BACTERIAL INFECTIONS ACNE Flashcards
normal skin flora?
firmicutes actinobacteria bacteriodetes proteobacteria dermatitis
MC cause of both bullous and non-bullous is S. aureus
S. pyogenes is another important cause of non-bullous impetigo
Non-bullous accounts for about 70% of cases
Most common bacterial infection in children
Lesions can become secondarily infected (impetiginized)
Treat with oral antibiotics (semi-synthetic PCN, cephalosporin) or topical mupirocin
Impetigo
S. aureus most common cause
Gram negative occasionally in acne patients on long term abx.
Pseudomonal folliculitis- hot tub, improperly chlorinated pool
Treatment:
Antibacterial washes
Mupirocin or topical clindamycin for localized disease
B-lactams, tetracyclines, macrolides-for widespread staph follic
Cipro for pseudomonal (though self-limited)
Recurrent - mupirocin 2% to nares for 5-10 days and bleach baths
Bacterial Folliculitis
usually caused by staph
entire follicle and surrounding tissue involved?
collection of furuncles?
tx: if large and fluctuant, adjuvant abx used
MRSA: doxycycline, bactrim, clindamycin
abscesses, furuncles, carbuncles
furuncle
carbuncle
Usually s. aureus or streptococcus
Wound or secondary infection
Well-demarcated erythema, edema, pain, warmth, may be purulence
Systemic symptoms may occur
Skin and subcutaneous tissue involved
Treat with antibiotic to cover s. aureus and streptococcus
Diabetics, burns, and immunosuppressed may have gram negatives and anaerobes
Cellulitis
tx: MSSA, MRSA
Group A streptococcal infection at site of puncture, surgery
Usually occurs in healthy individuals
Begins like cellulitis, but rapidly progresses
Dusky, bullous, red to black, ruptures with dark eschar
Systemically ill
Rapidly fatal
Surgical debridement and IV antibiotics indicated
Streptococcal Gangrene
Mixed infection: Anaerobes, strep, enterobacteriacea
Cellulitis that becomes deep purple, painful, bullous, crepitus
Systemically ill
Surgical debridement and IV antibiotics
Necrotizing Fasciitis
Group A streptococcus
Produces erythrogenic toxin
Source is either pharyngitis or wound
More common in children
Acute pharyngitis, fever, chills, nausea
Diffuse blanching erythematous fine sandpaper like papules
Peri-oral pallor
Pastia’s lines (linear petechiae in the body creases)
White and red strawberry tongue
Treat with oral antibiotics (synthetic penicillins, cephalosporins)
Scarlet Fever
Caused by s. aureus
Produces exfoliative toxin -> cleaves desmoglein 1
Infection is in body orifice, not skin
Abrupt redness and tenderness of the skin followed by blisters
Usually children or adults with adults kidney disease
Skin desquamates in sheets, leaving moist skin underneath
No scarring
Treat with anti-staph antibiotics
Staph Scalded Skin Syndrome
Caused by s.aureus
Tampons (50%), pyodermas, burns, surgical procedures, post-partum infections, nasal packing, insulin pumps
Toxin (TSST-1) causes cytokine release, leads to shock
Redness of pharynx, strawberry tongue, red conjunctiva, diarrhea, vomiting
Hypotension and organ failure
Toxic Shock Syndrome
Superficial bacterial infection
Corynebacterium
Red-brown patches of groin and web spaces
Fluoresces coral red with wood’s lamp
Treat with oral and topical erythromycin
Erythrasma
Aerobic, gram-negative diplococci
Many people are asymptomatic carriers
Outbreaks of meningitis among children and young adults in sudden close living spaces
Flu-like syndrome, headache, high fever, then coma
Treat immediately with IV PCN, 3rd gen cephalosporins or quinolones
Neisseria Meningitidis
Green nail syndrome: green/blue black nail discoloration
Pseudomonas hot-foot syndrome: painful red plaques/nodules on weight bearing surface
Pseudomonal folliculitis: self-resolving papulopustules
Treatment: topical or systemic abx, debridement, drying agents
Pseudomonas
Caused by spirochete Borrelia Burgdorferi
First described in 1977 as epidemic arthritis in Lyme, Connecticut
Vector is hard tick (ixodes) found on rodents and deer
Erythema migrans is characteristic skin lesion
Site of tick bite develops erythematous papule
Expands with central clearing
Can last for many months
Can get multiple cutaneous lesions
Other skin lesions include acrodermatitis chronica atrophicans
Also see arthritis, neurologic signs, carditis, join pains
Untreated disease can have late sequellae
Diagnosis difficult
Titers may not be elevated, especially later on
Can do PCR of lesion, serum
Treat with TCN, PCN, ceftriaxone
Lyme Lyme Disease
Causes by treponema pallidum
Sexually transmitted
Enters through skin or mucous membrane
Can cross placenta to infect fetus
Cutaneous as well as internal organ disease
Divided into early disease and late disease
Syphilis
