Mechanisms of Infectious Diseases Flashcards

Flashcards based on lecture notes about mechanisms of infectious diseases.

What is a host in the context of infectious diseases?

Any organism capable of supporting the nutritional and physical growth requirements of another organism.

Define microflora.

Bacteria inhabiting exposed surfaces of the body.

What is colonization?

The presence and multiplication of a living organism on or within the host, without causing harm.

Explain the difference between colonization and infection.

Colonization does not cause harm to the host, while infection involves the multiplication of an organism that causes harm.

Define infectious disease.

The disease state brought about by the interaction with another organism that causes harm to the host.

What does virulence refer to?

The disease-inducing potential of a microorganism.

Define pathogens.

Microorganisms so virulent that they are rarely found in the absence of disease.

What are saprophytes?

Free-living organisms obtaining their growth from dead or decaying organic material from the environment; humans are not usually affected.

Define opportunistic pathogens.

Microorganisms capable of producing infectious disease when the host's health and immunity are severely weakened.

Explain mutualism in the context of host-microorganism interaction.

An interaction in which both the microorganism and the host derive benefits from the interaction.

What is commensalism?

An interaction in which colonizing organisms acquire nutritional needs and shelter, but the host body is not affected.

Describe a parasitic relationship.

A relationship in which only the infecting organism benefits, while the host sustains injury or pathologic damage.

What are prions?

Protein particles that lack any kind of demonstrable genome and are able to transmit infection.

List some diseases caused by prions.

Creutzfeldt-Jacob disease and kuru.

Describe viruses.

Smallest obligate intracellular pathogens with no organized cellular structure, incapable of replication outside of a living cell.

What does a virus consist of?

A protein coat (capsid) that surrounds a nucleic acid core (genome) of DNA or RNA (but never both).

What are the effects viruses can have on host cells?

Cell lysis, continuous release of budding viral particles, latency, or oncogenesis.

What are prokaryotes?

Bacteria that lack an organized nucleus and contain both DNA and RNA, cytoplasmic (cell) membranes and rigid cell walls.

What are eukaryotes?

Fungi that contain a membrane-bound (organized) nucleus.

How do yeasts reproduce?

By budding.

What are molds?

Fungi that produce long, hollow, branching filaments called hyphae.

What are the three classifications of bacteria according to microscopic appearance?

Bacilli (rods), cocci (spherical), spirilla (helical).

How do Gram-positive and Gram-negative organisms stain?

Gram-positive stain PURPLE, Gram-negative stain RED.

Name the parasites discussed.

Protozoa (single-celled animals), Helminths (worms), Arthropods (insects).

What are Rickettsiaceae, Anaplasmataceae, Chlamydiaceae, Coxiella?

Organisms that combine characteristics of viral and bacterial agents to produce disease; obligate intracellular pathogens.

What is epidemiology?

The study of factors, events, and circumstances that influence the transmission of infectious diseases among humans.

Define incidence.

The rate at which a certain event occurs such as cases of disease during a certain period.

Define prevalence.

The number of new and old cases of a disease that is present in a population at a given time.

What is an endemic disease?

Found in a particular geographic region with a stable incidence and prevalence.

Define epidemic.

Abrupt and unexpected increase in the incidence of disease over endemic rates.

What is a pandemic?

Spread of disease beyond continental boundaries.

List some portals of entry for infectious diseases.

Penetration, Direct contact, Ingestion, Inhalation.

Define nosocomial and community-acquired infections.

Nosocomial infections develop in hospitalized patients, while community-acquired infections are acquired outside of health care facilities.

Distinguish an Endogenous and Exogenous source of infection.

Endogenous sources come from the host's own microflora, while exogenous sources originate outside the host.

What are fomites?

Inanimate objects that carry disease.

What are specific symptoms?

Symptoms that reflect the site of infection (e.g., diarrhea, rash, convulsions, hemorrhage, pneumonia).

Differentiate between acute and insidious disease courses.

Acute is an abrupt onset, insidious the prodromal phase is prolonged

Describe the incubation and prodromal stages.

Incubation is when pathogens replicate without symptoms; prodromal is the initial appearance of vague symptoms.

Describe the acute and convalescent disease stage.

Acute is when the host experiences maximum impact; convalescent is containment and elimination.

What are subacute infections considered?

Protracted and irregular course without clinically apparent symptoms.

How does the type of pathogen influence the site of infection?

Some pathogens are site-specific.

What are toxins?

Substances that alter or destroy the normal function of the host or host’s cells.

Describe exotoxins and endotoxins.

Exotoxins are proteins released from bacteria; endotoxins are found in Gram-negative bacteria.

Define invasive factors.

Factors that facilitate the penetration of anatomic barriers.

Outline the criteria for diagnosis of an infectious disease.

Recovery of a probable pathogen from the infected site and Accurate documentation of clinical signs and symptoms compatible with an infectious process.

How are bacteria identified by culture?

Based on microscopic appearance, Gram stain reaction, shape, texture/color of colonies, or biochemical reactions.

List three types of antimicrobial agents.

Antibacterial, antiviral, antifungal, antiparasitic agents.

What is bactericidal?

Causes irreversible and lethal damage to the bacterial pathogen.

What is bacteriostatic?

Inhibitory effects on bacterial growth are reversed when the agent is eliminated.

What are the three categories of bioterrorism agents?

Category A, B, and C.