Microbiology Quiz
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Questions and Answers

Replication occurs in the nucleus of:

  • All DNA viruses (correct)
  • Herpesviruses and orthomyxoviruses
  • All RNA viruses
  • Herpesviruses and paramyxoviruses

    • Rubella virus infection:

  • is always clinically manifested
  • is very dangerous in the third trimester of pregnancy (correct)
  • can be asymptomatic
  • is not dangerous in the first trimester of pregnancy

    • Which statement is true:

  • Rubella virus cannot be cultured
  • IgM antibodies can usually be detected shortly after rash appears (correct)
  • Immunohistochemistry is the method of choice for rubella virus identification
  • Prenatal diagnosis of rubella fetus is very easy

    • DNA viruses include:

    <p>CMV and hepatitis B virus</p> Signup and view all the answers

    Gastroenteritis is not caused by:

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

    Chronic carrier state does not persist after infection with:

    <p>Hepatitis A and hepatitis E</p> Signup and view all the answers

    Respiratory transmission occurs with:

    <p>Correct answers are a and c</p> Signup and view all the answers

    Viruses with negative RNA are:

    <p>Picornaviruses and rhabdoviruses</p> Signup and view all the answers

    Hepatitis C infection:

    <p>All of the provided answers are correct</p> Signup and view all the answers

    Measles virus:

    <p>Undergoes antigenic drift and antigenic shift</p> Signup and view all the answers

    What are CD4+ lymphocytes?

    <p>T helper lymphocytes</p> Signup and view all the answers

    What are CD8+ lymphocytes?

    <p>T cytotoxic lymphocytes</p> Signup and view all the answers

    Lifespan is measured in years for which type of cell?

    <p>B lymphocytes</p> Signup and view all the answers

    IgE binds to mast cells via which component?

    <p>Fc fragment</p> Signup and view all the answers

    Which immunoglobulin passes through the placenta?

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

    Thymus-independent antigens induce which type of immunoglobulin production?

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

    Thymus-dependent antigens induce the formation of which type of memory cells?

    <p>induce the formation of memory B lymphocytes</p> Signup and view all the answers

    Meningococcus most commonly reaches the central nervous system through:

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

    Erysipelothrix rhusiopathiae is the causative agent of:

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

    M.leprae can proliferate in:

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

    Rickettsiae are the causative agents of:

    <p>typhus fever</p> Signup and view all the answers

    Which of the following statements about chlamydiae is incorrect?

    <p>they independently synthesize sufficient ATP</p> Signup and view all the answers

    Chlamydia trachomatis includes:

    <p>over 80 serotypes</p> Signup and view all the answers

    During Mycoplasma pneumoniae infection, which host defense function is significantly impaired?

    <p>ciliary activity</p> Signup and view all the answers

    The family Mycoplasmataceae does not include:

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

    Microscopically, B.anthracis appears as:

    <p>Arabic letters</p> Signup and view all the answers

    Gram-positive lancet-shaped or flame-shaped diplococci suggest a diagnosis of:

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

    Virulence is:

    <p>the degree of pathogenicity</p> Signup and view all the answers

    Endotoxins:

    <p>are found in the cell wall of bacteria</p> Signup and view all the answers

    UV radiation is used in medicine for:

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

    What is virulence?

    <p>The degree of pathogenicity</p> Signup and view all the answers

    Where are endotoxins found?

    <p>Found in the cell wall of bacteria</p> Signup and view all the answers

    How is UV radiation used in medicine?

    <p>As a method of sterilization</p> Signup and view all the answers

    Which of the following is not included in the adherence factors of microorganisms?

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

    Which of the following is not included in the invasiveness factors of microorganisms?

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

    In an autoclave, what is the method of sterilization?

    <p>Moist heat</p> Signup and view all the answers

    What is examined using an antibiogram?

    <p>The sensitivity of bacteria to antibiotics</p> Signup and view all the answers

    How do bacteria divide?

    <p>Binary fission</p> Signup and view all the answers

    What is symbiosis?

