Respiratory Immunity and Clinical Microbiology Insights

Role of the Mucous Membrane in the Respiratory Tract

Describe the role of the mucous membrane in the respiratory tract:

• Mucociliary escalator:

  The mucus layer is moved by cilia to trap microorganisms and transport them to the throat to be expelled.

• Goblet cells:

  Goblet cells in the mucous membrane produce mucus. They are scattered throughout the membrane and resemble a goblet or wine glass.

• Protection:

  Protects the lower respiratory tract.

Why We Cannot Cure the Common Cold

Why cant we treat the common cold? (Two questions: why is it not possible to find a cure? And why can it not be treated with antibiotics?)

• Viruses cannot be treated with antibiotics.

• Vaccine development challenges: It is difficult to make a broadly effective vaccine because there are too many strains of rhinovirus.

  • Supportive treatments: Analgesics and antipyretics.

Why Penicillin Fails Against Mycoplasma pneumoniae

• Reason: All mycoplasmas lack a cell wall and, therefore, are inherently resistant to beta-lactam antibiotics (e.g., penicillin).

Development of an Abscess

Explain the development of an abscess:

• Describe the whole process of inflammation. There's a cut or a wound. That causes blood vessels to bring blood with neutrophils and macrophages causing phagocytosis. Then as a part of the immune system's reaction there will be dead cells with dead neutrophils and dead bacteria. They will collect as pus. Then there is swelling due to fluid retention and pain.

  • Localized collection: Localized collection of pus surrounded by inflamed body tissue.

  • Cause: Occurs because of the body's immune defenses and usually indicates an infection.

  • Function: Helps localize infection and prevent the spread.

  • Clinical significance: Indicates a serious situation 0 if microbial cells escape, they can enter the blood or lymph leading to infection in other parts of the body.

Causative Agent and Pathogenesis of Dental Caries

• S. mutans: S. mutans is cariogenic gram-positive cocci that live on teeth.

• Adhesion and plaque: Streptococci adhere to the pellicle (the protein film that attaches to tooth enamel) to create dental plaque.

Difference Between Enterotoxin and Cytotoxin

• Enterotoxin: Affects/damages the intestinal lining.

• Cytotoxin: Affects/damages general cells.

Preventive Measures for Listeriosis

• Prevention:

  • Thoroughly cook poultry, pork, beef, and other meats.

  • Avoid cross-contamination by:

    • Not placing uncooked meats with other foods.

    • Cleaning countertops and utensils.

    • Washing raw fruits and vegetables.

Bacteremia Versus Septicemia and Sepsis

• Bacteremia: Bacteria present in the blood.

• Septicemia: Presence of pathogens and their toxins in the blood; often involves endotoxins. Sepsis refers to the life-threatening organ dysfunction caused by a dysregulated host response to infection.

Difference Among HIV, HIV Disease, and AIDS

• HIV: The causative agent; human immunodeficiency virus.

• HIV disease: When a person is infected by the virus and begins showing signs and symptoms.

• AIDS: The end stage of HIV infection where a person's immune system is compromised; as a result, the person will suffer from other illnesses such as cancers, tuberculosis, bacterial, fungal, and viral infections, etc.

Three Important Enzymes Involved in HIV Replication

• Reverse transcriptase

• Protease

• Integrase