Soft Tissue infections Flashcards
What are furuncles?
a deep folliculitis, infection of the hair follicle. It is most commonly caused by infection by the bacterium Staphylococcus aureus,
What is the layer of the epidermis that folliculitis involves?
Epidermis
What are the five layers of the epidermis?
- Stratum Corneum
- Stratum lucidum
- Stratum Granulosum
- Stratum spinosum
- Stratum basale
Where in the epidermine do langerhans cells reside?
Stratum spinosum
What layer of the epidermis does erysiphales involve?
Junction between the epidermis and the dermis
What layer of the skin does cellulitis involve?
SQ tissue
What layer of the skin does impetigo involve?
Epidermis
What layer of the skin does ecthyma involve?
Epidermis
What is the cause of hand foot and mouth disease? Ssx?
Mild fever + flat, discolored macules and papules
Coxsackie virus (a picornaviridae virus)
What are the two most common causes of impetigo?
Strep pyogenes
Staph aureus
What is the most common cause of erysipelas?
Strep Pyogenes
What is the most common cause of folliculitis and fu
Staph Aureus
What are the two most common causes of cellulitis
Strep Pyogenes
Staph Aureus
What general type of bacteria cause skin infections?
Gram positive
Cat/dog bite cellulitis?
Pasteurella multocida
Cat scratch fever?
Bartonella Henselae
Wool sorter’s disease?
Bacillus anthracis
What are carbuncles?
Large furuncles (boils)
How do you distinguish between erysipelas and cellulitis?
Erysipelas has clear boundaries, whereas cellulitis does not
Hot tub folliculitis = ? What is the gram stain and morphology of this? Does it ferment lactose?
Pseudomonas aeruginosa
Gram negative rod
Does not ferment lactose
What is the gram stain and morphology of proteus mirabilis? Urease positive? Aerobic or anaerobic? What type of motility?
Gram negative rod
Urease positive
Anaerobic
Swarming motility
Where along the leg does the great saphenous vein run?
Medial
What are the complications of tinea pedis?
May be an entry point for staph and/or strep to cause cellulitis
True or false: I and D is usually sufficient for treating abscesses
True
What is the treatment for non-purulent cellulitis?
First gen cephalosporin
What is the treatment for purulent cellulitis? (2)
Vanco if MRSA
TMP-SMX
What is the treatment for hot tub folliculitis?
Self limited infection
What is the treatment for non-MRSA cellulitis?
First gen cephalosporin
What are the top three causes of necrotizing fasciitis?
- Group A strep
- Clostridium perfringens
What are the ssx of necrotizing fasciitis? (4)
- severe, constant pain
- Bullous lesions
- Gas in soft tissues
- Rapid spread
What is the cause of gas gangrene?
Tissue trauma + infection of Clostridium perfringens
What is the morphology and gram stain of clostridium perfringens?
Gram positive rod
Anaerobe
What is the toxin released by Clostridium perfringens that causes the gas part of the gas gangrene? MOA?
alpha-toxin–inserts into cell membranes
What are the histological characteristics of sporothrix schenckii?
Septated hyphae
What is the gram stain and morphology of bacillus anthracis?
Gram positive boxcar rods with a proteinaceous capsule
What are the two toxins associated with bacillus anthracis?
Edema factors
lethal factor
What is the gram stain of francisella tularensis? Aerobic or anaerobic?
Gram negative rod
Aerobic
What are the risk factors for septic arthritis?
RA
Steroid use
DM
What is the route of spread for septic arthritis?
Hematogenous
Direct inoculation
Contiguous spread
What are the two most common causes of septic arthritis?
Staph Aureus
Coagulase negative staph (if prosthetic joint)
What is the bacteria that commonly causes septic arthritis 2/2 prosthetic joint replacement?
Coagulase negative staph
What is the most common joint that is affected with septic arthritis? Is it usually only one joint, or multiple?
Knee
Usually just a single joint
What are the ssx of septic arthritis?
Fever
Joint erythema and TTP
What is hemarthrosis?
bleeding into joint spaces
What is the WBC level that is usually found in non-infected joints?
Less than 200
What are the features and WBC that are seen in inflammatory joints?
Cloudy/yellow
2000-10000
What are the features and WBC that are seen in infected joints?
Purulent fluid
More than 60,000
What is the treatment for septic arthritis?
Systemic abx
Drain joint
What is the difference between RA and septic arthritis?
RA is multi arthritis
What is the culture that should be obtained for pts with painful, erythematous joints that you suspect may be caused by gonorrhea?
Cervical culture
Who usually gets disseminated gonococcal infections?
Sexually active adolescents and adults, usually less than 30 yo
What are the two systemic syndromes that gonococcal infections can cause?
Arthritis
Tenosynovitis
What is the treatment for N. Gonorrhea?
3rd gen cephalosporin
What is the treatment for staph aureus?
Nafcillin or 1st gen cephalosporin
What is the treatment for GAS?
PCN or cephalosporin
What is the duration of abx for septic arthritis?
2-4 weeks IV
What are the three ways to get osteomyelitis?
Hematogenous
Contiguous
Direct Inoculation
What defines acute vs chronic osteomyelitis?
Acute is less than 1 month
More than 1 month
What are the most common sources for acute vs chronic osteomyelitis?
Acute = IVDA, bacteremia Chronic = surgery, trauma
What are the common underlying factors for acute vs chronic osteomyelitis?
Rare for acute
DM or PVD for chronic
What is the treatment, generally, for acute vs chronic osteomyelitis?
Acute = medical Chronic = Surgery
What is the most common cause of osteomyelitis?
Staph aureus
What are the three best ways to diagnose osteomyelitis?
- Probe to bone
- MRI
- Bone biopsy
What is the best imaging modality for diagnosing osteomyelitis?
MRI
Puncture wound osteomyelitis = ?
Pseudomonas
What is the most common cause of treatment failure with osteomyelitis?
Lack of adequate debridement
