Microbiology Exam 2
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Microbiology Exam 2
Microbiology microbes antibiotics
Review for exam 2
What is a Icosahedral?
3-D, 20-sided figure with 12 evenly spaced corners
Nucleic acid is packed into he center, forming a nucleocapsid
What is a Helical
Have rod-shaped capsomers that bond together to form a series of hollow discs resembling a bracelet
Discs link with other disc to form a continuous helix into which the nucleic acid strand is coiled
What is Complex virus?
May have have multiple types of proteins and take shapes that are not symmetrical
What does Enveloped mean?
Viruses that posses an additional covering external to the capsid that is usually a modified piece of the host's cell membrane
Envelope usually has special receptor spikes inserted into it
What is a Naked virus?
Viruses that consist of only a nucleocapsid
How does - sense RNA make proteins?
- RNA --> + RNA --> Proteins or - RNA
How does + sense RNA make protein?
+ RNA --> Protein
+ RNA --> - RNA --> + RNA
How does retrovirus make protein?
RNA --> DNA --> Protein
What is the order of the Viral Life Cycle?
Viral Life Cycle
Virus attaches to its susceptible host cell by specific binding of its spikes of cell receptors
Limited host Range
Viral Life Cycle
Virus is engulfed into a vesicle
: Entire virus engulfed by the cell and enclosed in a vacuole or vesicle
: Viral envelope directly fuses with the host cell membrane
Viral Life Cycle
Replication and protein production
Under the control of viral genes, the cell synthesizes the basic components of new viruses
: RNA, molecules, capsomers & spikes
DNA enters nucleus --> Transcribed into RNA --> Translation into viral proteins --> New DNA synthesized using host nucleotides
RNA viruses replicated and assembled in the Cytoplasm
Viral Life Cycle
Viral spike proteins are inserted into the cell membrane for the viral envelope; nucleocapsid is formed from RNA and capsomers
Viral Life Cycle
Enveloped Viruses bud off of the membrane, carrying away an envelope with the spikes
Noneveloped and Complex viruses released when they lyses or ruptures
What is Cytopathic Effects?
Virus-induced damage to the cell that alters its microscopic appearance
Used to identify virus infections
: Compacted masses of viruses or damaged cell organelles in the nucleus and cytoplasm
: Fusion of multiple host cells into single large cells containing multiple nuclei
What is Viral Transformation?
When viruses enter their host cell and permanently alter its genetic material, leading to cancer (oncoviruses)
Cells Lose Contact Inhibition:
Causes cells to have
-Increases rate of growth
-Alterations in chromosomes
-Changes in the cell's surface molecules
-Capacity to divide for an indefinite period
What is a bacteriophages?
Viruses that infect bacteria
In the Lytic Cycle, what happens in the Eclipse Phase?
Phage is developing but is not yet infectious
-Duplication of phage components; Replication of virus genetic material
In the Lytic Cycle, what happens in the Virion Phase?
virus matures and is capable of infecting a host
-Assembly of new virions
-lysis of weakened cell
-Release of viruses
What happens in the Lysogenic Cycle:
Host chromosome carries bacteriophage DNA
DNA phages undergo adsorption and penetration into the bacterial host and then enter an inactive prophage stage, during which it is inserted into the bacterial chromosome
Viral DNA retained by the bacterial cell and copied during its normal cell division so that the cell's progeny will also have the temperate phage DNA
What is a Prion?
Infectious protein that contains no DNA or RNA
How does Prion cause diseases?
An abnormal prion protein is acquired via ingestion or mutation
Infectious protein induces mis-folding or host protein
-Mis-folded protein can change other proteins
-Protein plaques and vacuoles harm neurological function
What are some examples of Prion Diseases?
Mad Cow Disease (Bovine Spongiform Encephalopathy [BSE])
Sum total of genetic material of a cell
Discrete cellular structure composed of neatly packaged DNA molecule
Certain segment of DNA that contains necessary code to make a protein or RNA
Traits created by the expression of the genotype
An organism's distinctive genetic makeup from the sum of all types of genes
What is a Hydrogen Bond?
Join Nitrogenous bases
Weak bonds that are easily broken, allowing the molecule to be unzipped into its complementary strands
What is a Covalent Bonds?
Nucleotides bond to form a sugar-phosphate linkage that becomes the backbone of each strand
What is a Nucleotide?
