Bacterial Infections of the Skin

Question 1

Superficial Cutaneous Infections:

Answer 1

• Erythrasma
• Pitted Keratolysis
• Intertriginous Infections
• Cellulitis
• Erysipelas
• Necrotizing Fasciitis
• Lymphagitis

Question 2

Erythrasma:

Answer 2

• Corynebacterium minutissimum
• Toes, groin, axilla
• Mimics fungal
• Wood’s Lamp shows Coral-Red fluorescence

Question 3

Pitted Keratolysis:

Answer 3

• Micrococcus sedentarius

- Keratinase released destroying keratin on feet showing pits

Question 4

Intertrigio:

Answer 4

• Non-specific inflammation of apposed skin
• More common in obese people
• Wood’s Lamp and KOH helpful to distinguish fungal vs bacterial

Question 5

Cellulitis:

Answer 5

• Staphylococcus aureus or Group A Strep
• Deep Dermis and Subcutaneous Fat
• Need to R/O DVT if on leg

Question 6

Erysipelas:

Answer 6

• Group A strep
• Variant of Cellulitis
• Affects Upper Dermis and Superficial Lymphatics
• Lymphatic involvement makes it different from cellulitis
• Legs and face

Question 7

Periorbital Cellulitis:

Answer 7

• 3x more common than orbital cellulitis
• Limited to eyelid and pre-septal region
• Maintain eye movement
• Staph or Strep in adults
• H. influenza in children

Question 8

Orbital Cellulitis:

Answer 8

• Emergency Diagnosis
• Involves muscles and fat of orbit but not eye itself
• Loss of eye movement due to inflamed muscle
• Associated with ethmoid and maxillary sinus infections

Question 9

Acute Lymphangitis:

Answer 9

• Inflammatory process involving the subcutaneous lymphatic channels
• Group A strep
• Starts from wound and red line moves from there proximally

Question 10

Pyodermas:

Answer 10

• Impetigo (Bullous and Non-Bullous)

- Acne

Question 11

Bullous Impetigo:

Answer 11

• Staphylococcus aureus or Group A Beta-Hemolytic Strep
• Exotoxin
• More common in infants and on the face
• Vesicles enlarge to form bullae, bullae collapse and form honey colored crust

Question 12

Non-bullous Impetigo:

Answer 12

• More common form
• Small vesicles rupture to form red moist base
• Nose mouth limbs
• Satellite lesions will be present
• Acute poststreptococcal glomerulonephritis association

Question 13

Dermal Layer Infections:

Answer 13

• Ecthyma
• Folliculitis
• Furuncle
• Carbuncle
• Hidradenitis Suppurativa

Question 14

Ecthyma:

Answer 14

• Ulcerative form of impetigo
• Same as impetigo except bacteria penetrate to dermal lay leaving a scar
• Distal extremities
• Can be viral from goat or sheep

Question 15

Folliculitis:

Answer 15

• Staphylococcus aureus infection of hair follicles
• Pustular lesion
• Hot Tub folliculitis -> Pseudomonas aeruginosa

Question 16

Hidradenitis Suppurativa:

Answer 16

• Chronic infection of apocrine sweat glands due to Staph aureus
• Groin and axilla most common
• Leads to abscess formation and scarring

Question 17

Acnes:

Answer 17

• Acne Vulgaris
• Acne Conglobata
• Acne Fulminans

Question 18

Acne Vulgaris:

Answer 18

• Chronic inflammatory disease of pilosebaceous follicles
• Propionibacterium acnes
• Risk for acne increases only in females that have an increased BMI
• Normal acne

Question 19

Acne Conglobata:

Answer 19

• Severe form of nodular acne
• Burrowing and interconnecting abscesses and irregular scars
• Back chest buttocks
• No Systemic Symptoms

Question 20

Acne Fulminans:

Answer 20

• Rare severe form of conglobata with systemic symptoms

- Systemic Symptoms -> Fever and Arthralgia

Question 21

Cat bite:

Answer 21

Paturella multocida

Question 22

Gram Positive Infections due to Toxin Production:

Answer 22

• Staphylococcal Scalded Skin Syndrome
• Toxic Shock Syndrome
• Scarlet Fever

Question 23

Scaled Skin Syndrome/Ritter’s Disease:

Answer 23

• Exfoliative exotoxin of S. aureus
• Children and neonates
• Sandpaper skin rash
• Positive Nikolsky Sign

Question 24

Toxic Shock Syndrome:

Answer 24

• Multisystem illness
• Exotoxin of Staphylococcus aureus
• Major release of cytokines
• Fever, rash, hypotension, tissue injury and shock

Question 25

Scarlet Fever/Scarlatina:

Answer 25

- Exotoxin from Group A strep - Rash begins from face neck upper chest and moves distally - Scarlet erythema and sand paper texture - Blanches under pressure - STRAWBERRY TONGUE

Question 26

Gram Negative Infections:

Answer 26

- Bartonella infections - Cat-Scratch Disease - Bacterial angiomatosis - Trench Fever - Tularemia - Meningococcemia

Question 27

Cat Scratch Disease:

Answer 27

- Bartonella henselae - Vesicles at site of wound - Regional lymphadenopathy

Question 28

Bacillary Angiomatosis:

Answer 28

- Bartonella henselae - Vascular proliferation - Same as cat scratch but in an IMMUNOCOMPROMISED PATIENT - The lesions bleed profusely

Question 29

Trench Fever:

Answer 29

- Bartonella quintana | - Fever, arthralgia, splenomegaly, HA, Truncal rash

Question 30

Tularemia:

Answer 30

- Francisella tularensis - Spread by small mammals - Fever, anorexia, abdominal pain, rash -> multiple presentation of rash - Skin ulcers

Question 31

Meningococcemia:

Answer 31

- Neisseria meningitides - MIXED PETECHIAL AND MACULO-PAPULAR RASH MOST PREVALENT ON EXTREMITIES AND EXTENSOR SURFACES (PATHOGNOMONIC) - Must diagnosis early

Question 32

Mycobacterium marinum:

Answer 32

- Non-chlorinated water - Occurs at site of minor trauma - Papule that develops into ulcers

Question 33

Mycobacterium ulcerans:

Answer 33

- Occurs at the site of inoculation - Legs most commonly - Contaminated water

Question 34

Mycobacterium abscessus and Mycobacterium fortuitum:

Answer 34

- Water soil dust - High resistance to antibiotics - Abscesses - Associated with renal transplant, post-surgical wounds, needle injections

Question 35

Mycobacterium leprae:

Answer 35

- Chronic granulomatous disease - Hypopigmentation with loss of sensation - Thickened peripheral nerves