Micro Lecture

Course Overview

  • Upcoming Assignments

    • Four questions due next Thursday, the 15th, related to Chapter 23

    • Group project outline due on the 11th

    • Classes moving quickly towards Chapter 24 and Chapter 26

Class Structure

  • Chapter Review and Case Study

    • Chapter 21 content will include:

      • Layers of the skin

      • Bacteria causing skin infections

      • Fungal skin infections

      • Conjunctivitis

  • Class Activities

    • Case study: learning through real-world application

    • Individual work on case study to be submitted at the end of the class

Chapter 21: Key Topics

  • Skin Layers

    • Various strata of the skin with unique functions

    • Epidermis: Outermost layer, composed of dead skin cells and keratin

    • Dermis: Thicker layer containing blood vessels, nerves, glands, and deeper structures

  • Skin Infections

    • Common skin bacteria

      • Staphylococcus epidermidis:

      • Non-pathogenic skin resident bacteria

      • Produces biofilms that can be dangerous if introduced into the bloodstream

      • Staphylococcus aureus:

      • Pathogenic bacteria that can cause diseases, including folliculitis

      • Produces toxins and enzymes to damage tissues

      • Streptococcus pyogenes:

      • Causes skin infections and requires breaks in the skin to enter

      • Pseudomonas aeruginosa:

      • Gram-negative pathogen causing rashes in moist environments

      • Identified by its blue-green pigmentation in culture

  • Fungal Infections

    • Cutaneous mycosis:

      • Fungal diseases affecting skin, hair, and nails

      • Examples: Athlete's foot, ringworm

      • Fungi can digest keratin, unlike bacteria

Case Study Overview: Rash Diagnosis

  • Scenario: Pediatric nurse examines Donald (9) and Sharon (6) for rashes

  • Initial Observations: Rashes present with bumps and clear fluid, not itchy

  • Possible Causes Explored:

    • Allergic reactions (food, environment, detergents)

    • Infection (insect bites, viral infections like chickenpox)

  • Discussion Points: Brainstorming potential triggers for skin rashes

    • Environmental exposures (e.g., poison ivy, soap)

    • Reactions to temperature or pressure

Important Concepts: Bacterial Skin Infections

  • Staphylococcus epidermidis:

    • Typically non-pathogenic, a significant resident of the skin microbiome.

    • Dominates skin flora but can cause infection in places like catheters if it enters the bloodstream.

  • Staphylococcus aureus:

    • Pathogen with multiple virulence factors including toxins.

    • Known to cause folliculitis and can lead to other serious infections such as scalded skin syndrome in infants.

  • Streptococcus pyogenes:

    • Gram-positive, can cause various skin infections depending on breaks in the skin.

    • Notable for its potential to cause necrotizing fasciitis (flesh-eating disease).

  • Pseudomonas aeruginosa:

    • Gram-negative, capable of surviving in moist environments like swimming pools.

    • Identified by its characteristic blue-green color on nutrient media.

Investigative Steps and Diagnosis

  • Next Steps for Diagnosis:

    • Collect swabs from affected areas

    • Perform microbiological cultures and Gram staining

    • Identification of bacterium by observing color and morphology in culture

Treatment Considerations

  • Importance of identifying the correct pathogen

  • Awareness that penicillin is not effective against gram-negative bacteria like Pseudomonas

  • Use of ciprofloxacin and other appropriate antibiotics for treatment of infections caused by Pseudomonas

Case Conclusion

  • Health department involvement in tracking outbreak related to community pool

  • Outcomes: Pool equipment and cleanliness checks confirmed issues leading to infection

  • Emphasized sanitation measures and steps to prevent future outbreaks

Fungal Infections and Pathogenicity

  • Differences between bacterial and fungal infections in humans

  • Significance of keratin as a nutritional source for fungi but not for bacteria

  • Noted case of Candida auris: new fungal infection, elevated concern due to potential epidemic spread and mortality rates

  • Discussion on climate change implications for future fungal virulence

Next Class

  • Discussion on conjunctivitis and the finalization of chapter coverage

  • Reminder about group project collaboration time for students in the following week