Bacterial, Fungal, Viral Infections Flashcards
Animal Bites: causative organism & treatment
All bites that break the skin require antibiotics
Organism: Most common = staph aureus or pasteurella multocida
Oral Amoxicillin Clavulanate
IV Ampicillin-Sulbavtam
PCN Allergy: Oral or IV Doxycycline
Impetigo and Ecthyma: Causative organisms & Presentation
Cause: Staph Aureus, GAS, or both
Bullous Impetigo: blisters or bullae, S. Aureus. Age <2
Impetigo: scattered macules –> vesicles + pustules –> honey colored crust
Ecthyma: Chronic, dermis involvement, vesicles –> ulcerations –> erythematous halo
Risk: poststreptococcal glomerulonephritis
Cellulitis and Erysipelas: Causative organisms & Presentation
Cellulitis Cause: GAS, S. Aureus
From Animal Bites or Scratches: Pasteurella Multocida
Erysipelas Cause: S. Pyogenes
Presentation Cellulitis: Skin and SQ layers, may spread systemically
Presentation Erysipelas: LE’s, scalp, face. Sharply demarcated erythema, orange-peel. spreads rapidly
Orbital Cellulitis First Line
Ceftin, Ceftaxamine plus MRSA coverage
First Line Tx Cellulitis: Animal Bites
Amoxicillin / Clavulanate for aerobic and anaerobic coverage
Grab a swab!
Pasteurella multocida is bacterium
First Line Cellulitis: Paranychia
Cefalexin, Augmentin
First Line Tx: Cellulitis & Erysipelas
Amoxicillin / Clavulanate: GAS, Staph, MSSA (no MRSA)
Cephalexin: GAS, MSSA (No MRSA)
Doxycycline: MRSA + MSSA (poor GAS)
PCN Allergy: Clindamycin: MRSA + MSSA (C.Diff Risk)
TMP/SMX: MRSA (Poor GAS)
IV: Vancomycin, Daptomycin, Linezolid
Folliculitis: Causative organism & Presentation
Most Common: S. Aureus, MRSA
Hot tub use: Pseudomonas aeruginosa
Presentation: Superficial infection of the hair follicle, erythematous pruritic papules –> pustules
Furunculosis and Carbunculosis: Causative organism & Presentation
Most common: S. Aureus
Presentation: Pus-filled nodule that encircles a hair follicle
Carbuncle: several furuncles together
Risk: Secondary infection like osteomyelitis and endocarditis
First Line Tx: Purulent Skin Infection
I&D
If systemic: Augmentin, Cefalexin
Second-Line: Bactrim, MRSA coverage
Diabetic Foot Infection: Causative organism & Presentation
Presentation: Must show purulence or 2 signs of inflammation
Erythema, warmth, tenderness, pain, induration
First-Line Tx Oral: Diabetic Foot Infection
MSSA: Clindamycin, TMP/SMX, Cephalexin (superficial ulcer +no MRSA)
MRSA: Clindamycin, TMP/SMX, minocycline, linezolid, vancomycin
Aerobic Streptococci: First-3rd line cephalosporins, clindamycin
Enterobacteriaceae: cephalosporins, TMP/SMX
Pseudomonas aeruginosa: Ciprofloxacin, levofloxacin
Bacteroides: metronidazole, clindamycin
Aerobic+Anaerobic: Cipro+Clinda
Necrotizing Fasciitis: Causative organism & Presentation
Organism: Pasturella multocida, Erysipeiothrix, MSSA, MRSA, GAS
Type 1: Polymicrobial
Type 2: Monomicrobial
Type 3: gas gangrene from Clostridium perfringens
Presentation: similar to cellulitis + severe pain, erythema, edema
First-Line: Impetigo & Ecthyma
Bullous & Non-Bullous: Mupirocin 2% if limited BSA
Retapamulin 1%
Oral ABX: Amoxicillin-Clavulanate or Dicloxacillin (PCN) or Cephalexin (1st Gen Cephalosporin) for Staph & Strep
GAS: PCN
MRSA or PCN allergy: Doxycycline, Clindamycin, or SMX-TMP
Streptococcal Glomerulonephritis: IV PCN
First Line Impetigo & Ecthyma if Steptococcus Pyogenes
First generation cephalosporin: Cephalexin (Keflex) or topical Mupirocin 2%
Topical Mupirocin 2%
Retapamulin 1%
Pen VK, PenG
Amoxicillin
Cephalexin
Cefadroxil
Second Line Impetigo & Ecthyma if Steptococcus Pyogenes
Amox/Clavulanate
Macrolides
First-Line Impetigo and Ecthyma if Staphylococcus Aureus:
Topical mupirocin 2%
Retapamulin 1%
Cephalexin (MSSA)
Cefadroxil (MSSA)
Dicloxacillin (MSSA)
Second-Line Impetigo and Ecthyma if Staphylococcus Aureus:
Amox/ Clavulanate (MSSA)
TMP/SMX (MRSA)
Doxycycline (MRSA)
Clindamycin (MRSA)
First Line: Necrotizing Fasciitis
