Focal infection:
local infection spreads to multiple sites
Sepsis:
systemic infection of the bloodstream
Subclinical infection:
Microbe present, but no apparent illness Individuals may be carriers, able to pass infection to others but showing no symptoms themselves
What is symbiosis?
The living together of two different organisms or populations
commensalism
A symbiotic relationship in which two organisms live in association and one is benefited while the other is neither benefited nor harmed,
mutualism
A type of symbiosis in which both organisms or populations are benefited.
parasitism
A symbiotic relationship in which one organism (the parasite) exploits another (the host) without providing any benefit in return.
What is normal microbiota?
microbes that natural colonize on/in your body. Not harmful
When does colonization begin?
begins at birth
Why are microbiota beneficial to us?
1-compete for attachment and nutrient (microbial antagonism)
2-produce bacteriocins that inhibit growth of other bacteria,
3-lower pH, inhibiting pathogen growth,
4-stimulate-shape immue system
What kind of things can change the normal microbiota?
diet, health, lifestyle, hygiene, stress, climate, occupation, emotional state, pH, temperature, sunlight, O2 and CO2, salinity, chafes over time, health, medication, host defenses
What is transient microbiota?
present for days, weeks, or months and then gone
What parts of the body would you expect to have populations of normal microbiota?
Skin, eyes, nose and throat, respiratory system, mouth, Digestive system (Large Intestine), Urinary system, Reproductive system.
What is the Human Microbiome Project? What is the purpose?
Develop reference set of microbial genomes Understand human microbiomes role in health and disease Coordinated center for data and research
pathology
Study of disease
etiology
The study of the cause of a disease
pathogenesis
The development of disease
infection
Colonization of the body by pathogens (doesn’t always cause disease)
disease
an abnormal state in which the body is not functioning normally
Symtoms v Signs
Symptoms - Subjective changes in body function
Signs - Objective, measurable, observable changes
Local infection:
confined to a single area
Systemic infection
spread throughout the body
Sepsis:
systemic infection of the bloodstream
Focal infection:
local infection spreads to multiple sites
Subclinical infection:
Microbe present, but no apparent illness Individuals may be carriers, able to pass infection to others but showing no symptoms themselves
Primary infection:
Initial infection in previously healthy individual
Secondary infection:
acquired after primary infection Opportunistic pathogen exploits weakening caused by primary infection
Opportunisitic:
Normal microbiota in places not normally found Or in compromised patient
Syndrome
group of symptoms or signs that accompany a particular disease
Communicable disease
a disease that is spread from one host to another
Contagious disease:
a disease that is EASILY spread from one host to another
Noncommunicable disease
a disease that is not transmitted from one host to another
Why can’t Koch’s postulates always be used to determine the cause of a disease? What are some examples?
More than one organism can present with similar signs and symptoms
Nephritis, pneumonia
Some pathogens cause several disease conditions
M. tuberculosis, Streptococcus pyogenes
Stage of Disease
Acute disease:
Disease Symptoms develop rapidly, lasts a short time
Chronic disease:
Disease develops slowly, continues or recurs for a long time
What are reservoirs of infection?
A continual source of infection,
What are zoonoses?
disease that occurs primarily in wild and domestic animals but
can be transmitted to humans.
What are examples of nonliving reservoirs?
Soil, Water
What are the main kinds of contact transmission?
Direct Contact
Indirect Contact
Droplet Transmission
Fomite:
nonliving object that can spread infection,
vehicle transmission:
transmission of a pathogen by an inanimate reservoir
(Water-borne, Food-Borne, Air-Borne)
What is the difference between droplet transmission and air-borne?
Droplet less than 1 meter, doesn’t stay suspended, Airborne greater than 1 Meter, remain airborne for hours.
What is a vector?
carries disease-causing organisms from one host to another
What kind of organisms are vectors usually?
Arthropods
What is the difference between mechanical and biological vector transmission?
Mechanical - passive (fly w/ shit on feet)
Biological – active (Mosquito)
nosocomial infections:
infection that develops during a hospital stay and was not present at the time the patient was admitted; infection associated with any health care facility
epidemiology:
the science that studies when and where diseases occur and how they are transmitted.
incidence
The incidence of disease is the number of new cases occurring in a population over a defined time interval
tells how fast the disease is occurring in a population, a measure of risk
- # of new cases in a population during a specific time/ # of persons at risk of developing the disease during a time period
prevalence
the fraction of a population having a specific disease at a given time,
viewed as a slice through a population to see who has the disease and who doesn’t
- # of affected persons present in the population at a specific time/ # in the population at that time
Annual Mortality Rate
- total # of deaths from a cause in 1 year/ # of persons in the population at midyear
morbidity
incidence of a specific disease
mortality
number of deaths from a specific notifiable disease,
Snow
Mapped the occurrence of cholera in London
Nightingale
Showed that improved sanitation decreased the incidence of epidemic typhus
Semmelweiss
Showed that handwashing decreased the incidence of puerperal fever
sporadic:
disease that occurs occasionally in a population.
endemic:
disease constantly present in a population
epidemic:
disease acquired by many hosts in a given area in a short time
pandemic disease:
worldwide epidemic
Koch's postulates are the essential foundation for:
the steps that relate a specific microbe to a specific disease (etiology)
What is the general term for observable changes in cells that occur as a result of viral infection?
cytopathic effects
Which of the following is a possible location for a bacterial adhesion?
fimbriae
flagella
pili
All of the Above
Which of the following virulence factors is specifically involved in helping an organism to physically spread throughout the body?
hyaluronidase
You conduct a Limulus amebocyte lysate (LAL) assay on a sample of fluid that should be sterile. The result is positive! What does this indicate?
