Microbiology Exam 5 Study Guide – Step-by-Step Guidance

Study Guide - Smart Notes

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Q1. Define the following terms: septicemia, sepsis, lymphangitis, and septic shock.

Background

Topic: Infectious Diseases of the Cardiovascular and Lymphatic Systems

This question tests your understanding of key terminology related to systemic infections and their progression in the human body.

Key Terms

Septicemia: The presence and multiplication of pathogenic microorganisms or their toxins in the blood.
Sepsis: A systemic inflammatory response to infection, often resulting from septicemia.
Lymphangitis: Inflammation of the lymphatic vessels, often visible as red streaks under the skin.
Septic shock: A severe and potentially fatal condition caused by sepsis, leading to dangerously low blood pressure and organ dysfunction.

Step-by-Step Guidance

Start by recalling the definitions of each term, focusing on how they relate to infection and the body's response.
Think about the progression: which term describes the presence of microbes in the blood, and which describes the body's systemic response?
Consider how lymphangitis is visually identified and what it indicates about the spread of infection.
For septic shock, focus on the consequences of severe sepsis and what happens to blood pressure and organ function.

Try solving on your own before revealing the answer!

Final Answer:

Septicemia: The presence and active multiplication of pathogenic bacteria or their toxins in the bloodstream.
Sepsis: A systemic inflammatory response to infection, often resulting from septicemia, that can lead to tissue damage and organ failure.
Lymphangitis: Inflammation of the lymphatic vessels, typically seen as red streaks under the skin, indicating the spread of infection.
Septic shock: A severe and life-threatening condition resulting from sepsis, characterized by dangerously low blood pressure and multiple organ dysfunction.

These terms describe the progression and complications of systemic infections in the body.

Q2. What is the difference between gram-negative sepsis and gram-positive sepsis?

Background

Topic: Bacterial Sepsis

This question tests your understanding of the differences in pathogenesis and clinical features between sepsis caused by gram-negative and gram-positive bacteria.

Key Concepts

Gram-negative bacteria: Bacteria with an outer membrane containing lipopolysaccharide (LPS, also known as endotoxin).
Gram-positive bacteria: Bacteria with a thick peptidoglycan cell wall and no outer membrane.
Endotoxin: A toxin present inside a bacterial cell that is released when the cell disintegrates, especially LPS from gram-negative bacteria.

Step-by-Step Guidance

Recall the structural differences between gram-negative and gram-positive bacteria, focusing on their cell walls and membranes.
Think about how gram-negative bacteria cause sepsis, especially the role of endotoxins (LPS).
Consider how gram-positive bacteria cause sepsis, and what toxins or components are involved.
Compare the clinical implications and severity of sepsis caused by each type.

Try solving on your own before revealing the answer!

Final Answer:

Gram-negative sepsis is primarily caused by the release of endotoxins (lipopolysaccharides) from the outer membrane of gram-negative bacteria, which can trigger a strong inflammatory response and lead to septic shock. Gram-positive sepsis is usually caused by the release of exotoxins and cell wall components (like teichoic acids) from gram-positive bacteria. Both can cause severe illness, but the mechanisms and toxins involved differ.

Q3. What is endocarditis? What is pericarditis?

Background

Topic: Infections of the Heart

This question tests your knowledge of infections affecting different layers of the heart.

Key Terms

Endocardium: The inner lining of the heart chambers and valves.
Pericardium: The outer sac surrounding the heart.
-itis: Suffix meaning inflammation.

Step-by-Step Guidance

Break down each term into its root and suffix to determine what part of the heart is affected.
Recall what causes inflammation in these areas (e.g., bacterial infection).
Think about the symptoms and complications associated with each condition.

Try solving on your own before revealing the answer!

Final Answer:

Endocarditis: Inflammation of the endocardium, the inner lining of the heart, often involving the heart valves and usually caused by bacterial infection.
Pericarditis: Inflammation of the pericardium, the outer sac surrounding the heart, which can be caused by infection, autoimmune disorders, or other factors.

