References:

Global Infectious Diseases and Epidemiology Online Network: Infectious Diseases of the Philippines, 2013 eBook Edition, ISBN 978-1-61755-582-4, by Stephen Berger. Accessed here.


Agent	BACTERIUM. Various (Staphylococcus aureus & Streptococcus pyogenes predominate)
Reservoir	Human
Vector	None
Vehicle	Endogenous Contact with infected secretions
Incubation Period	Variable
Diagnostic Tests	Clinical diagnosis usually sufficient Aspiration of lesion for smear and culture may be helpful in some cases
Typical Adult Therapy	Antibiotic directed at likely pathogens (Group A Streptococcus and Staphylococcus aureus)
Typical Pediatric Therapy	As for adult
Clinical Hints	Impetigo characterized by vesicles which progress to pustules (‘honey-colored pus’); highly contagious; may be complicated by acute glomerulonephritis
Synonyms	Acne vulgaris, Carbonchio, Carbuncle, Folicolite, Follicolite, Folliculite, Folliculitis, Follikulitis, Foroncolosi, Foronculose, Foruncolosi, Furunculosis, Furunkulose, Furunulose, Hydradenitis, Impetigine, Impetigo, Paronychia, Pyoderma.

Impetigo

Impetigo is characterized by multiple superficial lesions caused by group A-hemolytic streptococci and/or Staphylococcus aureus.

The lesions consist of pustules that rupture and form a characteristic honey-colored crust.
Lesions caused by staphylococci are associated with tense, clear bullae (bullous impetigo.).
Ecthyma is a variant of impetigo that usually presents as punched-out ulcers on the lower extremities.
Streptococcal impetigo is most common among children 2 to 5 years of age, and epidemics may occur in settings of poor hygiene, lower socioeconomic status or tropical climates.
The most important complication of impetigo is poststreptococcal glomerulonephritis.

Folliculitis

Folliculitis is most often caused by Staphylococcus aureus.

Blockage of sebaceous glands may result in sebaceous cysts, which may present as extensive abscesses or become secondarily infected.
Infection of specialized sweat glands (hidradenitis suppurativa) occur in the axillae.
Chronic folliculitis is a hallmark of acne vulgaris, in which normal flora (e.g., Proprionibacterium acnes) may play a role.
Diffuse folliculitis may herald infection by Pseudomonas aeruginosa or Aeromonas hydrophila, in waters that are insufficiently chlorinated and maintained at temperatures above 37°C. Although such Infection is usually self-limited, bacteremia and septic shock have been reported.

Erysipelas is caused by Streptococcus pyogenes and is characterized by abrupt onset of “fiery-red” superficial swelling of the face or extremities.

The lesion is typically recognized by the presence of well-defined indurated margins, particularly along the nasolabial fold; rapid progression; and intense pain.
Flaccid bullae may develop on the second or third day of illness; but extension to deeper soft tissues is rare.
Desquamation occurs between the fifth and tenth days of illness.

Cellulitis is characterized by local pain, erythema, swelling, and heat.

Cellulitis may be caused by any of a wide variety of bacteria or yeasts; however, S. aureus or S. pyogenes are most often implicated.
A history of preceding trauma, insect bite, needle insertion or surgery is often present.
Cultures of biopsy specimens or aspirates are positive in only 20% of cases.
Infection by S. aureus often spreads out from a localized infection (abscess, folliculitis) or foreign body.
Streptococcal cellulitis tends to be more diffuse and rapid in onset, and associated with lymphangitis and fever.
Streptococci also cause recurrent cellulitis in the setting of lymphedema resulting from elephantiasis or lymph node damage.
Recurrent staphylococcal cutaneous infections are encountered in patients with “Job’s syndrome” (eosinophilia and elevated serum levels of IgE); and nasal carriers of staphylococci.