Entry Routes for Pathogens and Infections

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Questions and Answers

What is the consequence of thymus development defects?

Inability to produce antibodies

Immunocompromised due to environmental toxins

Increased susceptibility to bacterial infections

No T cells circulating (correct)

Which of the following can be considered an acquired immune deficiency?

Alzheimer's disease

Aging population

Malnutrition (correct)

Genetic disorders affecting T cells

What symptoms are associated with the nervous system in individuals affected by HIV?

Chronic respiratory infections

Neurological dysfunction and cognitive changes (correct)

Reactivation of cold sores

Chronic diarrhea

What role do opportunistic infections play in individuals with immune deficiency?

Increase susceptibility to cancers Signup and view all the answers

Which pathogen is an etiological agent for AIDS?

HIV Signup and view all the answers

What is the role of lysozyme present in tears?

To target bacterial cell walls and lyse cells Signup and view all the answers

Which of the following pathogens can cross the placental barrier?

Toxoplasma gondii Signup and view all the answers

Which complication is associated with Cytomegalovirus infection during pregnancy?

Deafness Signup and view all the answers

What defines an infection?

An invasion and colonization by pathogenic microbes Signup and view all the answers

How do pathogens typically enter the body via the conjunctiva?

By infecting superficial ocular tissues Signup and view all the answers

What is a typical result of the sequelae following an illness?

The after-effects experienced post-recovery Signup and view all the answers

Which of the following is not a true entry portal for pathogens?

Respiratory droplets Signup and view all the answers

Which disease is an example of a disturbance in the state of health?

Measles Signup and view all the answers

What characterizes an opportunistic pathogen?

They take advantage of a compromised immune system. Signup and view all the answers

Which of the following conditions is NOT commonly associated with opportunistic infections?

Healthy adult individuals Signup and view all the answers

Infestation, as mentioned in the context of pathogens, refers to which of the following?

Presence of large parasites in or outside the body. Signup and view all the answers

Which of the following bacteria is known to produce spores?

Clostridium species Signup and view all the answers

What term describes the growth of microorganisms on the epithelial surface?

Colonization Signup and view all the answers

What is meant by the term 'syndrome' in the context of diseases?

A group of signs and symptoms associated with a common pathology Signup and view all the answers

What complication can arise from a strep throat infection caused by S. pyogenes?

Rheumatic fever Signup and view all the answers

A patient with Acute Glomerulonephritis typically experiences which of the following?

Deposits in the filtration units of kidneys Signup and view all the answers

Which of the following describes Guillain Barre Syndrome accurately?

An autoimmune disorder where the body attacks nerve cells Signup and view all the answers

What condition is characterized by an absence of both B and T cells?

Severe Combined Immune Deficiency (SCID) Signup and view all the answers

Which of the following symptoms is commonly associated with Guillain Barre Syndrome?

Weakness and tingling in extremities Signup and view all the answers

Which statement is true regarding infections and the presence of disease?

Infections can exist without causing apparent disease. Signup and view all the answers

What possible initial triggers are linked to the onset of Guillain Barre Syndrome?

Prior vaccination or respiratory illness Signup and view all the answers

What characteristic distinguishes primary pathogens from other microbes?

They evolve to overcome host defenses. Signup and view all the answers

How does Helicobacter pylori survive in the acidic environment of the stomach?

By secreting bicarbonate ions. Signup and view all the answers

Which of the following is a virulence factor associated with Mycobacterium tuberculosis?

Cord factor. Signup and view all the answers

What does the lophotrichous arrangement of flagella allow Helicobacter pylori to do?

Cross the mucosal barrier effectively. Signup and view all the answers

What role does mycolic acid play in Mycobacterium tuberculosis?

It prevents killing inside macrophages. Signup and view all the answers

How does Helicobacter pylori contribute to the formation of ulcers?

By disrupting the mucosal barrier of the stomach. Signup and view all the answers

Which pathogen is specifically known for targeting alveolar macrophages?

Mycobacterium tuberculosis. Signup and view all the answers

What is a consequence of the chronic inflammation induced by Mycobacterium tuberculosis?

Formation of tubercles in the lungs. Signup and view all the answers

Study Notes

Entry Portals for Pathogens

Moist, non-keratinized, thin mucosal cells are susceptible to pathogens.
Retinal blood vessels are superficial and lack connective tissue, making them an entry point for pathogens.

The Common Cold

Can enter through the conjunctiva.
Lysozyme in tears is a chemical barrier against bacteria, targeting peptidoglycan and lysing bacterial cells.

