Microbiology Week 2
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Questions and Answers

Which of the following cannot be used to visualize microbes

  • Compound microscope
  • CT scan (correct)
  • Transmission Electron Microscopy (TEM)
  • Scanning Electron Microscopy (SEM)

    • Which of the following lab diagnostic bacteriologic methods does blood agar fall under?

  • Bacteria stain
  • Culture (select media)
  • Antibiotic susceptibility
  • Culture (non-select media) (correct)

    • Which of the following lab diagnostic bacteriologic methods does gram or acid fast staining fall under?

  • Bacteria Stain (correct)
  • Patient Sample
  • Nucleic acid tests
  • Culture (select-media)

    • Which of the following lab diagnostic bacteriologic methods does MSA fall under?

    <p>Culture (select media)</p> Signup and view all the answers

    Which common lab test can differentiate between Streptococcus and Staphylococcus?

    <p>Catalase test</p> Signup and view all the answers

    Which common lab test differentiates Staph aureus from non-aureus staph?

    <p>Coagulase test</p> Signup and view all the answers

    Which common lab test is used to assess the activity of cytochrome c oxidase in the electron transport chain?

    <p>Cytochrome c oxidase test</p> Signup and view all the answers

    Which common lab test is used to test for usually gram-negative microbes that can survive the biliary system?

    <p>Bile culture</p> Signup and view all the answers

    Which common lab test detects a chemical that is toxic to some bacteria and is useful in identifying Strep. pneumoniae?

    <p>Optochin susceptibility test</p> Signup and view all the answers

    What common lab test includes automated molecular tests such as PCR and can detect the genetic material of a pathogen?

    <p>Nucleic Acid Based Test (NAATs)</p> Signup and view all the answers

    Which of the following lab diagnostic immunologic methods is described by the following criteria:

    • Can antigens clump RBCs
    • Serum contains pathogen: influenza (hemagglutinin binds RBCs)
    • Mix serum with RBCs (first add anti-HA antibodies)?

    <p>Agglutination</p> Signup and view all the answers

    Which of the following lab diagnostic immunological methods includes the following:

    • Serum with antibodies
    • Mix pathogen or antigen
    • Color readout?

    <p>ELISA (Enzyme linked immuno-assay)</p> Signup and view all the answers

    Which PCR method has the following characteristic: amplification and quantitation are combined in one reaction?

    <p>Quantitative PCR (qPCR)</p> Signup and view all the answers

    Which PCR method has the following description: RNA is the nucleic acid starting template. Used for RNA viruses or mRNA levels?

    <p>Reverse Transcription PCR (RT-PCR)</p> Signup and view all the answers

    What are self-replicating plasmids (replicons)?

    <p>Plasmids that can replicate independently of chromosomal DNA. They often carry virulence factors</p> Signup and view all the answers

    Which bacteria does not have a circular plasmid and is the causative agent for Lyme disease?

    <p>Borrelia burgdorferi</p> Signup and view all the answers

    Which bacteria has an episome and integrates into the genome?

    <p>Escherichia coli</p> Signup and view all the answers

    What is the plasmid copy number?

    <p>The number of plasmids per cell.</p> Signup and view all the answers

    What are bacteriophages?

    <p>Viruses that infect bacteria</p> Signup and view all the answers

    Which bacteriophage outcome is described as replication to high numbers that lyses cells?

    <p>Lytic cycle</p> Signup and view all the answers

    Which bacteriophage outcome is described as the integration into the host genome without killing the host bacteria?

    <p>Lysogenic cycle</p> Signup and view all the answers

    What is an example of a lysogenic bacteriophage that contains toxin genes?

    <p>Diphtheria toxin</p> Signup and view all the answers

    What are jumping genes responsible for in gene exchange?

    <p>Transposons</p> Signup and view all the answers

    Which of the following contains these characteristics:

    -Move within the genome, between plasmids, between plasmid and genomes -Can carry antibiotic resistant genes -Can insert and inactivate genes -Surround pathogenic islands that contain virulence factors?

    <p>Transposons</p> Signup and view all the answers

    Match each item to its definition

    <h1>Transformation = Active uptake Conjugation = Mating, exchange of material Transduction = Transfer of genetic information</h1> Signup and view all the answers

    Which DNA transfer method is competent because bacteria naturally take up exogenous DNA?

    <p>Transformation</p> Signup and view all the answers

    Which DNA transfer method involves bacteria that carry a sex pilus that can transfer plasmids from the donor (male) to recipient (female)?

    <p>Conjugation</p> Signup and view all the answers

    Which bacteria has F plasmids that contain all the elements necessary to transfer the F plasmid, including the ability to make sex pili?

