SSTI Flashcards
PathophysiologyofSSTIs
Disruptionofnormalhostdefensesbyprocesses
suchas puncture,abrasion,diseases
Normalprotectingfactors of skins
Normalprotectingfactors –Drysurface –AcidicpH(~5.6) –Fattyacids –Renewalofepidermis –Lowtemperature
Predisposingfactors to ssti
Predisposingfactors –Highbacterialinnocula –Excessivemoisture –Reducedbloodsupply –Presenceofbacterialnutrients –Poorhygiene –Sharingofpersonalitems
Classification of SSTIs
Presence/absenceofdischarge
–Purulentversusnon‐purulent
Severityorextent
–Mildversusmoderateversussevere
–Uncomplicatedversuscomplicated
–Superficialversusdeep
Microbiology
–Singlepathogen(primary)versuspolymicrobial(secondary)
Anatomicalsite
–Hairfolliclesversusepidermisversusdermis,etc.
Classification according to anatomical sites
- Epidermis
impetigo
Classification according to anatomical sites
- dermis
Erysipelas
Classification according to anatomical sites
- Hair follicules
Folliculitis
Furuncles
Carbuncles
Classification according to anatomical sites
- Subcutaneous fat
Cellulitis
Classification according to anatomical sites
- Fascia
Necrotizing fasciitis
Classification according to anatomical sites
- Muscle
Myositis
Skinandsofttissueinfections shouldgenerally be treatedwithantibiotics
—- some can be treated by draining
Antibiotics(systemicandtopical)areavailableby prescriptiononly
–Exception:topicalclindamycin≤1%(acneonly)
Pharmacistsplayanimportantrole
– Referpatientstoseekmedicalcareifindicated
– Counselonnon‐pharmacologic approaches
– Recommendappropriateantibioticregimens
– Monitor forsafetyandefficacyoftherapy
Skinandsofttissueinfections shouldgenerally be treatedwithantibiotics
—- some can be treated by draining
Antibiotics(systemicandtopical)areavailableby prescriptiononly
–Exception:topicalclindamycin≤1%(acneonly)
Pharmacistsplayanimportantrole
– Referpatientstoseekmedicalcareifindicated
– Counselonnon‐pharmacologic approaches
– Recommendappropriateantibioticregimens
– Monitor forsafetyandefficacyoftherapy
Exclusionsforself‐treatmentofwounds
–Woundscontainingforeignobjects
–Chronicnon‐healingwounds
–Deepwounds
–Involvementofface,mucousmembrane,orgenitalia
–Woundsduetoanimalorhumanbites
–Noimprovementorworseningafter5days
–Signsofinfection
(PayattentiontoclinicalpresentationofSSTIs)
what is Impetigo
UncomplicatedformofSSTIaffectingtheepidermisorup tothedermal‐epidermaljunction
Commoninchildren
Highlycontagious
Ecthymaisformofimpetigo –Ulcerative–> scarring Usuallymanagedoutpatient
1) non-bullous
2) bullous (due to bacterial toxin production).
May rupture –> erythematous erosion
3) Ecthyma - more severe form. tend to form scar even after infection is clear.
