Practice development The diagnosis and management of necrotising fasciitis
with myonecrosis they carry a very high mortality[7]
. Recently, increased cases of
monomicrobial NSTI caused by methicillin- resistant Staphylococcus aureus (MRSA) have been reported[8]
.
Most cases of type 1 NSTI are associated with penetrating injuries or abscesses[6]
.
Type 2 Type 2 is the more common form of NSTI and is characterised by the presence of polymicrobial organisms of both aerobes and anaerobes. It usually occurs in people with compromised immune systems or those who are debilitated, especially those with diabetes mellitus or morbid obesity[6]
. Multiple organisms have been
reported including gram-positive cocci, Enterococci, Gram-positive rods, Gram- negative organisms including Klebsiella and Escherichia coli, anaerobes and even fungi[1,7,9]
. The presence of such a wide
spectrum of organisms means that a range of antimicrobial medication is used initially, which can be adjusted according to the culture results[1,7,9]
.
DIAGNOSIS Early diagnosis is the key to survival for patients with NSTI[1,7]
Value
C-reactive protein (mg/dl) <150 >150
White blood cell (cells/cc) <15
15–25 >25
Haemoglobin level (g/dl) >13.5
11–13.5 <11
Sodium level (mmol/dl) > 135 < 135
Creatinine level (mg/dl) < 6 > 6
Glucose level (mg/dl) < 180 > 180
. It is very important to
differentiate necrotising from non-necrotising infections, as the former require surgical treatment as well as antibiotics and the latter only requires antibiotics[1]
. In addition, non-
necrotising soft tissue infections (like cellulitis and erysipelas) tend to occur in the skin layers themselves, whereas NSTIs tend to involve the fascial layers. Diagnosis has been made more difficult
by the different terms used to describe this condition[5]
, but physical examination and
taking an accurate patient history remain the mainstay for establishing a diagnosis. People who are more likely to have
NSTI include those with a history of self- injecting drug misuse (although NSTIs can occur with clinician-injected medication if the sterile technique has been violated), those with diabetes, a suppressed immune system and obesity[10-12]
. However, it has been repeatedly shown
in larger studies that about 20% of people who develop NSTI do not have any of these precipitating factors and have an idiopathic aetiology[13–15]
with group A Streptococcus[1] , or MRSA[8] Initial symptoms to look for when
examining a patient with suspected NSTI include pain, swelling, erythema and tachycardia. These will progress to discolouration, blister formation, eschar formation, crepitus, swelling outside the area of skin changes and pain out of proportion to the physical findings [Fig 1][1]
. Of these symptoms, the authors find a
disproportionate pain level to be a crucial indicator of NSTI. It has been found, however, that although these signs and symptoms are highly specific for NSTI, their sensitivity is low as they are present in only 10–40% of patients[16, 17]
. In most cases, especially those caused by . It has been observed that these idiopathic cases mostly occur in people infected
monomicrobial organisms, the progression of the signs and symptoms is rapid but conversely progression can be very slow, making accurate diagnosis challenging[1] Several diagnostic tools have been
. . Table 1 – LRINEC score variables.
LRINEC points
0 4
0 1 2
0 1 2
0 2
0 2
0 1
References
7. Elliott D, Kufera JA, Myers RAM. The microbiology of necrotizing soft tissue infections. Am J Surg 2000; 179: 361–66.
8.Miller LG, Perdreau-Remington F, Rieg G, Mehdi S, Perlroth J, Bayer AS, Tang AW, Phung TO, Spellberg B. Necrotizing fasciitis caused by community- associated methicillin-resistant Staphylococcus aureus in Los Angeles. N Engl J Med 2005; 352: 1445–53.
9. Endorf FW, Cancio LC, Klein MB. Necrotizing soft-tissue infections: clinical guidelines. J Burn Care Res 2009; 30: 769–75.
10.Wall DB, Klein SR, Black S, de Virgilio C. A simple model to help distinguish necrotizing fasciitis from non- necrotizing soft tissue infection. J Am Coll Surg 2000; 191: 227–31.
11.Wong CH, Khin LW, Heng KS, Tan KC, Low CO. The LRINEC (laboratory risk indicator for necrotizing fasciitis) score: a tool for distinguishing necrotizing fasciitis from other soft tissue infections. Crit Care Med 2004; 32: 1535–41.
12. Singh G, Sinha SK, Adhikary S, Babu KS, Ray P, Khanna SK. Necrotising infections of soft tissues — a clinical profile. Eur J Surg 2002;168: 366–71.
13. Singh G, Ray P, Sinha SK, Adhikary S, Khanna SK. Bacteriology of necrotizing infections of soft tissues. Aust N Z J Surg 1996; 66: 747–50.
14.Anaya DA, McMahon K, Nathens AB, Sullivan SR, Foy H, Bulger E. Predictors of mortality and limb loss in necrotizing soft tissue infections. Arch Surg 2005; 140: 151–7; discussion 158.
15.Childers BJ, Potyondy LD, Nachreiner R, et al. Necrotizing fasciitis: a fourteen- year retrospective study of 163 consecutive patients. Am Surg 2002; 68: 109–16.
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