    <p>Escherichia coli</p> Signup and view all the answers

    Which DNA transfer method is mediated by bacteriophages and is:

    • specialized if the phage transfers particular genes adjacent to the integration sites
    • generalized if incorporation of DNA is random due to accidental packaging of host DNA into the phage?

    <p>Transduction</p> Signup and view all the answers

    What does MRSA stand for?

    <p>Methicillin-resistant Staphylococcus aureus</p> Signup and view all the answers

    What does MVRSA stand for?

    <p>Methicillin-Resistant Vancomycin-Resistant Staphylococcus Aureus</p> Signup and view all the answers

    What is CRISPR Cas-9?

    <p>A gene-editing technology</p> Signup and view all the answers

    What motif is essential to CRISPR-Cas systems?

    <p>All of the above</p> Signup and view all the answers

    Which CRISPR-Cas motif is essential to ensure only foreign viral nucleic acids are cleaved?

    <p>PAM (Protospacer Adjacent Motif)</p> Signup and view all the answers

    What is required in a patient for a pathogen to persist, cause disease, and escape or defeat host defenses?

    <p>Virulence factors</p> Signup and view all the answers

    What type of bacteria produces enterotoxin or toxins that are able to cross the mucosa? Their natural habitats are the environment, and some secrete toxin into food.

    <p>Toxogenic bacteria</p> Signup and view all the answers

    What type of bacteria can enter and survive in parts of the body where bacteria are not normally present, such as the bloodstream, soft tissues, and meninges?

    <p>Invasive bacteria</p> Signup and view all the answers

    What is an example of a bacteria that can cause intracellular infection?

    <p>Mycobacterium sp. (TB)</p> Signup and view all the answers

    What is an example of a bacteria that causes extracellular infection?

    <p>Staphylococcus aureus</p> Signup and view all the answers

    Which bacterium is described by the following characteristics: - Facultative anaerobic, non-spore forming - Gram positive rods, uniformly shaped - Motile at room temperature but less so at body temperature - Grows at a broad temperature range of 1-45 degrees C - Weakly beta hemolytic - Can cause meningitis similar to Strep. Pneumonia?

    <p>Listeria monocytogenes</p> Signup and view all the answers

    Which bacteria causes a disease that is uncommon and usually affects susceptible populations: neonates, elderly, pregnant women, and patients with compromised cellular immunity? It rearranges the cytoskeleton to propel from cell to cell.

    <p>Listeria monocytogenes</p> Signup and view all the answers

    Which of the following is not a bacterium that can rearrange the cell cytoskeleton?

    <p>Pseudomonas Aeruginosa</p> Signup and view all the answers

    Match each stage of bacterial pathogenesis to its definition

    <p>Infection = Getting in: communicable diseases, normal flora, endemic disease Incubation = Bacteria growth expansion, general symptoms Prodrome = Early symptoms Specific disease = Specific symptoms</p> Signup and view all the answers

    What type of toxin is described by the following characteristics?

    • generated and released
    • B part binds to a target receptor
    • Toxin is taken in through endocytosis
    • A part carries out the activity of the toxin once inside the cell

    <p>Exotoxin</p> Signup and view all the answers

    Match each toxin to its corresponding organism

    <p>Anthrax toxins = Bacillus anthracis Bordetella = Bordetella spp. Botulinum toxin = Clostridium botulinum Cholera toxin = Vibrio cholerae</p> Signup and view all the answers

    Match each toxin to its biological effects

    <p>Anthrax toxins = Increase cAMP, localized edema, death of cells Bordetella = Adenylate cyclase toxin, increase in cAMP, cell death Botulinum toxin = Decrease in acetylcholine release, flaccid paralysis Cholera toxin = Activation of adenylate cyclase, increase cAMP, diarrhea</p> Signup and view all the answers

    Match each exotoxin to its corresponding organsim

    <p>Diptheria toxin = Corynebacterium diptheriae Heat-labile enterotoxins = Escherichia coli Pertussis toxin = Bordetella pertussis Pseudomonas exotoxin A = Pseudomonas aeruginosa</p> Signup and view all the answers

    Match each exotoxin to its biological effect

    <p>Diptheria toxin = Inhibits protein synthesis: death Heat-labile enterotoxins = Activate adenylate cyclase, increase cAMP, diarrhea Pertussis toxin = Block G protein signal transduction Pseudomonas exotoxin A = Inhibits protein synthesis: death</p> Signup and view all the answers

    Match each exotoxin to its organism

    <h1>Shiga toxin = Shigella dysenteriae Shiga like-toxin = Shigella spp., E. coli Tetanus toxin = Clostridium tetani</h1> Signup and view all the answers

    Which toxin can inhibit protein synthesis, leading to death?