Impetigo causative organism and culture
- S. aureus
- B-hemolytic streptococci (eg streptococcus pyogenes)
- Bullous form caused by toxin-producing strain of s. aureus
Cultures(optional)
– Maycultureifpusorexudate
– Reasonabletreatwithoutculture •EmpiricallycoverS.aureusANDβ‐hemolyticStreptococci
Hospital‐acquired(HA‐MRSA)
Community‐acquired(CA‐MRSA)
– Geneticallydifferentbackground
•Panton‐Valentineleucocidin(PVL)
•SCCmecIV
– Usuallysusceptibletooralnon‐beta‐lactams(e.g.clindamycin)
MRSA Risk factor
Hemodialysis Outpatientchemotherapy Long‐termcarefacilitiesresidents Athletes Militaryrecruits Menwhohavesexwithmen(MSM) HistoryofMRSAinfectionorcolonization
Impetigo treatment
Topicaltherapy
– Impetigo–limitedlesions
– Mupirocin1applicationBDx5days
Systemic(oral)therapy
– Ecthymaorimpetigo– numerouslesions
Streptococci only:
- PENICILLIN VK 250-500mg PO QDS
MSSA and Streptococci (empirical)
- Cloxacillin 250-500mg PO QDS
- Cephalexin 250-500mg PO QDS
MRSA & MSSA & streptococci
- Erythromycin 250mg PO QDS
- Clindamycin 300mg PO QDS
All for 7 days
Purulent SSTI
Cutaneousabscesses
– Puscollectioninthedermis(ordeeper)
Furuncles(“boils”)
– Infectionsofthehairfollicles
– Extendthroughthedermis
– Formsasmallabscess
Carbuncles
– Involvesfewadjacentfollicles
Cutaneous abscess is what
purulent SSTI
- fluctuant red nodules
- Encircled by erythematous swelling
Furuncle is ?
Inflammatory nodule
overlying pustule
(one follicule affected)
Carbuncle is ?
larger and deeper type of furuncle
affect many adjacent hair follicule
Causative organisms for purulent SSTI and culture
S. aureus
large skin abscesses may be polymicrobial
Cultures
– Culture of pus is recommended (if have pus)
– Reasonable to treat without cultures (coz predictable)
purulent SSTI treatment
Recommendedtreatmentisincisionanddrainage(I&D)
Adjunctivesystemicantibiotics
– Unabletodraincompletely
– LackofresponsetoI & D
– Extremesofage
– Immunosuppressed
– Severe/extensivediseaseandsystemicillness
• SIRScriteria:
- temperature>38 Cor90beats/min,
- respiratoryrate>24breaths/min,
- WBC>12,000or
systemicinflammatoryresponsesyndrome criteria
• SIRScriteria:
- temperature>38 Cor90beats/min, - respiratoryrate>24breaths/min, - WBC>12,000or
Adjunctivesystemicantibiotics for purulent SSTI
– Oral(PO)isadequateinmostcases
–Intravenous(IV)maybenecessarywithseverediseasesor systemicillness(MEET one or more SIRS criteria)
MSSA only
- cloxacillin 250 - 500mg PO QDS
- Cephalexin 250 - 500mg PO QDS
- Cefazolin 1g IV q8hr
MRSA and MSSA
- Clindamycin 300mg PO QDS
600mg IV Q8h
- Erythromycin 250mg PO QDS
500mg IV Q6h
ALL 5-7days
10 days for recurrent infection
Cellulitis
Acuteinflammationofepidermis,dermisandsometimes superficialfascia
Purulentornon‐purulent Bacteriacaninvadelymphatictissueandblood (___ERYSIPELAS__) – Affectsuptosuperficialdermis andlymphatictissues
- spreading poorly demarcated area of erythema
- may be complicated by skin peeling and bullae formation
Erysipelas
cellulitis
- bright red
- raised border
- sharply demarcated
Causative organisms for cellulitis
S. aureus
B-hemolytic strepto (strepto. pyogenes)
- almost always the cause of erysipelas
other based on comorbidities and mode of injury
- immunosuppressed = + Streptococcuspneumoniae, Escherichiacoli,Serratiamarcescens
