Jason M Cheyney, MPAS, PA-C

The “B” Side of Skin Infections

Objectives

⚫ Refresher on less Common Infections

– Bacterial

– Fungal

⚫ Treatment regimens

⚫ Laboratory evaluations

⚫ Follow-up

Bacterial Infections

⚫ Gram Positive

⚫ Gram Negative

Gram Stain Testing

Gram stain testing

⚫ Named after Hans Christian Gram who developed the technique

⚫ Bacteria is heat fixed to slide

⚫ Primary stain is applied, most commonly crystal violet stain

⚫ Iodide is added to bind the primary stain

⚫ The slide is then decolorized with ethanol or acetone

⚫ Counter stain applied, commonly safranin which gives red pink

⚫ Peptidoglycan in cell wall absorbs primary stain, lack of peptidoglycan allows absorption of counter stain.

⚫ Test is being replaced by more specific tests such as PCR, not all bacteria are able to be identified via this method so there are gram indeterminate species

Gram Positive1

– Bacteria that stain purple from the violet stain used in the

gram stain test

– Most antibiotics are produced by this class, because of this

it is felt gram negative bacteria are developing due to

antibiotic stress

– Contain a cytoplasmic lipid membrane and thick

peptidoglycan layer.

– Peptidoglycan layer responsible for retaining the stain after

the decolorization stage of the gram stain test

– Lack thick outer membrane allowing uptake of stain and

penetration of antibiotic which leads to greater response to

antibiotic therapy

Staphylococcal

⚫ Normal inhabitant of the anterior nares, umbilicus, and anus

⚫ Most common pathogen in:– Impetigo

– Folliculitis

– Furunculosis

⚫ Bacterial swab is important for diagnosis and treatment– >8-20% of cases MRSA2

⚫ Treatment– Antibiotic

⚫ Oral directed by resistance and sensitivity as well as host allergy

⚫ Topical mupirocin in the nares, umbilicus and anus

– Incision and drainage if abscess formation⚫ Warm compresses

Special Types

⚫ Paronychia

⚫ Botryomycosis

⚫ Impetigo

⚫ Scalded skin syndrome

⚫ Toxic shock syndrome

Paronychia

Botryomycosis

Impetigo

Staph scalded skin

Toxic shock

Streptococcal

⚫ Scarlet Fever– Occurs secondary to strep pharyngitis

– Strawberry tongue

– Pastias lines

– Produced by an exotoxin

– PCN drug of choice

⚫ Erysipelas– Erythematous edematous patch typically starts on cheek(s)

– Butterfly pattern on face can be confused with SLE

– PCN Drug of choice

⚫ Necrotizing Fasciitis– Anesthesia is very characteristic

– Refer for surgical debridement ASAP!

Scarlet fever

Erysipelas

Erysipeloid of Rosenbach

⚫ Purple marginated swelling of hands

⚫ Most distinquishing feature bluish erythema

⚫ Erysipelothrix rhusiopathiae causative organism

⚫ Found in dead animal matter– Common in swine and fish

– Widespread among commerical fisherman

– Seen in veterinarians, meat packers particularly those that deal with pork

⚫ Typically self limited

⚫ PCN is DOC

Erysipeloid of Rosenbach

Anthrax

⚫ Three forms– Cutaneous(Most common >95%)

– Inhalation(woolsorters disease)

– Gastrointestinal(No US cases)

⚫ Causative agent Bacillus anthracis

⚫ Acute, rapidly necrosing, PAINLESS carbuncle, suppurative regional adenitis

⚫ Begins with rapid inflammation and bulla formation.

