Chapter 21 OpenStax Microbiology

Summary

This video covers the anatomy and microbiota of the skin and eyes, focusing on the common diseases that affect these areas. It discusses various infections caused by bacteria (e.g., Staphylococcus, Streptococcus), viruses (e.g., HPV, herpes simplex), and fungi (e.g., tinea, Candida). The script highlights the protective role of the skin's layers and normal flora, as well as the symptoms, diagnosis, and treatments for skin and eye infections like acne, conjunctivitis, impetigo, and keratitis. The importance of understanding microbial classifications and their impact on health is emphasized, providing a comprehensive introduction to skin and eye diseases.

Takeaways

• 😀 The skin's primary role is to act as a barrier against pathogens, aided by multiple layers and natural defenses like sweat glands and sebaceous oils.
• 😀 Normal skin microbiota, including bacteria and fungi, help protect the skin by outcompeting harmful microbes.
• 😀 Skin infections can occur when normal bacteria move deeper into the skin layers or when skin barriers are compromised.
• 😀 Common bacterial skin infections include staph infections like folliculitis, abscesses, and MRSA, which can be resistant to antibiotics.
• 😀 Streptococcal infections, such as cellulitis and necrotizing fasciitis (flesh-eating bacteria), can cause severe tissue damage.
• 😀 Conjunctivitis (pink eye) is an inflammation of the eye caused by bacterial, viral, or fungal infections.
• 😀 Chlamydia trachomatis is a leading cause of preventable blindness worldwide, transmitted by flies and affecting the eye.
• 😀 Acne is commonly linked to hormonal changes, where trapped oil in pores leads to pimples, whiteheads, and blackheads.
• 😀 Viral infections like HPV cause warts, and herpes simplex causes cold sores. Both can be recurring and triggered by stress.
• 😀 Fungal infections such as ringworm (tinea) and athlete's foot are common but not deadly, often requiring antifungal treatment.
• 😀 Neonatal conjunctivitis caused by sexually transmitted diseases (e.g., gonorrhea and chlamydia) is now prevented by treating newborns with antibacterial eye cream.

Q & A

What is the first step in understanding diseases that affect the skin and eyes?

The first step is identifying the type of microbe causing the infection, whether bacterial, protozoan, fungal, helminth, or viral.

What is the role of the skin in preventing infections?

The skin serves as a barrier to pathogens with its multiple layers, including the stratum corneum, which is rich in keratin, and through processes like desquamation (shedding of outer skin layers) and sweat production.

How does normal microbiota contribute to skin protection?

Normal microbiota, such as bacteria and fungi, live on the skin and help prevent pathogenic microbes from establishing an infection.

What happens when normal skin bacteria move into deeper layers?

When normal skin bacteria move into deeper layers, they can cause infections like pimples, abscesses, or boils, as the immune system responds to these microbes.

What is MRSA, and why is it significant?

MRSA (Methicillin-resistant *Staphylococcus aureus*) is an antibiotic-resistant bacteria that can cause serious infections, especially in healthcare settings, and is often found in the skin of healthy individuals without causing symptoms.

What are common types of staphylococcal infections?

Common staphylococcal infections include folliculitis (pimples), boils, carbuncles, impetigo (especially in children), and staphylococcal scalded skin syndrome.

What is necrotizing fasciitis, and how is it treated?

Necrotizing fasciitis, also known as flesh-eating bacteria, is a severe, rapidly spreading infection of the skin and deeper tissue caused by *Streptococcus pyogenes* or *Staphylococcus aureus*. Treatment typically requires surgical removal of the infected tissue.

What causes conjunctivitis (pink eye), and how is it spread?

Conjunctivitis can be caused by bacteria such as *Haemophilus influenzae*, *Streptococcus pneumoniae*, and *Staphylococcus aureus*. It is highly contagious and spreads through contact with infected secretions.

How does Chlamydia trachomatis cause blindness?

Chlamydia trachomatis causes trachoma, an eye infection spread by flies, leading to scarring of the eyelid and potential inversion of the eyelid, resulting in blindness.

What are some common viral infections of the skin?

Common viral skin infections include warts caused by HPV, cold sores caused by herpes simplex virus type 1, and conditions like roseola and Fifth disease, which cause rashes following cold-like symptoms.