    <p>Shiga toxin/ Shiga-like toxin</p> Signup and view all the answers

    Match each item to its corresponding definition

    <p>Viruses = Obligate intracellular Bacteria = Intra or extracellular Fungi = Endemic mycoses oropportunisitic Parasite = Simple or complex</p> Signup and view all the answers

    Match each host type/ microbe interaction to its definition

    <p>Symbiosis = Two different organisms interact closely with typically mutual benefit to both Commensalism = Two different organisms are associated, and one benefits and there is no effect on the other Parasitism = Close relationship between species where one lives in or on the other and does harm Colonization = Presence of a microbe on/ in a host with growth of the organism but without interaction between the host and organism</p> Signup and view all the answers

    Which host interaction involves both species benefiting?

    <p>Mutualism</p> Signup and view all the answers

    Where could a symbiotic host/microbe interaction be found?

    <p>In the human gut microbiome</p> Signup and view all the answers

    Where would commensalism be found in the human body?

    <p>Skin</p> Signup and view all the answers

    Where could mutualism in the human body be found?

    <p>In the gut microbiome</p> Signup and view all the answers

    What is a bacterium that is known to exhibit colonization?

    <p>Staphylococcus aureus</p> Signup and view all the answers

    What microbe can cause a single well-defined disease?

    <p>C. tetani</p> Signup and view all the answers

    What is an example of a microbe that can cause exogenous infections?

    <p>Influenza</p> Signup and view all the answers

    What is a microbe that produces multiple manifestations of diseases such as endocarditis, pneumonia, wound infections, and food poisoning?

    <p>Staphylococcus aureus</p> Signup and view all the answers

    What disease can be caused by several organisms such as viruses, bacteria, fungi, and parasites that can cause the same disease?

    <p>Meningitis</p> Signup and view all the answers

    What are the three categories necessary for portals of entry for infection?

    <p>Mucous membranes, skin, parenteral route</p> Signup and view all the answers

    Which portal of entry is also a portal of exit for microbes?

    <p>Respiratory Tract</p> Signup and view all the answers

    In which portal of entry can gram negative and capsid viruses pass through, but gram positive and enveloped viruses are typically neutralized by the acidic environment?

    <p>Gastrointestinal tract</p> Signup and view all the answers

    What is an example of a bacteria that can be found in the upper digestive tract?

    <p>Actinomyces</p> Signup and view all the answers

    What is an example of a bacterium that can be found in the lower digestive tract?

    <p>Escherichia coli</p> Signup and view all the answers

    Which portal of entry for microbes causes more infections in women than in men?

    <p>Urogenital tract</p> Signup and view all the answers

    Which protease does Neisseria gonorrhoeae contain that cleaves hinge regions of IgA?

    <p>IgA protease</p> Signup and view all the answers

    Which portal of entry is impenetrable to most microbes?

    <p>Skin</p> Signup and view all the answers

    In which portal of entry is infection due to breaks in skin, injection, or insect bites?

    <p>Parenteral</p> Signup and view all the answers

    Which virulence factors can encourage bacterial establishment? (Select all that apply)

    <p>Adhesins</p> Signup and view all the answers

    What does LD50 stand for?

    <p>Lethal Dose for 50% of the population</p> Signup and view all the answers

    What does ID50 stand for?

    <p>Infectious Dose for 50% of the population</p> Signup and view all the answers

    Organisms with the lowest LD50 and ID50 are least virulent

    <p>False</p> Signup and view all the answers

    What is a passive strategy that microbes utilize to avoid, evade, and compromise host defenses?

    <p>Capsule</p> Signup and view all the answers

    Which bacteria contains pneumolysin and IgA protease?

    <p>Streptococcus pneumoniae</p> Signup and view all the answers

    Which bacteria is a facultative anaerobe that is non-motile?

    <p>Klebsiella pneumonia</p> Signup and view all the answers

    What bacteria can cause wound and soft tissue infections and UTIs with risk factors such as age, alcohol abuse, or diabetes mellitus?

    <p>Klebsiella pneumoniae</p> Signup and view all the answers

    Which bacteria incorporates M proteins into the cell wall?

    <p>Streptococcus pyogenes</p> Signup and view all the answers

    Which bacteria has a mycolic cell wall and can live within phagocytes?

    <p>Mycobacterium tuberculosis</p> Signup and view all the answers

    What type of bacteria can reptiles and amphibians carry?

    <p>Salmonella</p> Signup and view all the answers

    What disease can prairie dogs transmit to humans?

    <p>Monkeypox</p> Signup and view all the answers

    What virus can pet bats transmit?

    <p>Lyssaviruses</p> Signup and view all the answers

    What can hedgehogs and chinchillas transmit to humans?

    <p>Ringworms</p> Signup and view all the answers

    What does the 'O' in O157:H7 stand for?

    <p>LPS</p> Signup and view all the answers

    What does the H in O157:H7 stand for?