⚫ Bulla ruptures and is purulent

⚫ Dark brown eschar is present typically surrounded by vesicles

⚫ Regional lymph glands typically enlarge and suppurate

⚫ Death occurs in up to 20% of untreated cases

⚫ Typically results from contact with infected animals

⚫ PCN DOC

Anthrax

Cutaneous Diphtheria

⚫ Causitive agent Corynebacterium diphtheriae

⚫ Usually seen as punched out ulcers with pale blue tinge

⚫ Can be seen in chronically impetiginized, eczematous skin on culture

⚫ Common in tropical areas

⚫ Most cases in US are seen in unimmunized migrant farm workers

⚫ Treatment consists of immunization and Ax therapy

Cutaneous Diphtheria

Erythrasma

⚫ Causative agent Corynebacterium minutissimum

⚫ Sharply delineated, dry, brown, slightly scaling patches

⚫ Occurs in intertriginous areas

⚫ Woods light diagnositic– Coral red fluorescence

– Caused by a poryphorin released by the bacteria

⚫ Erthromycin DOC

⚫ Topical Ax very helpful

Erythrasma

Pitted Keratolysis

⚫ Causitive agent typically Corynebacteria

⚫ Infection of plantar stratum corneum

⚫ Soles covered with shallow asymptomatic discrete

round pits

⚫ Common in men with excessively sweaty feet

⚫ Typically asymptomatic but often very malodorous

⚫ Improved foot cleansing helpful

⚫ Topical antibiotics typically curative

Pitted Keratolysis

Gram Negative1

⚫ Bacteria that do not retain the violet stain in the gram stain decolorization step.

⚫ Alcohol degrades the thick outer membrane used in this step

⚫ Peptidoglycan layer much thinner and takes up the counter stain making them look pink or red

⚫ The thicker outer membrane makes this class more resistant to antibiotic therapy

Toe web infections

⚫ Typically caused by Pseudomonas aeruginosa

⚫ Commonly begins with dermatophytosis

⚫ Inflammation, maceration, bad odor and edema are typically seen

⚫ With widespread involvement it may be difficult to culture dermatophyte

⚫ Dual therapy with Ax and Antifungal typically necessary (shotgun tx)

Toe web infections

Hot tub folliculitis

⚫ Causative agent Pseudomonas aeroginosa

⚫ Characterized by pruritic follicular based papulo-

pustular lesions, particularly under covered areas

⚫ Occurs 1-4 days after being in hot-tub or whirlpools

⚫ Typically self-limited resolves in 7-14 days

⚫ Oral fluoroquinolones helpful in prolonged disease or

pts with constitutional symptoms.

Hot tub folliculits

External Otitis

⚫ In most cases causitive agent Pseudomonas

aeruginosa

⚫ Typically seen in swimmers

⚫ Malignant external otitis seen in elderly with DM II

– Facial nerve palsy can occur

– Can be life-threatening if left untreated

⚫ Therapy directed against causitive agent

– Systemic antibiotics and acetic acid compresses

External Otitis Media

Gram Negative Folliculitis

⚫ Multiple causative agents

⚫ Can complicate Isotretinoin therapy

⚫ Typically presents with “juicy” pustular

eruption

⚫ Systemic antibiotics

Gram Negative Folliculitis

Chancroid

⚫ Haemophilis Ducreyi causitive agent

⚫ STD

⚫ Tender ulcers on the genitalia

⚫ Adenitis,painful, present in over 50%

⚫ Characterized by chronic, painful, destructive ulcers

⚫ Therapy directed at causitive agent and consider STD workup and RPR and HIV test for several months after diagnosis

⚫ DOC is azithromycin 1 g, single dose

⚫ Partners should be treated.

Chancroid

Granuloma Inguinale

⚫ Calymmatobacterium granulomatis causitive

agent

⚫ Mildly contagious

⚫ Locally destructive, chronic, granulomatous

beefy red ulcerations

⚫ Typically painless

⚫ DOC sulfa or TCN class

Granuloma Inguinale

Gonococcal Dermatitis

⚫ Rare infection

⚫ Typically occurs after inoculation from GC to

an area of injury

⚫ Lymphangitis and pustules occur

⚫ Similar to herpetic whitlow

⚫ Infants can contract from delivery in infected

mother

⚫ TOC single dose cipro, 500 mg

Gonococcal Dermatitis

Gonococcemia

⚫ Hemorrhagic vesiculopustular eruption

⚫ Onset with fever and arthralgias

⚫ TOC ceftriaxone

Gonococcemia

Vibrio Vulnificus

⚫ Rapidly expanding cellulitis

⚫ Occurs mainly along Atlantic seacoast– Seen commonly in Atlantic seacoast fisherman