- chronic liver / renal disease = + Vibriospp.,Escherichiacoli, Pseudomonasaeruginosa
- Dog/cat bite = Pasteurella,Streptococcusspp., Staphylococcusspp.,oralanaerobes
cellulitis cultures
– Notroutinelyrecommended
– PurulentinfectionsifI&D,shouldbecultured
– Immunosuppressed,dog/catbites,immersioninjuriesor
severesystemicpresentation (Fever/chill)
• Culturecutaneousaspirates,biopsies,swabs
• Bloodcultures
cellulitis treatment
(\_\_\_ABX selection )and(_ROUTE_)dependon –Systemicsignsofinfection(e.g.fever) –Severityofillness •SIRScriteria * –Patientcomorbidities –MRSAriskfactors –Purulentversusnon‐purulent –Patientallergies
Non-purulent cellulitis tx
Mild (no SNS of infection)
- Organism = Strepto spp
- Penicillin VK PO 250-500mg QDS
- Cephalexin PO 250-500mg QDS
- Cloxacillin PO 250-500mg QDS
- Clindamycin PO 300mg QDS
Moderate - w >=1 SIRS
- Strep + saureus
- 1 SIRS = - Penicillin VK PO 250-500mg QDS
- Cephalexin PO 250-500mg QDS
- Cloxacillin PO 250-500mg QDS
- Clindamycin PO 300mg QDS
- >= 2 SIRS =
- IV cefazolin 1g q8h
- IV ceftriaxone 1-2g Q24h
- IV Penicilin G 2-4 MU q4-6h (strep only)
- IV Clindamycin 600mg q8h
Severe - with > 2 SIRS + hypotension/rapid progression, immunosuppressed, comorbidities (eg chronic liver / renal disease)
- Strep + MSSA + - gram -ve or anaerobes
- MSSA ONLY
- IV cefazolin 1g q8hr
- IV ceftriaxone 1-2g q24h
- IV amox/clav 1.2g q8h
- IV pip/tazo 3.375g q6h
- MRSA
- IV Vancomycin 15-20mg/kg q8-12h
PLUS
IV cefttriaxone 1-2g q24hr
OR
IV Pip/tazo 3.375g q6hr
OR
IV meropenam 1g q8h
ALL for 5 days
- may extend if not significantly improved
- immunosuppressed may need 7-14days
Purulent cellulitis treatment
Mild - no SNS of infection
- Strep + s.aureus
MSSA
- PO Cephalexin 250-500mg QDS
- PO Cloxacillin 250-500mg QDS
MSSA + MRSA
- PO TMP/SMX 960-1920 mg BD (T:S; 1:5)
- PO Clindamycin 300mg QDS
- PO Doxycycline 100mg BD
- PO Linezolid 600mg BD
Moderate - w >=1 SIRS
- Strep + saureus
- 1 SIRS =
MSSA
- PO Cephalexin 250-500mg QDS
- PO Cloxacillin 250-500mg QDS
MSSA + MRSA
- PO TMP/SMX 960-1920 mg BD (T:S; 1:5)
- PO Clindamycin 300mg QDS
- PO Doxycycline 100mg BD
- PO Linezolid 600mg BD
- >= 2 SIRS = MSSA
- IV Cloxacillin 1-2g q4-6h
- IV cefazolin 1g q8h
MSSA + MRSA
- IV Clindamycin 600mg q8h
- IV vancomycin 15-20mg/kg q8-12hr
- IV Linezolid 600mg BD
- IV Daptomycin 4mg/kg q24h
Severe - with > 2 SIRS + hypotension/rapid progression, immunosuppressed, comorbidities (eg chronic liver / renal disease)
- Strep + MSSA + - gram -ve or anaerobes
MSSA
- IV cefazolin 1g q8h
- IV ceftriaxone 1-2g q24h
- IV amox/clav 1.2g q8h
- IV Pip/tazo 3.375g q6h
MRSA - IV Vancomycin 15-20mg/kg q8-12h PLUS - IV ceftriaxone 1-2g q24h OR - IV Pip/tazo 3.375g q6h OR - IV meropenam 1g q8h
ALL for 5 days
- may extend if not significantly improved
- immunosuppressed may need 7-14days
monitoring for cellulitis tx
- safety
-efficacy- assess for clinical response in 48-72hr
- improved fever, pain, swelling, erythema, warmth (?)
YES
- if initial IV Abx, change to PO
- afebrile x 48h
- ALL for 5 days
- may extend if not significantly improved
- immunosuppressed may need 7-14daysNO
- consider resistant organisms and or alternative causes
Cellulitis complication
Bacteremia Endocarditis Toxicshock Glomerulonephritis Lymphedema Osteomyelitis Necrotizingsoft-tissueinfections,e.g.necrotizingfasciitis