Basic unit of DNA structure
composed of phosphate, deoxyribose sugar and a nitrogenous base
What are the parts of Nitrogenous Bases?
Purines and Pyrimidines
Attach by covalent bonds at the 1' position of the sugar
Spanned the center of the molecule & pair w/ complementary bases from other grands
Which enzymes are involved in DNA Replication?
: Unzip the DNA helix
: Synthesize an RNA primer
DNA Polymerase III
: Add base to new DNA chain; proofread chain for mastakes
DNA Polymerase I
: Remove primer, close gaps, repair mismatches
: Final binding of nicks in DNA during synthesis and repair
Origin of Replication and How it Starts
Origins of Replication
: Short sequence of rich in A and T held together by only two H-bonds
Helicases bind to the DNA at the origin
-Untwist the helix
-Break the H-bonds
-Results in two separate strands
Leading Strand vs. Lagging Strand
: Synthesized as a continuous, complete strand in 5' to 3' direction
: cannot be synthesized continuously due to the opposite orientation (3' to 5')
-Polymerase adds nucleotides a few at a time in the direction away from the fork (5' to 3')
What are Okazaki Fragments?
Fragments of DNA on the Lagging Strand
Few nucleotides added at a time in the 5' to 3' direction
Fork opens & next segment is synthesized backward to point of previous segment
Fragments attached to the growing end of the lagging strand by DNA Ligase
What is Transcription?
Master code of DNA is used to synthesize an RNA molecule
RNA Structure, Nucleotides and Base Pairing
Single-stranded molecule that exists in helical form
Contains Uracil instead of Thymine
Sugar in RNA backbone (alternating with phosphate) is Ribose (not Deoxyribose)
Enzymes in RNA
: Unwinds the DNA at the promotor
-Moves along the strand adding complementary nucleotides as dictated by the DNA template, forming the single-stranded mRNA
Promoter, Termination Sequence in Transcription
: Region of two sequences of DNA just prior to the beginning of the gene to be transcribed
Recognized by the RNA polymerase
: RNA Polymerase recognizes a code that signals the separation and release of the mRNA strand
What is the Direction of Transcription?
RNA Polymerase runs along the template strand in the 3' to 5' direction
Elongation proceeds in the 5' to 3' direction
The mRNA reads in the 5' to 3' direction
What are the Components of Translation?
: Located in the cytoplasm
Subunits specifically adapted to assemble & form sites to hold the mRNA & tRNA
Recognizes these molecules and stabilizes reactions between them
: Brings amino acids to ribosome during translation
Anticodon that designates the specificity of the tRNA & complements mRNA's codons
: Sequence of amino acids in protein
Carries the DNA master code to the ribosome and then translated
What are the steps of translation?
What happens in Initiation?
Small subunit binds to the 5' end of mRNA and large subunit supplies enzymes for making peptide bonds on the protein
Begins to scan the mRNA by moving in the 5' to 3' direction along the mRNA
The first codon is the START codon (AUG)
mRNA message in place on the ribosome, tRNA enter with their amino acids
-Complementary tRNA (anticodon) meets with the mRNA code
-Guided by the two sites on the large subunit called the P site & A site
-E site is where the tRNA's are released
What happens in Elongation during Translation?
Ribosome shifts its reading frame to the right along the mRNA from one codon to the next
-Brings the next codon into place on the ribosome and makes a space for the next tRNA to enter the A site
-Peptide bond is formed between the amino acids on the adjacent tRNA's
-Polypeptide grows in length
: Enzyme-directed shifting of the ribosome to the right along mRNA strand, which causes bland tRNA to be discharged from the ribosome at the E site
What happens in Termination during Translation?
Brought about by the presence of a Termination Codon - UAA, UAG, & UGA
-No corresponding tRNA (or amino acid)
Special enzyme breaks the bond between the final tRNA and the finished polypeptide chain
A particular amino acid can be coded for by more than a single codon
Only the first two nucleotides are required to encode the correct amino acid
-Permits some variation or mutation without altering the message
What happens in Prokaryote Transcription & Translation?
Translation of mRNA starts while transcription is still occurring
What happens in Eukaryote Transcription/Translation?
Start codon is also AUG but may code for an amino acid (methionine)
mRNAs code for just one protein
DNA is in nucleus so transcription and translation cannot be simultaneous
mRNA must pass through pores in the nuclear membrane and be carried to ribosome's in the cytoplasm
: Sequences of bases that do not code for protein
: Coding regions that will be translated into protein (Express)
In gene regulation, what is prokaryotic operons?