Surgical Debridement
IV: Piperacillin-Tazobactam, Clindamycin, Vancomycin
Culture
Special Considerations Pregnancy & Breastfeeding: Category B Preferred
Amoxicillin-Clavulanate
Cephalexin & Cephalosporins
Clindamycin
Daptomycin
Dicloxacillin
Tinea Versicolor / Pityriasis Versicolor: Organism & Presentation
Organism: overgrowth of Malassezia
Presentation: Well-demarcated, scaling patches of pink, tan, brown
First Line Tx: Tinea Versicolor / Pityriasis Versicolor
First-Line: Selenium Sulfide 2.5% x 7 days, Ketoconazole BID x 2 weeks (cream or shampoo)
Second-Line: Systemic Itraconazole 200 mg x 5 days(Sporanox), oral ketoconazole, oral fluconazole 300 mg once weekly x 2 weeks
Dx: Positive potassium hydroxide test
Candidiasis: Organism & Presentation
Organism: Candida albicans
Presentation: intertriginous areas, diaper, oral, nails, groin. Pustular satellite lesions
First Line Tx: Candidiasis
Topical: Clotrimazole, miconazole, nystatin BID until infection clears
Advantage of being applied only where needed, avoiding antibiotic resistance
Second Line Tx: Candidiasis
Fluconazole 150 mg once weekly x 4 weeks
itraconazole, Ketoconazole
If topical non-effective or infection severe / recurrent
More severe infections or causes that do not respond to tropicals
Typically used for oral, genital, or systemic
Tinea Types & Definition
Dermatophytes that infect nonviable keratinized cutaneous tissues
Tinea Capitis: Head
Tinea Corporis (Ringworm): Body
Tinea Cruris (Jock itch): groin
Tinea Pedis (athletes foot): Feet
Tinea Manuum: hand
Tinea Unguium (onychomycosis): Nails
First Line Tinea Capitis
Oral Therapy only
Griseofulvin 500 mg adults 10 mg/kg/d peds x 6 weeks
First Line Tinea Unguium
Oral therapy only
Terbinafine or Azole Antifungal
250 mg daily x 6 weeks fingernails
250 mg daily x 12 weeks toenails
Topical Allylamine Antifungals (Terbinafine, Lamisil): Drug Facts
MOA: disrupts production of ergosterol. Effective against Dermatophyte
Use: Tinea Corporis, tinea cruris, Tinea pedis
Dose: Apply BID to effect
SE: Burning, irritation
First Line Tinea: All other tineas
Topical Azoles, Miconazole, Lamisol, Tinactin
Griseofulvin Drug Facts
MOA: Depostis keratin precursor cells increasing keratin resistance to fungus
SE: N/V/D, HA, Photosensitivity
Interaction: increase levels of wararin, decrease levels of barbiturates and cyclosporines, decrease efficacy of oral contraceptives, disulfiram effect with alcohol
Systemic Allylamine Antifungal (Terbinafine, Lamisil): Drug Facts
MOA: inhibit squaline epoxidase, causing deficiency of ergosterol
Fingernail: 250 mg/d x 6 weeks
Toenail: 250 mg/d x 12 weeks
SE: diarrhea, dyspepsia, rash, HA, INCREASED LFTs
Systemic Azole Antifungals (Itraconazole, Cresemba): Drug Facts
MOA: inhibit CYP-450 enzymes and inhibits synthesis of ergosterol
Use: tinea capitis and tinea unguium
SE’s: GI, Elevated LFT’s, Visual disturbances
Selenium Sulfide (Selsun Blue) Drug Facts:
MOA: control yeast on the scalp
Use: Seborrheic dermatitis, dandruff, tinea versicolor
Apply: once daily for 10 min, rinse off. Prophylactic use
SE’s: Irritation, hair loss
Nystatin (Mycostatin) Drug Facts
MOA: bind to sterols of cell membrane of the fungus, changes membrane permeability
Use: moist areas, oral thrush, diaper rash, groin, candida species
CXN: not in immunocompromised patients
HSV Diagnostics
HSV-1: PCR is most sensitive and spcific
VZV: PCR
First-Line Tx: HSV-1
Topical: mild, immunocompetent
Acyclovir 5% or Penciclovir 1%
Second-Line Tx: HSV-1
Systemic therapy with Acyclovir, Famciclovir, or Valacyclovir
When topical ineffective or outbreak is severe
Topical Acyclovir 5% and Penciclovir 1% Drug Facts
MOA: inhibit viral DNA synthesis
Apply: 5 times daily x 4 days
SE: skin irritation, pruritus
Oral Acyclovir, Famciclovir, and Valacyclovir Drug Facts
MOA: inhibit viral DNA synthesis
Acyclovir: low bioavailability
Dosing: 5-10 days
CXN: renal disease
