Intro to Life Sciences Module 2: Microorganisms Study Guide

What is a pathogen?

A microbe whose relationship with its host is parasitic and results in infection and disease.

What is pathogenicity?

An organism’s potential to cause a disease.

What are true pathogens?

Pathogens capable of causing disease in individuals with normal immune defenses.

What are opportunistic pathogens?

Pathogens that cause disease when the immune system is compromised or when they inhabit non-natural areas of the body.

What does virulence refer to?

The severity of disease caused by a specific microbe.

What is a virulence factor?

Any characteristic or structure of a microbe that contributes to its ability to cause damage in a host.

What are polymicrobial infections?

Infections involving multiple organisms at the infection site.

Can primary and secondary infections occur at the same site?

Yes, primary and secondary infections can happen in the same location.

What is a chain of infection?

A series of events that allow for the transfer of a pathogen from one host to another.

What is an agent in the chain of infection?

The germs involved, which can include bacteria, viruses, and parasites.

What is a reservoir in the chain of infection?

The natural habitat where the germs live, such as people, animals, or the environment.

What is a portal of exit in the chain of infection?

The path by which a pathogen leaves its host, such as through secretions or excretions.

What is the mode of transmission for infections?

The method by which pathogens are transmitted from one host to another, such as contact or airborne droplets.

What is a portal of entry?

The manner in which pathogens enter a new host, like through cuts, mucous membranes, or inhalation.

Who are susceptible hosts in the chain of infection?

Individuals who are vulnerable to infections, such as babies, the elderly, or those who are immunocompromised.

What is disinfection in the context of infection control?

The process of destroying pathogens using chemicals or heat.

What is sanitation?

The practice of reducing microbial populations to safe levels through cleanliness.

What is sterilization?

The complete destruction of all forms of microbial life.

What is antiseptosis?

The removal of pathogens from living tissue.

What does degerming mean?

The removal of microbes from a limited area, typically through washing.

What are some portals of entry for pathogens?

Skin, gastrointestinal tract, respiratory tract, urogenital tract.

How can we reduce the spread of infections?

Washing hands is considered the most effective method.

What are the seven types of infections?

Localized, systemic, mixed, primary, secondary, acute, chronic.

What is a localized infection?

An infection where microbes remain confined to a specific tissue.

What is a systemic infection?

An infection that spreads throughout the body.

What is a mixed infection?

An infection where several agents establish themselves simultaneously at the site.

What is a primary infection?

The initial infection in a host.

What is a secondary infection?

An infection caused by a different microbe after the initial infection.

What is an acute infection?

An infection that comes on rapidly with severe but short-lived effects.

What is a chronic infection?

An infection that progresses and persists over a long period of time.

What are three methods microorganisms use to damage their host?

Directly through toxins, indirectly by inducing host defenses, and epigenetic changes to host cells.

What is a toxin?

A specific chemical product of microbes that is poisonous to other organisms.

What are neurotoxins?

Toxins that act on the nervous system.

What are enterotoxins?

Toxins that act on the intestine.

What are hemotoxins?

Toxins that lyse red blood cells.

What are nephrotoxins?

Toxins that damage the kidneys.

What are exotoxins?

Toxic substances that bacteria secrete into their environment.

What are endotoxins?

Toxins that are present inside a bacterial cell and are released when the cell disintegrates.

What are portals of exit?

Pathways for pathogens to leave the host, such as respiratory droplets or bodily fluids.

What are the six ways that infections can exit the body?

Coughing/sneezing, insect bites, removal of blood, feces, urine, skin cells.

What is the incubation period of an infection?

The time after infection when no symptoms are present but the pathogen is replicating.

What happens during the prodromal stage of an infection?

Symptoms begin to appear.

What occurs at the height of an infection?

Symptoms level off.

What is the convalescent period?

The time during which a person is recovering from the infection.

What is the continuation period?

A phase where only some diseases linger, with pathogens or symptoms remaining.

How long does recovery from an infection typically take?

Usually 5-7 days.

What are five common hospital pathogens?

Clostridioides, Staphylococcus aureus, Klebsiella, Escherichia coli, Enterococcus species.

What infections are considered the worst?

