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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?
⚫ Thank you for your time and attention.