MMG 301 Exam Latest Update
What are the typical sources of specimens? - Answer •Blood - look for bacteremia or
viremia•Can also test blood for the presence of antibodies to a pathogen.
•Urine - bacteriuria - presence of bacteria in urine; most often detected using urinalysis
dipstick or growth-dependent methods.
•Feces - look for intestinal pathogens (bacteria or eukaryotes).•Abscesses and wounds -
swab or needle aspiration.•Throat/nasal swabs - soft cotton swabs to collect samples to
test for bacteria or viruses. •Genital samples - to get specimens to test for sexually
transmitted pathogens.
Be able to state the medical terms of bacteria in the blood and urine. - Answer Bacteria
in Blood:Bacteremia or Viremia Bacteria in Urine: Bacteriuria
Know the Biosafety levels for laboratories working with pathogens. - Answer 4
classifications based on levels of risk; higher numbers for more dangerous pathogens.
● BSL1: Few safety controls; open lab bench; non-pathogenic organisms; limited
access.
● BSL 2: Can have an open bench, but gloves, lab coat, eye protection required; used
for
moderate pathogens.
● BSL 3: Designed for pathogens; organisms manipulated in biological safety cabinets;
room under slight negative pressure; extensive filtration of air.
● BSL 4: Used for life-threatening pathogens that can be transmitted by aerosols;
pressurized suits for workers; Ebola, Marburg viruses.
Be able to discern the difference between differential and selective media. - Answer
Selective Medium: Contains substances that inhibit growth of certain types of bacteria.
Differential Medium: Includes compounds that allows visualization of certain
biochemical pathways and products.
Describe the three common methods used to test sensitivity of a pathogen to an
antibiotic. - Answer Minimum inhibitory concentration (MIC): Using tube dilution assay.
Disk diffusion assay: Pure culture is spread on plate; then disks containing different
antibiotics are placed on plate. Also called a Kirby-Bauer test.
"Etest": MIC is read from the edge of the clear zone using the scale on the strips.
,Define an antibody titer and how it changes during the course of an infectious disease. -
Answer Antibody titer: The lowest concentration of serum at which an antibody-antigen
reaction is observed.
How is a Mantoux skin test performed and how is it interpreted? - Answer Performed:
Locate and clean the injection site. 2-4 inches below the elbow joint. Place forearm palm
side up on firm, well-lit surface. Select an area free of barriers (ex: scars / sores) to
placing and reading. Clean the area with an alcohol swab.
Check expiration date on vial and ensure that the vial contains tuberculin (5 TU per
0.1ml). Use a single-dose tuberculin syringe with a 1⁄4 - 1⁄2 inch, 27 gauge needle with a
short bevel. Fill the syringe with 0.1 ml of tuberculin.
Insert slowly, bevel up, at a 5-15 degree angle. Needle bevel can be seen just below the
skin surface. After injection, a tense pale wheal should appear over the needle.
Wheal should be 6-10 mm in diameter. If not, repeat test as a site at least 2 inches away
from the original site.
Record information.
Interpreted:
● Based on the size of induration dependent upon the test run. Famous is TB test.
Define serology. - Answer The use of antigen-antibody reactions to detect: ● Antigens
● Antibodies● For a few pathogens, previous exposure can be detected by an
inflammatory response
to injection of a purified antigen under the skin.
Describe what an epitope is. - Answer The part of an antigen molecule to which an
antibody attaches itself.
Understand how agglutination assays are used to detect antibodies or antigens from a
patient. - Answer Agglutination reactions use antigens that are attached to large
particles or whole cells to produce visible clumping and aggregation.Performed in tubes
or on slides.
Agglutination: Soluble antibodies cause clumping of antigens that are on the surface of
a synthetic particle or cell. TypicallyAgglutination of bacterial cells (serotyping)
Agglutination reactions use antigens that are attached to large particles or whole cells
,to produce visible clumping and aggregation.
Agglutination using synthetic latex beads coated with antibodies to a protein found on
the surface of Staphylococcus aureus cells.
Understand direct and indirect EIA. - Answer Enzyme Immunosorbent Assays (EIA)
Direct: Immunoassays are immobilized antibody to test for an antigen from the patient.
Indirect: Use immobilized antigen to detect antibodies from a patient.
Know how PCR can be used to identify pathogen DNA in a patient. - Answer •Strategy:
provide diagnostic primers into a PCR reaction that will give a specific PCR
double-stranded DNA product only if there is pathogen DNA (template DNA) in the
patient sample.
Briefly describe what qPCR is and how it works. - Answer qPCR quantitative real-time
PCR.
Requires:
● A PCR thermocycler that includes fluorescence measurements capabilities of each
individual reaction.
● A fluorescent probe that is included in the reaction.
○ Fluorescence increases as double-stranded DNA product is made.● RNA from
pathogens can be detected by first performing a reverse-transcriptase
reaction to convert RNA to DNA
Understand that different serotypes of a particular pathogen can have different
antibiotic susceptibilities and be able to explain how different strains arise. - Answer
Types of genome alterations:
Genome rearrangementsMobile genetic elementsPhage integrationsPathogenicity
islands**All of these alterations are associated withEnhanced virulence and increased
antibiotic resistance
The 16S rRNA gene sequences of two different serotypes of the same species will be
identical, but we can observe differences in the chromosome arrangements between
these strains.
