Bacterial Skin and Skin Structure Infection Flashcards
Symptoms of skin infections
Sspreading infections of dermis
Warmth, erythema, pain, swelling
Rapid onset, unilateral
Rredisposing factors:
_ diabetes and PVD
_ previous cutaneous damage
_ surgical procedures- disruption of lymphatic drainage
What other diseases or conditions may be mistaken with BSSSI?
deep vein thrombosis (DVT)
D-dimer
doppler ultrasound
CT/MRI
statis dermatitis | venous insufficiency
lipodermatosclerosis
drug-induced edema
Differences purulence between BSSSI and other types
White, yellowish, cloudy
What are the indicators for causative pathogen for BSSSI (purulence)?
Stalph Aureus
GAS
Gram (+) stalph and strep
MRSA/MSSA
B-hemolytic/ non-B hemolytic
Cellulitis vs Abscess
Cellulitis/erysipelas (non-purulent)
Diffuse, superficial, spreading skin infections
Cutaneous/skin Abscess (purulent)
Collections of pus within the dermis and deeper skin tissues
Painful, tender, fluctuant red nodules
Panton-Valentine leukocidin (PVL) toxin
“PVL toxin genes were present in almost all MRSA strains”
S.aureus produced PVL toxin –> punch hole on WBC —> WBC leak its contents –> degradative enzyme leak –> degrade skin –> cellulitis
CA-MRSA vs HA-MRSA
table in ppt
What kind of bacteria is Strep Pyogenes ?
GAS and MSSA and aerobic
Oral ABx for active against Strep. Pyogene
Active against Strep. pyogenes (GAS) & MSSA
Dicloxacillin 500mg PO Q6hrs
_short half-life = frequent dosing
_poor GNR coverage
Cephalexin 500mg PO Q6hrs _short half-life = frequent dosing _RENAL adjustment (80-100% unchanged in urine)
Oral ABx for active against Strep. Pyogene with PCN allergy
PCN allergy: Clindamycin 300mg PO QID
IV ABx for active against Strep. Pyogene
Cefazolin (Ancef) 1gm IV Q8hrs
_ More convenient than nafcillin, less bone marrow suppression
_ Renal Adjust CrCl <30
IV ABx for active against Strep. Pyogene with PCN allergy
SEVERE PCN allergy: Clindamycin 600mg IV Q8hrs
NSAIDs (w/ risk) or systemic steroid accelerate improvement
IBU 400mg PO QID x5days,
OR
Prednisone 40mg PO daily x7days
Cardiovascular, bleeding risk, CKD
Complete cellulitis resolution with IBU at 4-5 days 100% versus >7days 30% of patients without IBU
What should always be done to abscess/purulence cases?
I&D alone >85% cure rate
How to classify purulence?
No systemic signs & small abscess <2cm (MILD)
SYSTEMIC signs & purulent, large abscess
I&D + SYSTEMIC ABxs (route based on severity) EMPIRIC MRSA
MODERATE: oral or IV then oral
SEVERE: IV then oral
MRSA coverage (oral)
TMP-SMX Doxycycline Clindamycin Linezolid Tedizolid
MRSA coverage (IV)
Vancomycin Daptomycin Linezolid TMP-SMX Ceftaroline Dalbavancin Oritavancin Tedizolid
Length of therapy
5-day course
with 14 to 28 days for follow-up
S/sx of severe skin infection
severe local sxs severe pain rapidly spreading fevers and chills deep abscess
signs
hypotension
elevated SCr
Alternatives to Vancomycin
daptomycin (Cubicin) 4mg/kg IV Q24h
MOA: Binds cell membranes; depolarization
CIDAL; Inhibits RNA/DNA/Protein Synthesis
pros: daily dosing, no need to monitor levels
cons: inactivated by lung surfactants
rhabdomyolysis – monitor CK Qweek
– avoid statins
linezolid (Zyvox) 600mg IV Q12hrs
pros: no dose adjustments; oral/IV
cons: thrombocytopenia, serotonin syndrome
Clinical Impact Summary for BSSSI
Purulence to assess need for anti-MRSA
B-lactams for non-purulent cellulitis
NSAIDs to reduce inflammation
Shorter courses of therapy – 5days
Necrotizing Fasciitis
Flesh eating
Major destruction of deep tissues, highly lethal
Early diagnosis and expedited tx necessary:
_ severe, disproportionate constant pain
_ gas in soft tissue
_ fever, leukocytosis, renal failure
_ rapid spread despite abx’s
_ wooden-hard feel of subcutaneous tissue
_ elevated CPK, CRP >150
Pathogenesis of necrotizing fasciitis
S. pyogenes (Mostly, a very aggressive strain)
S. aureus
Facultative and anaerobic organisms: _ surgical procedures of bowel or penetrating abdominal trauma _ decubitus ulcer or perianal abscess _ injection drug users
General treatment for necrotizing fasciitis
Immediate surgical consult
Surgical debridement- source control
repeated 24-36hrs after 1st debridement
PLUS
ABx treatment: Combo for Empiric broad spectrumABx treatment for necrotizing fasciitis
Combo for Empiric broad spectrum _ Vancomycin (MRSA and gram (+)): needs LD because it is a severe condition _ Clindamycin (Anaerobic and toxin inhibition): 600mg TID IV _ FQ (gram (-)): Cipro 400mg Q8h IV
Hong long do we continue necrotizing fasciitis tx?
