Human Microbiology and Infections Quiz
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Questions and Answers

What is the primary cause of oral thrush and vaginitis?

  • Pediculus humanus capitis
  • Sarcoptes scabiei
  • Candida albicans (correct)
  • Sporothrix schenckii

    • Which condition results from a soil fungus penetrating the skin through a wound?

  • Sporotrichosis (correct)
  • Conjunctivitis
  • Madura foot
  • Chromoblastomycosis

    • Which of the following is characterized by verrucoid lesions on the skin?

  • Chromoblastomycosis (correct)
  • Oral thrush
  • Scabies
  • Pediculosis

    • What is the main treatment for Scabies?

    <p>Topical permethrin</p> Signup and view all the answers

    How is Pediculosis primarily transmitted?

    <p>Head-to-head contact</p> Signup and view all the answers

    What causes inflammation of the conjunctiva, known as conjunctivitis?

    <p>Allergic reactions</p> Signup and view all the answers

    Which organism is responsible for causing Scabies?

    <p>Sarcoptes scabiei</p> Signup and view all the answers

    What is the primary type of infection associated with Madura foot?

    <p>Bacterial and fungal</p> Signup and view all the answers

    What is a primary function of the normal microbiota in the human digestive system?

    <p>To prevent the growth of pathogenic microorganisms</p> Signup and view all the answers

    Which anatomical feature is NOT part of the human digestive system?

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

    How do microorganisms typically overcome the defenses of the digestive tract?

    <p>By forming protective biofilms</p> Signup and view all the answers

    What is a common sign associated with gastrointestinal infections?

    <p>Abdominal pain</p> Signup and view all the answers

    Which of the following is not considered a factor in how microorganisms infect the digestive system?

    <p>Absorption of anti-inflammatory drugs</p> Signup and view all the answers

    What disease is characterized by oral and pharyngeal ulcerations along with a vesicular rash on the palms and soles?

    <p>Hand-foot-and-mouth disease</p> Signup and view all the answers

    Which statement correctly describes pleurodynia?

    <p>It is typically characterized by sudden chest pain.</p> Signup and view all the answers

    Which condition is described as a severe disease in infants resulting from simultaneous viral infections of multiple organs?

    <p>Generalized disease of infants</p> Signup and view all the answers

    What is a notable feature of foot-and-mouth disease in humans?

    <p>It causes fever and vesiculation of mucous membranes.</p> Signup and view all the answers

    Which virus family is associated with gastroenteritis in humans?

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

    The Astroviridae family contains viruses that are primarily linked to which type of illness?

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

    What is the primary mode of transmission for astroviruses?

    <p>Fecal-oral route</p> Signup and view all the answers

    Which of the following best defines myocarditis?

    <p>Acute inflammation of heart tissues</p> Signup and view all the answers

    Study Notes

    Virology

    • Virology is the study of viruses
    • Viruses are infectious agents with both living and non-living characteristics.
    • Living characteristics:
      • Reproduce at a rapid rate only inside living host cells
      • Can mutate
    • Non-living characteristics:
      • Acellular (lacking cytoplasm, cell membrane, and cellular organelles)
      • Cannot metabolize on their own
      • Possess DNA or RNA, but never both
    • Viral Structure:
      • Genome: nucleic acid (DNA or RNA) that carries genetic information
      • Capsid: protein coat that protects the genome
      • Envelope: some viruses have an outer lipid layer derived from the host cell's membrane

    Viral Structure (1. Genome)

    • Molecule of nucleic acid that functions as the genetic material of the virus.
    • Codes for the synthesis of viral components and viral enzymes for replication.
    • Can be single or segmented
    • Can be circular or linear
    • Can be single-stranded or double-stranded
    • Contains DNA or RNA, but never both

    Viral Structure (2. Capsid)

    • Also known as the protein coat or core.
    • A protein shell surrounding the genome.
    • Composed of protein subunits called capsomeres.
    • Protects the genome and introduces it into host cells.
    • Some viruses consist of no more than the genome surrounded by the capsid, and these are called nucleocapsid or naked viruses.
    • Attachment proteins (spikes) project from the capsid and bind the virus to susceptible host cells.

    Viral Structure (3. Envelope)

    • Enveloped viruses have an envelope surrounding a polyhedral or helical nucleocapsid.
    • The envelope is composed of phospholipids and glycoproteins.
    • These are derived from the host cell membrane through a process called budding.

    Host Range

    • Host range refers to the spectrum of host cells in which a virus can multiply.
    • Most viruses infect only specific types of cells in one host species.
    • Host range is determined by the specific attachment site of the virus on the host cell's surface, and the availability of host cellular factors.

    Viral Size

    • Viral size is measured by electron microscopy.
    • Viruses range from 20 to 14,000 nanometers in length.

