Ch15 : Microbial Mechanisms of Pathogenicity Flashcards

Flashcards about Microbial Mechanisms of Pathogenicity

What is a Disease?

Any condition that damages or impairs the normal structure or function of the body.

What is an Infection?

Successful colonization of a host by a microorganism, involving the entry and growth of microbes.

What are Signs in the context of disease?

Objective and measurable by a clinician (e.g., body temperature, heart rate, blood pressure).

What are Symptoms in the context of disease?

Subjective experiences reported by the patient and cannot be directly measured (e.g., nausea, pain, loss of appetite).

What is a Syndrome?

Specific group of signs and symptoms that characterize a particular disease.

What is an Infectious Disease?

Caused by the direct effect of a pathogen, including cellular (bacteria, parasites, fungi) and acellular (viruses, viroids, prions) pathogens.

What are Communicable Diseases?

Spread from person to person.

What are Contagious Diseases?

Easily spread from person to person (a subset of communicable diseases).

What are Iatrogenic Diseases?

Result from medical procedures (e.g., necrotizing fasciitis from contaminated wound dressings).

What are Nosocomial Diseases?

Acquired in hospital settings, influenced by factors like pathogen presence, immunocompromised patients, and poor hygiene.

What are Zoonotic Diseases?

Transmitted from animals to humans (e.g., rabies, yellow fever).

What are Non-Communicable Infectious Diseases?

Not spread between people.

What are Noninfectious Diseases?

Not caused by pathogens; can be due to genetics, environmental factors, or immune system disorders.

What is the Incubation Stage of disease?

Time between pathogen entry and the appearance of symptoms.

What is the Prodromal Stage of disease?

Early stage where general symptoms begin to appear.

What is the Illness Stage of disease?

Disease symptoms are most severe and specific.

What is the Decline Stage of disease?

Symptoms and pathogen numbers start to decrease.

What is the Convalescence Stage of disease?

Recovery and return to normal function.

What are Acute Diseases?

Develop rapidly and last for a short time.

What are Chronic Diseases?

Develop slowly and persist for a long time, possibly life long.

What are Latent Diseases?

Pathogen remains inactive (dormant) in the host after an initial infection, with the potential to reactivate.

What are Koch's Postulates?

Robert Koch's set of four criteria to identify the causative agent of a particular disease.

What is the first point of Koch’s Postulates?

The microorganism must be found in all organisms suffering from the disease, but not in healthy organisms.

What is the second point of Koch’s Postulates?

The microorganism is isolated from an infected individual and grown in a pure culture.

What is the third point of Koch’s Postulates?

The same microorganism should reproduce the original disease when introduced into a healthy organism.

What is the fourth point of Koch’s Postulates?

The microorganism is re-isolated from the newly diseased host and confirmed to be the same as the first isolate.

What are Molecular Koch’s Postulates?

A revised form of Koch’s postulates focusing on specific genes that make a microbe harmful (pathogenic).

What is Pathogenicity?

Ability of a microbe to cause disease.

What is Virulence?

How strong or harmful a microbe is, indicated by ID50 (Infectious Dose 50) and LD50 (Lethal Dose 50).

What is Infectious Dose 50 (ID50)?

Number of microbes needed to infect 50% of a group of test subjects.

What is Lethal Dose 50 (LD50)?

Amount of a toxin, drug, or pathogen that will kill 50% of a group of test subjects.

What are Opportunistic Infections?

Occur when normal defenses of the body are weakened, often due to a weakened immune system, chronic illness, or use of antibiotics.

What is Pathogenesis?

Process by which a disease develops in the body.

What is Exposure (Contact) in relation to Pathogenesis?

The pathogen must come into contact with the host.

What is Adhesion in relation to Pathogenesis?

The pathogen attaches to host cells, usually using special structures or proteins.

What is Invasion in relation to Pathogenesis?

The pathogen enters deeper into tissues, often through cuts or mucous membranes, using exoenzymes or invasive toxins.

What is Infection in relation to Pathogenesis?

The pathogen grows and spreads inside the host, avoiding or fighting the immune system, causing tissue damage and symptoms.

What is the Mucous membranes route of entry?

Respiratory, Digestive, or Genital/urinary tracts.

What is the Skin route of entry?

Cuts, insect bites, and burns.

What is the Parenteral route of entry?

Direct entry through injection, puncture, or wound.

What is the placenta route of entry?

Some microbes can cross the placenta during pregnancy and harm the fetus.

What is the birth canal route of entry?

Newborns can get infections during delivery.

