Infections & Infestations Flashcards

Question

Varicella zoster (Herpes zoster, shingles)

Answer 1

● A cutaneous infection from the varicella-zoster virus (VZV) ○ It reactivates from its latent state in a posterior root ganglion, generally infecting a single dermatome ● Herpes zoster inflames the sensory root ganglia and the skin of the associated dermatome

Answer 2

● Pain, itching, burning localized to the dermatome; may precede eruption by 4-5 days ● Normally one dermatome is affected, sometimes 1-2 adjacent dermatomes ● Eruption begins with red swollen plaques of various sizes, spread along the dermatome ● Vesicles arise in clusters from the erythematous base, contain cloudy, purulent fluid by days 3-4

Answer 3

● Clinical evaluation ● Tzanck smear can confirm infection → will see multinucleated giant cells ● PCR or culture may differentiate the virus

Answer 4

● Symptomatic treatment ● Antivirals (acyclovir, famciclovir, valacyclovir) ○ Especially for immunocompromised pts ○ Begin as soon as possible (<48 hrs) ● Analgesics are often necessary ● Wet dressings may help

Answer 5

● Involvement of any branch of the ophthalmic nerve ● Vesicles of the side of tip of the nose (Hutchinson’s sign) are associated with the most serious ocular complications ● PO antiviral treatment results in decreased frequency of complications Consult with ophthalmology!!

Answer 6

● Persistent or recurrent pain in the involved distribution lasting more than 30 days after the rash ● Pain is often severe, may be intermittent or constant, may be debilitating ● More common in the elderly

Answer 7

● Can be difficult; there’s no reliable treatment ● Gabapentin, cyclic antidepressants (amitriptyline), topical capsaicin or lidocaine ointment ● Opioid analgesics may be necessary

Answer 8

● Immunocompetent adults (>50 years) should be given the recombinant zoster vaccine (Shingrix) ○ Two IM doses, 2-6 months apart

Answer 9

● Common warts (verruca vulgaris) ● Flat (plane) warts ● Plantar warts (verruca plantaris)

Answer 10

● Warts are benign epidermal proliferations; infects skin and mucous membrane Skin Disease Diagnosis and Treatment, 4th edition. Habif and Dinulos; Transmission: simple skin-to-skin contact, often at sites with small skin breaks, abrasions, or other trauma. Also, autoinoculation

Answer 11

● Flesh-colored papules evolve into dome-shaped, gray to brown, hyperkeratotic, discreet and rough papules ○ Black dots are thrombosed capillaries ● Common sites: hands/fingers, periungual skin, elbows, knees, and plantar surfaces ● Filiform warts are finger-like projections; often occur on the face ● Generally asymptomatic; occasionally itchy

Answer 12

squamous cell carcinoma

Answer 13

● OTC salicylic acid (most common) ○ Daily applications are needed ● Liquid nitrogen cryotherapy (most common) ○ May require several cycles of treatment ● Vinegar applications ● Imiquimod

Answer 14

● Avoid direct contact with warts. This includes your own warts. ● Don't pick at warts. Picking may spread the virus. ● Don't use the same emery board, pumice stone or nail clipper on your warts as you use on your healthy skin and nails. Use a disposable emery board. ● Don't bite your fingernails. Warts occur more often in skin that has been broken. Nibbling the skin around your fingernails opens the door for the virus. ● Groom with care. And avoid brushing, clipping or shaving areas that have warts. If you must shave, use an electric razor.

Answer 15

● Benign cutaneous hyperproliferation, also due to HPV ● Common in children and young adults ● Spread locally through mildly traumatized skin (shaving)

Answer 16

● Pink, light brown, or light yellow papules- slightly elevated and flat-topped; 0.1 to 0.3 cm in size ● May be grouped or in a line ● Typical sites: forehead, back of hands, chin, neck, legs ● Generally asymptomatic

Answer 17

Prognosis: may be very resistant to treatment ● Salicylic acid preparation, applied daily ● Imiquimod cream (high cost; off-label use) ● Tretinoin cream ● Liquid nitrogen (may not respond to therapy) ● 5-fluorouracil cream

Answer 18

● Frequently occur at points of maximal pressure at the bottom of feet, such as over the heel, toes, heads of metatarsal bones ● A cluster of warts = “mosaic warts”