Define toxic dose and therapeutic dose. - Answer Therapeutic dose: Concentration
required for effective clinical treatment.
Toxic dose: Level at which drugs become toxic to the host.
Ideal therapeutic strategies have a high toxic and low therapeutic dose.
, Understand broad vs. narrow spectrum antibiotics. - Answer Narrow-spectrum
antibiotics target a few types of bacteria. Broad-spectrum antibiotics target many types
of bacteria. Both types work well to treat infections. But using broad-spectrum
antibiotics when they're not needed can create antibiotic-resistant bacteria that are
hard to treat.
Know how isoniazid and quinolones function to impede bacterial growth. - Answer
Isoniazid is a growth factor analog of nicotinamide, and intermediate in the synthesis of
mycolic acids by Mycobacterium.
● Synthesis of mycolic acids (part of the cell wall/envelope) is blocked.
● Widely used for tuberculosis treatment.
● Is an example of a prodrug.
○ Prodrug metabolized to active form by a catalase enzyme (KatG).
Quinolones are inhibitors of DNA gyrase.
● DNA gyrase is required for supercoiling of DNA.
● Quinolones bind to DNA gyrase and block activity.
● Bacterial cell division is blocked.
Describe the bacterial enzyme that is inhibited by Beta-Lactam antibiotics and identify a
generalized chemical structure of a Beta-lactam antibiotic. - Answer Beta-Lactams
inhibit peptidoglycan synthesis.
Know the three classes of antibiotics that bind to bacterial ribosomes, and the examples
of each class. - Answer Aminoglycoside: Antibiotics such as kanamycin bind to bacterial
ribosomes (30S subunit)
Macrolide: antibiotics such as erythromycin bind to bacterial ribosomes (50S subunit)
Tetracyclines: Also bind to bacterial ribosome (30S subunit)
Many semisynthetic derivatives (different R groups) have been found.
Understand how an ionophore antibiotic such as daptomycin works to kill bacteria. -
Answer ● It is a cyclic lipopeptide that aggregates and insets into the cytoplasmic
membrane.
● Cretes pores in the membrane that result in de-energized membrane.
● Proton Motive Force is lost and the cell dies due to lack of energy.
Know the mechanisms of resistance presented in lecture. - Answer 1. Reduced ability of
What are the typical sources of specimens? - Answer •Blood - look for bacteremia or
viremia•Can also test blood for the presence of antibodies to a pathogen.
•Urine - bacteriuria - presence of bacteria in urine; most often detected using urinalysis
dipstick or growth-dependent methods.
•Feces - look for intestinal pathogens (bacteria or eukaryotes).•Abscesses and wounds -
swab or needle aspiration.•Throat/nasal swabs - soft cotton swabs to collect samples to
test for bacteria or viruses. •Genital samples - to get specimens to test for sexually
transmitted pathogens.
Be able to state the medical terms of bacteria in the blood and urine. - Answer Bacteria
in Blood:Bacteremia or Viremia Bacteria in Urine: Bacteriuria
Know the Biosafety levels for laboratories working with pathogens. - Answer 4
classifications based on levels of risk; higher numbers for more dangerous pathogens.
● BSL1: Few safety controls; open lab bench; non-pathogenic organisms; limited
access.
● BSL 2: Can have an open bench, but gloves, lab coat, eye protection required; used
for
moderate pathogens.
● BSL 3: Designed for pathogens; organisms manipulated in biological safety cabinets;
room under slight negative pressure; extensive filtration of air.
● BSL 4: Used for life-threatening pathogens that can be transmitted by aerosols;
pressurized suits for workers; Ebola, Marburg viruses.
Be able to discern the difference between differential and selective media. - Answer
Selective Medium: Contains substances that inhibit growth of certain types of bacteria.
Differential Medium: Includes compounds that allows visualization of certain
biochemical pathways and products.
Describe the three common methods used to test sensitivity of a pathogen to an
antibiotic. - Answer Minimum inhibitory concentration (MIC): Using tube dilution assay.
Disk diffusion assay: Pure culture is spread on plate; then disks containing different
antibiotics are placed on plate. Also called a Kirby-Bauer test.
"Etest": MIC is read from the edge of the clear zone using the scale on the strips.
,Define an antibody titer and how it changes during the course of an infectious disease. -
Answer Antibody titer: The lowest concentration of serum at which an antibody-antigen
reaction is observed.
How is a Mantoux skin test performed and how is it interpreted? - Answer Performed:
Locate and clean the injection site. 2-4 inches below the elbow joint. Place forearm palm
side up on firm, well-lit surface. Select an area free of barriers (ex: scars / sores) to
placing and reading. Clean the area with an alcohol swab.