⚫ Localized skin infection occurs after contact with seawater in an open wound

⚫ Most commonly on lower extremities

⚫ Pts with advanced liver disease susceptible to septicemia which is fatal >50% of cases

⚫ Surgical debridement and ax therapy

Dog and Cat Bite

⚫ Capnocytophaga canimorsus

⚫ Normal flora in dogs and cats

⚫ Complicated course in individuals who have undergone splenectomy, alcoholism or chronic disease

⚫ Most cases in sick individuals

⚫ Necrotizing eschar at site of bite

⚫ Fever, nausea and vomiting precede the eschar

⚫ Treatment is intensive IV ax

Cat scratch disease

⚫ Bartonella Henselae causitive agent

⚫ Common in children and young adults

⚫ Most common cause of chronic lymphadenopathy in this group

⚫ Transmitted from cat to cat by fleas and cat to human by scratches

⚫ Begins as small bump looks like and insect bite

⚫ Lymphadenopathy the hallmark of the dz begins one to two weeks after primary lesion

⚫ Most resolve spontaneously without ax therapy needed

⚫ Ax therapy may be needed

Cat Scratch Disease

Plague

⚫ Yersinia pestis causative agent

⚫ Transmitted from fleas on rodents to humans

⚫ Skunks, rabbits, rock squirrels, prairie dogs, chipmunks are some other common hosts

⚫ 90% of cases since 1945 have been in the rocky mountain states

⚫ IM streptomycin TOC

Plague

Tularemia

⚫ Francisella Tularensis causative agent

⚫ Characterized by sudden onset of chills, headache and leukocytosis.

⚫ Begins with a papule or nodule that rapidly ulcerates

⚫ Lymphangitis occurs at the primary site

⚫ Most common vector wild rabbits or the bite of the deer flies or ticks

⚫ Occurs most often in the western and southern US

⚫ Recommend protective gloves to anyone who dresses wild rabbits

⚫ IM streptomycin TOC

Tularemia

Mycoses

⚫ Superficial

– Tinea

– Candidiasis

⚫ Deep

Coccidioidomycosis

⚫ Inhalation of coccidioides immitis

⚫ 60% of pts asymptomatic

⚫ At onset papular rash may be present

⚫ Erythema nodusum can develop as course progresses, this is a favorable prognostic sign

⚫ The fungus is isolated from the soil and vegetation.

⚫ It is contracted from inhalation of dust laden with the organisms

⚫ Most commonly seen in the southwest

⚫ Cutaneous findings consist of granulomas around hair follicles and sweat glands

⚫ Fluconazole is TOC

Coccidiomycosis

Histoplasmosis

⚫ Contracted by inhalation of airborne spores

⚫ Predominantly a lung infection

⚫ 1 in 2000 cases involve skin

⚫ Immunocompromise and old age risk factors

⚫ Skin involvement is usually a chancre type lesion

⚫ Most commonly seen in North America in the central states, Mississippi River basin

⚫ Feces of birds and bats contain the fungus

⚫ Itraconazole for several months may be needed in cases that don’t clear spontaneously

Histoplasmosis

Cryptococcosis

⚫ Predominantly lung disease

– 10% involves other organs to include skin

⚫ Immunocompromised and elderly at greater risk

⚫ Skin involvement typically represents disseminated disease and poorer prognosis

⚫ Worldwide distribution

⚫ Human skin, soil, dust and pigeon droppings common vectors

⚫ Inhalation is the portal of entry

⚫ Amphotericin B IV followed by oral fluconazole is effective

Cryptococcosis

North American Blastomycosis

⚫ Two forms– Primary nodule with satellite lesions along

lymphatics

– Slow progressive granulomatous lesions

⚫ Predominantly a lung infection

⚫ Prevalent in SE US, Ohio and Mississippi River basins.

⚫ Itraconazole for several months

North American Blastomycosis

Sporotrichosis

⚫ Most common and least serious of deep infections

⚫ Typically seen as a nodule or ulcer that heals and nodules develop along draining lymphatics

⚫ Occupational disease– Gardners

– Florists

– Laborers

⚫ Contracted commonly from the thorn of plants or straw

⚫ Itraconazole for several months

Sporotrichosis

QUESTIONS?

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