Management of SSTI Flashcards
what are some protecting factors of the skin? and what is the function of these protecting factors
- dry surface
- fatty acids
- acidic pH (around 5.6)
- renewal of the epidermis
- low temperature (compared to body core temp)
- these factors inhibit excess microbial growth and entry into deeper layers
what are some predisposing factors for SSTI
- high bacterial innocula (cut with dirty knife)
- excessive moisture
- reduced blood supply (reduced WBC to that area to fight infection)
- presence of bacterial nutrients (glucose in urine)
- poor hygiene
- sharing of personal items
characteristics of impetigo and ecthyma?
uncomplicated, managed as outpatient
- superficial infection
- Impetigo: non-bullous vs bullous (pus); impetigo common in children, on face or extremities
- ecthyma: superficial, but deeper than impetigo, scarring is common
what are the causative organisms for impetigo & ecthyma?
S.aureus, B-hemolytic Streptococci (S.pyogenes)
(bullous form (pus) due to toxin-producing S.aureus strains
do we need to culture for impetigo & ecthyma?
its optional as empiric therapy covers for s.aureus and b-hemolytic strep alr
do we need to be concern and treat CA-MRSA?
Nope as prevalence is low
Treatment for mild impetigo
topical: Mupirocin BD for 5 days
Treatment for severe cases of impetigo and all cases of ecthyma
Empiric therapy:
1a. Cephalexin or cloxacillin
1b. Clindamycin (pen allergic)
Culture directed:
2a. Pencillin VK (S.pyogenes)
2b. Cephalexin or cloxacillin (MSSA)
Treatment duration: 7 days
difference between furuncles (boils) and carbuncles
furuncles: infection of a hair follicle
carbuncles: involve few adjacent follicles, forms small abscess
what are considered purulent SSTIs?
furuncles, carbuncles, cutaneous abscesses
risk factors of purulent SSTIs?
- close physical contact
- crowded living quarters
- sharing personal items
- poor personal hygiene
the causative organism for purulent SSTIs
S.aureus; polymicrobial for large skin abscesses
do we need to culture for purulent SSTIs
not needed, but reasonable to culture pus
treatment of purulent SSTIs
1st: InD
Adjunctive systemic Abx when:
- lack of response to InD (still red and swell)
- unable to completely drain completely
- extensive disease involving several sites
- extremes of age (young and old)
- immunosuppressed (chemo, organ transplant)
- SIRS criteria (systemic illness): fever >38c or <36c, HR > 90 beats/min, RR > 24 breaths/min, WBC >12 x 10^9/L or <4x10^9/L
what are the adjunctive systemic abx for purulent abx
for MSSA only:
- cephalexin (1st gen ceph, oral)
- cloxacillin (anti-staph, oral)
- cefazolin (1st gen ceph, oral/IV)
for MRSA, MSSA (if suspect MRSA)
- clindamycin (Oral/IV)
- Co-TS (Oral); trimethoprim/sulfamethoxazole
- Doxycycline (Oral/IV)
Outpatient: 5-7 days
inpatient: 7-14 days
What are the clinical manifestations (how does it look like) for cellulitis?
- Acute inflammation of epidermis, dermis, and sometimes superficial fascia
- Bacteria can invade lymphatic tissue and blood
- Purulent/ non-purulent
What are the clinical manifestations (how does it look like) for Erysipelas?
- Affects up to superficial dermis and lymphatic tissue
- non-purulent
What to take note with purulent cellulitis and purulent SSTIs?
Purulent cellulitis not = to
Furuncles, Carbuncles, Cutaneous abscesses
What is the visual difference btw Celluitis and Erysipelas?
Cellulitis: poorly demarcated area of erythema, purulent/non-purulent
Erysipelas: SHARPLY demarcated area of erythema with raised border
What are some complications of Cellulitis and Erysipelas?
