Skin and Soft Tissue Infections Flashcards
What is nonbullous impetigo?
Honey-yellow crusted lesions likely due to GAS
What is bullous impetigo
There are superficial flaccid bullae which rupture and give rise to crusted lesions. Due to toxin producing staph aureus.
Complication of strep impetigo?
Post strep glomerulonephritis
Skin soft tissue coverage for MRSA orally? [3]
- Bactrim
- Clinda
- Doxy
Treatment of folliculitis
- Mupirocin for mild infections
- Antistaph abx for more severe infections
What is “swimmers itch”
Due to avian schistosomes. Molluscan intermediate hosts release cercaria that trigger an allergic reaction within human hair follicles and pores after freshwater exposure.
Treatment of swimmers itch?
Topical corticosteroids
Antipruritics
What is a carbuncle?
Several furuncles [boils] which have merged
Empiric management of a carbuncle
- I and D
- Culture material
- Empiric treatment with MRSA coverage
Oral MRSA options for SSTI? [3]
- Bactrim
- Doxy
- Clinda
IV options for MRSA SSTI? [4]
- Vanco
- Dapto
- Linezolid
- Ceftaroline
Complication of a carbuncle/furuncle on the face/nares?
Septic cavernous sinus thrombosis
Presentation of cavernous sinus thrombosis?
HA, fever. periorbiral edema, ptosis, proptosis, chemosis, CN III, IV, V, VI [3-6] dysfunction
What area does erysipelas effect?
Upper dermis and superficial lymphatics
Etiology of erysipelas
GAS
Other beta-hemolytic strep
Erysipelas presentation
Raised, well demarcated erythematous indurated lesion of the face or lower extremities which is acute onset. May haver fever and chills.
Treatment of mild erysipelas
- oral penicillin [penicillin V, amoxicillin]
- Cephalexin
- Clinda
Treatment of moderate to severe erysipelas
- IV penicillin G
What area does cellulitis effect?
Deeper dermis and subcutaneous tissue
If cellulitis has fever and chills it is more likely due to what organism?
Strep.
Complication of lower extremity cellulitis?
Thrombophlebitis
Complication of orbital cellulitis? [4]
- Orbital abscess
- Subperiosteal abscess
- Brain abscess
- Septic cavernous sinus thrombosis
What is type 1 necrotizing fasciitis?
Mixed aerobic [Enterobacteriaceae] and anaerobic [Fusobacterium, peptostreptococcus, Bacteroiddes, Clostridum]
What is type 2 necrotizing fasciitis?
Monomicrobical infection with GAS, Staph aureus, aeromonas hydophilia or vibrio vulnificus
How often are blood cultures positive in necrotizing fasciitis?
Only 25% [more frequent than cellulitis though]
Work up of necrotizing fasciitis
CT scan if suspected to look for gas and edema along the fascial planes
MRI is too slow
What is the LRINEC? [6]
Laboratory risk indicator for necrotizing fasciitis, includes..
- CRP
- Leukocytosis
- Anemia
- Hyponatremia
- Renal insufficency
- High serum glucose
Treatment of necrotizing fasciitis
- Surgical debridement
2. Broad spectrum abx
What are the acceptable abx combinations empirically in necrotizing fasciitis [3]
- Pip-tazo + Vanco
- Cefipime + Flagly + Vanco
- Meropenem + Vanco
–> Add clinda to all therapy
What is pyomyositis?
Primary skeletal muscle abscess
Etiology of pyomyositis?
Staph aureus
Presentation of pyomyositis?
Fever with localized skeletal muscle swelling, tenderness, and fluctuance which progress in severity over time.
Sepsis wil develop
What type of infection is associated with pyomyositis? [2]
- HIV
2. Toxocariasis
Where is pyomyositis most common [region]
Tropics
Role of imaging in pyomyositis
- X-ray may show gas and edema
- CT and US identify abscess formation
- MRI is sensitive for focal muscle edema prior to abscess formation and mapping the extent of infection in detail
Treatment of pyomyositis [2]
- Surgery
2. Vancomycin
Complication of pyomyositis?
Compartment syndrome, esp if anterior tibial compartment is involved.
How does clostridium myonecrosis present?