Check expiration date on vial and ensure that the vial contains tuberculin (5 TU per
0.1ml). Use a single-dose tuberculin syringe with a 1⁄4 - 1⁄2 inch, 27 gauge needle with a
short bevel. Fill the syringe with 0.1 ml of tuberculin.
Insert slowly, bevel up, at a 5-15 degree angle. Needle bevel can be seen just below the
skin surface. After injection, a tense pale wheal should appear over the needle.
Wheal should be 6-10 mm in diameter. If not, repeat test as a site at least 2 inches away
from the original site.
Record information.
Interpreted:
● Based on the size of induration dependent upon the test run. Famous is TB test.
Define serology. - Answer The use of antigen-antibody reactions to detect: ● Antigens
● Antibodies● For a few pathogens, previous exposure can be detected by an
inflammatory response
to injection of a purified antigen under the skin.
Describe what an epitope is. - Answer The part of an antigen molecule to which an
antibody attaches itself.
Understand how agglutination assays are used to detect antibodies or antigens from a
patient. - Answer Agglutination reactions use antigens that are attached to large
particles or whole cells to produce visible clumping and aggregation.Performed in tubes
or on slides.
Agglutination: Soluble antibodies cause clumping of antigens that are on the surface of
a synthetic particle or cell. TypicallyAgglutination of bacterial cells (serotyping)
Agglutination reactions use antigens that are attached to large particles or whole cells
,to produce visible clumping and aggregation.
Agglutination using synthetic latex beads coated with antibodies to a protein found on
the surface of Staphylococcus aureus cells.
Understand direct and indirect EIA. - Answer Enzyme Immunosorbent Assays (EIA)
Direct: Immunoassays are immobilized antibody to test for an antigen from the patient.
Indirect: Use immobilized antigen to detect antibodies from a patient.
Know how PCR can be used to identify pathogen DNA in a patient. - Answer •Strategy:
provide diagnostic primers into a PCR reaction that will give a specific PCR
double-stranded DNA product only if there is pathogen DNA (template DNA) in the
patient sample.
Briefly describe what qPCR is and how it works. - Answer qPCR quantitative real-time
PCR.
Requires:
● A PCR thermocycler that includes fluorescence measurements capabilities of each
individual reaction.
● A fluorescent probe that is included in the reaction.
○ Fluorescence increases as double-stranded DNA product is made.● RNA from
pathogens can be detected by first performing a reverse-transcriptase
reaction to convert RNA to DNA
Understand that different serotypes of a particular pathogen can have different
antibiotic susceptibilities and be able to explain how different strains arise. - Answer
Types of genome alterations:
Genome rearrangementsMobile genetic elementsPhage integrationsPathogenicity
islands**All of these alterations are associated withEnhanced virulence and increased
antibiotic resistance
The 16S rRNA gene sequences of two different serotypes of the same species will be
identical, but we can observe differences in the chromosome arrangements between
these strains.
Define toxic dose and therapeutic dose. - Answer Therapeutic dose: Concentration
required for effective clinical treatment.
Toxic dose: Level at which drugs become toxic to the host.
Ideal therapeutic strategies have a high toxic and low therapeutic dose.
, Understand broad vs. narrow spectrum antibiotics. - Answer Narrow-spectrum
antibiotics target a few types of bacteria. Broad-spectrum antibiotics target many types
of bacteria. Both types work well to treat infections. But using broad-spectrum
antibiotics when they're not needed can create antibiotic-resistant bacteria that are
hard to treat.
Know how isoniazid and quinolones function to impede bacterial growth. - Answer
Isoniazid is a growth factor analog of nicotinamide, and intermediate in the synthesis of
mycolic acids by Mycobacterium.
● Synthesis of mycolic acids (part of the cell wall/envelope) is blocked.
● Widely used for tuberculosis treatment.
● Is an example of a prodrug.
○ Prodrug metabolized to active form by a catalase enzyme (KatG).
Quinolones are inhibitors of DNA gyrase.
● DNA gyrase is required for supercoiling of DNA.
● Quinolones bind to DNA gyrase and block activity.
● Bacterial cell division is blocked.
Describe the bacterial enzyme that is inhibited by Beta-Lactam antibiotics and identify a
generalized chemical structure of a Beta-lactam antibiotic. - Answer Beta-Lactams
inhibit peptidoglycan synthesis.
Know the three classes of antibiotics that bind to bacterial ribosomes, and the examples
of each class. - Answer Aminoglycoside: Antibiotics such as kanamycin bind to bacterial
ribosomes (30S subunit)
Macrolide: antibiotics such as erythromycin bind to bacterial ribosomes (50S subunit)
Tetracyclines: Also bind to bacterial ribosome (30S subunit)
Many semisynthetic derivatives (different R groups) have been found.
Understand how an ionophore antibiotic such as daptomycin works to kill bacteria. -
Answer ● It is a cyclic lipopeptide that aggregates and insets into the cytoplasmic
membrane.
● Cretes pores in the membrane that result in de-energized membrane.
● Proton Motive Force is lost and the cell dies due to lack of energy.
Know the mechanisms of resistance presented in lecture. - Answer 1. Reduced ability of
