
immunoglobulin
What is an antigen?
any molecule that stimulates the production of antibodies
What are antigens usually?
proteins or polysaccharides on the surface of a pathogen
What is the shape of an antibody?
Y
What are the three antibodies we need to know?
IgG, IgM, IgA
What does Ig stand for?
immunoglobulin
What is IgG?
a monomer
What is the most common antibody in the blood?
IgG
What is the most abundant antibody produced during an infection?
IgG
What does IgG do during pregnancy?
crosses the placenta and protects the fetus
What is IgM?
a pentamer
What is the first antibody produced during infection?
IgM
What is IgM especially good at?
agglutination
What is IgA?
a dimer
What antibody is secreted into fluids like mucus, saliva, tears, and breast milk?
IgA
What antibody protects our moist surfaces?
IgA
This provides protection for breast-fed infants.
IgA
What are three ways antibodies increase the effectiveness of the immune system?
agglutination
enhanced immune cell grip
complement activation
What is agglutination?
antibody binding causes clumps of the pathogen to form
How does agglutination destroy pathogens?
immobilizes them until immune cells can destroy them
Cytotoxic T Cells are also called what?
CD8 cells
What is CD8?
molecule of the surface of cytotoxic t cell's that is important to their function
What do cytotoxic t cells kill?
infected cells
The adaptive immune system can be divided into what two parts?
humoral immunity and cell-mediated immunity
What is humoral immunity?
immunity provided by antibodies
What is humoral immunity active against?
extracellular pathogens
What is cell-mediated immunity?
immunity provided by cytotoxic t cells
What is cell-mediated immunity active against?
intracellular pathogens
What are three types of vaccines?
whole agent vaccines
subunit vaccines
toxoids
What do whole-agent vaccines contain?
whole cells or whole virions, but these may be weakened or killed
What do subunit vaccines contain?
antigenic pieces of a pathogen, usually proteins or polysaccharides rom a cell membrane or viral capsid
What are subunit vaccines usually safer?
they only contain necessary cell parts, so they're less likely to cause disease or have side effects
What do toxoid vaccines contain?
inactivated toxins
Why do attenuated whole-agent vaccines provide the longest-lasting immunity?
they reproduce in the host and mimic an actual infection
What is the goal of immunizing a community?
establish herd immunity and prevent outbreaks - if a large enough population is immune the risk is reduced because the chances of susceptible people coming into contact with someone infected is decreased
What is herd immunity usually reached?
85-90% of population becomes vaccinated
What do antitoxins contain?
antibodies against a toxin
Antitoxins are used when?
after exposure to a toxin (like a snake bite) in order to provide immediate relief by neutralizing the toxin
What are some antitoxins available for bacterial toxins?
toxins that cause botulism or tetanus
What are some examples of serological tests?
agglutination and immunofluorescence
What indicates a positive result during an agglutination test?
clumping
What can be used in agglutination tests?
microscopic latex beads - they can be coated with antibodies - latex agglutination
When clumping involves red blood cells, what is it called?
hemagglutination
What is an example of hemagglutination?
blood typing
Immunofluorescence uses antibodies that have been treated how?
bonded with fluorescent dye
What type of microbe that causes infection would you use an immunofluorescence test on?
Mycobacterium tuberculosis and Treponema pallidum (causes syphillus)
What is an immunodeficiency?
an inability to produce a normal immune response
What is an example of an immunodeficiency?
AIDS (acquired immunodeficiency), SCID (severe combined immunodeficiency syndrome)
What is HIV?
an enveloped retrovirus
What does HIV mostly infect?
CD4 cells - a protein in the envelope called gp120 attaches to the CD4 cells
How can the progression of HIV be described?
the first stage is usually asymptomatic
as infection progresses, cell numbers drop, and susceptibility increases
when tH cell count reaches 200/mm3 the CDC diagnoses AIDS
What are some common indications of a failing immune system?
persistent yeast infections (oral in males, vaginal in females)
What is the average period of time from initial infection to the development of AIDS
10 years
What are some diseases associated with AIDS?
Candida albicans (yeast infections that can spread to esophagus and lungs), Pneumocystis jiroveci (yeast that causes severe pnuemonia), and humans herpesvirus (causes Kaposi's sarcoma, a skin cancer)
What region has the most HIV-infected persons in the world?
sub-saharan africa
How was HIV probably first transmitted?
contact with the blood of monkeys killed or food
What are the most common drugs used to fight HIV infection?
reverse transcriptase inhibitors, usually in combination with other drugs
What are half of the antibiotics used in the US each year used for?
in animal feeds to encourage weight gain
What is tetracycline effective against?
gram-postive, gram-negative, and obligate intracellular bacteria
What is an example of a narrow spectrum antibiotic?
penicillin
What is penicillin effective against?
only gram-positive bacteria
The ability to inhibit a microbe without harming the host.
selective toxicity
Finding selective toxicity agents is easiest for what pathogens? Harder for who? Hardest for who?
-