Continue until surgery no longer needed and no signs of systemic inflammation (10-14 days after the surgery)
Prevention of Diabetic Foot Infection
daily foot examination forcallus, blister, trauma properly fitting shoes look in shoes no barefoot walking clean, dry feet properly manicured toenails
Diabetic Foot Infection Microbiology
Superficial infxns: aerobic GPC (S. aureus, S. agalactiae, S. pyogenes, CoNS)
Ulcerations/chronic infxns:
may include gram negative: enterobacteriaceace, Pseudomonas
Extensive wounds, necrosis, toxic:
may further include anaerobes (Bacteroides, Clostridium, Streptococci spp)
ABx for diabetic foot infection
Received antibiotics in the past month?
Yes = include gram-negative bacilli coverage
No = target aerobic gram-positive cocci only
mild to moderate (OUTPATIENT) & no recent antibiotics, targeting aerobic GPC sufficient
First, Mild and NO Abx past month: use Keflex
Then, Mild and Abx past month: use Augmentin
If Mild and purulence (MRSA) use Bactrim, Clinda, Dox
most severe infections (HOSPITALIZED), broad-spectrum empiric antibiotic therapy, pending culture results
Amp-Sulbactam 3gm IV Q6h
+ Vancomycin wt based dosing (Severe need LD)
Pseudomonas aeruginosa in diabetic foot infection
Often a nonpathogenic colonizer when isolated from wounds
P. aeruginosa is isolated in <10% of wounds
Risk factors:
patients who have been soaking their feet or prolonged water exposure.
(remember: Pseudomonas inhabits moist environments)
who have failed therapy with nonpseudomonal therapy
Recommended agents for empiric coverage are:
Piperacillin/Tazobactam: 4.5g Q6h
Ciprofloxacin
Duration for diabetic foot infection
Mild-moderate (Oral): 1-3 weeks
Severe (Initial parenteral, switch to oral when possible): 2-4 weeks
Bone/Joint (Initial parenteral, switch to oral when possible): >3 months
Why long duration in treating diabetic foot infection?
Diabetes –> Low vascularization to foot –> Low blood supply –> Low ABx concentration –> Needs longer time to reach optimal concentration
Osteomylitis (Suspicious)
open, exposed fracture
ability to probe bone at base of ulcer
local swelling with bone pain on examination
Osteomylitis (Heightened Suspicion)
elevated ESR and CRP: inflammation
infectious signs: WBC, temp, HR, RR
Osteomylitis (Diagnostic)
plain films (x-ray) may be falsely negative early blurred margins MRI/CT- may reveal destruction if x-ray normal
Treatment for Osteomylitis
Intravenous Route and Long Duration
Empiric coverage in adults
vancomycin
+ Gram negative coverage if:
IVDU/surgical (pseudomonas risk)- cefepime; if allergy cipro
vertebrae- ceftriaxone; FQ if allergy
vascular insufficiency- refer to diabetic foot
Osteomylitis tx duration
Acute therapy – parenteral therapy x 6-8 weeks
Best to prevent recurrence
BSSSI monitoring
fever, HR, RR
WBCs
skin/clinical improvement/progression
serum creatinine- renally adjusted medication
cultures
specific drug tolerance, side effects, interactions
Pt education
Keep draining wounds covered with clean, dry bandages
Maintain good personal hygiene with regular bathing and cleaning of hands with soap and water or an alcohol-based hand gel, particularly after touching infected skin or items that have directly contacted draining wound
Avoid reusing or sharing personal items that contact skin (razors, towels, linens)