Coordinated set of genes, all of which are regulated as a single unit
What is Lac operon? (Inducible)
Operon is turned on by the substrate of the enzyme for which the structural genes code
-Normally off; Adding Lactose turn it on
: in the absence of lactose, a repressor protein attaches to the operator of the operon
-Locks the operator & prevents any transcription of the structure gense downstream
-Supression of transcription prevents the unneccessary synthesis of enzymes for processing lactose
: Upon entering the cell, lactose (substrate) becomes a gentic inducer by attaching to the repressor, which loses its grip and falls away
The RNA polymerase is free to bind to the promotor and initiate transcription
What is Arg operon? (Repressible)
Contain genes coding for anabolic enzymes
Several genes in a series are turned off by the product synthesized by the enzyme
-Normally on; Turned off when the nutrient is not longer required
: A repression operon remains on when its nutrient products are in great demand by the cell
-The repressor is unable to bind to the operator at low nutrient levels
: The operon is repressed when
-Arginine builds up & serves as a corepressor, activating the the repressor (negative feedback)
-Repressor complex affixes to the operator and blocks the RNA polymerase and further transcription of genes for arginine synthesis
Microorganisms that bears a mutation (Phenotypic changes due to the changes in the genotype)
Define Wild Type
Microorganism that exhibits a natural, non-mutated characteristic
Spontaneous vs. Induced
: Random change in the DNA arising from errors in replication that occur randomly
: Result from exposure to known mutagens (physical or chemical agents that interact with DNA in a disruptive manner)
What are the types of mutation and the results to protein function?
: Involve addition, deletion, or substation of single bases
-May or may not change protein
: Any change in code that leads to placement of a different amino acid
-Can create a faulty, nonfunctional protein
-Can produce a protein that functions in a different manner
-Can cause no significant alteration in protein function
: Changes a normal codon into a stop codon
Stops the production of the protein wherever it occurs
Almost always results in a nonfunctional protein
: Alters a base but does not change the amino acid
-Has no effect on the protein function
: Gene that has undergone mutation reverses to its original base composition
: Mutations that occur when one or more bases are inserted into or deleted from a newly synthesized DNA strand
-Changes the reading frame of the mRNA
-Nearly always result in a nonfunctional protein
: Special for finding and fixing such mutations; Most common way
DNA that has been damaged by UV radiation
-Restored by Photoactivation or Light Repair
--DNA photolyase- Light sensitive enzyme
-Excise mutations by a series of enzymes
-Remove incorrect bases and add correct one
When one bacterium donates DNA to another bacterium
In recombination, what happens in Conjugation?
Requires the attachment of two related species and the formation of a bridge that can transport DNA
: The pilus of donor cell attaches to receptor on recipient cell and retracts to draw the two cells together
--An opening or pore forms between the cell walls, creating a bridge to transmit genetic material
-F Factor Transfer
: F Factor (plasmid) copies and then transferred though a bridge
-H factor Transfer
: F factor integrated into chromosome and then duplicated and transmitted in part to a recipient cell, where it is integrated into the chromosome
In recombination, what happens in Transformation?
Entails the transfer of naked DNA and requires no special vehicle
-Recipient cell takes up donor DNA
-Donor DNA align with complementary bases
-Recombination occurs between donor DNA and recipient DNA
In recombination, what happen in Transduction?
DNA transfer mediated though action of a bacterial virus (bacteriophage)
-Random fragments of disintegranting host DNA are taken up the the phage during assembly
-Any gene from the bacterium can be transmitted
: Lyses the cell to infect others
--Releases the mature phases, including the genetically altered one
-Highly specific part of host genome is regularly incorporated into the virus
: Integrated in bacterial chromosome
What happens in Transposons?
Shift from one part of the genome to another
-From one chromosomal site to another
-From a chromosome to a plasmid
-From a plasmid to a chromosome
Contain DNA that codes for the enzymes needed to remove and reintegrate the transposon at another site in the genome
Overall Effect- Scrambles the genetic language
How is heat use to manipulate DNA?
Heating to 90
C separates DNA strands exposing nucleotides
Cooling to allow annealing
Complementary strands from different organisms hybridize
How does Restriction Enonucleases manipulate DNA?
