SSTI

Question 1

what are the normal protecting factors in skin

Answer 1

- dry - inhibits growth 
fatty acids 
acidic ph 
renewal of epidermis - bact removed 
low temp - inhibit growth

Question 2

what causes ssti

pathophysiology

Answer 2

injury diseases - lead to disruption of normal host defences
= normal skin bact penetrates depper
= other bact introduces
= excessive bact growth

Question 3

risk factors of ssti

Answer 3

• innocula with high bact eg dirty knife
• excessive moisture
• red blood supply ( dec wbc , inc infection risk )
  bacterial nutrients eg diabetic
  poor hygiene
  sharing personal items

Question 4

4 categories for classification of ssti

Answer 4

severity - mild mod severe
depth - superficial or deep uncomp or comp
presence of absence of discharge - purulent or non purulent
microbiology
- single pathogen ( pri ) or polymicrobial ( secondary )

Question 5

impetigo and ecthyma category

Answer 5

mild, 
uncomplicated,
 purulent or non  ,
 primary 
epidermic or up to the dermal epidermal junction

Question 6

impetigo treatment for mild

Answer 6

mupirocin bd 5 days topical

Question 7

severe impetigo ( not common ) or all ecthyma treatment

Answer 7

empiric w no allergy OR MSSA CULTURE DIRECTED  
cephalexin or cloxacillin 
if pen allergy use clindamycin 
culture directed for s.pyogenes use 
penicillin vk 

7 days for all

Question 8

hair follicles which 3 types

think of the clue related to hair

Answer 8

furuncles
carbuncles
cutaneous abscesses

Question 9

furuncles /boils
carbuncles
cutaneous abscess
differeniate btwn them

Answer 9

furuncles - 1 hair follicle

carbuncles - few adjacent hair follicles
- small abscess

cutaneous abscess

• pus collection
• not necessary near foliccle

Question 10

mainstay treatment for fur carb cute

Answer 10

incision and drainage

Question 11

when to use ab for fur carb cute

Answer 11

• if cant drain fully
• no response to draining
• extensive and alot of sites involved
• v old or v young
• immunosuppressed
• sirs critera

Question 12

what are the sirs critera

Answer 12

1. fever > 38 deg 
or temp < 36 
2. rr > 24 breaths / min 
3. HR > 90 bpm 
4. WBC < 4x 10^9/L or > 12x10^9/L

Question 13

AB treatment for fur carb cute

and duration

Answer 13

mssa only
= cloxacillin, cephalexin or cefazolin

mssa, mrsa

• clindamycin
• trimethoprim/sulfamethoxazole
• doxycycline

outpatinet 5-7 days
inpatient 7-14 days

Question 14

cellulitis affect what and purulence

Answer 14

dermis to fascia

can be purulent or non purulent

Question 15

erysipelas affect what and purulence

Answer 15

superficial dermis

non purulent

Question 16

cellulitis and erysipelas complications 7

Answer 16

1. bacteremia
2. endocarditis
3. toxic shock
4. glomerulonephritis
5. lymphedema
6. osteomyolitis
7. necrotising soft-tissue infections eg necrotisng fasciitis

Question 17

types of microbio cultures

Answer 17

1. cultaneous aspirates
2. tissue samples from bipsies
3. blood
4. peripheral skin swab but may not be causation organism

Question 18

MRSA risk factors

Answer 18

1. immunosuppression
2. failed treatment priot without mrsa coverage
3. critically ill - hypotensive

Question 19

cellulitis and erysipelas
categorise severity
and what to cover

Answer 19

mild - no sirs - cover strep spp

mod - 2 or more sirs
- cover s.aureus also

severe - more than 2 sirs + hypo <100, rapid prog, immunosuppression, comorb = cover p.aureg also ( gram neg )

Question 20

treatment for mild non purulent cellulitis/erysipelas

and treatment for mild PURULENT cellulitis/erysipelas

Answer 20

po 
pen vk - narrowest 
cloxacillin 
cephalexin 
^ broader 
clindamycin for allergy

if purulent must cover s.aureus also 
cefalexin 
cloxacillin
clindamycin 
and if mrsa risk factors add any one of the 3 mild ones

