Bacterial Skin Infections Flashcards

Flashcards covering the signs, symptoms, causative organisms, virulence factors, and reservoirs of various skin infections.

Folliculitis

Small, painful bumps around hair follicles, potentially with pus-filled blisters.

Impetigo

Red, itchy sores that rupture and form honey-colored crusts, often around the nose and mouth.

Erysipelas

A superficial skin infection with well-demarcated, bright red, swollen, and tender areas.

Cellulitis

A deeper skin infection, also causing redness, swelling, and tenderness, but with less distinct borders.

SSSS (Staphylococcal Scalded Skin Syndrome)

Widespread blistering and skin peeling, often starting with a rash and fever.

Necrotizing fasciitis

A rapidly spreading, severe infection with intense pain, fever, and potentially tissue death.

Cutaneous anthrax

A painless, black lesion (eschar) at the site of infection.

Folliculitis (Causative Organism)

Primarily caused by Staphylococcus aureus.

Impetigo (Causative Organism)

Can be caused by Staphylococcus aureus, Streptococcus pyogenes, or both.

Erysipelas (Causative Organism)

Almost exclusively caused by Streptococcus pyogenes.

Cellulitis (Causative Organism)

Commonly caused by Staphylococcus aureus or Streptococcus pyogenes.

Staphylococcal Scalded Skin Syndrome (SSSS) (Causative Organism)

Caused by Staphylococcus aureus.

Necrotizing Fasciitis (Causative Organism)

Can be caused by Streptococcus pyogenes or other bacteria.

Cutaneous Anthrax (Causative Organism)

Caused by Bacillus anthracis.

S. epidermidis (Virulence Factors)

Primarily relies on biofilm formation to colonize and persist in infections, particularly those involving medical devices.

S. aureus (Virulence Factors)

Uses a broader array of virulence factors, including toxins, enzymes, and immune evasion strategies.

S. pyogenes (Virulence Factors)

Utilizes adhesins, toxins, and enzymes to invade and damage host tissues.

P. aeruginosa (Virulence Factors)

Employs biofilm formation, adhesins, and toxins to establish and maintain infections, especially in immunocompromised individuals.

S. epidermidis (Reservoirs)

The skin and mucous membranes of humans, as well as other animals. It is also found in the environment, including untreated water, soil, and contaminated objects.

S. aureus (Reservoirs)

The skin and mucous membranes of humans, with a significant portion of the population being healthy carriers, particularly in the nasal cavity. It can also be found in food-producing animals and raw foods.

S. pyogenes (Reservoirs)

The upper respiratory tract, specifically the pharynx (throat), is the primary reservoir.

P. aeruginosa (Reservoirs)

This bacterium is found in moist environments, including hospital environments, and can be a reservoir on fomites like medical equipment and contaminated objects.

Why is S. aureus resistant to antibiotics like penicillin?

Arises from the production of an enzyme called β-lactamase, also known as penicillinase. This enzyme hydrolyzes the β-lactam ring in penicillin, rendering the antibiotic inactive.

Causative organism of necrotizing fasciitis

Primarily caused by Group A Streptococcus (GAS) bacteria. Other bacteria, including Staphylococcus aureus and those found in water (like Vibrio vulnificus), can also cause this disease.

Virulence factors associated with necrotizing fasciitis

Toxins that destroy tissue, enzymes that degrade tissue, and components that impede the immune system.