- Bacteremia
- Endocarditis
- Toxic shock
- Glomerulonephritis
- Lymphedema
- Osteomyelitis
- Necrotising soft-tissue infections (necrotising fasciitis)
What are the causative organisms for C and E?
Staph Aureus (>> purulent infections) b-haemolytic Strep (Strep pyogenes) (almost always the cause of erysipelas)
For comorbidity of immunosuppresion, what is the pt at risk for additional causative organisms?
Strep pneumoniae, E. coli, Serratia marcescens, P. aeruginosa (more Gram -ve)
For comorbidity of Chronic liver/renal disease, what is the pt at risk for additional causative organisms?
Vibrio spp, E.coli, P. aeruginosa (more -ve as well)
When to consider cultures in situations for C & E?
- purulent infections after I&D
- Immunosuppressed (chemo, transplant), signs of severe systemic illness (SIRS criteria)
What types of cultures can you collect?
- Cutaneous aspirates
- Tissue samples (biopsies)
- Blood
- Swabs
What is considered a mild non-purulent infection for C&E?
What is the organism to cover?
no signs of systemic infection (no SIRS)
Strep spp (+ve)
What is considered a moderate non-purulent infection for C&E?
What are the organisms to cover?
1 or more SIRS criteria
Strep spp +/- S.aureus (+ve gram)
What is considered a severe non-purulent infection for C&E?
What are the organisms to cover?
> 2 SIRS criteria (3 and above) + hypotension, rapid progression, immunosuppressed, comorbidities
Strep spp and S.aureus and Gram -ve (Incl P. aeruginosa)
What are the ABx used for mild non-purulent C&E?
PO Abx
“Penicillin VK” (most narrowest against streptococcus)
Cloxacillin / Cephalexin (covers MSSA, a bit broader thus not recommended)
Clindamycin (for penicilin allergy)
What are the ABx used for moderate non-purulent C&E?
1 SIRS criteria: treat like mild Abx; Pen VK, Cloxa, Cepha, Clinda
2 or more SIRS criteria: IV ABx
- “Cefazolin” (strep and MSSA)
- Pen G
- Clindamycin (pen allergy)
What are the ABx used for severe non-purulent C&E?
IV Abx:
- Pip/Tazo (anti-pseudomonal pen)
- Cefepime (4th gen)
- Meropenem (carbapenem, reserved for ESBL resistant organisms)
If MRSA risk factor(s), add IV:
- Vanco
- Dapto
- Linezolid
What are the 3 MRSA risk factors?
1: immunosuppression
2: critically ill, hypotensive (in ICU)
3: previously failed Abx without MRSA activity
What is the value for hypotension?
<100/60
What is considered a mild purulent infection for C&E?
Which organisms to cover?
No signs of systemic infection (no SIRS)
Strep spp + S.aureus (+ve gram)
What is considered a moderate purulent infection for C&E?
Which organisms to cover?
1 or more SIRS criteria
Strep spp + S.aureus (+ve gram)
What is considered a severe purulent infection for C&E?
Which organisms to cover?
> 2 SIRS criteria (3 and above) + hypotension, rapid progression, immunosuppressed, comorbidities
Strep spp and S.aureus and Gram -ve (Incl P. aeruginosa)
What are the ABx used for mild purulent C&E?
PO ABx
- Cephalexin
- Cloxacillin
- Clindamycin
If MRSA risk factors:
- Co-TS
- Clinda
- Doxy
What are the ABx used for moderate purulent C&E?
1 SIRS criteria: follow like mild: Cepha, Cloxa, Clinda
2 = or more SIRS criteria: IV
- Cloxacillin
- Cefazolin
- Clindamycin
MRSA risk factors:
- Vanco
- Daptomycin
- Linezolid
What are the ABx used for severe purulent C&E?
IV Abx:
- Pip/Tazo (anti-pseudomonal pen)
- Cefepime (4th gen)
- Meropenem (carbapenem, reserved for ESBL resistant organisms)
If MRSA risk factor(s), add IV:
- Vanco
- Dapto
- Linezolid
What are the MO that causes cellulitis from bite wounds?