Question 21

treatment for moderate non purulent cellulitis/erysipelas

Answer 21

if only 1 sirs treat for same as mild
pen v, cloxacillin, cephalexin, clindamycin
preferably cloxacillin and cephalexin bc broader

if 2 sirs or above fails
then use
IV - cefazolin, penicillin G
or clindamycin ( allergy )

Question 22

treatment for severe non purulent cellulitis /erysipelas

Answer 22

iv -
piptazo
cefepime
meropenem

if mrsa risk factors 
add iv vanco 
daptomycin or 
linezolid 
^ last 2 more ex and broader , vanco common

Question 23

3 abs for coverage of mrsa in milder cases

Answer 23

clindamycin
trimethoprim, sulfamethoxazole
doxycycline

Question 24

3bs for coverage of mrsa in more SEVERE cases

Answer 24

vancomycin
daptomycin
linezolid

Question 25

diff between cefalexin and cefazolin

Answer 25

both cover strep and staph cefazolin only iv alternative for anti staph penicillins in patients allergic to penicillins

Question 26

diff between pen g and pen v

Answer 26

pen v is oral ( vomit ) pen g is parental

Question 27

treatment for moderate PURULENT cellulitis/erysipelas

Answer 27

``` cover for staph aureus also if only 1 sirs criteria - cefalexin - cloxacillin - clindamycin ``` 2 sirs criteria or if above fails iv cefazolin cloxacillin clindamycin if mrsa risk factor add any one of the severe ones

Question 28

treatment for severe purulent cellulitis/erysipelas

Answer 28

same as non purulent iv piptazo cefepime meropenem and if mrsa risk factor then add one of the 3 severe ones

Question 29

cellulitis from bite wounds organisms

Answer 29

``` s.aureus strep spp animal - pasteurella multocida human - eikenella corrodens oral anerobes eg prevotella spp, peptostreptococcus spp ```

Question 30

treatment for bite cellulitis what to cover then whats the treatment

Answer 30

augmentin ( gram neg ) ceftriaxone/cefuroxime or cipro/levo for pen allergy add clindamycin or metronidazole if need anaerobic coverage po or iv depends on severity

Question 31

monitoring for cellulutis and erysipelas when to look for changes when t o switch to oral duration of ab what if no culture results

Answer 31

2-3 days response switch to po if afebrile 48 hrs and clinical improvement - if no culture then choose oral agent w similar coverage as initial iv agent ab for 5 days at least if immunocompromsed 7-14 days

Question 32

3 pathophysiology paths for dfi

Answer 32

1. neuropathy peripheral - dec pain sensation and altered pain response motor - muscle imbalance autonomic - inc dryness cracks and fissures 2. vasculopathy - early atherosclerosis - peripheral vascular disease - worsened by hyperglycemia and hyperlipidemia 3. immunopathy impaired immune response - inc susceptibility to infections - worsened by hyperglycemia all these cause ulcer formation or wounds - bacterial colonisation, penetration, proliferation = dfi

Question 33

dfi and PU | diagnosis criteria

Answer 33

purulent discharge or at least 2 signs of inflammation ``` erythema warmth tenderness pain induration ( localised hardening of the sst) ```

Question 34

dfi and Pu microbio when gram neg present when anaerobes present

Answer 34

strep and staph aureus most common gram neg when chronic or prev treated w ab - ecoli, klebsiella, proteus spp anaerobic when ishchaemic or necrotic - peptostreptococcus, veillonella , bacteriodes

Question 35

when to culture for dfi and pui

Answer 35

dont culture if not infected - dont culture how deep is not related to whether infected mod to severe - use tissue culture after cleansing and before starting ab - dont use skin swab

