SBI241 Week 2 - Inflammation and the Immune System

What is the normal body flora and what benefits does it provide?

Beneficial microbes present in the body

What are opportunistic infections?

Infections that occur when the body's defenses are weakened

What is the normal body flora and what benefits does it provide?

Beneficial microbes present in the body

What are opportunistic infections?

Infections that occur when the body's defenses are weakened

Define pathogens

Microorganisms capable of causing disease

What are the classes of microorganisms?

Bacteria, viruses, fungi, protozoa, and parasitic worms

What are the different ways an infection can spread?

Direct, droplet, indirect, airborne/aerosol, vector-dependent, and fecal-oral

What factors contribute to infection?

Mechanism of action, infectivity, pathogenicity, virulence, immunogenicity, and toxigenicity

What are the host defenses against invading organisms?

Intact skin and mucous membranes, innate immunity, and acquired immunity

What are the classes of infectious microorganisms?

Viruses, bacteria, fungi, protozoa, rickettsiae, chlamydiae, helminths, and mycoplasmas

Describe the Gram staining procedure:

A dye colors all bacteria purple. Alcohol washes off the purple from some bacteria, while others retain the color. A red counterstain colors gram-negative bacteria red.

What is the significance of peptidoglycan in bacteria?

Peptidoglycan defines bacteria: Gram-positive = thick layer; Gram-negative = thin layer + outer membrane

What are exotoxins?

Enzymes released during bacterial growth that damage cell membranes and inhibit protein synthesis

What are endotoxins?

Lipopolysaccharides from the outer membrane of dead gram-negative bacteria, released during cell lysis, causing pyrogenic effects and septic shock

What is the difference between septicaemia and bacteraemia?

Septicaemia is the presence of microorganisms in the blood, while bacteraemia is the presence of bacteria in the blood

Describe gram-negative septic shock:

Endotoxins release vasoactive peptides and cytokines that affect blood vessels, causing vasodilation, reduced blood pressure, and decreased oxygen delivery

What are viruses?

Obligate intracellular parasites dependent on host cells for replication

How do viruses infect host cells?

A virion binds to receptors on the plasma membrane, alters the host cell's activity, and causes viral replication

What are some effects of viral infections on host cells?

Inhibition of host cell DNA/RNA/protein synthesis, disruption of lysosomal membranes, promotion of apoptosis, fusion of host cells, alteration of antigenic properties, transformation into cancerous cells, and promotion of secondary bacterial infections

What are fungi?

Large eukaryotic microorganisms with thick cell walls lacking peptidoglycan

What are mycoses?

Diseases caused by fungi, classified as superficial, deep, or opportunistic

What are dermatophytes?

Fungi that invade the skin, hair, or nails, causing tineas (ringworm)

Examples of laboratory diagnostics for Bacteria:

Culture, Gram stain, sensitivity testing

Examples of laboratory diagnostics for Viruses

Immuno-fluorescence, serology, cell cultures

Examples of laboratory diagnostics for Fungi

Microscopy

How can Infections be prevented?

Good hygiene, like hand washing, isolation, and quarantine

What are vaccines intended to do?

Induce long-lasting protective immune responses without causing disease in a healthy recipient

Examples of antimicrobials:

Antivirals, antibacterials, Fungicidal drugs, Antiparasitic drugs

What do antimicrobials do?

Inhibit synthesis of cell wall, Inhibit synthesis of nucleic acids, Inhibit protein synthesis, and Modify metabolism

Examples of Antimicrobial resistance

Inactivation of the drug, Reduced membrane permeability, Alteration of the drug target, and Active efflux of the antimicrobial drug

What are healthcare-acquired infections?

Infections that are acquired by individuals during a stay in a healthcare setting

What is a pandemic?

A disease that spreads rapidly and widely throughout the world

What are the roles of the microorganisms that make up the normal human flora?

Preventing colonisation of pathogens

What is the potency of a pathogen measured in terms of the number of microorganisms required to kill a host?

Virulence

A patient is infected by a microorganism that is motile. What microbe is it?

Bacterium

How do some bacterial pathogens defend themselves from an immune response?

Producing capsules

A 5-year-old male becomes ill with a severe cough. Histological examination reveals a bacterial infection and further laboratory testing reveals cell membrane damage and decreased protein synthesis. What is the most likely cause?

Exotoxin

Endotoxins are produced by _____ and are made of ______:

Gram-negative bacteria, lipopolysaccharide

What is a characteristic of viruses?

Replicate their genetic material inside host cells

What is a common symptom of individuals with immunodeficiency?

Recurrent infections

A 30-year-old female complains of fatigue, arthritis, rash and changes in urine colour. Laboratory testing reveals anaemia, lymphopenia and kidney inflammation. Assuming a diagnosis of SLE, which of the following is also likely to be present?

Autoantibodies

A 10-year-old male is stung by a bee and develops itching, pain, swelling, redness, low blood pressure and respiratory difficulties. What is he suffering from?

Anaphylaxis

What is a purpose of the inflammatory process?

To prevent infection of injured tissue

A child fell off a swing and scraped her knee. The injured area becomes red and painful. What would also occur?

