SSTI

Question 1

PathophysiologyofSSTIs

Answer 1

Disruptionofnormalhostdefensesbyprocesses

suchas puncture,abrasion,diseases

Question 2

Normalprotectingfactors of skins

Answer 2

Normalprotectingfactors
–Drysurface 
–AcidicpH(~5.6) 
–Fattyacids 
–Renewalofepidermis 
–Lowtemperature

Question 3

Predisposingfactors to ssti

Answer 3

Predisposingfactors 
–Highbacterialinnocula 
–Excessivemoisture 
–Reducedbloodsupply 
–Presenceofbacterialnutrients 
–Poorhygiene 
–Sharingofpersonalitems

Question 4

Classification of SSTIs

Answer 4

Presence/absenceofdischarge
–Purulentversusnon‐purulent

Severityorextent
–Mildversusmoderateversussevere
–Uncomplicatedversuscomplicated
–Superficialversusdeep

Microbiology
–Singlepathogen(primary)versuspolymicrobial(secondary)

Anatomicalsite
–Hairfolliclesversusepidermisversusdermis,etc.

Question 5

Classification according to anatomical sites

- Epidermis

Answer 5

impetigo

Question 6

Classification according to anatomical sites

- dermis

Answer 6

Erysipelas

Question 7

Classification according to anatomical sites

- Hair follicules

Answer 7

Folliculitis
Furuncles
Carbuncles

Question 8

Classification according to anatomical sites

- Subcutaneous fat

Answer 8

Cellulitis

Question 9

Classification according to anatomical sites

- Fascia

Answer 9

Necrotizing fasciitis

Question 10

Classification according to anatomical sites

- Muscle

Answer 10

Myositis

Question 11

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

Answer 11

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

Question 12

Exclusionsforself‐treatmentofwounds

Answer 12

–Woundscontainingforeignobjects
–Chronicnon‐healingwounds
–Deepwounds
–Involvementofface,mucousmembrane,orgenitalia
–Woundsduetoanimalorhumanbites
–Noimprovementorworseningafter5days
–Signsofinfection
(PayattentiontoclinicalpresentationofSSTIs)

Question 13

what is Impetigo

Answer 13

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.

Question 14

Impetigo causative organism and culture

Answer 14

• 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)

Question 15

MRSA Risk factor

Answer 15

 Hemodialysis 
 Outpatientchemotherapy 
 Long‐termcarefacilitiesresidents 
 Athletes 
 Militaryrecruits 
 Menwhohavesexwithmen(MSM) 
 HistoryofMRSAinfectionorcolonization

Question 16

Impetigo treatment

Answer 16

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

Question 17

Purulent SSTI

Answer 17

 Cutaneousabscesses
– Puscollectioninthedermis(ordeeper)

 Furuncles(“boils”)
– Infectionsofthehairfollicles
– Extendthroughthedermis
– Formsasmallabscess

 Carbuncles
– Involvesfewadjacentfollicles

Question 18

Cutaneous abscess is what

Answer 18

purulent SSTI

• fluctuant red nodules
• Encircled by erythematous swelling

Question 19

Furuncle is ?

Answer 19

Inflammatory nodule
overlying pustule

(one follicule affected)

Question 20

Carbuncle is ?

Answer 20

larger and deeper type of furuncle

affect many adjacent hair follicule

Question 21

Causative organisms for purulent SSTI and culture

Answer 21

S. aureus

large skin abscesses may be polymicrobial

Cultures
– Culture of pus is recommended (if have pus)
– Reasonable to treat without cultures (coz predictable)

Question 22

purulent SSTI treatment

Answer 22

 Recommendedtreatmentisincisionanddrainage(I&D)
 Adjunctivesystemicantibiotics
– Unabletodraincompletely
– LackofresponsetoI & D
– Extremesofage
– Immunosuppressed
– Severe/extensivediseaseandsystemicillness
• SIRScriteria:
- temperature>38 Cor90beats/min,
- respiratoryrate>24breaths/min,
- WBC>12,000or

Question 23

systemicinflammatoryresponsesyndrome criteria

Answer 23

• SIRScriteria:

          - temperature>38 Cor90beats/min,
          - respiratoryrate>24breaths/min,
          - WBC>12,000or

Question 24

Adjunctivesystemicantibiotics for purulent SSTI

Answer 24

– 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

Question 25

Cellulitis

Answer 25

Acute inflammation of epidermis, dermis and sometimes  superficial fascia Purulent or non‐purulent Bacteria can invade lymphatic tissue and blood (___ERYSIPELAS__) – Affects up to superficial dermis  and lymphatic tissues - spreading poorly demarcated area of erythema - may be complicated by skin peeling and bullae formation

Question 26

Erysipelas

Answer 26

cellulitis - bright red - raised border - sharply demarcated

Question 27

Causative organisms for cellulitis

Answer 27

S. aureus B-hemolytic strepto (strepto. pyogenes) - almost always the cause of erysipelas other based on comorbidities and mode of injury - immunosuppressed = + Streptococcuspneumoniae,  Escherichia coli, Serratiamarcescens - chronic liver / renal disease = + Vibrio spp.,Escherichia coli,  Pseudomonas aeruginosa - Dog/cat bite = Pasteurella,Streptococcus spp.,  Staphylococcus spp., oral anaerobes

Question 28

cellulitis cultures

Answer 28

– Not routinely recommended – Purulent infections if I&D, should be cultured – Immunosuppressed, dog/cat bites, immersion injuries or  severe systemic presentation (Fever/chill) • Culture cutaneous aspirates, biopsies, swabs • Blood cultures

Question 29

cellulitis treatment

Answer 29

``` (___ABX selection ) and (_ROUTE_) depend on –Systemic signs of infection (e.g. fever) –Severity of illness •SIRS criteria * –Patient comorbidities –MRSA risk factors –Purulent versus non‐purulent –Patient allergies ```

Question 30

Non-purulent cellulitis tx

Answer 30

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

Question 31

Purulent cellulitis treatment

Answer 31

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

Question 32

monitoring for cellulitis tx

Answer 32

- 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 7-14days NO - consider resistant organisms and or alternative causes

Question 33

Cellulitis complication

Answer 33

``` Bacteremia  Endocarditis Toxic shock Glomerulonephritis Lymphedema Osteomyelitis  Necrotizing soft-tissue infections, e.g. necrotizing fasciitis ```