cutaneous bacterial infections and infestations david r. carr, md faad division of dermatology the...
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Cutaneous Bacterial Infections and Infestations
David R. Carr, MD FAAD
Division of Dermatology
The Ohio State University
Learning Objectives At the end of this module, you will know
the following:
IMPETIGO/FOLLICULITISCutaneous Bacterial Infections and Infestations
Impetigo
Common superficial cutaneous infection usually caused by staphylococcus aureus (sometimes streptococcus, incidence decreasing)
Presents as superficial ulcerations with honey-colored crusts, especially face, around mouth
Caused by a strain of staph aureus that produces an exfoliative toxin that cleaves desmoglein type 1. Toxin is released locally leading to blistering at the site of infection
Cellulitis
Common cutaneous infection, most often caused by staphylococcus aureus & streptococcus pyogenes
Skin demonstrates erythema, edema, warmth, tenderness
Patients may demonstrate fevers, chills, malaise, leukocytosis
Blood cultures should be obtained and patient started on a beta-lactamase resistant antibiotic or other appropriate coverage
Staph Scalded Skin Syndrome
Most common in children or in adults with renal failure or immunosuppression
Caused by a toxin produced by certain strains of staphylococcus aureus
Toxin cleaves desmoglein 1, causing superficial skin cleavage
Infectious focus is usually in the nasopharynx or conjunctivae, whereas staphylococcal pneumonia or bacteremia may be present in adults
Staph Scalded Skin Syndrome (cont.)
Patients demonstrate fever, malaise, tender skin
Widespread erythema develops with flaccid bullae that easily rupture, slough off
Treatment consists of antibiotics to kill bacteria and prevent further toxin production, local wound care, and supportive care
Hot Tub Folliculitis
Due to pseudomonas contamination of recreational water source, especially hot tubs, swimming pools that are not adequately chlorinated
Patients develop red papules that may be itchy or burn
Lesions are often follicular based, involve skin covered by bathing suit or in contact with wall of hot tub
Infection usually improves spontaneously in
immunocompetent patients, but may require treatment, if patients are symptomatic or immunosuppressed
These patients require anti-pseudomonal antibiotics
Abscess/Furuncle
Red, painful nodules with surrounding erythema and localized collection of pus
Most commonly caused by staph, especially methicillin resistant staph aureus (MRSA)
Abcesses should be immediately lanced with a scalpel
Pus should be expressed and cultured In some circumstances, antibiotics should be
prescribed after lanced (trimethoprim/sulfamethoxaszole, cephalexin)
SCABIESCutaneous Bacterial Infections and Infestations
Scabies
Caused by itch mite Sarcoptes scabiei
Common in children, nursing home residents, recently hospitalized individuals
Infestation produces intense pruritus, especially at night
Typical patient has 10-20 mites on their body and rash is caused by allergic reaction to mites and feces
Scabies Clinical Manifestations
Areas commonly involved include finger webs, abdomen, breast, groin, including penis
Classic lesions are borrows – thin white lines
Crusted scabies – thick crusts on hands, feet, scalp due to thousands or millions of mites
Scabies Treatment
Topical permethrin
Oral ivermectin in resistant cases
Wash sheets, bedclothes, etc.
Treat contacts
Pediculosis Capitis (Head Lice)
Most common in children of preschool age through elementary school; uncommon in African Americans
Presents as intense scalp pruritus due to hypersensitivity to lice saliva or stool
Physical exam reveals nits (eggs) attached to hair shafts, occasionally adult lice
Spread by head to head contact or fomites, like hats or combs
Pediculosis Capitis Treatment
Topical permethrin – some resistance develops
Topical malathion
Oral ivermectin for resistant cases
Pediculosis Pubis (crab lice)
Caused by crab louse (phthirus pubis)
Most commonly sexually transmitted
Produces intense pruritus in genital region
Treatment involves permethrin 5% cream and sometimes oral ivermectin in resistant cases
Cutaneous Bacterial Infections and Infestations Quiz
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QUESTIONSCutaneous Bacterial Infections and Infestations