Endotoxin is present.
Some organisms are capable of orchestrating alterations that are collectively termed antigenic variation. This allows the organism to __________.
evade the host's immune system
True or False A-B toxins are PROTIENS
TRUE
True or False: In some cases, viral infections may cause cells to lose contact inhibition
TRUE
What cell wall component that contributes to invasiveness?
M protein
The symptoms of protozoan diseases are usually due to __________.
metabolic waste products
Hepatitis B virus transmitted by a finger-stick device enters the host via which portal of entry?
parenteral
Which type of organism produces the toxin responsible for paralytic shellfish poisoning?
an alga
True or False:
Microbes are more likely to enter the body through the skin than through the mucous membranes.
False
True or False:
Although some pathogens cause disease after entering the body via food and water consumption, many such microbes are killed by chemicals involved in the digestive process.
True
True or False:
The same disease symptoms result, regardless of how a particular microbe enters the body.
False
True or False:
If bacteria A and B have LD50 values of 109 and 1010, respectively, more cells of A than B will be needed to kill the host.
False
True or False:
If bacteria attach to host tissue, they will cause disease.
False
True or False:
Adhesin molecules can vary in structure among strains of a given bacterial species.
True
True or False:
The glycocalyx (capsule/slime layer) can affect bacterial virulence by allowing attachment and by hindering phagocytosis.
True
True or False:
Most host damage resulting from bacterial infection is the result of direct damage by the microbe.
False
True or False:
Patient symptoms may worsen after antibiotic treatment of infections caused by gram-negative bacteria due to the sudden release of endotoxins.
True
True or False:
Accumulations of viral proteins and nucleic acids inside infected host cells are called inclusion bodies.
True
The dose of microbes required to produce a measurable infection in half of the animals tested is referred to by the abbreviated term __________.
ID50
Infections acquired by bites, cuts, wounds, punctures, or surgery occur via the __________ route.
parenteral
__________ are bacterial enzymes that lyse erythrocytes.
hemolysins
Fibrin clots can be dissolved by enzymes called __________.
kinases
fibrinolysin
streptokinase
staphylokinase
kinase
The scum that builds up on shower doors, the formation of dental plaque on teeth, and the algae growth on the walls of swimming pools are all examples of __________.
biofilms
__________ are toxins modified to retain their ability to induce antibody formation but lose their toxicity.
toxoids
Toxins that stimulate proliferation of T cells nonspecifically and provoke intense immune responses are called __________.
superantigens
__________ are molecules on bacterial cell surfaces that enable them to adhere to the surface of host cells.
adhesins
ligands
The release of endotoxins as bacteria are destroyed by phagocytes causes the phagocytes to release tumor necrosis factor (TNF). The life-threatening loss of blood pressure occurring due to the action of TNF is called __________. (2 words)
endotoxic shock
septic shock
Lysogenic bacterial cells may express prophage DNA, causing them to take on different characteristics in a process referred to as __________.
lysogenic conversion
Saxitoxin is produced by ________.
fungi
pathogenicity:
the ability of a microorganism to cause disease by overcoming the defenses of a host
virulence:
the degree of pathogenicity of a microorganism.
What is the ID50?
What conditions can affect the ID50
infectious dose for 50% of the population
can depend on portal of entry
depends on host environment
What are the main portals of entry?
Mucous membranes
Skin
Parenteral
How can the portal of entry affect the ID50?
Respiratory - sweep mucous out
GI - Hostile environment
Urinary - Urine flushing
Conjuctiva - tears
How do pathogens attach once they have gained entry?
Adhesions, Ligands
adhesins:
carbohydrate-specific binding protein that projects from prokaryotic cells; used for adherence, also called a ligand.
ligands:
carbohydrate-specific binding protein that projects from prokaryotic cells; used for adherence, also called a adhesion
What do host cells have that help with adherence?
Surface receptors
Usually sugars
Different receptors vary in structure-different cells in same host can have different receptors
Altering adhesins and/or receptors may be a way to prevent infection.
How are biofilms involved in attachment? Why are they significant in infection?
Allow cells to stick to surfaces and each other. Protects them from ABx and disinfectants
What are some strategies pathogens use for invasion?
Capsules
Cell wall components
Enzymes
Antigenic variation
Penetration into host cell cytoskeleton
How do capsules and cell wall components help with invasion?
Impairs phagocytosis by host
What does antigenic variation mean?
changes in surface antigens that occur in a microbial population.
What is antigenic drift and antigenic shift?
Antigenic drift A minor variation in the antigenic makeup of influenza viruses that occurs with time.
