Microbial Pathogenesis and Immunopathogenesis

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Questions and Answers

Which of the following is a characteristic of a syndrome?

It is a measurable biological marker, like a blood test result.

It is a subjective experience of the patient, like a headache.

It is a group of symptoms and signs characteristic of a disease. (correct)

It is a single symptom that can be observed and measured by others.

Which of the following is a local effect of an infection?

Muscle pain

Fever

Inflammation (correct)

Altered immune response

Which of the following is a mechanism by which an infectious organism can evade the host's immune system?

Producing toxins that damage the immune system.

Attaching to cells and forming a biofilm.

Mutating rapidly to avoid recognition by antibodies.

All of the above. (correct)

Which of the following is an example of an organism's entry and spread in the body?

A virus attaching to a cell and entering through endocytosis. Signup and view all the answers

Which of the following is NOT a mechanism by which an infectious organism can evade the host's immune system?

Stimulating the production of antibodies. Signup and view all the answers

Which of the following is an example of a sign of infection?

Fever Signup and view all the answers

What is the primary characteristic of a persistent infection?

The pathogen remains in tissues of infected individuals and is not cleared following primary infection. Signup and view all the answers

What is the main difference between latent and chronic persistent infections?

Latent infections are asymptomatic, while chronic infections are symptomatic. Signup and view all the answers

What is the term for infections acquired in a hospital or medical facility?

Nosocomial infection Signup and view all the answers

What is the outcome of the balance between microbial replication and spread and the host's ability to respond or resist?

Disease Signup and view all the answers

What is the term for the reactivation of a latent infection?

Reactivation disease Signup and view all the answers

Why are nosocomial infections common?

Because microorganisms can be easily moved around by staff, patients, or visitors and hand washing is not always effective. Signup and view all the answers

What is an example of a latent infection?

Latent tuberculosis Signup and view all the answers

What is the outcome of the host's ability to respond or resist microbial replication and spread?

Recovery Signup and view all the answers

What is the primary reason normal flora can cause opportunistic infections?

They can move to other parts of the body under certain conditions. Signup and view all the answers

Which of the following conditions is likely to predispose an individual to opportunistic infections?

Neutropenia or mucosal injury from chemotherapy Signup and view all the answers

What does the term 'carriers' refer to in the context of infectious diseases?

Individuals who harbor pathogens but do not exhibit symptoms. Signup and view all the answers

Which microorganism is cited as a common cause of urinary tract infections when it ascends the urethra?

Escherichia coli Signup and view all the answers

What does 'colonization' imply regarding microorganisms?

Microorganisms growing on body surfaces without invading the body. Signup and view all the answers

How can antibiotic use lead to yeast infections in the vagina?

By eliminating competing normal flora. Signup and view all the answers

Which statement best describes a pathogen?

A microorganism capable of causing disease. Signup and view all the answers

What role does host defense play in preventing opportunistic infections?

Weakened defense mechanisms increase susceptibility to infections. Signup and view all the answers

What is the role of sickle cell trait in relation to malaria?

It provides protection against malaria. Signup and view all the answers

Which age group is most susceptible to influenza infection?

Infants and the elderly Signup and view all the answers

What underlying characteristic does NOT increase susceptibility to infections?

Healthy diet Signup and view all the answers

Which condition exemplifies immunodeficiency related to pathogenesis?

Opportunistic infections in AIDS patients Signup and view all the answers

What is a potential consequence of surgical implants in terms of infections?

They make it easier for bacteria to cause infection. Signup and view all the answers

Which immune response is notably associated with severe influenza infections?

Cytokine storm Signup and view all the answers

HIV long-term non-progressors are best described as individuals who:

Remain asymptomatic while controlling the virus. Signup and view all the answers

What factor is NOT considered a determinant of pathogenesis related to the host?

Personal habits Signup and view all the answers

What is the primary factor in immunopathogenesis that leads to cell death during many infections?

Host immune system's response Signup and view all the answers

Which of the following best describes the role of Cytotoxic T cells in disease pathology?