Question 36

when to empirically cover pseudomonas aeruginosa

Answer 36

severe | prev treatment failure when not active against p.aerug

Question 37

dfi and pui mild classification and what to treat and treatment duration

Answer 37

classification - no sirs - erythema 2 cm orless around the ulcer - skin and sc infection ``` cover strep and staph po cloxacillin cephalexin clindamycin ``` if mrsa risk factor add one of 3 mild one po ( trimethoprim, sulfomethoxazole doxycycline , clindamycin) duration 1-2 weeks

Question 38

dfi and pui moderate classification what to treat and treatment duration

Answer 38

classification - no sirs - infection of deeper tissues like bone or joints - erythema >2cm around ulcer cover strep, staph , gram neg , anaerobes ``` treatment IV amox/clav ertapenem( reserved for esbl) ceftriaxone + metronidazole/clindamycin ( for anaerobic coverage ) ``` if mrsa risk factor add one of 3 iv severe options vanco, dapto, linezolid and strep down to po if improvement duration 1-3 weeks

Question 39

dfi and pui severe classification what to cover and treatment and duration

Answer 39

classification - as long as 1 sirs criteria present cover strep, staph, gram neg including p.aerug and anaerobes treatment iv piptazo meropenem cefepime + metronidazole/clindamycin for anaerobic coverage if mrsa risk factor add one of 3 iv severe options vanco, dapto, linezolid can step down to po if patient improves duration 2-4 weeks

Question 40

duration of dfi and pui treatment for bone involved

Answer 40

surgery amputated 2-5 days surgery w infected tissue left 1-3 weeks surgery w residual viable bone - 4-6 weeks no surgery or surgery w residual dead bone - at least 3 months

Question 41

for dfi and pui do we continue ab until complete wound healing

Answer 41

no ab may resolve th einfection but ulcer or wound may take longer to heal, not necessary to continue ab til wound healing ocurs

Question 42

dfi wound care | and foot care

Answer 42

wound care - debridement - procedure to remove infected tissue - offloading - supporitive shoes - dressing for healing environemnt and control excess exudation foot care - daily inspection - prevent wound and ulcers

Question 43

4 factors causing pressure ulcers

Answer 43

moisture pressure shearing force friction

Question 44

risk factors for pressure ulcers ( PU ) 6

Answer 44

``` red mobility debilitated red consciousness sensory and autonomic impairment eg incontinence extreme age malnutriiton ```

Question 45

pui adjuctive measures what kind of liquid to use

Answer 45

debridement local wound care - normal saline and avodi harsh chemicals relief of pressure turn every 2 hrs for prevention

Question 46

antibiotic dosing

Answer 46

``` Amoxicillin/clavulanate 625mg PO BD-TDS*; 1.2g IV Q8H* Cefepime 2g IV Q8H* Cefazolin 1-2g IV Q8H* Cefepime 2g IV Q8H* Cephalexin 250-500mg PO QDS* Cloxacillin 250-500mg PO QDS; 1-2g IV Q4-6H Penicillin G 2-4 million units Q4-6H* Penicillin VK 250-500mg PO QDS Piperacillin/tazobactam 4.5g IV Q6-8H* ``` Trimethoprim/sulfamethoxazole 800/160mg PO BD* Vancomycin 15mg/kg Q8-12H Clindamycin 300mg PO QDS; 600mg IV Q8H Metronidazole 500mg PO/IV TDS

Question 47

is nausea and vomitting an allergy | and whats considered true allergy

Answer 47

no its side effect anaphylaxis , hives

Question 48

diff between ertapenem and meropenem/imipenem

Answer 48

mero and imipenem covers p.aureg - used for severe dfi/pui ``` erta dosent - use for moderate dfi/pui but we like to reserve this class for esbls ! ```

Question 49

diff between augmentin and piptazo

Answer 49

piptao covers p.aerug -severe dfi/pui augmentin dosent - used for moderate dfi/pui

Question 50

diff between cefepime and ceftriaxone

Answer 50

cefepime - 4th gen covers p.aureg used for severe dfi/pui ceftriaxone -3rd gen - dosent cover so used for moderate dfi/pui