Q4. What is Brucellosis? What bacterial genus causes this? How is it transmitted? Why is it called undulant fever?

Background

Topic: Zoonotic Bacterial Diseases

This question tests your understanding of Brucellosis, its causative agent, transmission, and clinical features.

Key Terms

Brucellosis: A bacterial zoonosis affecting humans and animals.
Genus Brucella: The group of bacteria responsible for Brucellosis.
Undulant fever: A fever pattern that rises and falls (undulates).

Step-by-Step Guidance

Recall the main features of Brucellosis and which animals are commonly involved.
Identify the bacterial genus responsible for the disease.
Think about how humans typically acquire the infection (e.g., direct contact, consumption of unpasteurized dairy).
Consider why the fever is described as 'undulant' and what that means clinically.

Try solving on your own before revealing the answer!

Final Answer:

Brucellosis: A zoonotic bacterial infection caused by bacteria of the genus Brucella.
It is transmitted to humans through direct contact with infected animals or consumption of unpasteurized dairy products.
It is called undulant fever because the fever rises and falls in waves (undulates) over time.

Q5. What is Anthrax? What bacterial species causes this? How is it transmitted?

Background

Topic: Bacterial Zoonoses

This question tests your knowledge of anthrax, its causative agent, and modes of transmission.

Key Terms

Bacillus anthracis: The bacterial species that causes anthrax.
Anthrax: A serious infectious disease affecting both animals and humans.

Step-by-Step Guidance

Recall the main features of anthrax and the type of organism that causes it.
Identify the bacterial species responsible for the disease.
Think about the different ways anthrax can be transmitted to humans (e.g., cutaneous, inhalation, gastrointestinal).

Try solving on your own before revealing the answer!

Final Answer:

Anthrax: A disease caused by the bacterium Bacillus anthracis.
It can be transmitted to humans through contact with infected animals or animal products, inhalation of spores, or ingestion of contaminated food.

Q6. What bacterial species causes gas gangrene?

Background

Topic: Anaerobic Bacterial Infections

This question tests your knowledge of the causative agent of gas gangrene.

Key Terms

Gas gangrene: A severe infection characterized by tissue death and gas production.
Clostridium perfringens: The main bacterial species responsible.

Step-by-Step Guidance

Recall the main features of gas gangrene and the type of bacteria involved (anaerobic, spore-forming).
Identify the genus and species most commonly associated with this condition.

Try solving on your own before revealing the answer!

Final Answer:

The bacterial species that causes gas gangrene is Clostridium perfringens.

Q7. Which bacterial species causes cat-scratch disease?

Background

Topic: Zoonotic Bacterial Infections

This question tests your knowledge of the causative agent of cat-scratch disease.

Key Terms

Cat-scratch disease: A bacterial infection transmitted by scratches or bites from cats.
Bartonella henselae: The causative bacterial species.

Step-by-Step Guidance

Recall the main features of cat-scratch disease and how it is transmitted.
Identify the bacterial species responsible for this infection.

Try solving on your own before revealing the answer!

Final Answer:

The bacterial species that causes cat-scratch disease is Bartonella henselae.

Q8. What was the cause of the plague (Black Death)? How was it transmitted?

Background

Topic: Historical Bacterial Pandemics

This question tests your knowledge of the causative agent and transmission of the plague.

Key Terms

Yersinia pestis: The bacterium responsible for the plague.
Vector: An organism that transmits a pathogen (e.g., fleas).

Step-by-Step Guidance

Recall the bacterial species responsible for the Black Death.
Think about the main vector involved in transmission to humans.
Consider the role of rodents and fleas in the disease cycle.

Try solving on your own before revealing the answer!

Final Answer:

The cause of the plague (Black Death) is the bacterium Yersinia pestis. It was transmitted to humans primarily by the bite of infected fleas that lived on rodents.

Q9. What is the bacterial cause of Lyme disease? How does it involve ticks and other animals? What regions of the USA have higher rates of Lyme disease infection?

Background

Topic: Vector-Borne Bacterial Diseases

This question tests your understanding of the causative agent, transmission cycle, and epidemiology of Lyme disease.