What are Adhesins?

Special molecules (proteins or sugars) on the surface of pathogens that bind to receptors of host cells.

What are Glycocalyces?

Sticky layers around some bacteria that helps them attach to surfaces and cells.

What are Biofilms?

Communities of bacteria that stick together and to surfaces using a sugary coating called EPS (extrapolymeric substance).

What are Extracellular Pathogens?

Invade tissues using enzymes and toxins.

What are Exoenzymes?

Break down tissue barriers.

What are Toxins?

Damage host cells and help the pathogen move through the body.

What are Virulence factors?

Protect the pathogen from the immune system.

What are Intracellular Pathogens?

Invade by entering the host’s cells and reproducing.

What are Obligate intracellular pathogens?

Must live and reproduce inside cells.

What are Facultative intracellular pathogens?

Can live inside or outside cells.

What is Phagocytosis?

Phagocytes engulf pathogens to destroy them.

What is a Local infection?

Stays in one small area, near the entry point.

What is a Focal infection?

Stays in one place but spread (or its toxins spread) to another part of the body.

What is a Systemic infection?

Spreads throughout the whole body.

What is a Portal of Exit?

The place where a pathogen leaves the body.

What is a Virulence Factor?

Produced by individual pathogens, determining the extent and severity of disease.

What does Hyaluronidase do?

Breaks apart the glue between cells, allowing bacteria to slip through tissues.

What does DNase do?

Cuts up DNA from burst cells (or immune traps) so the bacteria can escape and spread.

What does Phospholipase do?

Destroys cell membranes, helping some bacteria escape the phagosome.

What does Collagenase do?

Destroys collagen, letting pathogens tunnel deeper into tissues.

What is Toxigenicity?

The ability of a pathogen to produce toxins to cause damage to host cells.

What are Endotoxins?

Found in the outer membrane of gram-negative bacteria, released upon cell death, triggers the immune system, can lead to septic shock.

What are Exotoxins?

Produced by living bacteria (mainly gram-positive), very potent, heat-sensitive proteins that can kill in tiny amounts.

What does the A (Active) component of A-B exotoxins do?

Disrupts a vital function inside the host cell.

What does the B (Binding) component of A-B exotoxins do?

Attaches to a specific receptor on the host cell surface.

What are Membrane-Disrupting Toxins?

Damage host cells by forming pores or degrading membranes with phospholipases, leading to cell lysis and immune evasion.

What are Superantigens?

Bacterial proteins (exotoxins) that trigger an extreme immune response, leading to massive cytokine release (cytokine storm).

How do Capsules act as a virulence factor?

Prevent phagocytosis by forming a slippery outer layer.

How do Proteases act as a virulence factor?

Degrade host antibodies (especially IgA), stopping immune tagging.

How does M protein act as a virulence factor?

Interferes with complement binding, blocking opsonization and phagocytosis.

How does Mycolic Acid act as a virulence factor?

Waxy coat in the cell wall that acts as a protective barrier, allowing the bacterium to survive inside immune cells.

How does Coagulase act as a virulence factor?

Triggers blood clotting to form a protective clot around bacteria, hiding them from immune cells.

How do Kinases act as a virulence factor?

Breaks down clots, allowing trapped bacteria to escape and spread through the body.

How does Antigenic Variation act as a virulence factor?

Bacteria change their surface proteins so they can’t be recognized by the immune system, preventing long-term immunity.

What is Antigenic drift?

Small changes caused by tiny mutations in spike proteins.

What is Antigenic shift?

A big change caused when two different influenza viruses infect the same host and swap genes, creating a new virus.

What virulence factors are released by Candida albicans?

Proteases (break down proteins) and phospholipases (break down cell membranes) to invade tissues.

How does Cryptococcus help avoid immune attack?

Produces a capsule made of glucuronoxylomannan, protecting it from being swallowed by immune cells.

How does Claviceps purpurea act as a virulence factor?

Produces ergot toxin, causing ergotism with gangrenous (poor blood flow) and convulsive (nervous system) types.

How does Aspergillus act as a virulence factor?

Releases toxins like aflatoxin (damages DNA, causes liver cancer) and gliotoxin (suppresses immune response).

What are Protozoan virulence factors?

Uses adhesins, antigenic variation, intracellular survival, and immune evasion mechanisms, resulting in chronic, hard-to-eliminate infections.

What are Helminth virulence factors?

Uses proteases for tissue invasion, surface mimicry (glycans), physical defenses (cuticle), and immune system modulation.