They directly attack and kill infected cells Signup and view all the answers

What is a common outcome of antibody-mediated damage in infections like Streptococcus pyogenes?

Development of autoimmune reactions Signup and view all the answers

In the context of infectious diseases, what do symptoms refer to?

Subjective experiences reported only by the patient Signup and view all the answers

Which of the following conditions is primarily associated with antibody-mediated complement fixation?

Chronic infection by Hepatitis C virus Signup and view all the answers

What is the relationship between exposure, infection, and clinical syndrome in the course of infectious diseases?

Infection can occur without symptoms Signup and view all the answers

What role does the complement system play in immunopathogenesis, especially in Hepatitis C infections?

It helps in viral persistence in the host Signup and view all the answers

Which of these statements about microbial pathogenesis is accurate?

It involves the progression from exposure to disease Signup and view all the answers

Study Notes

Harmful Effects of Flora: Opportunistic Infections

Caused by non-pathogenic microorganisms that act as pathogens in certain circumstances
Normal flora can move to other parts of the body and cause infection, e.g. Escherichia coli can ascend urethra and cause urinary tract infections (UTIs)
Weakened host defense mechanisms (immunocompromised patients) can lead to fungal or bacterial infections, e.g. Candida spp., Aspergillus spp., or Pseudomonas aeruginosa
Lack of competition from normal flora due to its loss from the body can lead to infections, e.g. vaginal yeast infections due to antibiotic use

Pathogenesis: Basic Definitions and Concepts

Infection: presence of microorganisms in the body
Colonisation: growth of new microorganisms on superficial body sites without invading the body
Carrier: person who harbors a microorganism and can be a source of infection for others
Pathogen: microorganism capable of causing disease
Microbial pathogenesis: process by which infection leads to disease

Course of Infectious Diseases

Organism exposure leads to infection, which can cause a clinical syndrome
Immunopathogenesis: killing of infected cells by the host immune system can lead to cell death, e.g. cytotoxic T cell mediated attack, antibody-mediated damage to the host, or antibody-mediated complement fixation

Clinical Manifestations of Disease

Symptoms: subjective features of disease experienced only by the patient
Signs: objective manifestations of disease that can be observed and measured by others
Syndrome: group of symptoms and signs characteristic of a disease
Infections can be asymptomatic (sub-clinical) or symptomatic

Host Response to Infection

Local effects: inflammation, tissue necrosis, and nasal congestion
Systemic effects: fever, altered immune response, and muscle pain (myalgia)

Obligatory Steps for Infectious Organisms

Entry and spread: attach and enter with local or general spread in the body, evading host's primary defenses
Evasion: evade host's immune system long enough for full cycle in host to be completed

Types of Infections: Based on Outcome

Acute infection: balance between microbial replication and spread, and the host's ability to respond or resist
Persistent infection: pathogen is not cleared from the host following primary infection, and remains in tissues of infected individuals
Latent infection: microorganism persists after initial clearance, and may have asymptomatic or symptomatic reactivation
Chronic infection: continued production of the infectious organism and immune evasion

Nosocomial Infections

Definition: any infection acquired in a hospital or medical facility
Can affect patients and health care workers
Common due to ease of transmission by staff, patients, or visitors, and imperfect prevention by hand washing

Determinants of Pathogenesis: Host

Age: infants and elderly are more susceptible to influenza infection
Underlying characteristics: increase susceptibility, e.g. asthma, obesity, diabetes, or malnutrition
Genetic variation: e.g. sickle cell trait provides protection to malaria, or HIV long-term non-progressors
Immunodeficiency: e.g. opportunistic infections in AIDS patients
Immune response: e.g. "cytokine storm" in influenza infection
Trauma/surgery/foreign body: e.g. surgical implants make it easier for bacteria to cause infection and more difficult to eradicate it

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Description

This quiz covers the process of how infections lead to disease, including exposure, infection, and clinical syndrome. It also explores immunopathogenesis and the host's immunological response.