S. aureus, Strep spp, specific organisms
What is the MO for animal bites?
Pasteurella multocida
What is the MO for human bites?
Eikenella corrodens
What is another specific organism in cellulitis from bite wounds?
- Oral anaerobes (e.g. Prevotella spp., Peptostreptococcus spp.)
What is the Abx treatment for bite wounds?
- Augmentin
- Ceftriaxone or Cefuroxime + Clinda or metronidazole (For anaerobe coverage)
- Cipro/levo (FQs for pen allergy) + clinda/metronidazole
IV/Oral depends on severity of infection
What is the first monitoring aspect to look out for?
assess clinical response in 48-72 hrs
What is the first question that you will ask after assessing the clinical response?
Improved fever, pain, swelling, erythema, warmth?
No- consider resistant organisms and/or alternative causes
Yes - If initial IV Abx, change to PO
Afebrile for 48 hrs
Clinical improvement
How long is the ABx duration for conditions that have gotten better? for purulent SSTI
at least 5 days
May extend if no sig improved
Immunocompromised may need 7-14 days
Areas of Diabetic Foot Infections
skin ulceration (peripheral neuropathy) wound (trauma)
soft tissue or bone infection below the malleolus (below ankle)
complications of DFI
- hospitalization
- osteomyelitis (bone infection) –> amputation
pathophysiology of DFIs (3 things)
- neuropathy
- peripheral: reduce pain sensation and response to pain
- motor: muscle imbalance
- autonomic: increase dryness, cracks and fissures - Vasculopathy
- early atherosclerosis
- peripheral vascular disease
- worsened by hyperglycemia or hyperlipidemia - Immunopathy
- impaired immune response
- increase susceptibility to infection
- worsened by hyperglycemia
all this lead to ulcer formation and wounds
–> causing bacterial colonisation, penetration, proliferation –> causing DFI
Definition of DFI/pressure ulcer infection
(1) purulent discharge OR
(2) >= 2 signs and symptoms of inflammation
- -> erythema,
- -> warmth
- -> tenderness
- -> pain
- -> induration (area becomes firm; localised hardening of soft tissue)
causative microorganisms for DFIs and pressure ulcers?
both usually polymicrobial
most common: s.aureus, streptococcus spp
gram -ve bacilli: e coli, klebsiella, proteus,
less common: P.aeruginosa
–> seen in chronic wounds or previously treated with Abx
anaerobes: peptostreptococcus, veillonella, Bacteroides spp
- -> seen in ischemic or necrotic wounds
does culture need to be taken for DFI or pressure ulcers?
Mild DFIs = optional
Moderate-severe DFIs/ pressure ulcers
- deep tissue culture after cleaning and before starting abx (if possible; don’t take if patient critically ill and need to start on abx immediately)
- or biopsy specimens for pressure ulcers
- AVOID skin swabs (for both DFIs and pressure ulcer)
- do not culture uninfected wounds
criteria for mild DFI/pressure ulcer
(1) infection of skin and SC tissue +
(2) if erythema: =<2cm around ulcer + No signs of SIRS
criteria for moderate DFI/pressure ulcer
(1) infection of deeper tissue (e.g. bone, joints) OR
(2) if erythema: > 2cm around ulcer + No signs of SIRS
criteria for severe DFI/pressure ulcer
Any sign of SIRS
organisms to cover for mild DFI/pressure ulcer
Streptococcus spp + S.aureus
organisms to cover for moderate DFI/pressure ulcer
Streptococcus spp + S.aureus +
gram -ve (+/- P.aeruginosa) + anaerobes
organisms to cover for severe DFI/pressure ulcer
Streptococcus spp + S.aureus +
gram -ve (INCLUDING P.aeruginosa) + anaerobes
when do we add empiric coverage for p.aeruginosa for DFIs or pressure ulcers?