Infections that are the most resistant and most virulent.

What is a bactericide?

A substance that kills bacteria.

What is a fungicide?

A substance that kills fungi or inhibits their growth.

What is a virucide?

A substance that inactivates viruses.

What is a sporicide?

A substance capable of killing endospores.

What is a germicide?

A chemical agent that kills microorganisms.

What is sepsis?

The growth of microorganisms in blood or other tissues overwhelming the host's response.

What is asepsis?

Any practice that prevents the entry of infectious agents into sterile tissues.

What is antisepsis?

Chemical agents applied to skin membranes through wounds and surgical incisions.

What is the impact of chemical agents on the cell wall?

They block and damage the cell wall.

How do chemical agents affect the cytoplasmic membrane?

They disrupt the lipid layer, causing it to open.

What is the impact of chemical agents on cellular synthesis?

They interrupt protein synthesis through ribosomes and growth.

How do chemical agents affect proteins in cells?

They attach to the active site, causing denaturation.

What is the goal of antimicrobial drugs?

To stop or break normal functions in germs and inhibit their reproduction.

What is drug resistance in microbes?

When germs adapt and survive doses of medicine that used to kill them.

What is intrinsic resistance?

Natural resistance built into the microbe.

What is acquired resistance?

Resistance developed over time through genetic changes.

How can microbes become resistant?

By mutating, acquiring new genes from other microbes, or slowing down metabolism.

What are the types of Gram-positive bacteria?

Staphylococcus aureus, Streptococcus, and Clostridia.

What are some examples of Gram-negative bacteria?

E. coli, Klebsiella, and Pseudomonas.

What is epidemiology?

The study of how often and where diseases happen in specific populations.

What is germ theory?

The theory that infectious diseases are caused by specific microbes.

Who is known as the father of epidemiology?

John Snow.

What did John Snow discover during the cholera outbreak?

He found that cholera spread through contaminated water.

What is prevalence in epidemiology?

The total number of existing cases in a given population.

What is incidence in epidemiology?

The number of new cases over a certain time period.

What does morbidity refer to?

The number of cases of a disease and its spread.

What is mortality?

The total number of death rates from a disease.

What is a common-source epidemic?

An epidemic resulting from common exposure to a single infection source over time.

What is a propagated epidemic?

An epidemic sustained over time from person to person.

What is an index case?

The first case in an epidemic.

What does endemic mean?

Confined to a particular country or area.

What is a sporadic disease?

A disease that occurs irregularly.

What is a pandemic?

The spread of an epidemic across continents.

What are microorganisms?

Living organisms that are too small to be seen by the naked eye.

How fast do organisms reproduce?

Rapidly, allowing testing in labs.

What is taxonomy?

The science of classifying and naming living organisms.

What is nomenclature in biology?

Scientific names assigned to categorize organisms.

What is the binomial system?

A system that uses genus and species names to classify organisms.

What are the types of microorganisms?

Prokaryotic, eukaryotic, helminths, fungi, and viruses.

What are prokaryotic cells?

Cells without a nucleus, including bacteria and archaea.

What are the defining features of bacteria?

They have cell walls made of peptidoglycan.

What is a defining feature of archaea?

They have cell walls made of substances different from peptidoglycan.

Where do most bacteria live?

On/in humans, animals, plants, and the environment.

What is the normal flora or human microbiome?

Usual bacteria in/on our bodies that can be helpful or harmful.

How do bacterial cells reproduce?

Mainly through binary fission, leading to two daughter cells.

What are endospores in bacteria?

Resistant structures formed in response to adverse conditions.

What is the structure of bacterial cells?

They're composed of cytoplasmic membrane, ribosomes, and DNA, not enclosed in a nucleus.

What components contribute to bacterial cell movement?

Flagella (for movement) and pili (for adherence to surfaces).

What are the two types of bacterial cell walls?

Gram-positive (thick peptidoglycan layer) and Gram-negative (thin peptidoglycan, outer membrane).

What is the significance of staining in bacteria?

Helps categorize bacteria and anticipate treatment.

What is biofilm?

A community of bacteria that adhere to surfaces, forming protective structures.

Why do bacteria form biofilms?

To protect against antibiotics and access nutrients.