panniculitis definition

hospitalizations for skin andsoft tissue infections, or sstis, are rising in frequency. according to a recent ahrq study,hospital stays with a principal diagnosis of ssti grew75% from 1997 to 2010. there's no clear explanation for this phenomenon although it islikely due in part to the rise in community-acquired methicillin-resistantstaph aureus or mrsa infections. according to the 2014 infectiousdiseases society of america guidelines, the first step in diagnosing andmanaging skin and

soft tissue infections is determining ifthe process is purulent or non purulent. purulent sstis include furuncles, or boils, carbuncles, andcutaneous abscesses. non purulent skin andsoft tissue infections include erysipelas, cellulitis, and necrotizing fasciitis. this clinical distinction iscritical as the management of both groups of infections differs. incision and drainage ori and d is necessary for the resolution of purulent sstis.

and according to the 2014 idsa guidelines,antibiotics, as an adjunct to ind, are only recommended if patients haveseverely impaired immune systems or evidence of a systemicinflammatory response. next, clinicians must determine iftheir patient has mild, moderate or severe disease. patients without signs to suggestsa systemic inflammatory response qualifies having mild infection. the majority of skin andsoft tissues infections in the u.s. are mild, andcan be treated in an out-patient clinic.

purulent sstis can betreated with i & d alone, while patients with non-purulentsstis can be treated with empiric oral antibiotics effectiveagainst the common pathogens, namely group a streptococcus, plus orminus methicillin sensitive staphoreous. patients with typical sstis togetherwith signs to suggest a system inflammatory response haveinfections of moderate severity. the guidelines recommend that patientswith purulent sstis of moderate severity be managed with i & d plus empiric oralantibiotics with activity against mrsa, namely trimethoprim-sulfamethoxazoledoxycycline or clindamycin.

patients with nonpurulent sstis ofmoderate severity should be treated with intravenous antibiotics directedagainst streptococcus and methicillin sensitive staph aureus. as discussed earlier, the patient inthis case had non-purulent cellulitus of moderate severity when she was admitted,and should've been started on antibiotics targeted against streptococcus andmethicilin sensitive staph aureus alone. the idsa guidelines include patients whofail initial management among those with severe infections. they suggest broadening antibiotic therapyin these patients to include anti-mrsa

coverage, as well as coverage directedagainst gram negative organisms in specific situations,like necrotizing fasciitis. so that begs the question, has this patient failed herinitial antimicrobial management? the involved area of her leg has notchanged significantly since admission. and she has received broad spectrumantibiotics for almost 48 hours. most patients treated with the rightantibiotics begin to improve symptomatically by 24 to 48 hoursafter the initiation of therapy, but some do not see improvement for 72 hours.

according to the fda guidelines forssti studies, a clinical response is defined as the cessation of spread orreduction of size of the ssti, plus resolution of fever 48 to 72hours after starting antibiotics. in this patient's case,she meets the general criteria for a positive clinical response. she is afebrile, her tachycardia hasresolved, and the arythema, edema, and tenderness have not spread sincethe initiation of antibiotics. thus her antibiotics have not failed,they've worked. in the absence of specificepidemiologic risk factors

most sstis are caused by streptococcus orstaphylococcus species. as previously discussed,her initial antibiotic regimen was inappropriate because it was overly broad,providing gram negative, and anti mrsa activity when it wasnt needed,and is actually contraindicated now, in the era of rising clostridiumdifficile infection rates, and the emergence of multidrug resistant organisms. for that reason it isappropriate to de-escalate her therapy now to a regiment that wouldhave been appropriate from the start. in this case, cefazolin.

it is important to clarify whatmight already seem obvious to you. you do not have to wait until the 48hour timeout to make this switch. you could have done it assoon as you began to care for the patient based upon her presentationand the likely microbiologic ideology. given her clinical scenario you couldconsider making an iv to po switch during your 48 hour time out. she has improved clinically, although you don't know ifshe's taking oral medications. in this case,the narrowest agent with antistrep and

antiemesis activity as well as goodoral bioavailability is dicloxacillin. other potential optionswith broader coverage but good oral bioavailability includecephalexin, doxycycline, and clindamycin. again, these oral antibiotics can beused from the start in mild cases of nonpurulent cellulitis. if your patient is not responding to, or slowly recovering on antibiotics,it is important to consider non-infectious etiologies thatcan masquerade as cellulitis. stasis dermatitis may be the most common.

stasis dermatitis describes the chronicskin changes associated with chronic venous insufficiency includingerythema and desquamation. it is typically bilateral, which isvery uncommon in acute cellulitis. and stasis dermatitis istypically non-tender. lipodermatosclerosis in its acute formis a common cause of pseudo cellulitis. it is a severe fibrosing panniculitisof the subcutaneous tissue, and is another consequence ofchronic venous insufficiency. this process typically starts nearthe medial region of the ankle and progresses to involvethe leg circumferentially.

the leg then takes on the appearanceof what's called the inverted champagne bottle. in its acute form, the affected region canbe erythematous, tender, and edematous. although these patients maybe at an increased risk for acute cellulitis due to their abnormalskin, the chronicity of their symptoms, which can last for months in the absenceof systemic symptoms can help you make the distinctionfrom acute cellulitis. contact dermatitis, both irritant andallergic, often present with erythematous patches limited for the most partto the area of initial exposure.

the lesions can be warm andpainful, but again, systemic signs of infection are absent. other mimics include thrombophlebitis,drug reactions, radiation recall syndromes,and insect stings or bites. for a more in depth discussion ofnon-infectious etiologies that are often confused with sstis please seethe two articles lifted in the for further reading section of this case.