SSTI Flashcards
(57 cards)
Name some protecting factors of the skin
- Dry surface
- Fatty acids
- Acidic pH (5.6)
- Renewal of epidermis (bacteria fall out)
- Low temperature (inhibits bacterial growth)
Some predisposing factors of SSTI
- High bacterial innocul
- Excessive moisture
- Reduced blood supply (hence less WBC flow)
- Presence of bacterial nutrients (e.g. diabetes)
- Poor hygiene ans sharing of personal items
What are the five ways in which SSTIs are classified?
- Severity or extent (mild vs moderate vs severe)
- Depth of infection (superficial vs deep)
- Presence/absence of discharge (purulent vs non-purulent)
- Microbiology (single pathogen or polymicrobial)
- Anatomical site (epidermis vs dermis vs hair follicles, etc.)
List the anatomical site and the type of SSTI(s) associated with it
- Epidermis: impetigo
- Dermis: Ecthyma, Erysipelas
- Hair follicles: Furuncles, Carbuncles
- SC fat: Cellulitis
- Fascia: Necrotising fasciitis
- Muscle: Myositis
The culture of skin from a patient with a severe case of impetigo contains MSSA. What is the appropriate culture-directed treatment, assuming that Cloxacillin was started 3 days prior to culture results?
PO Cloxacillin 250-500mg QDS, 4 more days (total 7 days)
What are the SIRS criteria
- Fever >38 deg C
- Hypothermia <36 deg C
- Tachycardia > 90 bpm
- Tachypnea > 20 breath/min
- Leukocytosis > 12 *10^9 /L
- Leukopenia < 4*10^9 /L
The culture of skin from a patient with Ecthyma contains S.pyogenes. What is the best culture-directed treatment, assuming that Cloxacillin was started 3 days prior to culture results?
PO Penicillin VK 250-500mg PO QDS for 4 more days
because pen VK has narrower spectrum than cloxacillin
The only condition that can be treated with topical antibiotics
Impetigo (muprocin BD for 5 days)
Oral antibiotics used for severe impetigo and ecthyma, and duration of treatment
- Cephalexin/cloxacillin
- Penicillin VK
- Clindamycin
Treatment for 7 days
Common causative organisms of Impetigo and Ecthyma
- S.aureus
2. Streps
Must a culture be obtained before treating Impetigo and Ecthyma?
Not necessary, it is usually mild and does not require hospital admission
Treatment for Impetigo
Topical Mupirocin BD for 5 days
Empirical treatment of Ecthyma for a patient with Penicillin allergy
PO Clindamycin 300mg PO QDS, 7 days
The culture of skin from a patient with a severe case of impetigo contains MSSA. What is the appropriate culture-directed treatment, assuming that Cloxacillin was started 3 days prior to culture results?
PO Cloxacillin 250-500mg QDS, 4 more days
What are the indications for adjunctive systemic antibiotics in purulent SSTIs?
- I&D: unable to drain completely, or lack response
- Extensive disease involving multiple sites
- Extremes of age
- Immunosuppressed
- Signs and sx of systemic illness
The culture of skin from a patient with Ecthyma contains S.pyogenes. What is the best culture-directed treatment, assuming that Cloxacillin was started 3 days prior to culture results?
PO Penicillin VK 250-500mg PO QDS for 4 more days
because pen VK has narrower spectrum than cloxacillin
Distinguish between Furuncles Carbuncles
- Furuncles: infection of a single hair follicle, extending through dermis
- Carbuncles: Involes a few adjacent follicles, and forms small abscess
Causative organisms for Cellulitis and Erysipelas
- S.aureus, usually causing purulent infections
- B-hemolytic Strep
- Almost always the cause of erysipelas
What are some risk factors for purulent SSTIs
- Close physical contact
- Crowded living quarters
- Sharing personal items
- Poor hygiene
The most common causative organism for purulent SSTIs
S.aureus
Main treatment for purulent SSTI
Incision & Drainage (I&D)
What is considered “Severe, non-purulent Cellulitis/erysipelas”? What are the organisms to cover?
> 2 SIRS criteria with:
- Hypotension
- Rapid progression
- Immunosuppression
- Comorbidities
Need to cover:
- streps, S. aureus, gram negs (includes P. aeruginosa)
What could cellulitis be caused by in patients who are immunosuppressed?
S. aureus, B hemolytic streptococci, Streptococcus pneumoniae, E. Coli, Serratia marcescens, P. aeruginosa
For adjunctive systemic antibiotics in purulent SSTIs, PO is adequate in most cases. However, when will IV antibiotics be necessary?
In systemic illness (usually those that are admitted to hospitals, or may be required to do so)