Lecture 37 - Dermal Infections and Nails

what are protective mechanisms of the skin

Epidermis forms protective barrier

Sebaceous glands secrete oily sebum providing an acidic pH of 5.5 that is unfavourable for microbial growth

Normal flora of the skin competes with potential pathogenic organisms

Effective immune cells: Langerhans cells, mast cells and macrophages in the dermis

what are the 4 main types of skin infections

bacterial

viral

fungal

parasitic

what are the most common bacteria causing skin infections

Staphylococcus and Streptococcus species.

what comorbidities increase susceptibility to bacterial infections

diabetes, vascular insufficiency, and being immunocompromised Intravenous drug use may increase risk

what are complications of bacterial skin infections

Skin breakdown

Abscess formation

Sepsis (can be life-threatening)

Septic emboli

Scarring or postinflammatory hyperpigmentation

Infections due to resistant bacteria (eg, methicillin-resistant Staphylococcus aureus/MRSA) may be more difficult to treat.

what is impetigo characterized by

Characterized by pustules and honey-coloured crusted erosions.

Secondary infection of wounds or other skin lesions with the same pathogens is called ‘impetiginization’.

Classified into non-bullous (starts with one lesion, limited erythema, lesions burst and form honey colored crust, patients generally feel well) and bullous impetigo (quick bullae formation, ruptures and oozes yellow fluid, systemic symptoms may be present)

is impetigo contagious

yes

what organism causes impetigo

Staph aureus

Strep pyogenes

what is the appearance of impetigo as it develops

The first sign of impetigo is a patch of red, itchy skin. Pustules develop on this area, soon forming crusty, yellow-brown sores that can spread to cover entire areas of the face, arms, and other body parts.

how long does impetigo last

Impetigo is considered self-limiting (~2-3 weeks to heal) but antibiotics provide quicker resolution and prevents the spread

what are non-pharm treatments for impetigo

Avoid sharing clothing and towels

Frequent hand-washing, hot wash bedding, towels etc.

Avoid close contact with others when you have impetigo

Antiseptic washes to cleanse area may be recommended (chlorhexidine)

when is systemic antibacterial treatment needed for impitego

Patient has systemic symptoms (e.g.fever)

Widespread disease

Immunocompromised

Renal disease

Valvular heart disease

No improvement with topical treatment

what should be done before applying a topical antibacterial

impetigo crusts should be removed with warm water or saline compresses or soap-and-water washes

what topical antibiotics can be used for impetigo

Mupirocin

Fusidic acid

Polysporin®

how is mupirocin used for

Effective against gram-positive organisms only

Apply BID–TID × 5 days or until all lesions are healed

how is fusidic acid used

Effective against gram-positive organisms only

Apply BID–TID × 5 days or until all lesions are healed

how is polysporin used

E.g. polymyxin B, bacitracin, gramicidin and neomycin

Inferior to mupirocin and fusidic acid

Apply TID for up to 7 days or until all lesions are healed

when might recurrent impetigo occur

may occur when there is S. aureus carriage in the anterior nares or perineum

how should you treat a positive culture of impetigo

5-day eradication regimen consisting of topical mupirocin applied to the nares 2–3 times daily and daily washing with topical chlorhexidine or hexachlorophene (particularly the perineum and axilla)

what systemic antibiotics can be used for impetigo - MSSA

Usually 7 day regimen with any of the following: amoxicillin/clavulanate, cefadroxil, cephalexin and cloxacillin

what systemic antibiotics can be used for impetigo - MRSA

Doxycycline, clindamycin or sulfamethoxazole/trimethoprim

what are monitoring and follow up considerations for impetigo

Patients are no longer considered infectious approximately 48 hours after initiation of therapy

Monitor for development of systemic symptoms

Monitor for vesicle, crust and bullous resolution

Monitor for development of hypo or hyper pigmentation from infection

Resolution of symptoms should occur within a week, refer if persistent symptoms or recurrent

what is folliculitis

Small, raised, inflamed, pruritic pustules less than 5 mm in diameter

Noninfectious causes may be termed “pseudofolliculitis” and are induced by friction and/or occlusion (e.g., hair removal)

what is the most common cause of folliculitis

Staph aureus

other organisms may be causative such as Pseudomonas (exposure to hot tub/swimming pool)

what is a skin abscess

a collection of pus within the dermis and deeper skin tissues. Painful, tender, inflamed nodule

May have overlying pustule surrounded by a rim of inflammation and edema. Spontaneous drainage of pus may occur

what are Furuncles

a subtype of an abscess which occurs in skin containing hair follicles. Extension into dermis and subcutaneous tissue. Commonly: MSSA or MRSA.

what is a carbuncle

subtype of an abscess which occurs in skin containing hair follicles. Interconnecting multiple furuncles that coalesce into a single purulent mass are termed a carbuncle. Commonly: MSSA or MRSA.

what are non-pharm treatments for folloculitis/abscesses

Lesions will spontaneously rupture, however, carbuncles may needs to be incised

Warm water or saline compresses to promote drainage

Wash area with soap and water to decrease bacterial colony

Cover with sterile dressing

• Drainage from lesions can spread infection to other parts of the body or to other people!

