Cutaneous Bacterial Infections and Infestations David R. Carr, MD FAAD Division of Dermatology The Ohio State University

Learning Objectives How to diagnose cutaneous bacterial infections and cutaneous infestations of the skin based on their clinical findings. How to plan treatment approaches for bacterial infections of the skin. At the end of this module, you will know the following:

IMPETIGO/FOLLICULITIS Cutaneous 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)

SCABIES Cutaneous 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 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

Thank you for completing this module David R. Carr, MD FAAD

QUESTIONS Cutaneous Bacterial Infections and Infestations