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:

CMV and hepatitis B virus Signup and view all the answers

Gastroenteritis is not caused by:

Enteroviruses Signup and view all the answers

Chronic carrier state does not persist after infection with:

Hepatitis A and hepatitis E Signup and view all the answers

Respiratory transmission occurs with:

Correct answers are a and c Signup and view all the answers

Viruses with negative RNA are:

Picornaviruses and rhabdoviruses Signup and view all the answers

Hepatitis C infection:

All of the provided answers are correct Signup and view all the answers

Measles virus:

Undergoes antigenic drift and antigenic shift Signup and view all the answers

What are CD4+ lymphocytes?

T helper lymphocytes Signup and view all the answers

What are CD8+ lymphocytes?

T cytotoxic lymphocytes Signup and view all the answers

Lifespan is measured in years for which type of cell?

B lymphocytes Signup and view all the answers

IgE binds to mast cells via which component?

Fc fragment Signup and view all the answers

Which immunoglobulin passes through the placenta?

IgG Signup and view all the answers

Thymus-independent antigens induce which type of immunoglobulin production?

IgM Signup and view all the answers

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

induce the formation of memory B lymphocytes Signup and view all the answers

Meningococcus most commonly reaches the central nervous system through:

blood Signup and view all the answers

Erysipelothrix rhusiopathiae is the causative agent of:

erysipeloid Signup and view all the answers

M.leprae can proliferate in:

armadillos Signup and view all the answers

Rickettsiae are the causative agents of:

typhus fever Signup and view all the answers

Which of the following statements about chlamydiae is incorrect?

they independently synthesize sufficient ATP Signup and view all the answers

Chlamydia trachomatis includes:

over 80 serotypes Signup and view all the answers

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

ciliary activity Signup and view all the answers

The family Mycoplasmataceae does not include:

the genus Mycobacterium Signup and view all the answers

Microscopically, B.anthracis appears as:

Arabic letters Signup and view all the answers

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

Streptococcus pneumoniae Signup and view all the answers

Virulence is:

the degree of pathogenicity Signup and view all the answers

Endotoxins:

are found in the cell wall of bacteria Signup and view all the answers

UV radiation is used in medicine for:

sterilization Signup and view all the answers

What is virulence?

The degree of pathogenicity Signup and view all the answers

Where are endotoxins found?

Found in the cell wall of bacteria Signup and view all the answers

How is UV radiation used in medicine?

As a method of sterilization Signup and view all the answers

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

Spore Signup and view all the answers

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

Flagella Signup and view all the answers

In an autoclave, what is the method of sterilization?

Moist heat Signup and view all the answers

What is examined using an antibiogram?

The sensitivity of bacteria to antibiotics Signup and view all the answers

How do bacteria divide?

Binary fission Signup and view all the answers

What is symbiosis?

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

What category do bacteria fall into, clinically speaking?

Extracellular parasites Signup and view all the answers

Enveloped viruses include:

all icosahedral and some spherical viruses Signup and view all the answers

Viruses are primarily classified into several large groups based on:

nucleic acid characteristics Signup and view all the answers

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

density gradient Signup and view all the answers

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

normal bacterial flora of the digestive tract Signup and view all the answers

Endotoxin is released during:

lysis of Gram-negative bacteria Signup and view all the answers

Neisseria gonorrhoeae is a bacterium that causes:

gonorrhea Signup and view all the answers

Gonococcal infection elicits a more severe clinical reaction:

in women Signup and view all the answers

The evasion phenomenon is described in gonococci and represents:

evasion of gonococci from polymorphonuclear leukocytes during phagocytosis Signup and view all the answers

In a direct Gram stain preparation, meningococci and gonococci:

can be differentiated 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:

6-8 weeks Signup and view all the answers

Koch's bacillus can survive in dust for:

several years Signup and view all the answers

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

Coagulase Signup and view all the answers

Staphylococcus epidermidis is:

conditionally pathogenic bacterial species Signup and view all the answers

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

urinary tract Signup and view all the answers

Choose the correct sentence:

the main reservoir of group B streptococcus (Streptococcus agalactiae) is the vaginal mucosa 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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Description

Test your knowledge of microbiology concepts, including virulence, endotoxins, and UV radiation. Answer questions about the characteristics of microorganisms and their effects on the body.