Skin Infections Types

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Questions and Answers

What is the main difference between coagulase-negative Staphylococcus epidermidis and coagulase-positive S. aureus?

Coagulase-positive is less virulent

Coagulase-positive can enter the body through natural openings (correct)

Coagulase-negative is more pathogenic

Coagulase-negative is more resistant to antibiotics

Which of the following is a type of acne characterized by inflammatory papules and pustules?

Impetigo

Seborrheic dermatitis

Folliculitis

Acne vulgaris (correct)

What is the primary mode of transmission of impetigo?

Airborne transmission

Vector-borne transmission

Direct contact (correct)

Contaminated food and water

Which of the following bacteria is commonly associated with streptococcal skin infections?

Streptococcus pyogenes Signup and view all the answers

What is the name of the yeast that is associated with the scaling skin condition known as dandruff?

Malassezia furfur Signup and view all the answers

What is the name of the bacteria that produces propionic acid, which helps maintain the low pH of the skin?

Propionibacterium acnes Signup and view all the answers

What is the primary route of entry for the pathogen that causes impetigo?

Through minor breaks in the skin Signup and view all the answers

What is the characteristic of bullous impetigo?

It is a form of staphylococcal scalded skin syndrome Signup and view all the answers

What is the primary cause of inflammatory acne?

Infection by Propionibacterium acnes Signup and view all the answers

What is the characteristic of erysipelas, a type of streptococcal skin infection?

It can cause sepsis Signup and view all the answers

What is the primary cause of viral warts?

Papillomavirus Signup and view all the answers

What is the characteristic of nodular cystic acne?

It is a severe form of acne that leaves scars Signup and view all the answers

How does the tetanus neurotoxin affect the muscles?

It causes muscle spasms Signup and view all the answers

What is the primary mode of transmission for poliomyelitis?

Ingestion Signup and view all the answers

What type of bacteria causes botulism?

Obligately anaerobic Signup and view all the answers

What is the effect of the botulinal toxin on the nervous system?

It blocks the release of acetylcholine Signup and view all the answers

What is the characteristic symptom of tetanus?

Muscle spasms Signup and view all the answers

What is the prevention method for tetanus?

Vaccination Signup and view all the answers

What is the mortality rate of Haemophilus influenzae Meningitis?

6% Signup and view all the answers

Which of the following bacteria is a gram-positive, encapsulated diplococcus?

Streptococcus pneumoniae Signup and view all the answers

What is the mode of transmission for Neisseria meningitidis Meningitis?

Droplet aerosols or direct contact with secretions Signup and view all the answers

What is the primary habitat of Listeria monocytogenes?

Soil and water Signup and view all the answers

Which of the following is a common inhabitant of the nasopharyngeal region?

Streptococcus pneumoniae Signup and view all the answers

What is the primary treatment for Neisseria meningitidis Meningitis?

Penicillin and cephalosporins Signup and view all the answers

What is the primary characteristic of Listeria monocytogenes that allows it to grow at low temperatures?

Psychrotrophic Signup and view all the answers

Study Notes

Bacterial Skin Infections

Staphylococcal skin infections:
- Caused by Staphylococcus aureus, a coagulase-positive bacterium
- Can enter the body through natural openings such as hair follicles and cause folliculitis or furuncles
- Impetigo is a type of staphylococcal skin infection, mostly affecting children aged 2-5 years
- Symptoms: fever, headache, stiff neck, nausea, and vomiting
- Treatment: Cephalosporins, vancomycin
Streptococcal skin infections:
- Caused by Streptococcus pyogenes, a Group A beta-hemolytic streptococcus
- Can cause impetigo and erysipelas
- Erysipelas can cause sepsis
- Necrotizing fasciitis is a serious complication of streptococcal skin infections
- Streptococcal toxic shock syndrome can cause bacteremia and organ damage

Viral Skin Infections

Warts:
- Caused by Papillomavirus
- More than 50 types of papillomavirus can cause different types of warts
- Incubation period: several weeks
- Treatment: cryotherapy, electrodesiccation, and salicylic acid
Smallpox:
- Caused by Orthopoxvirus
- Variola major has a mortality rate of 20-60%, while variola minor has a mortality rate of less than 1%
- Transmitted by the respiratory route
- Eradicated in 1977 by vaccination
Chickenpox:
- Caused by Varicellazoster virus (human herpesvirus 3)
- Transmitted by the respiratory route
- Causes pus-filled vesicles
- Lesions on the face, lower back, chest, and shoulders
- Prevention: Live attenuated vaccine
Herpes Simplex:
- Caused by Human herpesvirus 1 (HSV-1) and 2 (HSV-2)
- Causes cold sores and fever blisters
- Herpes gladiatorum is a common manifestation among wrestlers
- Herpes encephalitis can occur
- HSV-1 can remain latent in trigeminal nerve ganglia

Microbial Diseases of the Eye

Conjunctivitis:
- Inflammation of the conjunctiva
- Haemophilus influenzae is the most common bacterial cause
- Viral conjunctivitis is usually caused by adenoviruses
- Swimming pool conjunctivitis is caused by Chlamydia trachomatis
- Trachoma is an eye infection caused by Chlamydia trachomatis
Herpetic Keratitis:
- Caused by Herpes Simplex virus type 1
- Acanthamoeba Keratitis is caused by an ameba found in fresh water, tap water, hot tubs, and soil

Infectious Diseases of the Nervous System

Tetanus:
- Caused by Clostridium tetani
- Obligately anaerobic, endospore-forming, gram-positive rod
- Growth in deep wounds
- Prevention: vaccination
- Treatment: tetanus immune globulin
Botulism:
- Caused by Clostridium botulinum
- Obligately anaerobic, endospore-forming, gram-positive rod
- Found in soil and many aquatic sediments
- Food poisoning occurs in anaerobic environments, such as sealed cans
- Intoxication occurs from ingesting botulinal toxin
- Toxin blocks release of neurotransmitter acetylcholine, causing flaccid paralysis
Poliomyelitis:
- Caused by Poliovirus
- Transmitted by ingestion
- Initial symptoms: sore throat and nausea
- Viremia may occur, and if persistent, the virus can enter the CNS and cause destruction of motor cells and paralysis

Normal Microbiota of the Skin

The epidermis is the thin outer portion of the skin, composed of several layers of epithelial cells
The dermis is the inner, relatively thick portion of skin, composed mainly of connective tissue
Normal microbiota of the skin includes:
- Staphylococcus epidermidis
- Staphylococcus aureus
- Micrococcus species
- α-Hemolytic and nonhemolytic streptococci
- Corynebacterium species
- Propionibacterium species
- Peptostreptococcus species
- Acinetobacter species
- Small numbers of other organisms (Candida species, Pseudomonas aeruginosa, etc.)

Acne

Classification of acne:
- Comedonal (mild) acne: caused by blocked sebum channels with shed cells
- Inflammatory (moderate) acne: caused by Propionibacterium acnes
- Nodular cystic (severe) acne: characterized by nodules or cysts filled with pus
Treatment of acne:
- Azelaic acid
- Salicylic acid preparations
- Retinoids (derivatives of vitamin A)
- Isotretinoin for severe acne

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Description

This quiz covers different types of skin infections, including impetigo and erysipelas, caused by staphylococcal and streptococcal toxins and bacteria.