Wash items touching lesion daily

what are phamrmacological treatments for folliculitis and abscesses

Topical antibiotic regimens as seen in impetigo

Topical clindamycin/benzoyl peroxide formulations have also been prescribed for folliculitis

what are systemic antibiotics considered in folliculitis and abscesses

Inadequate clinical response to incision and drainage

Multiple lesions

Lesions in an area where drainage may be difficult

Associated comorbidities

Immunosuppression

Systemic signs of infection (fever, tachypnea, tachycardia, leukocytosis)

what are oral antibiotic options for folliculitis and abscesses

Sulfamethoxazole/trimethoprim (SMX/TMP), doxycycline, minocycline and clindamycin

MSSA: Cephalexin or cloxacillin

when should IV antibiotics be considered for folliculitis and abscesses

Immunocompromised patients

Patients who fail oral antibiotic therapy combined with incision and drainage and who exhibit signs of severe systemic infection

what are monitoring and follow up parameters for folliculitis and abscesses

Monitor for development of boils and lesions with pus

Systemic symptoms (e.g. fever resolution)

Pain resolution

Recurrent infection development

Allergy to medications (drug eruptions)

what is cellulitis

Infection from an entry point such as a wound, maceration between toes, fingers

Unilateral often and most commonly found in limbs

First sign of infection, feeling unwell with fever, chills and shakes.

Systemic symptoms are soon followed by the development of a localised area of painful, inflamed, swollen skin.

Skin may also be dimpled, warm to touch, blistering, and abscess, ulceration or purpura (red, purple or brown, non-blanchable spots caused by bleeding into the skin) may be present.

what are non-pharm treatments for cellulitis

Elevation of affected area helps to reduce edema

Cool, wet compresses can be used to relieve local discomfort.

Given the higher recurrence rates for lower-extremity cellulitis, contributing factors (e.g., edema, stasis dermatitis, interdigital tinea pedis) should be identified and treated in all patients

Daily compression stocking use in patients with chronic lower extremity edema have been shown to reduce recurrent cellulitis (15% vs. 40%)

what oral antibiotics can be used for cellulitis (mild-moderate disease)

Cephalexin PO x 5 days OR Cefuroxime PO x 5 days

Allergy to above: Clindamycin, cloxacillin

what are monitoring and follow up considerations for cellulitis

After initiation of cellulitis treatment, the affected area can appear to worsen (i.e., deepening of erythema and extension beyond demarcated area) within the next 24–48 hours before clinically improving.

No improvement within 48-72 hours, refer immediately (redo culture and sensitivity and adjust therapy)

what viruses cause palmar/plantar warts

HPV Types 1, 2, 27, 57

Thick, endophytic, sloping sides, central depression

Can be painful

what viruses cause common warts

HPV Types 1, 2, 4, 27, 57

Fingers, knees, elbows, nailfold

Hyperkeratotic, exophytic, dome shaped, punctate black dots

what viruses cause flat warts

HPV Types 3, 10, 28 and 29

Skin colored or pink on white skin, smooth surface, flat topped

Mainly dorsal hands, arms and face

what is the treatment paradigm for warts

Confirm it is a wart (do not forget about the mimics) - refer for a biopsy

Start with topical therapy (i.e salicylic agents and/or physical modalities)

Progress to alternative topical/physical therapies for refractory disease

what are non-pharm treatments for warts

Discussed in PMCO 1

salicylic aicd, OTC products

what are Rx treatments for warts

Cantharidin (0.7%) (in office)

Bleomycin sulphate (0.1–1 units/mL) intralesional injection (in office)

Imiquimod 5% cream

5-Fluorouracil 5% cream

DPCP (in office)

Topical Retinoid

Cimetidine

what are monitoring and follow up parameters for warts

Warts may take 3-4 months to resolve

Monitor for resolution of size of warts

Monitor for change in shape or color of wart - could suggest that this is not a wart!

Signs of infection (redness, pus, pain)

Warts that continue to grow quickly require further assessment

rIritation to topical agent

Address any pigmentary changes (hypo- or hyperpigmentation)

Failure in response - check for adherence and how the patient uses the medication

what is Onychomycosis

fungal infection of the nail

The distal end and sides of the nail lift or become discoloured and crumble.

Flaky, white patches and pits appear on the top of the nail plate.

Discolouration of the nail, eg, yellow, white, grey, or green discolouration

Ridging, crumbling, and sometimes eventual complete nail plate destruction.

Scaling occurs under the nail.

what are pathogens that commonly cause Onychomycosis

Dermatophytes (Epidermophyton, Microsporum and Trichophyton genera) Yeasts (mainly Candida)

how is Onychomycosis diagnosed

Direct microscopy (potassium hydroxide [KOH] examination of scrapings from the nail bed)

Biopsy (nail tissue/clippings with periodic acid–Schiff stain)

Culture

what are non-pharm treatments for Onychomycosis

Wearing footwear and socks that minimize humidity

Don’t share nail clippers or foot wear

Keeping nails clean and cut short

Prevent further physical trauma to nails

what is the typical duration of treatment for Onychomycosis

3-6 months

what are monitoring parameters for Onychomycosis

Complete clinical cure = 0% nail plate involvement ■

Clinical improvement = <5–10% nail plate involvement

Incomplete clinical response = >10% nail plate involvement (reassessment is required)

Monitor for irritation from topical agents or adverse effects from systemic agents

Monitor for recurrence of a nail infection or a concurrent skin infection

what agents are used for Onychomycosis

Efinaconazole 10% solution

Ciclopirox olamine 8% lacquer

Propylene glycol 66.4%/urea 20%/lactic acid 10% solution

Itraconazole

Terbinafine

how long does resolution of Onychomycosis take

approx 12 months

solution of the fungal infection takes months (~12 months) ○ Pharmacist can check in monthly or at refills

Measure distance of outgrowth of disease-free nail (normal growth rate is 1.5–2 mm/month)