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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Thank you for completing this module

David R. Carr, MD FAAD

David.carr@osumc.edu

QUESTIONSCutaneous Bacterial Infections and Infestations