    <p>Flagella</p> Signup and view all the answers

    Which bacteria can be transmitted to humans from cat scratches?

    <p>Bartonella henselae</p> Signup and view all the answers

    Study Notes

    Koch's Postulates

    • Koch's postulates define a series of criteria for establishing a causal relationship between a microbe and a disease.
    • Common postulates include isolating the pathogen from a diseased host and inoculating a healthy host to reproduce the disease.

    Visualization of Microbes

    • Techniques such as light microscopy and electron microscopy are commonly used to visualize microorganisms.
    • Certain microbes cannot be directly visualized due to extremophilic nature or if they are unculturable.

    Diagnostic Bacteriologic Methods

    • Blood agar is categorized under enrichment and differential media.
    • Gram staining and acid-fast staining are crucial methods for classifying bacteria based on cell wall composition.
    • Mannitol Salt Agar (MSA) serves as both a selective and differential medium primarily for isolating Staphylococci.

    Differentiating Bacteria

    • Catalase test differentiates between Streptococcus (catalase-negative) and Staphylococcus (catalase-positive).
    • Coagulase test is used to distinguish Staphylococcus aureus (coagulase-positive) from other Staphylococcus species.

    Common Lab Tests

    • The oxidase test assesses cytochrome c oxidase activity in bacteria.
    • Bile esculin test identifies gram-negative bacteria that can survive the biliary system.
    • Quellung reaction detects the capsule of Streptococcus pneumoniae through serological methods.
    • Automated molecular tests, including PCR, detect genetic material from pathogens.

    Immunologic Methods

    • Hemagglutination test involves clumping of red blood cells by specific antibodies in the presence of pathogens.
    • Enzyme-linked immunosorbent assay (ELISA) uses serum containing antibodies, detecting color changes indicating the presence of specific antigens.

    PCR Methods

    • Quantitative PCR (qPCR) combines amplification and quantification in one reaction.
    • Reverse transcription PCR (RT-PCR) uses RNA as a template, primarily applied for RNA viruses.

    Plasmids and Gene Exchange

    • Self-replicating plasmids (replicons) can replicate independently within bacteria.
    • Borrelia burgdorferi, the causative agent of Lyme disease, lacks a circular plasmid.
    • Episomes can integrate into bacterial genomes, exemplified by certain types of plasmids.

    Plasmid Copy Number

    • Refers to how many copies of a plasmid exist within a single bacterial cell.

    Bacteriophages

    • Bacteriophages are viruses that infect bacteria; they can have lytic or lysogenic cycles.
    • Lytic outcome leads to high replication and cell lysis.
    • Lysogenic outcome integrates phage DNA into the bacterial genome without immediate cell death.

    Gene Transfer Methods

    • Transformation involves competent bacteria naturally taking up exogenous DNA.
    • Conjugation uses sex pili for plasmid transfer from donor to recipient bacteria.
    • Hfr strains contain F plasmids enabling integration and transfer of chromosomal DNA via conjugation.

    Hospital-Acquired Resistance

    • MRSA stands for Methicillin-Resistant Staphylococcus aureus.
    • MVRSA stands for Methicillin-Resistant Vancomycin-Sensitive Staphylococcus aureus.

    CRISPR Technology

    • CRISPR Cas-9 is a genome-editing tool allowing specific DNA modifications.
    • The essential motif in CRISPR-Cas systems distinguishes foreign nucleic acids from host DNA.

    Pathogen Survival and Infections

    • Pathogens require specific conditions to persist, escape host defenses, and cause disease.
    • Certain bacteria produce enterotoxins that cross the mucosa, often from environmental sources.
    • Intracellular bacteria can survive in atypical environments, causing systemic infections.

    Disease Manifestations

    • Some bacteria exhibit polymicrobial infections, while others cause defined diseases.
    • Diseases can result from various organisms, complicating diagnosis and treatment.

    Portals of Entry for Infection

    • Three primary portals of entry include mucosal surfaces, skin breaks, and natural openings.
    • The gastrointestinal tract is significant for nutrient absorption and serves as a portal for infections.

    Host-Microbe Interactions

    • Symbiotic interactions benefit both host and microbes.
    • Mutualism and commensalism occur in various human body sites, influencing health.

    Virulence Factors

    • LD50 refers to the lethal dose that kills 50% of test subjects; IDs indicate the infectious dose.
    • Active evasion strategies help microbes survive host defenses.

    Bacteria and Diseases

    • Neisseria gonorrhoeae produces IgA protease, impacting immune response.
    • Certain bacteria can be transmitted through animal bites or contaminated food sources, establishing zoonotic disease risk.

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    Test your knowledge of Koch's postulates and identify which statement is not a part of the original criteria. This quiz will challenge your understanding of microbiology and disease causation principles.

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