Fluid movement from vessels to tissues

The mast cell, a major activator of inflammation, initiates the inflammatory response through what process?

Degranulation

A 20-year-old apprentice shoots their hand with a nail gun. Which cell type would be the first to aid in killing bacteria to prevent infection?

Neutrophils

What is phagocytosis?

The ingestion of large particles

A 10-year-old male is diagnosed with a large tapeworm. Which cells would be produced in response?

Eosinophils

What is the directional movement of cells in response to a chemical gradient called?

Chemotaxis

Histamine is released from what cells?

Mast cells

Leukotrienes differ from histamine in which of the following ways?

They have a later and prolonged response

What is the end product of the clotting system?

Fibrin

Opsonins are molecules that:

Enhance phagocytosis

A 30-year-old male was involved in a motor vehicle accident. The scar was raised and extended beyond the original boundaries of the wound. What is the cause of this pattern of scarring?

Impaired collagen synthesis

Pathogenicity

Ability of a pathogen to cause disease

Virulence

Severity/Harmfulness of a disease

Immunogenicity

Ability to cause an immune response

Toxigenicity

Ability to produce toxins that cause disease

What is the toilet plume?

Viral aerosols from toilet flushing

How are Hospital Acquired Infections (Nosocomial) transmitted?

Transmission of infection from healthcare workers to patients, patient to patient, doctor to visitor and vice versa, visitor to patient and vice versa

How can we Classify Bacteria by Shape?

Coccus, bacillus, vibrio, spirillum, spirochete, fusiform and coccobacillus

What substances are used to classify bacteria by gram staining?

Crystal violet, iodine, 95% ethyl alcohol, and safranin

The Gram stain is based on the amount of what in the Bacterium?

Peptidoglycan

What Antibiotics interfere with Cell Wall Synthesis?

Beta Lactams, Penicillins, Cephalosporins, Carbapenems, Monobactams, Vancomycin, and Bacitracin

What Antibiotics interfere with the Cell Membrane?

Polymyxins

What Antibiotics interfere with Folate synthesis?

Sulfonamides and Trimethoprim

What Antibiotics interfere with Nucleic Acid Synthesis?

Quinolones and Rifampin

What Antibiotics interfere with the 50S subunit of Protein Synthesis?

Macrolides, Clindamycin, Linezolid, Chloramphenicol, and Streptogramins

What Antibiotics interfere with the 30S subunit of Protein Synthesis?

Tetracyclines and Aminoglycosides

What is Sepsis?

The body’s extreme reaction to an infection

What is Septic Shock?

the last stage of sepsis

How are viruses classified?

Classified by their genome (DNA and RNA) and Shape

What are the steps in Virus Replication?

Virus becomes attached to a cell, the cell engulfs the virus, viral genetic materials are released and replication begins, the cell replicates viral proteins, new viral particles are released

How do we treat viral infections?

Antiviral drugs target specific life cycle stages

Can antibiotics be used to treat virus infections?

No

What are the Host Defenses?

Intact skin and mucous membranes, innate immunity, and acquired immunity

What are the Components of the Immune system?

The lymphatic system, the circulatory system, lymphocytes, phagocytic cells, dendritic cells, thrombocytes, and complement proteins

What are the Types of immunity?

Non-specific (or innate) and Specific (or acquired/adaptive)

What are the Cellular Components of the Immune system?

Lymph nodes, Mucosa, Thymus, Bone marrow

What are the steps in Phagocytosis?

Chemotaxis and adherence of microbe to phagocyte, Ingestion of microbe by phagocyte, Formation of a phagosome, Fusion of the phagosome with a lysosome to form a phagolysosome, Digestion of ingested microbe by enzymes, Formation of residual body containing indigestible material, Discharge of waste materials

Acquired Immunity

Produced by prior exposure or antibody production

Innate Immunity

Genetically determined. No prior exposure or antibody production involved

Active Immunity

Produced by antibodies that develop in response to antigens (Immune response)

Passive Immunity

Produced by transfer of antibodies from another person

Cell-Mediated Immunity

Involves direct physical and chemical attack

Antibody-Mediated Immunity

Attack by antibodies

How does the body defend against bacteria?

All of the above

How does the body defend against viruses?

All of the above

What is the purpose of inflammation?

All of the above

What are the Characteristic changes during Inflammation?

All of the above

What processes occur during Inflammation?

All of the above

What are Mast Cells?

All of the above

How do Immunoglobulins act?

All of the above

What do B Cells Make?

Make antibodies

What are Neutrophils?

White cells which are the major defense against bacterial infections

Neutrophils enter the tissues by what multi-step process:

All of the above

What are the general steps in Phagocytosis?

Adherence, Engulfment, Phagosome formation, Fusion with lysosomal granules, Digestion and Expulsion

What is neutrophil opsonization?

Complement-mediated microbial tagging and destruction

What is Melioidosis?

A bacterial infection caused by B. pseudomallei

What are some of the clinical presentations of Meliodosis?

Brain infection, Lymph nodes enlargement, Muscle cramps, Septic shock, Pneumonia, Pericarditis

Innate Immune Response

Fast response (0-4 hours)

Adaptive Immune Response

Slow response (4-14 days)