Answer 19

● Round, single or multiple, coalescing, flesh-colored, rough keratotic papules ● Punctate black dots are capillary loops ● May be tender with pressure ● Some warts are depressed, resembling numerous small pits

Answer 20

● Often difficult ● Therapy not required as long as they are painless ● Keratolytic therapy with salicylic acid ● Imiquimod ● Blunt dissection ● Cryosurgery ● Vinegar applications ● Electrodesiccation/curettage ● Diluted intralesional cidofovir

Answer 21

● An acute infection of the dermis and subcutaneous tissue ○ Characterized by fever, erythema, edema, and pain ● Often caused by Group A beta-hemolytic strep/Strep pyogenes and Staph aureus

Answer 22

● Risk factors include skin abnormalities (eg, trauma, ulcers, fungal infections), diabetes, cirrhosis, poor lymph circulation, being malnourished or immunocompromised. Also IV drug or alcohol abuse. ● Infection is most common in the lower extremities

Answer 23

● A spreading red, swollen, tender, or painful area with an indefinite border ● Skin appears tight ● Palpation causes pain but rarely crepitus ● Patient may have nausea, chills, shaking ● May have regional lymphadenopathy ● Abscesses (collection of pus) may develop if cellulitis worsens

Answer 24

● Clinical examination ○ Skin will be red, warm, tender, and swollen ○ Borders are indistinct ● Mild to mod leukocytosis and slightly elevated ESR may be present ● If abscess is present, I&D and culture of drainage is helpful

Answer 25

● Antibiotic ○ Nonpurulent cellulitis: dicloxacillin or cephalexin ○ High risk for MRSA cellulitis: TMP-SMX, clindamycin, doxycycline, vancomycin ○ If severe, may require IV or IM antibiotics for 2-5 days ● Elevate affected limb ● Abscesses require drainage

Answer 26

● An acute, inflammatory form of cellulitis; more superficial than other types and includes lymphatic involvement, “streaking” ● Margins are sharply demarcated ● Sudden onset of symptoms ● Usually infection of Group A Strep

Answer 27

Erysipelas

Answer 28

Prodromal symptoms last for 4 - 48 hours and consist of malaise, myalgias, chills, fever, and, occasionally, decreased appetite and vomiting

Answer 29

● Raised, clearly marginated borders ● Red, tender, and firm spots → deep red, hot, elevated shiny area ● Frequent lymphangitic streaking

Answer 30

● Clinical evaluation ● Leukocytosis is common ● Blood culture (in toxic-appearing patients)

Answer 31

● First line: penicillin V, dicloxacillin, amoxicillin ● For patients with PCN allergies: cephalexin, TMP-SMX, azithromycin or clarithromycin ● Bed rest and elevation of affected limb If the disease is severely advancing, hospitalization and IV antibiotics are indicated. Must treat promptly, otherwise death may result due to systemic toxicity

Answer 32

● An infection and inflammation of hair follicles ● Often worsens with perspiration, trauma, and friction ● May be infectious or noninfectious ○ Several types will be discussed shortly ● Common bacterial pathogens include: ○ Staph aureus ○ Pseudomonas aeruginosa → “hot tub folliculitis”

Answer 33

● An acneiform eruption worsens and becomes pustular ● Overgrowth can occur in people treated chronically with antibiotics ● Treatment with Isotretinoin

Answer 34

● Caused by Pseudomonas aeruginosa ● Occurs 1-4 days after bathing in a contaminated hot tub, swimming pool etc ● Often clears spontaneously, may require Cipro

Answer 35

● Results from chronic frictional exposure (ie wearing tight pants)

Answer 36

● A chronic problem, caused by ingrown hairs, most often at the neck; affects men and women; common in people with tight, curly hairs; worsens with shaving ● Discontinue shaving; only cure is permanent hair removal

Answer 37

● Pruritic, extensive papules suddenly appear on face, neck, chest ● Test for HIV; confirm testing with biopsy

Answer 38

● Results from occlusion (ie exposure to oil, greases, or occlusive ointments

Answer 39

● Dome-shaped pustules with small erythematous halos arising in the follicle ● Lesions are sometimes tender and itchy

Answer 40

● Clinical diagnosis ● Culture not usually necessary ● May do a KOH exam to rule out other conditions