Muscle pain out of proprotion to physical exam findings
Progresses to tense muscle swelling, crepitation, skin discoloration [red to purple] with bullae
Who gets clostridium myonecrosis? [5]
- Contaminated open fractures
- Penetrating wounds
- Bowel or biliary tract surgical wound complication
- Septic abortion
- Black tar heroin use [skin popping]
Who gets C. septicum myonecrosis? [2]
- GI malignancy
2. neutropenic colitis
Role of imaging in clostridium myonecrosis
- CT and X-ray will show gas and edema along fascial planes
Treatment of clostridium myonecrosis
- Surgery
- Empiric is same as nec fasc
- Targeted: Penicillin G and clindamycin combination
Bacteria associated with leech therapy?
Aeromonas hydrophila
Bacteria associated with freshwater and estuarine [brackish] water?
Aeromonas hydrophila
Treatment of Aeromonas hydrophila?
- 3rd gen cephalosporin
- Bactrim
- Fluoquinolone
Who should receive prophylactic therapy for aeromonas infection and with that?
Leech therapy
Cipro
Risk factors for vibrio vulnificus infection?
Exposure to salt or brackish water
Handling or ingesting raw or undercooked shellfish
Presentation of vibrio vulnificus infection [3]
- SSTI
- Necrotizing SSTI
- Septicemia following ingestion in those with liver disease or hemochromatosis
Treatment of vibrio vulnificus infection?
Doxy + Ceftriaxone
May convert to Cefotaxime PO
Utility of blood cultures in vibrio vulnificus infection?
GOOD utility. Def get them.
What type of exposure is mycobacterium marinum a/w? [2]
Aquarium
Swimming pools
Presentation of mycobacterium marinum?
Minor skin trauma followed by aquatic exposure leads to small , violet papules that ulcerate superficially and scar over several weeks
Treatment of mycobacterium marinum
Clarithromycin with either ethambutol of rifampin for 3-4 months.
Percent of dog bites that become infected?
Cat bites?
- 5%
2. 80%
Bacteria a/w dog and cat bites?
- Pasteurella
- Capnocytophaga canimorsus [dogs]
- Anaerobes
- Strep
- Staph
- Barontella henselae [cats]
Treatment of a dog/cat bite? [4]
- Augmentin
- Cipro + clinda [alt]
- Bactrim + clinda [alt]
- Doxy + clinda [alt]
Who gets severe capnocytophaga?
- Asplenics
2. Cirrhotics
Etiology of human bite infection? [3]
- Staph
- Strep
- Anaerobes [Eikenalla corrodens]
Treatment of human bite? [2]
Augmentin
Unasyn +/- vanco if severe
Bites that predispose to Aeromonas hydrophila? [3]
- Leech
- Alligator
- Snake
Bites that predispose to vibro?
Shark
Bites that predispose to serratia marcescens?
Iguana
What might a macaque bite transmit?
B virus [a herpesvirus]
Treatment of a macaque bite?
Postexposure prophylaxis with valavivlovir or aciclovir
Presentation of B virus infection
Vesicles or ulcers at site of bite, flu like illness.
May lead to fatal encephalomyelitis
Punctures through rubber-soled shoe is a/w what organism?
Pseudomonas. May cause septic arthritis and osteomyelitis
Traumatic wounds sustained after MVA [motorcyclists and unrestrained passengers], natural disasters, and military blast injuries are a/w what type of infection? [3]
- Mucorales
- Aspergillus
- Fusarium
Etiology of infection in early burns?
Staph and strep
Etiology of infection late in burns?
- Pseudomonas
- Acinetobacter
- Enterobacteriaceae
Diagnosis of burn wound sepsis
- Clinical features
2. Burn wound biopsy demonstrating bacterial count >10^5
Etiology of surgical site infections
- Staph [coag neg and aureus]
- Pseudomonas
- Enterococcus
What should be considered in surgical site infections that develop rapidly within the first 48 hours of surgery? [2]
- GAS
2. Clostridium
When is a surgical site infection attributed to surgery?
If infection develops within 30 days
Window is longer with prosthetics
Presentation of cutaneous anthrax?
Pruritic papules evolve into vesicles and bullae that ulcerate leaving behind a painless black eschar with surrounding induration.
Exposure that predisposes to anthrax?
Wool, animal hides
Treatment of cutaneous anthrax and how long? [2]
- Cipro
- Doxy
60 days of therapy
Presentation of erysipelothrix rhusiopathiae infection?
Cellulitis leading to painful violaceous lesions with associated lymphangitis. Looks like erysipelas but occurs slowly.
What exposures put the patient at risk for erysipelothrix infection?
- Shrimp
- Crab
- Fish
- Animal meat and hides.
