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Questions and Answers
What characterizes Gram positive bacteria?
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?
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?
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?
Which scenario best exemplifies an opportunistic infection?
Which statement correctly describes fungi?
Which statement correctly describes fungi?
What is a significant way that infectious organisms can evade host immune defenses?
What is a significant way that infectious organisms can evade host immune defenses?
How do normal flora inhibit pathogen growth?
How do normal flora inhibit pathogen growth?
Which category of infectious organisms does prion fall under?
Which category of infectious organisms does prion fall under?
What is NOT a clinical condition in which opportunistic infections can occur?
What is NOT a clinical condition in which opportunistic infections can occur?
Which of the following is NOT a method of transmission of infectious organisms?
Which of the following is NOT a method of transmission of infectious organisms?
Which of the following conditions would most likely inhibit the mucociliary action of the lungs?
Which of the following conditions would most likely inhibit the mucociliary action of the lungs?
What type of spread occurs through blood and can reach distant sites in the body?
What type of spread occurs through blood and can reach distant sites in the body?
Which of the following is NOT a characteristic of an obligate intracellular parasite?
Which of the following is NOT a characteristic of an obligate intracellular parasite?
Which factor is likely to predispose a person to a urinary tract infection?
Which factor is likely to predispose a person to a urinary tract infection?
What is the role of normal vaginal bacteria in relation to infections?
What is the role of normal vaginal bacteria in relation to infections?
Which of the following is NOT a route of person-to-person transmission of pathogens?
Which of the following is NOT a route of person-to-person transmission of pathogens?
Which of the following statements about prions is true?
Which of the following statements about prions is true?
What type of pathogen is inhibited by disrupting the normal gut flora?
What type of pathogen is inhibited by disrupting the normal gut flora?
What is the most accurate description of prokaryotic organisms?
What is the most accurate description of prokaryotic organisms?
Which of the following is commonly caused by viral infection and can be spread through respiratory droplets?
Which of the following is commonly caused by viral infection and can be spread through respiratory droplets?
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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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