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

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Study Guide - Smart Notes

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Q1. What is lysozyme? What does it do to bacteria?

Background

Topic: Innate Immunity – Antimicrobial Enzymes

This question tests your understanding of the natural defenses present in the skin and mucous membranes, specifically the role of lysozyme in protecting against bacterial infections.

Key Terms and Concepts:

  • Lysozyme: An enzyme found in various body fluids (e.g., tears, saliva, mucus).

  • Peptidoglycan: A major component of bacterial cell walls, especially in Gram-positive bacteria.

Step-by-Step Guidance

  1. Recall where lysozyme is commonly found in the human body (think about secretions that protect exposed surfaces).

  2. Consider what part of the bacterial cell lysozyme targets (hint: structural component unique to bacteria).

  3. Think about the effect of breaking down peptidoglycan on bacterial cells (what happens to the cell wall?).

  4. Summarize how this action helps protect the body from bacterial infection.

Try solving on your own before revealing the answer!

Final Answer:

Lysozyme is an enzyme present in body fluids such as tears, saliva, and mucus. It breaks down the peptidoglycan layer of bacterial cell walls by hydrolyzing the bonds between N-acetylmuramic acid and N-acetylglucosamine. This action weakens the bacterial cell wall, leading to cell lysis and death, especially in Gram-positive bacteria. Thus, lysozyme is an important part of the body's innate immune defense.

Q2. Define the terms exanthem and enanthem.

Background

Topic: Infectious Disease Terminology – Skin and Mucous Membrane Lesions

This question checks your understanding of medical terms used to describe rashes and lesions associated with infectious diseases.

Key Terms:

  • Exanthem: A rash or eruption on the skin.

  • Enanthem: A rash or eruption on mucous membranes (e.g., inside the mouth).

Step-by-Step Guidance

  1. Think about the difference between the skin and mucous membranes in terms of location in the body.

  2. Recall which term refers to a rash on the skin and which refers to a rash on mucous membranes.

  3. Consider examples of diseases that might cause each type of lesion.

Try solving on your own before revealing the answer!

Final Answer:

An exanthem is a widespread rash that appears on the skin, often as a result of an infectious disease. An enanthem is a rash or lesion that appears on mucous membranes, such as the inside of the mouth or throat. Both terms are used to describe characteristic findings in various viral and bacterial infections.

Q3. Define the terms: folliculitis, sty (stye), furuncle, and carbuncle.

Background

Topic: Bacterial Skin Infections – Terminology

This question tests your ability to distinguish between different types of localized skin infections, often caused by Staphylococcus species.

Key Terms:

  • Folliculitis: Infection of hair follicles.

  • Sty (Stye): Infection of an eyelash follicle.

  • Furuncle: A deeper infection of a hair follicle, also called a boil.

  • Carbuncle: A cluster of connected furuncles.

Step-by-Step Guidance

  1. Start by defining folliculitis and identifying its location and cause.

  2. Relate a sty (stye) to folliculitis, but specify its unique location.

  3. Describe how a furuncle differs from simple folliculitis in terms of depth and severity.

  4. Explain what a carbuncle is and how it forms from multiple furuncles.

Try solving on your own before revealing the answer!

Final Answer:

Folliculitis is an infection of the hair follicles, usually resulting in small, red, pus-filled bumps. A sty (stye) is a type of folliculitis that occurs at the base of an eyelash. A furuncle (boil) is a deeper, more severe infection of a hair follicle and surrounding tissue. A carbuncle is a larger, more serious infection formed by the joining of several furuncles, often resulting in a mass with multiple drainage points.

Q4. What does MRSA stand for? What is HA-MRSA? What is CA-MRSA?

Background

Topic: Antibiotic Resistance – Staphylococcus aureus

This question tests your knowledge of antibiotic-resistant bacteria and the difference between hospital- and community-acquired infections.

Key Terms:

  • MRSA: Methicillin-resistant Staphylococcus aureus.

  • HA-MRSA: Hospital-acquired MRSA.

