Integumentary - Week 6

Gram + Organisms

Normal flora on the skin: 2 common org responsible for skin infections --
Staph Aureus

Staph aureus

GPC in clusters


GPC in chains or pairs
ABCDG strains


-Infections that affect deeper dermis/SQ
-Arise from minor breaks in skin/can occur anywhere bacteria enter under skin
-We are colonized with staph and strept

Cellulitis s/sx

-Rapidly spreading edema, redness, and heat with systemic manifestations (possible sepsis)
-erythema, edema, shiny

Cellulitis predisposing factors

-venous insufficiency (pooling of fluid = good medium for bacteria)
-lymphatic obstruction - mastectomy
-disruption of cutaneous barrier by ulcer/abscess
-fissured toe webs
-inflammatory dermatosis: eczema, obesity, skin previously damaged by trauma,

Cellulitis treatment: mild

Based upon severity of infection*
Start as narrow as possible*
MILD - oral; most likely not see in hospital
-PCN** (aminopenicillin - ampicillin or Unasyn)
-Cephalosporin - 1st gen (Keflex) - excellent strept coverage! even better than vanco!

Cellulitis treament: moderate

MODERATE (fever, chills, leukocytosis)
-PCN: ampicillin/Unasyn
-1st/3rd gen cephalosporin (Ancef/Rocephin>broaden coverage)

Cellulitis treatment: severe

SEVERE - hospitalized, require IV abx; likely can d/c home on PO; recurrent? may need longer IV abx and go home on it
-vanco**(typical first line for inpt/outpt, tx failure, or immunocompromised)
-other considerations:
-measures to decrease edema

Furuncle/Carbuncle/Abscess Treatment: mild

-may need I&D and IV abx for short course or secondary cellulitis
MILD: skin boil, inflammed hair follcile

Furuncle/Carbuncle/Abscess Treatment: moderate

-Empiric: staph or strept;
>TMP/SMX (Bactrim)
>MSSA - Keflex/Ancef (no RF for MRSA)
>MRSA (can be community acquired)- TMP/SMX,

Furuncle/Carbuncle/Abscess Treatment: severe

SEVERE (septic?)
>ceftaroline (5th gen)
>MSSA: Nafcillin (PCN), Ancef (1st gen),
>MRSA: same as empiric


-Increased prevalence causing community onset disease; differs from HA MRSA
>causes infections in patients lacking typical risk factors
>not related to local hospital strains
>contains genes associated with mild to severe soft tissue infections

CA-MRSA risk factors

Prevalent occurrences:
-contact sports (moisture)
-day care workers, bus drivers, group home, nursing home, healthcare workers
-diabetes (immunocomp)
-prison inmates


*Differs from HA
Non beta lactam antibiotics
-vancomycin (hospitalized, septic; x24 hours - then PO bactrim, clinda, or doxy)
-zyvox ($$$)

CA-MRSA tx recurrent

-5 day decolonization BID intranasal mupirocin (Bactroban) (decrease the load, can get infected from increased burden)
-daily chlorhexidine washes x 3 days
-daily decontamination of personal items (hot water and bleach)

Cellulitis from animal bites: H&P

-HPT: stray vs house pet; vaccine status; provoked? recurrence? (time of bite)
-ROS: fevers/chills; pain? out of proportion? (worry about nec fasc);
-PE: puncture, swelling, erythema, drainage, ROM - esp cat bite
*Eval s/sx infection
*take joints thru ful

Cellulitis from animal bites: tx considerations

1. Empiric - early antimicrobial tx not warranted in low-risk wounds
-no puncture
-pts who are immunocompetent: no significant co-morbidities or meds that suppress
-wounds NOT involving the hands, face, foot
2. Empiric - early antimicrobial tx warranted f

Cellulitis from animal bites: Decision to admit

-Multiple severe injuries (head/hand)
-spreading infection, systemic symptoms> sepsis? leukocytosis? significant fevers, severity of injury, puncture to hand (hand surgeon?)
-immunocompromised host
-failed outpt therapy
Further complications

Human Bites

-3rd most common
-mix of bacteria - aerobic/anaerobic
-history > time/circumstance, hand dominance - any bite, tetanus (last vaccine), co-morbid conditions - HIV, Hep B/C, herpes
>assessment: s/sx infection, injuries to deeper

necrotizing fasciitis

SEVERE complication
-organisms> strept, staph, peptostreptococcus
-deep, involves fascia/muscle compartments
-devastating, a major destruction of tissue - leading to a fatal outcome
-common in diabetes, ASHD, valvular disease, venous insufficiency

necrotizing fasciitis manifestations

*starts with minor skin infection, the severe pain
-severe, constant pain
-bullae (big pustular lesion)
-skin necrosis or eccymosis
-hard wood "feel" of SQ tissue
-gas in soft tissue (crepitus)
-edema that extends beyond margin of erythema (significant -

Necrotizing fasciitis/gas gangrene Diagnostics/Tx

-surgery on board
-CT/MRI - edema along fascial plane
-clinical judgement
-surgery w/ multiple debridements (clean, then leave open - several times then close)
-broad coverage to include anaerobes (if skin - PCN + clindamycin)