    <p>Living together in a community of two or more different organisms</p> Signup and view all the answers

    What category do bacteria fall into, clinically speaking?

    <p>Extracellular parasites</p> Signup and view all the answers

    Enveloped viruses include:

    <p>all icosahedral and some spherical viruses</p> Signup and view all the answers

    Viruses are primarily classified into several large groups based on:

    <p>nucleic acid characteristics</p> Signup and view all the answers

    Viruses can be purified based on their size and density using:

    <p>density gradient</p> Signup and view all the answers

    Coli, Enterobacter sp., and Proteus sp. are:

    <p>normal bacterial flora of the digestive tract</p> Signup and view all the answers

    Endotoxin is released during:

    <p>lysis of Gram-negative bacteria</p> Signup and view all the answers

    Neisseria gonorrhoeae is a bacterium that causes:

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

    Gonococcal infection elicits a more severe clinical reaction:

    <p>in women</p> Signup and view all the answers

    The evasion phenomenon is described in gonococci and represents:

    <p>evasion of gonococci from polymorphonuclear leukocytes during phagocytosis</p> Signup and view all the answers

    In a direct Gram stain preparation, meningococci and gonococci:

    <p>can be differentiated</p> Signup and view all the answers

    M.tuberculosis forms visible colonies on solid nutrient medium for approximately 3 weeks, and a negative result is issued after:

    <p>6-8 weeks</p> Signup and view all the answers

    Koch's bacillus can survive in dust for:

    <p>several years</p> Signup and view all the answers

    Which of the following exoproducts is considered a virulence factor of Staphylococcus aureus:

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

    Staphylococcus epidermidis is:

    <p>conditionally pathogenic bacterial species</p> Signup and view all the answers

    E.coli most commonly causes pyogenic infections localized in the:

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

    Choose the correct sentence:

    <p>the main reservoir of group B streptococcus (Streptococcus agalactiae) is the vaginal mucosa</p> Signup and view all the answers

    Study Notes

    Microbiology

    Enveloped Viruses

    • Enveloped viruses include all icosahedral and some spherical viruses
    • Examples of enveloped viruses: influenza, HIV, and herpesvirus

    Viral Classification

    • Viruses are primarily classified based on nucleic acid characteristics (DNA or RNA) and capsid symmetry (icosahedral or helical)

    Viral Purification

    • Viruses can be purified using density gradient centrifugation or differential centrifugation
    • These methods separate viruses based on their size and density

    Indirect Virus Counting

    • The most commonly used method of indirect virus counting is plaque counting
    • Plaque counting involves infecting a layer of cells with a virus, and then counting the number of plaques (areas of dead cells) that form

    Virus Isolation

    • Embryos of chickens are most commonly used for virus isolation
    • Viruses are isolated by inoculating the virus into the embryo, and then harvesting the virus after replication

    Influenza Virus

    • Adhesion of the influenza virus to the target cell surface is enabled by the presence of hemagglutinin

    Viral Replication

    • In an infected cell, viruses can do everything except stimulate macromolecule synthesis
    • Viral RNA replicates in the host's cytoplasm

    Hepadnaviruses

    • Hepadnaviruses (hepatitis B) differ from other DNA viruses by replicating using reverse transcriptase
    • Reverse transcriptase is an enzyme that converts RNA into DNA

    Prokaryotic and Eukaryotic Cells

    • Prokaryotic cells do not have a nucleus or membrane-bound organelles
    • Eukaryotic cells have a nucleus and membrane-bound organelles

    Bacterial Cell Walls

    • The main structural component of bacterial cell walls is peptidoglycan
    • Bacterial cell walls are not found in Mycoplasma

    Fungi

    • Fungi are eukaryotic organisms that can cause infections
    • Fungal infections are called mycoses

    Protozoa

    • Protozoa are classified into groups based on their mode of locomotion
    • Malaria is caused by a protozoan of the genus Plasmodium