Treatment of mild erysipelothrix infection?
- Penicillin V
- Cephalexin
- Cipro
Treatment of severe erysipelothrix infection? [3]
- IV Pen G
- Ceftriaxone
- Imipenem
What are dermatophytosis?
- Epidermophyton
- Microsporum
- Trichophyton
–> Causes “tinea”
Treatment of tinea except capitis or unguium
- Topical azoles [itraconazole, fluzonazole]
- Oral azoles if refactory
–> Topical nystatin DOES NOT WORK.
Treatment of tinea capitis or unguium
- Terbinafine
2. Griseofluvin
Treatment of sporotrichosis?
Itraconazole
What is toxic shock syndrome?
Superantigen mediated disease due to toxic shock syndrome toxin-1 and enterotoxins produced by toxigenic staph aureus
What is erythroderma?
Painless sunburn like rash that gives way to desquamation in toxic shock syndrome.
Treatment of toxic shock syndrome?
Vanco + clinda or linezolid
IVF
Removal of retained foreign body
What is streptococcal toxic shock syndrome?
Superantigen mediated disease due to exotoxins produced my GAS
Rash is less pronounced than in staph toxic shock.
Risk factors for strep toxic shock? [3]
- Vaginal or c-section
- Viral infection
- Traumatic injury
Blood cultures of strep vs staph toxic shock.
- Step toxic shock has cultures positive in about 60%.
2. Staph toxic shock rarely has positive cultures
Treatment of strep toxic shock syndrome?
Penicillin in combination with clindamycin
IVF
Surgical debridement of infected wounds
Morality of staph vs strep toxic shock?
Staph <5% mortality
Strep 20-45% mortality
What is staph scalded skin syndrome
Bilstering disease due to exfoliative toxin A or B produced by toxigenic staph
Presentation of SSSS?
Superficial scarlatiniform rash that rapidly progresses to large flaccid bullae that rupture easily giving way to widespread exofliation exposing bright red areas of skin. Fever and skin tenderness are common. More common in children and neonates.
Clinical criteria of Strep Toxic Shock?
- Hypotension
- Multiorgan involvement with at least 2 systems
- Cr 2x ULN
- Platelets <100,000 or DIC
- ALT/AST 2x ULN
- ARDS
- Characteristic Rash
- Soft tissue necrosis
Lab criteria of Strep Toxic Shock?
Isolation of GAS
Probable diagnosis of Strep Toxic Shock
All clinical criteria met with no other etiology and GAS isolated from a non-sterile site.
Confirmed Strep Toxic Shock
All clinical criteria met and GAS isolated from a sterile site. [Blood, CSF, synovial fluid, pleural or pericardial fluid].
Clinical criteria of staph toxic shock?
- Fever
- Diffuse macular erythroderma with desquamation 1-2 weeks after onset
- Hypotension
- Multiorgan involvement with 3 or more systems
Laboratory criteria for staph toxic shock?
- Negative blood or CSF culture [or staph grews]
- Negative work up for…
- RMSF
- Lepto
- Measles
Probable vs confirmed Toxic Stock?
- 4 or more clinical criteria + lab criteria met
2. 5 clinical criteria + lab criteria [unless patient dies before desquamation
Etiology of rat bite fever?
- Streptobacillus moniliformis [USA]
2. Spirillium minus [Asia]
Presentation of rat bite fever?
Fever, rash that is macular/papular petechial/pustular with symmetric polyarthralgia
Treatment of rat bite fever?
- Penicillin
2. Doxy [if pen allergic]
Eikenella gram stain?
Pleomorphic gram negative rods.
Ddx of folliculitis? [5]
- Staph
- Pseudomonas
- Malassezia furfur
- Candida albicans [obese, hospitalized]
- Idiopathic eosinophilic pustular folliculitis in AIDS patient
Treatment of impetigo?
- Topical mupirocin
NOTE:
Erysipelas on the face CANNOT be differentiated [strep or staph] due to the loose subcutaneous tissue. TREAT AS STAPH.
Diagnosis of erysipelothrix?
Culture of the deep dermis
Gram stain of erysipelothrix?
Gram + rod.
Difference between SSSS and TEN
- Intraepidermal split is SSSS
2. Dermal epidermal junction is TEN
Organisms whose growth is stimulated by iron excess? [6]
- Vibrio vulnificus
- E. coli
- Listerisa
- Aeromonas
- Rhizopus
- Yersenia
“VELARY”