Answer 41

● If mild, may resolve without treatment ● Topical antibiotic therapy ○ Mupirocin ○ Clindamycin ● If severe, oral antibiotics may be required ○ Dicloxacillin ● If fungal, treat with oral antifungal ● Avoid heat, friction, and occlusion ● Antibacterial soap and warm, wet dressings may be helpful

Answer 42

● A furuncle (“boil”) is a walled-off, deep and painful, firm or fluctuant mass enclosing a collection of pus ● A carbuncle is an extremely painful, deep, interconnected collection of multiple infected, abscessed follicles; comprised of several furuncles

Answer 43

Staph aureus

Answer 44

-Any hair-bearing site can be affected; also, sites of high friction and sweating -Common regions: waistline, anterior thighs, buttocks, groin, axillae

Answer 45

Furuncle: ● Red, swollen, and painful mass that drains at the surface ● Patient is afebrile Carbuncle: ● Deep, tender, firm subcutaneous erythematous papules enlarge to nodules that may be stable or become fluctuant ● Coalesces to form a larger mass with multiple draining points ● Malaise, chills, and fever may precede or occur during the height of inflammation

Answer 46

● Clinical diagnosis ● Culture of the lesion

Answer 47

● Incision and drainage for fluctuant lesions ○ Obtain specimen to send for culture ● Systemic antibiotics (should be effective against MRSA) ○ If multiple lesions or signs of systemic illness ○ TMP-SMX, clindamycin, doxycycline, dicloxacillin, or cephalexin ● Apply warm compresses to the area several times per day ● Caution - septicemia is a concern

Answer 48

● A common, highly contagious, skin infection of the epidermis ○ Staph aureus (80% of cases) ○ Strep pyogenes

Answer 49

nonbullous impetigo (most common form) and bullous impetigo

Answer 50

flaccid bullae with clear yellow fluid, later becomes darker; ruptured bullae leave a thin brown crust. Fewer lesions and on the trunk more frequently than non-bullous impetigo

Answer 51

most common form; lesions begin as papules, progress to vesicles, then pustules that enlarge and break down to form thick golden crusts. Usually occur on face and extremities. Honey-colored crusts.

Answer 52

● Clinical evaluation ● May gram-stain or culture lesions to confirm diagnosis

Answer 53

Course is self-limiting, but if untreated, may spread and lasts for weeks to months ● Topical antibiotic ointment (for limited skin involvement) ○ Mupirocin ○ Retapamulin ● Oral antibiotics (for widespread impetigo) ○ Cephalexin (or Doxycycline) ● Soaks and scrubbing can be beneficial

Answer 54

● A skin and mucous membrane infection with Candida species, most commonly Candida albicans ○ A yeast that is part of normal skin flora but is an opportunistic pathogen ● Most commonly in skinfolds, digital web spaces, genitals, cuticles, and oral mucosa

Answer 55

● Obesity ● Immunodeficiency ● Hot, humid weather ● Altered flora resulting from antibiotic therapy ● Inflammatory diseases (eg, psoriasis) that occurs in skinfolds ● Poor hygiene ● Tight-fitting clothing ● Infrequent diaper or undergarment changes ● Use of topical steroids

Answer 56

● Intertriginous - red, moist, glistening plaques with satellite pustules and papules with fringes of white scale. Patches vary in size and are pruritic. ● Oropharyngeal - causes white plaques on mucous membranes that may bleed when scraped ● Vulvovaginal- causes pruritus and discharge

Answer 57

● Clinical evaluation ● KOH prep from a pustule or scaly border will show spores and pseudohyphae - is diagnostic

Answer 58

● Topical or oral antifungals ○ Fluconazole (PO if infection is severe or extensive) ○ Nystatin ○ Clotrimazole ■ (troches = an oral formulation) ● Keep affected regions dry

Answer 59

● Fungal infections of keratin in the skin and nails ○ Tinea barbae- beard ○ Tinea capitis- scalp ○ Tinea corporis- body (“ringworm”) ○ Tinea cruris- groin ○ Tinea pedis- foot ○ Tinea unguium or onychomycosis - nail infection ● Dermatophytes are molds that require keratin for nutrition and must live on stratum corneum, hair, or nails to survive

