Lecture 2: Normal Flora & Host-Parasite Relationship

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Questions and Answers

What is the benefit of brushing teeth regularly?

Improved digestion

Stronger bones

Increased risk of atrial fibrillation and heart failure

Lower risk of atrial fibrillation and heart failure (correct)

What is the definition of host-pathogen interaction?

The interaction between a host and its environment

The interaction between a pathogen and its environment

The interaction between a host and a pathogen (correct)

The interaction between different pathogens

What is the result of host-pathogen interactions?

Beneficial effects on the host

No effect on the host

Damage or disease to the host (correct)

Increased immunity to the host

What is the main mechanism used by bacteria to interact with the host?

Expressing molecules that bind host cell targets Signup and view all the answers

What is the difference between virulence and toxigenicity?

Virulence refers to the ability of a pathogen to cause disease, while toxigenicity refers to the production of toxins Signup and view all the answers

What is an example of direct contact in host-microbe interaction?

Direct contact between a host and a microbe Signup and view all the answers

What is an example of indirect contact in host-microbe interaction?

Indirect contact through a contaminated surface Signup and view all the answers

What is the role of molecular strategies in host-microbe interaction?

To facilitate the microbe's interaction with the host Signup and view all the answers

What is the purpose of host-pathogen interaction?

For the pathogen to sustain itself within the host Signup and view all the answers

What is an opportunistic pathogen?

A harmless microbe that infects a compromised host Signup and view all the answers

Why is it important to know the normal flora of the human body?

To predict the pathogens causing infection Signup and view all the answers

What is the definition of a microbe?

A microscopic organism, too small to be seen with the naked eye Signup and view all the answers

What is the main reason for opportunistic infections?

All of the above Signup and view all the answers

Which of the following is an example of a disease caused by a fungus?

Ringworm Signup and view all the answers

Which of the following is NOT a normal flora site in the human body?

Muscles Signup and view all the answers

What is the term for the ability of an organism to cause disease?

Pathogenicity Signup and view all the answers

What is the study and diagnosis of disease called?

Pathology Signup and view all the answers

What can be inferred from the isolation of Escherichia coli from blood cultures?

Probable intra-abdominal pathology Signup and view all the answers

What is the term for the mechanisms by which a disease develops and progresses?

Pathogenesis Signup and view all the answers

What is the significance of Viridans Streptococcus in blood cultures?

Indicates infective endocarditis Signup and view all the answers

What is an example of a parasite that causes disease?

Toxoplasma Signup and view all the answers

Why is the human body not sterile?

Because bacteria colonize us at birth Signup and view all the answers

What is the term for an organism that causes disease to its host?

Pathogen Signup and view all the answers

What is the significance of identifying the normal flora of the human body?

To predict the pathogens causing infection Signup and view all the answers

What is the result of a breach in the body's natural defenses?

Opportunistic infection Signup and view all the answers

Which of the following is an example of a disease caused by a bacteria?

TB Signup and view all the answers

What is the term for the severity of disease symptoms caused by a pathogen?

Virulence Signup and view all the answers

What is the primary role of physical structures like pilus or flagellum in pathogen survival?

To aid in adhesion to surfaces Signup and view all the answers

What is the result of collagenase production by bacterial pathogens?

Breakdown of collagen in connective tissue Signup and view all the answers

What is the term for the presence of bacteria in the bloodstream?

Bacteraemia Signup and view all the answers

What is the primary function of leukocidins produced by bacterial pathogens?

To destroy host white blood cells Signup and view all the answers

What is the life-threatening condition that occurs when blood pressure drops to a dangerously low level after an infection?

Septic shock Signup and view all the answers

What is the term for the ability of pathogens to spread to other locations in the host?

Invasion Signup and view all the answers

What is the result of hemolysins produced by bacterial pathogens?

Release of iron from host red blood cells Signup and view all the answers

What is the term for the process of pathogens increasing in number and utilizing resources at a site?

Colonization Signup and view all the answers

What is the role of toxins in pathogen invasion?

To penetrate and damage host cells Signup and view all the answers

What type of transmission involves vehicles such as water, food, and air?

Vehicle transmission Signup and view all the answers

What is an example of airborne transmission?

Tuberculosis transmission through coughs Signup and view all the answers

What is an example of a fomite?

A contaminated doorknob Signup and view all the answers

What is vector transmission?

Transmission through an animal vector Signup and view all the answers

What is an example of waterborne transmission?

Transmission of disease through contaminated water Signup and view all the answers

What is the distance range for airborne transmission?

Greater than one meter Signup and view all the answers

What is the causative agent of tuberculosis?

Mycobacterium tuberculosis Signup and view all the answers

What is the term for fine particles that can carry pathogens and facilitate airborne transmission?

Aerosols Signup and view all the answers

What is the term for an animal that carries disease from one host to another?

Vector Signup and view all the answers

Study Notes

Host-Microbe Interaction and Normal Flora

Microbes are microscopic organisms that can cause disease, including bacteria, fungi, archaea, protists, viruses, and parasites.
Normal flora refers to the microorganisms that live on or inside the human body, often in specific sites, and do not typically cause disease.
Opportunistic pathogens are harmless microbes that can cause infection in a host with a weakened immune system or compromised natural defenses.

Pathogen and Host-Pathogen Interaction

A pathogen is an organism that causes disease in its host, with the severity of the disease symptoms referred to as virulence.
Pathogenicity is the ability of an organism to cause disease, which is a genetic component of the pathogen.
Pathogenesis is the mechanism by which a disease develops, progresses, and either persists or is resolved.
Host-pathogen interaction is the process by which microbes sustain themselves within host organisms on a molecular, cellular, organismal, or population level.

Mechanisms of Pathogenicity, Virulence, and Toxigenicity

Bacterial pathogens express a wide range of molecules that bind to host cell targets to facilitate various host responses.
Adherence is the ability of a pathogen to attach to a host cell surface, often using physical structures such as pili or flagella.
Invasion refers to the ability of a pathogen to spread to other locations in the host, often by invading host cells or tissue.
Toxins can be used to penetrate and damage cells, aiding the producing bacterium.

Routes of Transmission

Direct transmission occurs through direct contact or droplet transmission.
Indirect transmission occurs through vectors, vehicles, or fomites.
Vehicle transmission refers to the transmission of pathogens through vehicles such as water, food, or air.
Airborne transmission occurs when pathogens are carried in small particles, such as aerosols, and can transmit disease over distances greater than one meter.
Vector transmission occurs when an animal, typically an arthropod, carries the disease from one host to another.

Normal Flora and Disease

Knowledge of the normal flora of the human body allows for the prediction of the pathogens causing infection and the investigation of underlying abnormalities in specific areas of the body.
Brushing teeth has been linked to a lower risk of atrial fibrillation and heart failure due to the reduction of bacteria in the mouth.

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Description

This quiz covers the interaction between host and microbe, including normal flora, opportunistic microorganisms, and the mechanisms of pathogenicity, virulence, and toxigenicity.