BACTERIAL SKIN INFECTIONS
I. Bacteria Skin Infections Are Common Problems
in Dermatology and General Medicine
A.
Appropriate diagnosis and treatment with appropriate presentation
B.
Approach to recurrent and resistant infections
C.
Review use of some of the new antibiotics
D.
Stress importance of proper diagnosis culture and and underlying health
status
II. Impetigo (Superficial epidermal bacterial
infection)
A.
Clinical characteristics
1. Golden-crusted erosions, superficial bullae
or vesicles with turbid fluid
2. Expansion laterally in annular fashion
3. Usually on face, hands, genitalia, scalp
4. Pruritus possible
5. Typically, no accompanying constitutional symptoms
6. Ecthyma: deep impetigo often on legs, healing
with scars
B.
Etiology
1. Cause: cocci-type bacteria
a. Streptococcus: usually non bullous
b. Staphylococcus: commonly bullae and pustules
2. Poor hygiene, moist climates, crowding possibly
exacerbating susceptibility
C.
Associated conditions
1. Staphylococcal impetigo - possible association
with immunodeficiency disease (e.g.
chronic granulomatous disease of childhood)
2. Neonatal type - highly contagious and constant
threat in nurseries
3. STAPHYLOCOCCAL SCALDED SKIN SYNDROME
(SSSS) - Can be a true
derm. emergency
a. Generalized, confluent, superficially exfoliated.
Dx occurring most commonly in
neonates and young children.
b. Must differentiate from TEN, which may be drug
induced
c. Caused by Staphylococcus, group 2-phage
71 - effect of exotoxin
4.. Streptococcal impetigo
a. Post streptococcal glomerulonepohritis in 2-5%
cases
b. Glomerulonephritis (GLN): resolution in many
cases but possible precursor of
chronic renal disease (may not influence course, even if treated)
c. Usually strains type 49, 55, 57, 60 and M-2
related to nephritis
5. Blistering Distal Dactylitis
a. Characteristic - tense, superficial blisters
over tender erythematous base over
volar fat pad of the phalanx
b. Age - usually 2 to 16
c. Group A - beta streptococcus as cause
d. Similar to Strep. cellulitis
D.
Therapy
1. Removal of crusts
2. Topical antiseptics (Betadine) or antibiotics
four times daily - mupirocin, bacitracin
or polysporin; No neosporin (common topical sensitizer)
3. Systemic antibiotics
a. Pen VK - (drug of choice if Strep.) 250
mg QID
b. Erythromycin, cloxacillin or cephalosporin -
PO 250-500 ig P.O. QID if
Staph
4. Prevention of contact with other children (avoidance
of same towels)
E.
Recurrent Staphylococcal Impetigo
1. Topical Bacitracin or Mupirocin for chronic
carriage (usually nasal)
2. Rifampin and Dicloxacillin
3. Rifampin and Trimethoprim
4. Bacterial Interferences - (S. aureus
502A)
F.
Methicillin-resistant Staphylococcus aureus
1. Parenteral Vancomycin
2. Trimethoprim/sulfamethoxazole
3. Rifampin and Trimethoprim
4. Fluoroquinolones
III. Erythrasma
A.
Clinical characteristics
1. Dry, scaly, reddish-brown plaques with the fine
inconspicuous scale (looks like T.
cruris)
2. Most commonly in axilla, groin, submammary areas
3. Frequently in obese, diabetic, or debilitated
patients
4. Wood's lamp examination: coral red fluorescence
visible
B. Etiology: Corynebacterium minutissimum
C.
Differential diagnosis
1. Intertrigo: negative Wood's light examination
2. Dermatophytosis: positive KOH, active scaly
border
D. Therapy
1. Cleansing, drying agents
2. Systemic erythromycin or tetracycline
3. Recurrence not infrequent
IV. Folliculitis - Furuncles - Carbuncles
A. Clinical Characteristics and Types
1. Superficial pustular follicular infection, usually
Staphylococcal
(Impetigo of
Backhart).
2. Folliculitis
a. Follicular pustules
b. Pruritus very common
c. Intertriginous areas commonly involved
d. Exacerbation from moisture, poor hygiene
3. Sycosis Vulgaris
a. Perifollicular beard area region presence of
pustules and papules
b. Pustules rupture after shaving and then from
a fresh crop.
4. Furuncle (boil): deep infection with centra
necrosis
5. Carbuncle
a. Multiple boils with fistula formation
b. Surrounding skin erythematous and tender
c. Usual location: back, neck, intertriginous areas
B. Therapy
1. Folliculitis
a. Removal of exacerbating factors
b. Topical antiseptics, cleansing
c. Recurrent folliculitis: culture from patient's
nose and contacts' noses; long
term antibiotics perhaps required
2. Carbuncles and furuncles
a. Incision and drainage, lesion packed with gauze
b. Systemic antibiotics after appropriate cultures
c. If recurrent, search for underlying illnesses
necessary: diabetes, leukemia,
immunodeficiency disorders
3. Recurrent furunculosis, carbuncles and folliculitis
a. Bacterial interferences
b. Rifampin and dicloxacillin
c. Clindamycin
V. Erysipelas (Streptococcal Cellulitis)
A.
Clinical characteristics
1. Erythematous, swollen, tender, sharply marginated
area with active advancing
borders
2. Induration common
3. Blisters over lesion possible
4. Acute course
5. Malaise, fever (usually greater than 100 F),
leukocytosis, and lymphadenitis
6. Lymphedema: possible result from recurrent episodes
B.
Etiology and pathogenesis
1. Beta-hemolytic Streptococci
2. Inoculation in skin, dissection along tissue
planes
3. Occurrence more frequent in patients with chronic
lymphedema, recurrent tendency
C.
Therapy
1. Systemic penicillin, 1 gm daily for 10 days,
or erythromycin
2. For recurrent infections prolonged therapy perhaps
necessary
D.
Resistant Streptococcal Cellulitis
1. Confirm organism is strept
2. Rifampin and Dicloxacillin
3. Prophylactic Benzathine - Pen.
4. Prophylactic erythromycin
VI. Cellulitis and Fascitis
A.
Cellulitis
1. Characteristic suppurative inflammation involving
particularly the subcutaneous tissue.
2. Causative agent - Streptococcus pyogenes,
staph and others also implicated.
3. Usually some type of discernilele wound.
4. Often mild erythema, tenderness, malaise, chills
and fever
5. Aggressive antibody therapy
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