(1) severe infection (IDSA) OR
(2) failure of abx not active against P.aeruginosa
treatment for mild DFI/pressure ulcer
PO antibiotics:
cloxacillin, cephalexin, clindamycin
If MRSA risk factor(s), use PO:
trimethoprim/sulfamethoxazole
clindamycin
doxycycline
treatment for moderate DFI/pressure ulcer
Initial IV Abx:
(1) amoxicillin/clavulanate (augmentin)
(2) ceftriaxone**
(3) ertapenem (not preferred as broad-spectrum; reserve for ESBL producing organism)
- *if no anaerobe coverage, add IV:
- metronidazole
- clindamycin
if have MRSA risk factor(s); add IV:
- vancomycin
- daptomycin
- linezolid
May step down to PO abx(s) after patient improves
treatment for severe DFI/pressure ulcer
Initial IV Abx:
(1) piperacillin/tazobactam
(2) cefepime**
(3) Meropenem
- *if no anaerobe coverage, add IV:
- metronidazole
- clindamycin
if have MRSA risk factor(s); add IV:
- vancomycin
- daptomycin
- linezolid
May step down to PO abx(s) after patient improves
when can be step down from IV to oral therapy?
if patient improves - seen in culture
OR
if no culture was obtained but patient improve in terms of sx and symptoms, choose oral abx with similar activity to IV abx
duration of therapy for DFIs/pressure ulcer
No bone involved
(1) Mild: 1-2 weeks
(2) moderate: 1-3 weeks
(3) severe: 2-4 week
Bone involved:
(1) surgery (all infected bone and tissue removed (e.g. amputation): 2-5 days
(2) surgery (residual infected soft tissue): 1-3 weeks
(3) surgery (residual viable bone): 4-6 weeks
(4) No surgery or surgery (residual dead bone): >= 3 months
DO NOT continue Abx until complete wound healing (abx resolves infection but not the wound healing)
DFIs non-pharmacological interventions and preventions
wound care
- debridement (cleaning and remove infected tissues)
- off-loading (supportive shoe, relieve pressure on wound area)
- apply dressing to promote healing env and control excess exudation
Foot care
- daily inspection
- prevent wound and ulcers
why do pressure ulcers occur (4 factors)
moisture, pressure (amt and duration), shearing force, friction
pressure ulcers also known as?
decubitus ulcers, or bed sores
risk factors of pressure ulcers?
(1) reduced mobility (spinal cord injuries, paraplegic)
(2) debilitated by severe chronic disease (multiple sclerosis, stroke, cancer)
(3) reduced consciousness
(4) sensory and autonomic impairment (incontinence; increases moisture)
(5) extremes of age
(6) malnutrition
non-pharmacological intervention for pressure ulcers
(1) debridement of infected or necrotic tissue
(2) local wound care
- normal saline preferred
- avoid harsh chemicals
(3) relief of pressure
- turn or reposition every 2 hours
- also important for prevention
dosing for abx covering strep and stap
(1) cephalexin: 250-500mg PO QDS*
(2) cloxacillin: 250-500mg PO QDS; 1-2g IV Q4-6H
(3) clindamycin: 300mg PO QDS; 600mg IV Q8H
(4) cefazolin 1-2g IV Q8H*
dosing for abx covering anaerobes/ broad?
(1) augmentin: 625mg PO BD-TDS; 1.2g IV Q8H
(2) metronidazole: 500mg PO/IV TDS
(3) clindamycin
dosing for abx covering P.aeruginosa
(1) piperacillin/tazobactam: 4.5g IV Q6-8H*
(2) cefepime: 2g IV Q8H*
dosing for abx covering MRSA risk factors
(1) trimethoprim/sulfamethoxazole: 800/160mg PO BD*
(2) clindamycin
(3) doxycycline
(4) vancomycin: 15mg/kg Q8-12H*
dosing for abx covering strep only
(1) pen G: 2-4 million units Q4-6H*
(2) pen VK: 250-500mg PO QDS