  • CA-MRSA: Community-acquired MRSA.

Step-by-Step Guidance

  1. Break down the acronym MRSA and identify the organism and resistance involved.

  2. Distinguish between HA-MRSA and CA-MRSA based on where the infection is acquired.

  3. Think about the typical risk factors and populations affected by each type.

Try solving on your own before revealing the answer!

Final Answer:

MRSA stands for Methicillin-resistant Staphylococcus aureus, a type of bacteria resistant to many antibiotics. HA-MRSA refers to hospital-acquired MRSA, typically found in healthcare settings and associated with invasive procedures. CA-MRSA is community-acquired MRSA, which occurs in otherwise healthy individuals outside of hospitals.

Q5. What does GAS stand for? What is necrotizing fasciitis?

Background

Topic: Streptococcal Infections – Terminology and Disease Mechanisms

This question tests your understanding of important bacterial pathogens and the severe diseases they can cause.

Key Terms:

  • GAS: Group A Streptococcus (Streptococcus pyogenes).

  • Necrotizing fasciitis: A rapidly progressing infection that destroys fascia and surrounding tissue.

Step-by-Step Guidance

  1. Identify what the acronym GAS stands for and the species involved.

  2. Define necrotizing fasciitis and describe its main characteristics.

  3. Consider why this disease is considered a medical emergency.

Try solving on your own before revealing the answer!

Final Answer:

GAS stands for Group A Streptococcus, specifically Streptococcus pyogenes. Necrotizing fasciitis is a severe, rapidly spreading infection that destroys the fascia (connective tissue) and surrounding tissues, often referred to as "flesh-eating disease." It requires immediate medical intervention due to its rapid progression and high mortality rate.

Q6. What genus causes acne? What is sebum? What were the 3 treatments discussed in lecture for acne?

Background

Topic: Microbial Skin Diseases – Acne Pathogenesis and Treatment

This question tests your knowledge of the causative agent of acne, the role of skin secretions, and common treatment strategies.

Key Terms:

  • Genus: Propionibacterium (now Cutibacterium).

  • Sebum: Oily substance produced by sebaceous glands.

Step-by-Step Guidance

  1. Recall the bacterial genus most commonly associated with acne.

  2. Define sebum and its role in skin health and acne development.

  3. List the three main types of treatments for acne discussed in class (think about topical, oral, and physical methods).

Try solving on your own before revealing the answer!

Final Answer:

The genus that causes acne is Propionibacterium (now called Cutibacterium). Sebum is an oily secretion from sebaceous glands that can clog pores and promote bacterial growth. The three treatments discussed are: (1) topical antibiotics, (2) benzoyl peroxide to loosen clogged follicles, and (3) visible (blue) light to kill bacteria.

Q7. What type of viruses can cause warts?

Background

Topic: Viral Skin Infections – Warts

This question tests your knowledge of the viral family responsible for causing warts.

Key Terms:

  • Warts: Benign skin growths caused by viral infection.

  • Human papillomavirus (HPV): The main viral group causing warts.

Step-by-Step Guidance

  1. Recall the family of viruses most commonly associated with warts.

  2. Think about the diversity of HPV types and the different kinds of warts they cause.

Try solving on your own before revealing the answer!

Final Answer:

Warts are caused by viruses in the human papillomavirus (HPV) family. Different types of HPV cause different types of warts on the skin and mucous membranes.

Q8. What was the most common route of transmission for smallpox? How was the smallpox disease nearly eliminated?

Background

Topic: Viral Diseases – Smallpox Transmission and Eradication

This question tests your understanding of how smallpox spreads and the public health measures that led to its eradication.

Key Terms:

  • Smallpox: A serious viral disease caused by the variola virus.

  • Transmission: The way a disease spreads from person to person.

  • Eradication: Complete elimination of a disease worldwide.

Step-by-Step Guidance

  1. Identify the main way smallpox was transmitted between people (think about respiratory routes).

  2. Recall the global public health strategy that led to smallpox eradication (hint: vaccination).

  3. Consider why smallpox was a good candidate for eradication (e.g., no animal reservoir).

Try solving on your own before revealing the answer!