Answer 60

● Transmission occurs via direct skin contact with an infected individual or animal, contact with fomites, or from secondary spread from other sites of infection (eg, scalp, feet, etc)

Answer 61

● Moist, macerated skin ● Obesity ● Diabetes ● Exposure to animals ● Affected family members ● Topical corticosteroid use ● Immunosuppressed states ● Athletics

Answer 62

● Slightly raised border, papules and plaques with a rounded edge and white scales; an advancing border and a relatively clear center ● Asymptomatic or mildly itching lesions

Answer 63

● Clinical appearance ● Potassium hydroxide wet mount (KOH prep)→ hyphae will be present

Answer 64

● Topical or systemic antifungals ○ “Azoles” ○ Allylamines (terbinafine, naftifine, butenafine) ○ Ciclopirox ○ Tolnaftate ● Nystatin DOES NOT work for dermatophyte infections (however, is effective for Candida infections) ● Recommend NOT using combination antifungal and corticosteroid medications

Answer 65

● Lice are flattened, wingless insects that infest the hair of the scalp, body, and pubic region ● Lice attach to the skin and feed on human blood. They lay eggs or nits on hair shafts

Answer 66

○ Head lice - Pediculus humanus var. Capitis ○ Body lice - P. humanus var. Corporis ○ Pubic lice (“crabs”) - Pthirus pubis

Answer 67

● Highly contagious ● Transmitted via direct contact ● More frequent in children ● An obligate human parasite, cannot survive on other animals or furniture ● Does not carry any known human diseases ● Lice have a blood meal every 3-6 hours ● Eggs (nits) are firm casts cemented to the hair shaft, about 1 cm from scalp surface, and hatch in 8-10 days

Answer 68

● Itching is the primary symptom ● Head lice are 3-4 mm in length, often seen on scalp and hair shafts ○ Commonly seen at back of head or behind the ears ● Nits are fluorescent, may use a Wood’s light exam to screen children

Answer 69

● OTC Permethrin rinse 1% (Nix) ○ Treatment of choice ○ Shampoo and dry hair. Saturate hair and scalp with medication. Rinse after 10 minutes ● Other topical pediculicides (eg, pyrethrin shampoos, permethrin 5%, malathion lotion 0.5%) ● Lindane shampoo (UpToDate- not first line d/t safety concerns) ● Repeat treatments in one week, if necessary ● PO Ivermectin- as a single dose, may repeat if needed ● May administer antibiotics if needed for secondary infection

Answer 70

● A parasitic infestation caused by the mite Sarcoptes scabiei ● Causes intensely itching lesions with erythematous papules and burrows in web spaces, wrists, waistline, and genitals ● Patients may complain of a rash with severe itching and an inability to stop scratching

Answer 71

● A severe form of scabies ○ The skin contains thousands of mites and eggs ● May be the source of epidemic scabies ● Often seen in institutionalized or immunocompromised patients ● Characterized by thick scale, crusts, and fissures ● May also accompany long-term use of topical corticosteroids

Answer 72

direct and prolonged skin-to-skin contact; common among family members or sexual partners Transmission through fomites is uncommon for people with classic scabies, but more likely with crusted scabies

Answer 73

● Severe itching is generally present ● A linear or curved burrow ○ Slightly elevated vesicle or papule up to 1-2 mm wide ● May also present with scattered inflamed pustules, linear vesicles, papules etc ● The scabies rash and accompanying pruritus appear 2-6 weeks after exposure

Answer 74

● Often a clinical diagnosis ● Mites, eggs, or feces can be identified via microscope in a scabies preparation ○ Mineral oil is applied to the burrow, vesicle, or papule to preserve the mite feces. The burrow is then scraped with a #15 blade and placed on a glass slide and viewed under a microscope. ○ Often times it is easier to identify mite body parts, feces, or eggs, rather than the mites themselves

Answer 75

● Apply permethrin to entire skin surface, neck down. Bathe after 12 hours; repeat process in one week. ● Wash all bedding and clothing in hot water, or put in hot dryer, at time of medication application ● May also give single dose of PO ivermectin (Use cautiously in elderly patients) ● Topical steroids may help with pruritus and inflammation that may continue after eradication of scabies ● Treat all symptomatic people in family and institution at the same time