emDocs - April 14, 2015 - By Marvinia Charles & Jill R. Ripper.
Editor: Alex Koyfman & Justin Bright
"Definition
Cellulitis comes from a Latin derivation literally meaning “inflammation of the cell”. Cellulitis is a spreading infection of the skin and its underlying tissues associated with leukocyte invasion and localized capillary dilatation.
Etiology
Primary cellulitis usually follows a breach in the skin’s integrity but occasionally occurs from hematogenous or lymphangitic spread from more distal sources. Micro-damage can cause the opening to be non-visible on physical exam. Predisposing conditions to cellulitis commonly include trauma, venous stasis, obesity, lymphedema, pre-existing dermatitis, co-morbid conditions, burns, and surgical wounds.
In primary cellulitis, the natural bacterial skin flora of S. aureus and S.pyogenes are the usual causative agents. Secondary cellulitis occurs when pathogens infect larger wounds or areas of pre-existing dermatitis. Conditions surrounding the occurrence may dictate the pathogen especially in the immunocompromised patient such as fresh water (Aeromonas hydrophilia), sea water (Vibrio vulnificans), fish tanks (Mycobacterium marinum), soil (Clostridium perfringens), plants (Sprorothrix schenickii) and human bites (Eikenella corrodens). Physical sites also may dictate different pathogens for example peri-anal infections have more of a mixed flora than peripheral body parts. A wide variety of atypical pathogens can invade the skin of immunocompromised patients including fungi, mycobacteria, pseudomonas, aspergillus, and cryptococcus. MRSAshould always be considered due to its increasing frequency in both healthy and immunocompromised populations."
http://www.emdocs.net/management-of-cellulitis-in-the-immunocompromised-patient/