Antigenic shift A major genetic change in influenza viruses causing changes in H and N antigens.
How can pathogens disrupt the host cell cytoskeleton?
Actin-protein in cytoskeleton - can be used by microbes to penetrate host cell and move through and between cells.
Invasins - proteins produced by microbes to rearrange actin filaments.
What are the main ways pathogens damage host cells?
1. Using host’s nutrients
2. Direct damage in immediate vicinity of invasion
3. Producing toxins
4. Inducing hypersensitivity reactions
What are siderophores?
How do they cause damage?
By what method is most damage done?
Bacterial iron-binding proteins
exotoxins:
protein toxin released from living, mostly gram-positive bacterial cells.
endotoxins:
part of the outer portion of the cell wall (lipid A) of most
gram- negative bacteria; released on destruction of the cell,
toxigenicity:
the capacity of a microorganism to produce a toxin,
Toxemia:
the presence of toxins in the blood,
antitoxins:
a specific antibody produced by the body in response to a bacterial exotoxin or its toxoid.
toxoids:
an inactivated toxin.
What are the different kinds of exotoxins?
Which do most bacteria produce?
AB, Superantigen, Membrane Disrupting
AB exotoxin most common
leukocidins:
substances produced by some bacteria that can destroy
neutrophils and macrophages,
hemolysins:
an enzyme that lyses red blood cells,
superantigen
antigen that activates many different T cells, thereby eliciting a large immune response.
Where do endotoxins come from?
A-Protein, gram negative cell wall
Why is the LD50 higher than with exotoxins?
Toxins are enzymes and can be used multiple times w/o being used up
What kind of body reactions are produced by endotoxins?
Not usually fever, usually specific, neurotoxin ect...
What are portals of exit?
Which are the most common?
Upper respiratory tract saliva from the oral cavity sneezing
coughing
Gastrointestinal tract
feces / diarrhea from the bowel vomitus
saliva
Blood
infected blood
Urogenital tract semen
vaginal secretions
infected urine
Skin and mucous membranes
discharges from infected skin lesions and infected wounds
Descriptive Epidemiology:
collection and analysis of data
Analytical Epidemiology:
comparison of a diseased group and a healthy group
Experimental Epidemiology:
controlled experiments
Invasins
proteins produced by microbes to rearrange actin filaments.
What roles did Ehrlich, Fleming, and Domagk play in the development of antimicrobial drugs?
Ehrlich - "magic bullet" (Salvarsan-) Tx - syphilis
Flemming - Penicillin - 1st true ABx
Domagk - Sulfonimides - Inhibit Folic Acid Synthesis by mimicking PABA (Static)
What is an antibiotic? What was the first true antibiotic? What was the first synthetic antimicrobial?
a substance made by one organisms that acts against another.
sulfonamide-Prontosil
Know the following terms: bacteriostatic, bacteriocidal, narrow and broad-spectrum antibiotics.
Bacteriostatic: Inhibits bacterial growth
Bacteriocidal: Kills bacteria
Narrow-spectrum antibiotics: Active against a limited number of organisms e.g. Penicillin- active primarily against gram- positive
Broad-spectrum antibiotics:Active against broad range of organisms Disadvantage-kill normal florae.g. Ampicillin- modified penicillin active against gram-negative bacteria as well as gram-positive
What does selective toxicity mean? Why is it important?
antimicrobial drugs must act within the host without damaging the host.
Lessen harm to host w/ Tx.
What are the 5 main modes of action of antimicrobial drugs? Which ones use the differences between prokaryotic and eukaryotic cells to target pathogens? How does penicillin work? How does chloramphenicol work? Which drugs are structural analogs of PABA?
1.) Cell Wall - PEN (Beta-lactam disrupts cell wall)
2.) Protein Synthesis (Chloramphenicol, binds to 50S, inhibits peptide bonde formation)
3.) Metabolite Synthesis (Sulfonamides)
4.) Plasma Membrane
5.) DNA replication
What about Mycobacterium provides a target for chemotherapy? What is the target of amphotericin B on fungal cells?
Mycolic Acid
fungal membranes contain ergosterol, not cholesterol
What are the major modes of action of antiviral drugs? Antiprotozoan? Antihelminth?
Antiviral - Nucleotide analogs, Interferons, Antiretrovirals
Antiprotozoan - DNA synthesis, Anaerobic metabolism
Antihelminth - ATP synthesis, Nutrient Absorption, Paralysis
What are the 4 modes of bacterial resistance to antimicrobial drugs? What is beta-lactamase? Where does it attack certain antibiotics?
1 - Blocking Entry
2 - Inactivation by enzymes
3 - Efflux of ABx
4 - Alteration of target
How can bacteria acquire resistance?
Transformation
Transduction
Conjugation
What do MIC and MBC mean? Why is important to know the MIC?
Minimum Inhibitory concentration (Minimum dose to stop growth for Tx)
Minimum bacterialcidal concentration
What does synergy and antagonism mean pertaining to chemotherapy?
Syn - 2 together better than sum of each sep
Antag - 2 together less than sum of each sep