    Viral Serology

    • Serological methods for virus detection include ELISA, Western blot, and complement fixation test
    • Serological diagnosis of primary viral infections involves detection of anti-viral IgM

    Molecular Methods

    • Molecular methods for virus detection include PCR, Northern blot, and Southern blot
    • PCR (Polymerase Chain Reaction) is a widely used method for amplifying specific DNA sequences

    Oncogenic Viruses

    • Oncogenic viruses include EBV, HSV-2, HCV, and HHV-8
    • These viruses can cause cancer in infected individuals

    Viral Zoonoses

    • Viral zoonoses are viruses that can be transmitted from animals to humans
    • Examples of viral zoonoses include Lassa fever, Japanese encephalitis, and rabies

    Prions

    • Prions are infectious proteins that can cause diseases
    • Prions have a long incubation period and are resistant to heat and radiation

    Bacteriology

    Bacterial Cell Structure

    • The cytoplasmic membrane is a double-layer membrane
    • The cell wall of Gram-positive bacteria is primarily composed of peptidoglycan
    • The periplasmic space is located between the cell wall and the cytoplasmic membrane

    Gram Staining

    • Gram staining is used to differentiate between Gram-positive and Gram-negative bacteria
    • Gram-positive bacteria stain blue-purple, while Gram-negative bacteria stain yellow

    Capsules

    • Capsules are composed of extracellular polysaccharide polymers
    • The primary function of the capsule is protection of the bacterial cell

    Antimicrobial Agents

    • Antimicrobial agents are substances that kill or prevent the multiplication of microorganisms
    • Mechanisms of resistance to antimicrobial agents include enzymatic destruction, modification of the target enzyme, and alteration of cell wall permeability

    Infection

    • Infection is a host-parasite relationship where the parasite is metabolically dependent on the host
    • The primary sterile region is the blood

    Asepsis

    • Asepsis is the process of preventing infection by eliminating or reducing the number of microorganisms
    • Material prepared by aseptic methods is sterile### Bacteriology
    • Spores are highly resistant forms of bacteria.
    • Exotoxins are secreted by both Gram-positive and Gram-negative bacteria.
    • Microscope magnification is calculated by multiplying the magnification of the objective lens and the magnification of the eyepiece.
    • Gram staining is a special type of staining used to differentiate bacteria into Gram-positive and Gram-negative.
    • Bacteria have a single chromosome.
    • Bacteremia is a condition that occurs after the invasion of pathogenic microorganisms.
    • Septicemia is the invasion of the blood by pathogenic microorganisms.
    • The signs of inflammation are: rubor (redness), calor (heat), tumor (swelling), and function laesa (loss of function).
    • Adherence occurs between receptors on the surface of microorganisms and target tissue.
    • L-forms of bacteria can occur in vitro and are significant in antibiotic resistance.

    Virulence and Pathogenicity

    • Pathogenicity is the ability of bacteria to damage tissue and cause disease.
    • Infectivity is the ability of a microorganism to establish an initial site of infection.
    • Virulence is the degree of pathogenicity.
    • Bacterial resistance to antibiotics is a result of inadequate antibiotic use.

    Antibiotics and Treatment

    • An antibiogram is used to examine the sensitivity of bacteria to antibiotics.
    • Benzylpenicillin is the drug of choice for streptococcal angina.

    Special Bacteriology

    • Endotoxins are lipopolysaccharides and are highly toxic.
    • Klebsiella pneumoniae is a causative agent of urinary tract infections.
    • Mycoplasmas are bacteria that do not have a cell wall and are resistant to penicillin.
    • Koch's phenomenon is a skin test used to diagnose tuberculosis.
    • Chlamydia trachomatis is a causative agent of urinary tract infections.
    • Lymphogranuloma venereum is a disease caused by Chlamydia trachomatis.

    Diagnostic Tests

    • The Widal test is used to diagnose typhoid fever.
    • The Weil-Felix reaction is used to diagnose Lymphogranuloma venereum.
    • Hayflick medium is used to isolate Chlamydia.