Enzymes that can clip strands of DNA crosswise at selected positions
Can recognize and clip at Palindromes (Identical sequences of DNA when read from 5' to 3' direction on one strand and the 5' to 3' direction on the other strand)
Used to cut DNA in to smaller pieces for study or remove & insert sequences
Can make a blunt cut or a "sticky end"
: The pieces of DNA produced
What is cDNA?
Copies made from messenger, transfer, ribosomal and other forms of RNA
Synthesize eukaryotic genes from mRNA transcripts
Synthesized gene will be free of the intervening introns
What is Electrophoresis?
Produces a readable pattern of DNA fragments
How does Electrophoresis works?
Samples placed in wells in a soft agar gel and subjected to an electrical current
Phosphate groups in DNA give the molecule an overall negative charge
-Causes DNA to move toward the positive pole in the gel
Rate of movement based on size of fragments
-Larger fragment move slowly and remain near the top of the gel
-Smaller fragments move faster and positioned farther from the wells
Positions of DNA fragments determined by staining the DNA fragments in the gel
What information can you get with Electrophoresis?
Characterize DNA fragments and compare the degree of genetic similarities among samples
PFGE (Pulsified-Field Gel Electrophoresis)
Pathogens isolated from a patient and their DNA is harvested
-DNA is cut up with restriction enzymes to get a few very large pieces of DNA
-DNA separated using the pulsed-field method of gel electrophoresis
--Constantly changes the direction of (pulsing) the electrical field
--Allows effective separation of the large pieces
Fragments of different lengths seen as dark bands after special stain on gel
Patterns different t/t enzyme cut in different places on genome where small DNA changes exist, correspond to different strain types
Define Nucleic Acid Hypridization
Two different nucleic acids hybridize by uniting at their complementary regions
Define Gene Probes
Specifically formulated oligonucleotide tracers
Consists of a short stretch of DNA or a known sequence that will base-pair with a stretch of DNA with a complementary sequence (if in the test sample)
Carry reporter molecules so areas of hybridization can be visualized
What is a Southern Blot?
Type of Hybridization
DNA fragments are first separated by electrophoresis and then denatured and transferred to a special filter
DNA probe incubated with the sample
-Wherever this probe encounters the segment of which it is complementary, it will attach and form a hybrid
Development of hybridization pattern will show up as one or more bands
Sensitive and specific way to isolate fragments from a complex mixture and to find specific gens sequences on DNA
What is FISH (Fluorescent in Situ Hybridization)?
Probes applied to intact cells
Observed microscopically for the presence and location of specific genetic marker sequences
Effective way to locate genes on chromosomes
What is DNA sequencing?
Determines the actual order and types of bases in DNA
: Most common technique
-Sanger technique is old and expensive (reaching the end of its useful life)
-May not be specific - None-specific binding of the primer to the DNA
What is PCR (Polymerase Chain Reaction)?
Rapidly increases the amount of DNA in a sample
How it is done
: Heat to separate into two strands
: Primers added in a concentration that favors binding to the complementary strand of test DNA
--Prepares the two strands (amplicons) for synthesis
: DNA Polymerase and nucleotides are added to primer
: 20-30 cycles to amplify DNA
: Amplified DNA to be anayzed
What is Recombinant DNA Technology?
Deliberately removes genetic material from 1 organisms & combines it with that of a different one
-Forms genetics closes
--Genes is selected
--Insert gene into a vector
--Vector insets DNA into a cloning host
What are the results?
-Mass produce substances that are difficult to synthesize by the usual industrial methods
--Hormone, enzymes, vaccines
What is a vector?
Plasmid or virus that a gene is inserted into
Inserts the DNA into a Cloning Host
-Capable of carrying a significant piece of the donor DNA
-Must be readily accepted by the cloning host
-Must have a promotor in front of the cloned gene
-Origin of Replication needed somewhere so that it will be replicated by the DNA polymerase of the cloning host
-Must accept DNA of the desired size
-Contain a gene that confers drug resistant to their cloning host
What is a host?
Bacterium or yeast that can replicate the gene & translate it into the protein product
-Rapid turnover, fast growth rate
-Can be grown in large quantities using ordinary culture methods
-Genome that is well delineated
-Capable of accepting plasmid or bacteriophage vectors
-Maintains foreign gene though multiple generations
-Will secrete a high yield of proteins from expressed foreign genes
What is Gene Therapy?
Correcting or repairing a faulty gene in humans suffering from a fatal or debilitating disease.
How does Antisense RNA work in gene therapy?