Placenta

Pathogens that can cross the placental barrier include:
- Toxoplasma gondii
- Syphilis, gonorrhea, Chlamydia
- Rubella virus
- Cytomegalovirus
- Herpes simplex and other herpes viruses (HSV I/II)
Potential complications and consequences of placental infection include:
- Deafness (CMV infection)
- Abortion (Toxoplasma gondii)
- Mental retardation (Toxoplasma gondii)
- Premature births (Toxoplasma gondii)
- Birth defects (Zika virus, Rubella virus)

Parenteral Route

Includes voluntary punctures, injections, bites, and areas of dry and cracked skin (due to malnutrition, etc.).
Not a true entry portal.
Examples of diseases transmitted via this route:
- Tetanus
- Gangrene
- HIV
- Hepatitis C and B virus
- HPV

Definitions

Disease: A disturbance or impairment in health that restricts normal bodily function.
- Examples: atherosclerosis, measles, cystic fibrosis
Sequelae: After-effects of a disease following recovery.
- Examples: post-polio paralysis, SSPE (subacute sclerosing panencephalitis) following measles infection, sequelae of strep throat infection.
Infection: Invasion and colonization of the body by pathogenic microbes.
- Examples: HIV
Syndrome: A variation of a disease characterized by a group of signs and symptoms associated with a common pathology.
- Examples: Down syndrome, Guillain Barre syndrome, AIDS (Acquired Immune Deficiency syndrome)

Strep Throat Infection

Complications:
- Rheumatic fever
- Glomerulonephritis
Antibodies against strep throat bacteria can react with heart valve antigens, weakening the heart valves over time.
Acute glomerulonephritis can occur later due to antigen-antibody complexes depositing in the glomerulus of nephrons.

Infection vs Disease

An infection can exist without apparent disease.
Infections can be transient, with the body’s defense cells eliminating the pathogen before visible signs.
Not all microbes cause disease; most are harmless or beneficial.
Individuals can be HIV-infected but asymptomatic for AIDS.

Guillain Barre Syndrome

A potentially serious neurological condition.
The body's immune system attacks nerve cells, often triggered around two weeks after vaccination (J&J).
Muscle weakness and paralysis can result as nerve cell function is disrupted.
Usually reversible, but recovery can be prolonged in some cases.
Symptoms include:
- Weakness and tingling in arms and legs
- Double vision
- Difficulty walking, chewing, and swallowing
- Difficulty controlling bladder and bowel
- Often diarrhea or a respiratory illness for several weeks before developing GBS
There is no cure, but plasma exchange therapy is available.

Congenital Immune Deficiency

Also known as primary immune deficiency.
Results from genetic defects or developmental abnormalities.
Often inherited and associated with defects in the adaptive immune system.
Examples:
- SCID (Severe Combined Immune Deficiency): Absence of B and T cells.
- Defect in thymus development: Lack of circulating T cells (T cells mature in the thymus).
- B cell deficiency: Leads to a deficiency of antibodies (antibodies are secreted by differentiated B cells, called plasma cells).

Acquired Immune Deficiency

Also known as secondary immune deficiency.
Occurs due to environmental factors rather than genetic ones.
Contributing factors include:
- Aging
- Emotional or physical stress
- Malnutrition
- Environmental toxins
- Certain drugs or radiation treatments
- Malignancy
- Infectious agents (Ex: HIV, measles, TB, leprosy can cause immunosuppression)

Immune Deficiency Consequences

Increased susceptibility to cancer and infections (opportunistic infections).
Compromised immunotherapy, such as vaccination.

Pathogens

Also called etiologic agents.
Parasites that cause disease in their host.
Examples:
- HIV (etiological agent for AIDS)
- SARS CoV-2 (etiological agent for COVID-19)
Two types:
- Primary pathogens:
  - Evolved to overcome host defenses.
  - Possess virulence factors.
  - Examples: Helicobacter pylori, tuberculosis and Mycobacterium species, Salmonella species, cholera pathogen.
  - Helicobacter pylori (H. pylori):
    - Survives the acidic barrier of the stomach.
    - Crosses the thick mucosal lining of the stomach.
    - Causes ulcers and possesses several virulence factors.
    - Secretes bicarbonate ions to survive in the hostile stomach environment.
    - Secretes urease to neutralize the acidic environment.
    - Has lophotrichous flagella to propel it through the mucosal barrier and target epithelial cells.
  - Tuberculosis (Mycobacterium tuberculosis):
    - Targets alveolar macrophages.
    - Possesses a cell wall containing mycolic acid, which prevents killing by macrophages and induces chronic inflammation (tubercles) in the lungs.
    - Cord factor (a glycolipid molecule found in the cell wall) acts as a virulence factor.
- Opportunistic pathogens:
  - Cause disease when the body's defenses are weakened.
  - Take advantage of compromised immune systems.
  - Often colonize epithelial surfaces, including skin and mucous membranes.
  - Examples: E. coli, Pneumocystis jerovicci, yeast infection (thrush), CMV (associated with retinitis in AIDS patients).
  - Commonly observed in:
    - Elderly individuals
    - Young individuals undergoing chemotherapy or radiation treatment
    - Cancer patients (immunocompromised due to immune system overdrive)
    - Organ transplant patients (on immunosuppressive drugs)
    - AIDS individuals
- Colonization: Growth of microorganisms on epithelial surfaces.
- Infestation: Presence of large parasites in or outside the body.
  - Examples: Head lice, worms.
- Intoxication: Disease caused by toxin ingestion or presence in the blood.
  - Examples: Clostridium botulinum, Salmonella intoxication

Anatomy of Bacterial Cell - Spores

Refractile structures commonly produced by Gram-positive bacteria belonging to Bacillus species and Clostridium species.

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Description

This quiz covers various entry portals for pathogens, including the common cold and placental infections. Explore the implications of these entry points, the specific pathogens involved, and potential complications. Test your knowledge on how different routes contribute to infections.