    Classification of Viruses

    • Classified by these characteristics:
      • Type of nucleic acid (DNA or RNA) for the genome
      • Shape of the capsid (helical or polyhedral)
      • Whether they are enveloped or naked (lack an envelope)
    • Helical viruses resemble long rods, with capsids that are hollow cylinders surrounding the nucleic acid.
    • Polyhedral viruses have many sides, and their capsids are often icosahedrons.
    • Enveloped viruses are roughly spherical but highly pleomorphic.
    • Complex viruses have complex structures (e.g., many bacteriophages have a polyhedral capsid with a helical tail attached).
    • Viruses can store their genetic information in six different types of nucleic acid which are named based on how that nucleic acid eventually forms the viral mRNA able to bind to host cell ribosomes and be translated into viral proteins

    Stages of Viral Replication

    • Adsorption or Attachment:

      • Process in which the virus adheres to the host cell surface
      • The process is selective, depending on host cell receptors and viral surface anti-receptors.

    • Penetration:

      • Also referred to as viral entry
      • Follows attachment and happens almost instantaneously the moment the virus attaches to the cell
      • Three types: viral translocation across the plasma membrane; endocytosis; and membrane fusion

    • Uncoating

      • Happens after viral entry wherein the capsid protecting the viral genome is removed.
      • Removed through enzymatic degradation, whether viral enzymes or host enzymes, or through simple dissociation.
      • Releases the genetic material of the virus.

    • Synthesis

      • After the genome is released, viral parts are now synthesized from the genome.
      • The first step is replication of the mRNA (except for (+)RNA viruses).
      • The viral mRNA is then used to synthesize the necessary different proteins needed by the virus.

    • Assembly:

      • Step after synthesis of viral parts
      • All the viral needed components to complete a virion are assembled

    • Release:

      • Viruses are released by cell lysis (lytic cycle).
      • If enveloped, release occurs by budding.

    • Lysogenic cycle:

      • Some viruses have a lysogenic cycle where the viral genome integrates into the host cell's chromosome and becomes a provirus (or prophage).
      • The cell replicates the viral genome until such time the virus will be synthesized and the cell becomes lysed.

    Isolation, Cultivation, and Identification of Viruses

    • Viruses must be grown in living cells
    • Bacteriophages are the easiest viruses to cultivate.

    Taxonomy of Viruses

    • Classification of viruses is based on type of nucleic acid, morphological class, and presence or absence of an envelope.
    • Virus family names end in -viridae; genus end in -virus.
    • A viral species is a group of viruses sharing the same genetic information and ecological niche.

    Medically Important DNA Viruses

    • Herpesviridae:
      • Herpes simplex virus 1 and 2 (HSV-1 and HSV-2): oral and genital lesions
      • Varicella-zoster virus (VZV): chicken pox, shingles
      • Epstein-Barr virus: infectious mononucleosis
      • Cytomegalovirus is a virus that causes a cytomegalic inclusion disease

    Medically Important RNA Viruses

    • Picornaviridae:

      • Rhinovirus: common colds
      • Hepatitis A virus (HAV)

    • Togaviridae:

      • Rubella virus: German measles

    • Other viruses that are included as well are:

      • Parvoviridae, Papovaviridae, Poxviridae, Hepadnaviridae

    Viral Families

    • RNA viruses:

      • Picornaviridae
      • Reoviridae
      • Astroviridae
      • Arenaviridae
      • Flaviviridae
      • Filoviridae
      • Orthomyxoviridae
      • Retroviridae

    • DNA viruses:

      • Hepadnaviridae
      • Herpesviridae
      • Adenoviridae
      • Poxviridae
      • Papovaviridae
      • Parvoviridae

    Antiviral Drugs

    • Nucleoside Reverse Transcriptase Inhibitors (NRTIs)
    • Protease Inhibitors (PIs)
    • DNA Polymerase Inhibitors
    • Interferons
    • Other classes: entry inhibitors, fusion inhibitors, integrase inhibitors

    COVID-19 (SARS-CoV-2)

    • Characteristics

      • Virus
      • RNA
      • Enveloped

    • Transmission

      • Respiratory droplets and aerosols
      • Direct contact with eyes, nose, and mouth
      • Transmission from infected people is maximum just before symptoms occur, and during the early phase of infection

    • Symptoms

      • Fever or chills
      • Cough
      • Shortness of breath or difficulty breathing
      • Fatigue
      • Muscle or body aches
      • Headache
      • New loss of taste or smell
      • Sore throat
      • Congestion or runny nose
      • Nausea or vomiting
      • Diarrhea

    • Diagnosis

      • RT-PCR (reverse transcription polymerase chain reaction).

    • Management

      • Vaccination

    • Comorbidities

      • CA
      • Cerebrovascular disease
      • CKD
      • COPD
      • DM
      • Heart conditions
      • Immunocompromised state from solid organ transplant
      • Obesity
      • Pregnancy
      • Smoking (current or former)

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    Related Documents

    Virology Past Paper PDF - Our Lady of Fatima University

    Description

    Test your knowledge on various human microbiology topics, including infections, their causes, and treatments. This quiz covers questions related to oral thrush, scabies, and the roles of microorganisms in the digestive system.

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