Key Terms

Borrelia burgdorferi: The spirochete bacterium that causes Lyme disease.
Ixodes ticks: The vector (deer tick) that transmits the bacterium.
Reservoir hosts: Animals that maintain the bacterium in nature (e.g., mice, deer).

Step-by-Step Guidance

Recall the bacterial species responsible for Lyme disease.
Describe the role of ticks in the transmission cycle.
Identify which animals serve as reservoirs for the bacterium.
Think about which regions of the USA have the highest incidence of Lyme disease and why.

Try solving on your own before revealing the answer!

Final Answer:

The bacterial cause of Lyme disease is Borrelia burgdorferi.
It is transmitted to humans by the bite of infected Ixodes ticks, which acquire the bacterium from reservoir hosts like mice and deer.
Higher rates of Lyme disease are found in the Northeastern, upper Midwestern, and Pacific Northwestern regions of the USA.

Q10. What is the viral cause of mononucleosis? How is the virus transmitted?

Background

Topic: Viral Infections of the Blood and Lymphatic System

This question tests your knowledge of the causative agent and transmission of infectious mononucleosis.

Key Terms

Epstein-Barr virus (EBV): The virus that causes mononucleosis.
Transmission: The way the virus spreads from person to person.

Step-by-Step Guidance

Recall the name of the virus responsible for mononucleosis.
Think about the common modes of transmission (e.g., saliva, close contact).

Try solving on your own before revealing the answer!

Final Answer:

The viral cause of mononucleosis is the Epstein-Barr virus (EBV). It is primarily transmitted through saliva, often by kissing or sharing drinks/utensils.

Q11. What is the Ebolavirus? What does it do to the human body?

Background

Topic: Viral Hemorrhagic Fevers

This question tests your understanding of the Ebolavirus and its effects on the human body.

Key Terms

Ebolavirus: A virus that causes severe hemorrhagic fever in humans.
Hemorrhagic fever: A syndrome characterized by fever and bleeding disorders.

Step-by-Step Guidance

Recall the classification of Ebolavirus and the type of disease it causes.
Think about the main symptoms and effects on the body, especially regarding bleeding and organ failure.

Try solving on your own before revealing the answer!

Final Answer:

Ebolavirus is a filovirus that causes Ebola virus disease, a severe hemorrhagic fever. It damages blood vessels, leading to internal and external bleeding, organ failure, and often death.

Q12. What is the cause of Toxoplasmosis? What kingdom is that organism classified in? How are cats involved in the life cycle?

Background

Topic: Protozoan Infections

This question tests your knowledge of the causative agent of toxoplasmosis, its classification, and the role of cats in its life cycle.

Key Terms

Toxoplasma gondii: The protozoan parasite that causes toxoplasmosis.
Kingdom Protista: The kingdom to which protozoa belong.
Definitive host: The organism in which the parasite completes its sexual cycle (cats for T. gondii).

Step-by-Step Guidance

Recall the name and classification of the organism that causes toxoplasmosis.
Think about the role of cats in the parasite's life cycle and how humans can become infected.

Try solving on your own before revealing the answer!

Final Answer:

The cause of toxoplasmosis is the protozoan Toxoplasma gondii.
It is classified in the kingdom Protista.
Cats are the definitive host, shedding oocysts in their feces, which can infect other animals and humans.

Q13. What is the cause of malaria? What type of organism causes this disease? How is it transmitted?

Background

Topic: Protozoan Vector-Borne Diseases

This question tests your knowledge of the causative agent, classification, and transmission of malaria.

Key Terms

Plasmodium species: Protozoan parasites that cause malaria.
Vector: An organism that transmits the parasite (Anopheles mosquito).

Step-by-Step Guidance

Recall the genus of protozoa responsible for malaria.
Identify the type of organism (protozoan) and its classification.
Think about how malaria is transmitted to humans (vector and method).

Try solving on your own before revealing the answer!

Final Answer:

Malaria is caused by protozoan parasites of the genus Plasmodium.
It is transmitted to humans by the bite of infected female Anopheles mosquitoes.