    Other

    • A focus of infected tissue in tuberculosis is called a "tuberculoma".
    • M.leprae can proliferate in armadillos.
    • Rickettsiae are the causative agents of typhus fever.
    • Erysipelothrix rhusiopathiae is the causative agent of erysipeloid.
    • Cholera enterotoxin causes the excretion of sodium and water into the intestinal lumen.
    • Neutralizing antibodies to diphtheria toxin can be demonstrated by the Schick test.Here are the study notes for the provided text:

    Immunology

    • Immune Response
      • Phagocytosis: process by which macrophages and granulocytes ingest microorganisms
      • Opsonins: products of the immune system that mark pathogens for destruction, e.g. IgG, C3b component of complement
      • Chemotaxis: movement of leukocytes towards bacteria
      • Reverse transcriptase: enzyme that transcribes viral RNA into DNA, used by HIV virus
      • Integration of HIV provirus into cellular genome: assisted by viral enzymes integrases

    Cells of the Immune System

    • B Lymphocytes
      • Mature in bone marrow
      • Produce antibodies (IgM, IgG, IgE, IgA, IgD)
      • Express Class II MHC products
      • Can present antigens to T lymphocytes
    • T Lymphocytes
      • Mature in thymus
      • Responsible for cell-mediated immunity
      • Cytotoxic T lymphocytes (CTLs) kill virus-infected cells
      • Helper T lymphocytes assist activation of B lymphocytes and CTLs
      • Regulatory T lymphocytes modulate immune response
    • Macrophages
      • Phagocytic cells that ingest foreign substances
      • Express Class II MHC products, can present antigens to T lymphocytes
      • Involved in processing and presentation of antigens
    • Dendritic Cells
      • Antigen-presenting cells that activate T lymphocytes
      • Found in interstitial tissues, lymphoid organs, and skin
    • Mast Cells
      • Involved in allergic reactions, express Fcε receptor for IgE
      • Release histamine and other mediators upon activation
    • Eosinophils
      • Involved in parasitic infections and allergic reactions
      • Mature in response to IL-5
    • NK Cells
      • Non-specific, cytotoxic cells that recognize and kill tumor cells and virally infected cells

    Antibodies and Antigens

    • Antibody Structure
      • Fab fragment: antigen-binding region, composed of entire light chain and N-terminus of heavy chain
      • Fc fragment: constant region, involved in complement activation, placental transfer, and binding to mast cells and basophils
    • Antibody Classes
      • IgM: first antibody produced in response to infection, activates complement
      • IgG: most abundant antibody class, can cross placenta, activates complement
      • IgE: involved in allergic reactions, binds to mast cells and basophils
      • IgA: found in mucosal surfaces, protects against infections
      • IgD: found on surface of mature B lymphocytes, activates B lymphocyte activation
    • Antigen Presentation
      • Antigens are processed and presented to T lymphocytes by antigen-presenting cells (APCs)
      • APCs include dendritic cells, macrophages, and B lymphocytes

    MHC and Immune Response

    • MHC Class I
      • Found on surface of all nucleated cells
      • Presents endogenous antigens (viral proteins, tumor antigens) to CD8+ T lymphocytes
    • MHC Class II
      • Found on surface of APCs (dendritic cells, macrophages, B lymphocytes)
      • Presents exogenous antigens (bacterial proteins, toxins) to CD4+ T lymphocytes
    • MHC Products
      • HLA-A, HLA-B, HLA-C: Class I MHC products
      • HLA-DP, HLA-DQ, HLA-DR: Class II MHC products

    Immune Disorders

    • Autoimmune Diseases
      • Result from failure of self-tolerance, immune system attacks self-antigens
      • Examples: type I insulin-dependent diabetes mellitus, rheumatoid arthritis, lupus
    • Immunodeficiency Diseases
      • Result from defects in immune system, increased susceptibility to infections
      • Examples: HIV/AIDS, DiGeorge syndrome, severe combined immunodeficiency (SCID)

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