Infectious Disease Overview

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Questions and Answers

What characterizes Gram positive bacteria?

They have a thick cell wall and retain crystal violet. (correct)

They possess no cell wall and are resistant to antibiotics.

They reproduce only through asexual reproduction.

They have a thin cell wall and do not retain crystal violet.

Which of the following accurately describes ectoparasites?

They are microscopic organisms that lack a cell wall.

They are multicellular organisms that primarily reproduce sexually.

They attach to the skin and may include insects or arachnids. (correct)

They reside within host cells and depend on host energy for replication.

Which barrier is considered an effective physical barrier to infection?

Normal flora that competes with pathogens.

Acid produced in the stomach.

Antibodies produced by the immune system.

Intact skin and mucous membranes. (correct)

Which scenario best exemplifies an opportunistic infection?

A person undergoing chemotherapy develops a fungal infection. Signup and view all the answers

Which statement correctly describes fungi?

They possess thick cell walls made of chitin and can exist as yeast or hyphae. Signup and view all the answers

What is a significant way that infectious organisms can evade host immune defenses?

Producing enzymes that inhibit immune cell functioning. Signup and view all the answers

How do normal flora inhibit pathogen growth?

By competing for resources and space with pathogens. Signup and view all the answers

Which category of infectious organisms does prion fall under?

Proteinaceous infectious agent Signup and view all the answers

What is NOT a clinical condition in which opportunistic infections can occur?

A healthy adult with regular vaccinations Signup and view all the answers

Which of the following is NOT a method of transmission of infectious organisms?

Boosting diet to enhance immunity Signup and view all the answers

Which of the following conditions would most likely inhibit the mucociliary action of the lungs?

Chronic obstructive pulmonary disease Signup and view all the answers

What type of spread occurs through blood and can reach distant sites in the body?

Hematogenous spread Signup and view all the answers

Which of the following is NOT a characteristic of an obligate intracellular parasite?

Contains both DNA and RNA Signup and view all the answers

Which factor is likely to predispose a person to a urinary tract infection?

Prolonged use of indwelling catheters Signup and view all the answers

What is the role of normal vaginal bacteria in relation to infections?

They inhibit pathogen growth Signup and view all the answers

Which of the following is NOT a route of person-to-person transmission of pathogens?

Vector transmission Signup and view all the answers

Which of the following statements about prions is true?

They are associated with CNS degenerative diseases Signup and view all the answers

What type of pathogen is inhibited by disrupting the normal gut flora?

Bacteria Signup and view all the answers

What is the most accurate description of prokaryotic organisms?

Single-celled organisms with a cell wall and no nucleus Signup and view all the answers

Which of the following is commonly caused by viral infection and can be spread through respiratory droplets?

Tuberculosis Signup and view all the answers

Study Notes

Opportunistic Infections

Defined as infections by non-pathogenic organisms in individuals with normal immune systems, primarily affecting immunocompromised individuals.
Common clinical scenarios include congenital immunodeficiency, drug-induced immunosuppression (cancer treatment, organ transplants), and HIV/AIDS.

Host Physical Barriers to Infection

Effective physical barriers include intact skin, mucous membranes, and mechanical actions like cilia in the respiratory tract that help remove pathogens.
Barriers can be compromised by wet skin, injuries, iatrogenic disruptions (e.g., catheters), and skin diseases.

Spread of Infectious Organisms

Local spread occurs along tissue planes, e.g., cellulitis and abscesses.
Lymphatic spread leads to swollen lymph nodes.
Hematogenous spread involves transport through the bloodstream, termed septicemia.
Neural spread can occur with certain viruses like rabies.

Transmission Methods

Person-to-person transmission can occur via:
- Fecal-oral route (e.g., hepatitis A)
- Respiratory droplets (e.g., tuberculosis)
- Bloodborne pathways (e.g., HIV)
- Sexual contact (e.g., gonorrhea).
Vector transmission involves organisms like malaria carried by insects.
Zoonotic transmission occurs from animals to humans, such as rabies.

Major Categories of Infectious Organisms

Prions: Abnormal proteins spreading via contaminated instruments or tissues, linked to diseases like Creutzfeldt-Jakob Disease.
Viruses: Obligate intracellular parasites requiring host for replication (e.g., herpes virus, influenza).
Bacteria:
- Gram-positive (thick walls).
- Gram-negative (thin walls).
- Mycoplasma (no cell wall).
Parasites: Reproduce sexually and asexually using hosts and vectors.
Fungi: Have chitin cell walls and include yeast and hyphae forms.
Protozoa: Single-cell eukaryotes.
Ectoparasites: Insects or arachnids, such as lice.

Mechanisms of Disease and Host Response

Infectious agents initiate disease through various mechanisms, prompting host immune defenses in response.
Hosts may produce antibodies and recruit immune cells to fight infections.

Evasion of Immune Defenses

Pathogens evoke immune evasion tactics, including altering surface proteins and rapid mutation.
Examples include antibiotic resistance exhibited by MRSA and VRE.

Laboratory Diagnosis Techniques

Diagnostic methods include cultures, serological tests, and molecular techniques like PCR to identify infectious organisms.

Impact of Infectious Diseases

Not major causes of death in developed nations due to public health measures, antibiotics, vaccinations, and nutritional advancements, except during epidemics (e.g., COVID-19).
Major cause of mortality persists in underdeveloped countries.

Host and Barrier Compromise

Intact skin is crucial for preventing infection, while skin trauma, wetness, or disruption increase infection risk.
Normal microbial flora plays a protective role and can be disturbed by antibiotics.
Gastric acid and immune responses serve as chemical barriers against pathogens.

Examples of Infectious Diseases by Organism

Viral diseases include herpes, chickenpox, common cold, hepatitis, influenza, and HPV-related conditions.
Bacterial infections might involve resistant strains like VRE and MRSA, emphasizing the significance of antibiotic resistance.

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Description

Explore the key concepts of infectious diseases, including opportunistic infections and the conditions under which they occur. Understand host physical barriers against infections and how they can be compromised. Additionally, learn about the transmission methods of infectious organisms throughout the body.