Bases are complementary to the sense strand of mRNA in the area surrounding the initiation
-When it binds to the mRNA, the dsRNA is inaccessible to the ribosome
-Translation cannot occur (stop bad proteins)
How does Antisense DNA work in gene therapy?
When delivered into the cytoplasm and nucleus, it binds to specific sites on any mRNAs that are the targets of therapy
: Treat Cytomegalovirus Retinitus
Destroys most microbial life, reducing contamination on inanimate surfaces
Destruction of all microbial life
Same as disinfection except a living surface is involved
Any cleansing technique that mechanically removes microorganisms to reduce contamination to safe levels
What are the 2 most resistant microbes?
Factors that influence the rate at which microbes are killed by antimicrobial agents
Length of Exposure to Agent
Effect of the Microbial Load
Relative Resistance of Spores vs. Vegetative Forms
Action of the Agent (Microbicidal or Microbiastatic
What are the mechanisms to kill bacteria?
Change Membrane permeability
-Lose selective permeability so can't prevent the loss of vital molecules or stop the entry of damaging chemicals
Damage the Cell Wall
-Block its synthesis
-Break down its surface
-The cell becomes fragile and is lysed easily
-denature (disrupt) proteins
-Binding to ribosomes to stop translation
-Bind irreversibly to DNA preventing transcription and translation
How is head use to control bacteria?
: occurs in the form of hot water, boiling water, or steam
-Ranges from 60 to 135 Celsius
: Denotes air with a low moisture content that has been heated by a flame or electric heating coil
-Ranges from 160 to several thousand degrees of Celsius
Steam under pressure
Pressure raises the temperature of steam
Most efficient pressure-temperature combination for sterilization
: 15 psi which yiels 121 degree celsius for 15 minutes
Heat is applies to liquids to kill potential agents of infection and spoilage *disinfect)
Maintains the liquids' flavor and food values
Does not kill endospores or thermoduric microbes
Does not sterlize
Expose material to boilng water for 30 minutes
Baking in Oven
Used for heat-resistant items that do not sterilize well with moist head
-Glass, metallic instruments; powders, oils
Ignites and reduces microbes to ashes and gas
What does Ionizing Radiation do?
Cells' molecules absorb some of the available energy
Radiation ejects orbital electrons form an atom, causing ions to form
Gamma Rays, X Rays & Cathode Rays
What does UV (Nonionizing Radiation) Do?
Excites atoms by raising them to a higher energy state, but it does not ionize them
Atomic excitation leads to formation of abnormal bonds within molecules and is a source of mutations
Not as penetrating as ionizing radiation
doesn't kill bacterial spores
: Hospital rooms, operating rooms, schools, food prep areas, dental offices
-Treat drinking water or purify liquids
Mechanical technique for removing microbes
Effective for removing microbes from air and liquids
Fluid strained through a filter with openings large enough for fluid but too small for microorganisms
Filters are usually thin membranes of cellulose acetate materials
Pore size can be standardized
Prepare liquids that can't withstand heat
Can't decontaminate beverages without altering their flavor
Removing airborne contaminants (HEPA filters)
Examples of Chemical
Halogen - betadine; Bleach
Phenol- Listerine; Lysol
Alcohols- Hand sanitizer
Heavy metal compounds- Mercury; Silver; Silver nitrate
Aldehydes- Glutaraldhyde; Formaldehyde
What chemical can be used on people?
Chlorohexadine- Yes (had scrubbing, preparing skin for surgery, neonatal wash)
Hydrogen peroxide- Yes
Heavy metals- Yes (topical)
-Ethylyne Oxide- No
-Hydrogen Peroxide- No
Use of a drug to prevent imminent infection of a person at risk
Substances produced by the natural metabolic processes of some microorganisms than can inhibit or destroy other microorganisms
Define narrow Spectrum
Antimicrobial effective against a limited array of microbial types (e.g., gram-positive bacterial)
Define Broad Spectrum
Antimicrobial effective against a wide variety of microbial types (e.g., both gram-positive and gram-negative bacteria)
Mechanism of Action of Antimicrobial
Inhibition of Cell Wall synthesis
Inhibition of Nucleic Acid Structure and Function
Inhibition of Protein Synthesis
Interference with Cell Membrane Structure or Function
Inhibition of Folic Acid Synthesis
Bind and block peptidases that cross-link the glycan molecules
Interrupts the completion of the cell wall
Cephalosporins vs. Penicillins
Resistant to most beta lactamases (penicillinases)
Cause fewer allergic reactions than penicillins
PBP's (Penicillin Binding Proteins)
Catalyze cross-linking of peptidoglycan chains
Penicillin must bind to them to produce antibacterial effects
Why so many PCNs?