SE: HA, Depression, Increased LFTs
First-Line Tx: VZV
Immunocompromised, Pregnant, Rash <72 hrs, Age >50:
Systemic Acyclovir or Valacyclovir x 5 days
Immunocompetent: Treat symptomatically
Capsaicin: reduces substance P, helps postherpetic neuralgia
First-Line Verrucae
Common Verruca Vulgaris (HPV-2): Topical Salicylic Acid 17% at bedtime for 8-12 weeks until wart healed
Plantar Wart (HPV-1): 40% salicylic acid at bedtime for 24-48 hours at a time x 12 weeks
Psoriasis: Drug Causes
Systemic corticosteroids
Lithium Carbonate
Antimalarials
Beta Blockers
Systemic Interferon
Alcohol
Psoriasis Diagnostics:
Clinical Presentation: well-demarcated erythematous papules or plaques surrounded by silvery or whitish scales
Psoriasis Types
Guttate: small, scattered, teardrop papules & plaques. Triggered by infection
Erythrodermic: generalized erythema & scale shedding. Burned appearance. Medical emergency
Pustular: Generalized, localized, palmar-plantar types. 2-3 mm sterile pustules
First-Line Tx: Psoriasis
Moisturizers & topical steroids x 2 weeks
High-potency or very-high potency steroid BID with occlusive dressing
Second-Line Tx: Psoriasis
1 week rest from TCS then 2wks of therapy with same agent x 2 more times
Add a Vitamin D analog BID
Third-Line Therapy: Psoriasis
UV B light treatments, Antimetabolites, Etanercept, or
Psoralens plus UVA light therapy
Psoriasis Topical Agents: Corticosteroid Drug Facts
MOA: promote vasoconstriction
Apply: BID x 2 weeks, decrease to alternating days
Psoriasis Topical Agents: Coal Tar Drug Facts
MOA: depresses DNA synthesis, antiinflammatory and antipruritic properties
Apply: dissolve in hot bath x 10-20 min soak for 30-45 days, 3-7 days per week
CXN: odor, stains clothes and tubs, photosensitivity
Psoriasis Topical Agents: Anthralin Drug Facts
MOA: inhibit DNA synthesis, decrease epidermal proliferation
Apply: 30min -1H, remove
Contraindicated: acute psoriasis, inflammation
CXN: staining
Psoriasis Topical Agents: Vitamin D Analogs Drug Facts
Calcipotriene & Calcipotriol: Mild to moderate psoriasis
MOA: reduction of cell proliferation by binding to receptors in epidermal keratinocytes
Apply: BID x 6-8 weeks
Contraindicated: Hypercalcemia, Vit D toxicity
SE: dry skin, hypercalcemia, rash
Psoriasis Topical Agents: Retinoid Drug Facts
Tazarotene: mild to moderate Psoriasis
MOA: normalizes epidermal differentiation, diminishes inflammation
Apply: once daily at bedtime. 1 week to improvement, clear in 8 weeks
Contraindication: Pregnancy
SE: Pruritis, erythema, burning
Psoriasis Systemic Agents: Retinoid Drug Facts
Acitretin: Long-term therapy
MOA: normalizes epidermal differentiation, decreases inflammation
P/T Therapy: CBC, CMP, Lipid profile
Dosing: 10 mg daily up to 50 mg daily until lesions clear
Contraindicated: pregnancy
SE: elevated lipids, abnormal LFT’s, alopecia, skin peeling, pruritus, dry skin
Psoriasis Systemic Agents: Methotrexate Drug Facts
MTX: generalized psoriasis
MOA: inhibits folic acid reductase
Dosing: 7.5 mg / week administered in 3 doses over 24 hour period
Contraindicated: pregnancy and lactation
SE: HA, Blurred vision, fatigue, malaise, GI distress
Psoriasis Systemic Agents: Cyclosporine Drug facts
MOA: suppresses cell-mediated immune reactions and humoral immunity, inhibits IL-2
Dose: 2-5 mg/kg/d
Contraindication: pregnancy and lactation
CXN: Nephrotoxic
Psoriasis systemic agents: Phosphodiesterase 4 Inhibitors Drug Facts
Apremilast (Otezla)
MOA: Oral small molecule specific to cyclic adenosine monophosphate
Dose: 30 mg BID
SE: Diarrhea, weight loss
Psoriasis Systemic Agents: Biologics Drug Facts
Etanercept (Enbrel), Infliximab, Adalimumab
MOA: binds and inhibits TNF decreasing inflammation
Screening: TB screening p/t initiation
Dose: 50 mg SQ BID x 3 mon
Contraindication: live vaccine, active infection
SE: infection, erythema, rash, URI, ABD pain
CXN: neurotoxicity, liver toxicity