Final Answer:

The most common route of transmission for smallpox was respiratory droplets (person-to-person via the air). Smallpox was nearly eliminated through a worldwide vaccination campaign that broke the chain of transmission, leading to its official eradication in 1980.

Q9. What is shingles? Where does the latent disease “hide” in the human body? What diseases are covered in the MMR vaccination?

Background

Topic: Viral Diseases – Latency and Vaccination

This question tests your understanding of viral latency, reactivation, and the diseases prevented by the MMR vaccine.

Key Terms:

  • Shingles: Reactivation of the varicella-zoster virus.

  • Latency: The ability of a virus to remain dormant in the body.

  • MMR vaccine: Immunization against three viral diseases.

Step-by-Step Guidance

  1. Define shingles and identify the virus responsible.

  2. Recall where the varicella-zoster virus remains latent in the body after initial infection.

  3. List the three diseases prevented by the MMR vaccine.

Try solving on your own before revealing the answer!

Final Answer:

Shingles is a disease caused by reactivation of the varicella-zoster virus (which also causes chickenpox). The virus remains latent in nerve ganglia (specifically, dorsal root ganglia) and can reactivate later in life. The MMR vaccine protects against measles, mumps, and rubella.

Q10. What is thrush? What genus causes it? What kingdom is it from?

Background

Topic: Fungal Infections – Oral Candidiasis

This question tests your knowledge of fungal diseases, their causative agents, and classification.

Key Terms:

  • Thrush: Oral candidiasis, a fungal infection of the mouth.

  • Genus: Candida.

  • Kingdom: Fungi.

Step-by-Step Guidance

  1. Define thrush and describe its typical appearance and location.

  2. Recall the genus of fungus most commonly responsible for thrush.

  3. Identify the biological kingdom to which this organism belongs.

Try solving on your own before revealing the answer!

Final Answer:

Thrush is a fungal infection of the mouth, also known as oral candidiasis. It is caused by the genus Candida, most often Candida albicans. This organism belongs to the Kingdom Fungi.

Q11. What is pediculosis? What type of organism causes it? What kingdom is it from?

Background

Topic: Parasitic Skin Infections – Lice

This question tests your understanding of parasitic infestations, their causative organisms, and classification.

Key Terms:

  • Pediculosis: Infestation with lice.

  • Type of organism: Arthropod (insect).

  • Kingdom: Animalia.

Step-by-Step Guidance

  1. Define pediculosis and describe the symptoms or signs associated with it.

  2. Identify the type of organism (e.g., insect, fungus, protozoan) that causes pediculosis.

  3. State the biological kingdom to which this organism belongs.

Try solving on your own before revealing the answer!

Final Answer:

Pediculosis is an infestation of the skin and hair by lice. Lice are arthropods (insects) belonging to the Kingdom Animalia.

Q12. Why are newborn babies given eye drops with silver nitrate or antibiotics?

Background

Topic: Prevention of Neonatal Infections – Ophthalmia Neonatorum

This question tests your understanding of preventive medicine and the rationale for treating newborns' eyes after birth.

Key Terms:

  • Ophthalmia neonatorum: Eye infection in newborns, often caused by Neisseria gonorrhoeae or Chlamydia trachomatis.

  • Prophylaxis: Preventive treatment.

Step-by-Step Guidance

  1. Recall which infections can be transmitted from mother to baby during birth and affect the eyes.

  2. Explain how silver nitrate or antibiotic eye drops prevent these infections.

  3. Consider the consequences if this preventive measure is not taken.

Try solving on your own before revealing the answer!

Final Answer:

Newborn babies are given eye drops containing silver nitrate or antibiotics to prevent ophthalmia neonatorum, a serious eye infection that can be caused by bacteria such as Neisseria gonorrhoeae or Chlamydia trachomatis acquired during passage through the birth canal. This prophylactic treatment helps prevent blindness and other complications.

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