Involved in different stages of bacterial cell wall synthesis
When one type is inhibited, it inhibits the specific stage of peptidoglycan synthesis
Enzymes that are cable of destroying the beta-lactam right of penicillin
Not beta lactam
Vancomycin (Important for treating MRSA)
Affect Nucleic Acid
List of Actions
-Block synthesis of nucleotides
-Inhibit DNA synthesis
Metronizadole for parasites
Affect Protein Synthesis
Inhibit translation by reacting with the ribosome-mRNA comlex
Classes of Antibiotics
Affect Cell Membrane
Disruption in metabolism
Affect Folic Acid Synthesis
Supplied to cells in high concentrations to make sure enzyme is constantly occupied with the metabolic analog rather than the true substrate
Sulfonamides and Trimethoprim
: Competitive Inhibition
For main groups of Antifungals
Macrolide Polyene Antibiotics
-Bind to fungal membranes and cause loss of selective permeability
-Especially active Skin fungal infections
-Broad spectrum antifungal agents
-Can be used to treat certain cutaneous mycoses
Some also antibiotics
Selective toxicity is almost impossible to achieve because a single metabolic system is responsible for the well-being of both virus and host
Three Major modes of Action
Barring penetration of the virus into the host cell
Blocking the transcription and translation of viral molecules
Preventing the maturation of viral particles
Glycoprotein produced by fibroblast and leukocytes in response to various immune stimuli
Produced by recombinant DNA technologies
Known therapeutic benefits
Reducing the time of healing and some of the complications in certain infections
Prevent or reducing some symptoms of cold and papilomaviruses
slowing the progress of certain cancers
Treating a rare Cancer called hairy-cell leukemia, hepatitis C, genital warts, and Kaposi's sarcoma in AIDS patients
Mechanisms of Resistance
-Due to now enzymes being synthesized
-Activation of Drug pumps
: Uptake of drug into bacterium is decreased/eliminated
Change in Drug binding site
-Binding sites decreased in number or affinity
Use of Alternate metabolic pathway
-Affected metabolic pathway shut down or an alternate pathway is used
Negative Side Effects
Suppression of normal flora
-Complication that occurs when antimicrobial therapy destroys beneficial resident species, causing microbes that were once in small numbers begin to overgrown and cause disease
C. difficile example
-Oral therapy with tetracycline, clindamycin, and broad-spectrum PCN and cephalosporins is associated with antibiotic-associated colitis due to C. Difficile
Uses a strip to produce a zone of inhibition
Strip contains a gradient of drug calibrated in micrograms
MIC can be measured by observing the mark on the strip that corresponds to the edge of the zone of inhibition
Agar diffusion test that provides useful data on antimicrobial susceptibility
Surface of a plate of special medium is spread with the test bacterium
Small disc containing a premeasured amount of antimicrobial dispensed onto bacterial lawn
Zone of inhibition surrounding disc measured and compared with a standard for each drug
Profile of antimicrobial sensitivity provides data for drug selection
MIC (Minimum Inhibitory Concentration)
Smallest concentration (highest dilution) of drug that visibly inhibits growth
Useful in determining the smallest effective dosage of drug & in providing a comparative index against other antimicrobials
Reasons for Treatment Failure
The inability of the drug to diffuse into that body compartment
A few resistant cells in the culture that did not appear in the sensitivity test
An infection caused by more than one pathogen, some of which are resistant to the drug
Define True Pathogen
Capable of causing disease in healthy person with normal immune systems
Define Opportunistic Pathogen
Cause disease when the host's defenses are compromised or when they become established in part of the body that is not natural to them
Define Acute disease
Infections that come on rapidly, when severe but short-live effects
Define Chronic Disease
Infection that progress and persist over a long period of time
Define Subacute infection
Describes the degree of pathogenicity
-Determined by its ability to
--Establish itself in the holt
Portal of entry
A route in which the microbe enters the tissues of the body
Transplacental or Congential Infection
Comes across the placenta and invade the fetal circulation
Considered a vertical transmission
How many organisms need to make 50% of people sick
How does it affect Virulence?
-Microorganisms with smaller IDs have greater virulence