Immunology and Pathogens Quiz

Immune System Overview

• The immune system is a complex network of organs, cells, and proteins that works to defend the body against pathogens.
• This system has two main branches: innate immunity and adaptive immunity.
• Innate immunity provides a rapid, non-specific defense against a broad range of pathogens.
• Adaptive immunity is more specific, targeting particular pathogens and developing memory for future encounters.

Host-Pathogen Interactions

• Pathogenicity is the ability of a microorganism to cause disease.
• Virulence is a quantitative measure of a pathogen's ability to cause disease.
• Factors influence virulence: Adhesion factors, exoenzymes, toxins, and metabolic pathways.

Mechanisms of Pathogenicity

• Virulence factors can contribute to a pathogen's ability to adhere to host cells or tissues.
• Some pathogens produce exoenzymes and/or toxins that help them invade tissues, evade host defenses, or cause damage to cells/tissues.
• Exotoxins are proteins that are secreted by microorganisms into their surroundings.
• Endotoxins are part of the outer membrane of Gram-negative bacteria, released when the cell dies or breaks apart.
• Factors like the number of infecting organisms, the nature of the wound, and the host's immune status can influence the severity of a wound infection and pathogenicity.

Types of Immunity

• Natural immunity—acquired through the normal life experiences of humans.
• Active immunity—produced when a person develops his/her own immune response to a microbe.
• Passive immunity—occurs when a person receives preformed immunity made by another person.
• Artificial immunity—produced through medical procedures.

Specific/Adaptive Immunity

• Pathogens/microbes have a wide range of shapes/structures that the immune system must learn to recognize.
• Adaptive immunity recognizes specific antigens.
• A division of labor, between T and B cells, occurs in the bone marrow and thymus, respectively.
• T cells recognize processed antigen on antigen presenting cells (APCs).
• T cells can be differentiated into Helper T cells or Cytotoxic T cells.
• B cells make antibodies in response to an antigen, and also differentiate into plasma cells and memory B cells.

Infectious Diseases

• Infection - colonization of the host by microorganisms.
• Not all infections lead to noticeable adverse effects.
• Infectious Disease—infection resulting in disease.
• Disease—deviation from normal health, often due to damage or injury by the microbe or its products.

Categories of Skin Infections

• Diphtheroids
• Staphylococcal infections
• Fungi (Yeast)

Staphylococcus aureus Infections

• Common skin pathogen.
• Significant cause of wound infections.
• Transmission occurs from person to person/fomites
• Characteristic of being able to produce pus and have certain toxins e.g., coagulase, clumping factor, protein A, toxin.
• Community and Hospital-acquired infections are distinguished by how they are acquired.

Staphylococcus epidermidis Infections

• Maintain themselves on skin and are not extremely invasive, but can cause infections and biofilm formation.

Group A Streptococcal Infections (GAS)

• Most common bacterial cause of pyoderma infections.
• Causes an array of infections/diseases ranging from mild to life threatening.
• Common symptoms include throat infections and skin infections.

Pseudomonas aeruginosa Infections

• Opportunistic pathogen, often associated with hospitals
• Causes infections in individuals with compromised immune systems.
• Symptoms can include a systemic inflammatory response as well as discoloration/changes in skin and tissues.

Bacterial Pneumonia

• Bacterial infection of the lungs.
• Usually involves several bacteria.
• Pneumococcal—caused by Streptococcus pneumoniae.
• Klebsiella—caused by Klebsiella pneumoniae. Mycoplasma—caused by Mycoplasma pneumoniae.

Common Cold

• Caused by rhinoviruses.
• Symptoms are usually mild: scratchy throat, runny nose, and slight cough.
• Not typically a serious infection treated by antibiotic therapy. Viral infections typically go away on their own.

Diphtheria

• Caused by Corynebacterium diphtheria.
• Characterized by a thick, whitish film in the throat.
• Can lead to heart and nervous system issues (toxin).

Pertussis

• Caused by Bordetella pertussis.
• Typically impacts parts of upper respiratory tract.
• Results in excessive coughing and other respiratory issues.

Streptococcal Pharyngitis

• Caused by Streptococcus pyogenes.
• Bacterial infection characterized by throat soreness and difficulty swallowing.
• The bacterium is highly contagious.
• Can lead to serious complications such as rheumatic fever or glomerulonephritis.

Herpes Simplex

• Caused by human herpesvirus type 1 (HSV-1) or 2 (HSV-2).
• HSV-1 causes cold sores around the mouth.
• HSV-2 can cause genital sores.
• Both viruses can lay dormant, and reactivate later on.

Chickenpox

• Caused by the varicella-zoster virus.
• Characterized by a rash that spreads to the body.
• Often contracted during childhood and generally clears up without serious issues.

Shingles

• Reactivation of the varicella-zoster virus.
• Primarily impacts one side of the body.
• Characterized by an intense eruption of rash and blistering.
• This virus remains dormant and can reactivate later in life.

Viral Infections Overview

• Diseases caused by viral infections are diverse.
• A wide variety of symptoms can result from viral infections.
• Prevention methods often focus on vaccines and hygiene.

Additional Notes

• A specific list of characteristics of any particular bacteria or virus isn't included in these notes.