This document discusses necrotizing soft tissue infections (NSTI), which are characterized by rapidly progressive necrosis of subcutaneous tissue, fascia, or muscle. NSTIs are classified as fasciitis or myositis based on the affected tissue layer. The document outlines the differences between NSTI, cellulitis, and abscesses. It describes the types, presentations, risk factors, investigations, scoring systems, and treatment approaches for NSTI. Early and aggressive surgical debridement combined with broad-spectrum antibiotics is critical to reduce mortality from these severe infections.

1. 13/10/2010

2. 13/10/2010
• NECROTIZING SOFT-TISSUE INFECTIONS (NSTI) comprise a
spectrum of disease entities that are characterized by extensive ,
rapidly progressive soft-tissue necrosis that usually involve deep
subcutaneous tissue, superficial or deep fascia, or muscle, or
any combination of the three.
• Necrotizing soft-tissue infections are classified as fasciitis , or
myositis, based on the principal soft-tissue layer involved with
necrosis

3. .CELLULITIS
Is a soft tissue infection with an
intact blood supply and viable
tissue
Marked by an acute inflammatory
response with small vessel
engorgement and stasis,
endothelial leakage with interstitial
edema, and leukocyte infiltration
It is typically located in a more
superficial plane.
ABSCESS
An infectious process characterized
by a necrotic center, without a blood
supply
Composed of debris from local
tissues, dead and dying WBC’s,
components of blood and plasma,
and bacteria.
Pus is surrounded by a vascularized
zone of inflammatory tissue.
NON NECROTISING SOFT TISSUE INFECTIONNSTI VS

4. 13/10/2010
First reported by Hippocrates as “flesh, sinews, and bones fell away in large
quantities...There were many deaths.”2
They were labeled as Streptococcal gangrene, Phagedena, and Phagedena
gangrenosum
An army surgeon was the first to report a necrotizing infection in the United
States in 1871
In 1883, FOURNIER described a gangrenous infection of the scrotum
In 1924, MELENEY documented the pathogenic role of streptococci in soft
tissue infection.
In 1952, Wilson coined the term necrotizing fasciitis

5. 13/10/2010
A substantial number of classifications based on anatomic location,
microbiology, and depth of infection have been described.
The wide range of classifications makes understanding of this entity
rather confusing, when the only important factor to be determined is
the presence or absence of a necrotic component requiring surgical
intervention

6. 13/10/2010
Necrotizing soft tissue infections types:
1) Necrotizing fasciitis type I (Polymicrobial),
2) Necrotizing fasciitis type II (Group A streptococcal),
3) Necrotising fasciitis type III(marine vibrios)
4) Specfic syndromes:
a. Clostridial myonecrosis
b. Fourniers gangrene

7. 13/10/2010
Usually occurs after trauma or surgery
Subcutaneous fat and fascia overlying muscle are prominently
involved
Primarily includes 3 categories (locations) of infection
Diabetes Mellitus- infections of the feet
Cervical necrotizing fasciitis- infection of the neck
Fournier’s Gangrene- infection of the perineum
Course of disease is usually somewhat slower than that seen with
type II (streptococcal) necrotizing fasciitis and clostridial
myonecrosis,

8.  2/3 of cases have mixed aerobic and anaerobic infections
The bugs: The average case had 4-6 isolates
•Staphylococcus aureus
•Streptococci
•Enterococci
•Escherichia coli
•Peptostreptococcus
•Preveoella and Porphyromonas
•Bacteroides fragilis
•Clostridium

9. 13/10/2010
Caused by virulent subtypes of streptococcus pyogenes.
The bacteria is often referred to as a flesh-eating bacteria.
The incidence of this infection increased in the last two decades,
• Improvements in diagnosis and reporting.
• Result of an organism virulence
The presence of the M1 and M3 proteins is associated with virulent
infection.
C/F
Most of the general features of NSTI
the presence of gas in tissues is unusual.

10.  Third type
 Caused by the marine vibrios(gram
negative rods)
 Vibrio vulnificus, vibrio parahemolyticus,
vibrio damsela, vibrio alginolyticus
 Puncture wound from fish, cut or insect
bite exposed to sea water, shellfish or fish
in tropical water
 Synthesize an extracellular toxin
 This bacteria has an alarming mortality
rate of 50%.

11.  First described by French verenologist JEAN
ALFRED FOURNIER who witnessed a rapidly
progressing gangrene of the penis and scrotum of 5
previously healthy young men.
 A polymicrobial necrotizing fasciitis (NF) of the
perinium, perianal area, or genitals. It may involve
either men or women.
 Mostly age 30-60, although all ages have been
reported

12. I (EARLY)
Tenderness to palpation (beyond area of
cellulitis)
Erythema/warmth
Edema
II (INTERMEDIATE)
Bullae formation
Skin fluctuation or induration
III (LATE)
Hemorrhagic bullae or skin necrosis
Crepitus
Skin anesthesia

13.  Fever
 Tachycardia
 Hypotension
 Tense edema around involved skin
 Disproportionate pain
 Blisters/ bullae
 Crepitus (present 10% of time)
 Subcutaneous gas
• These are all fairly specific, but have a sensitivity of
only 10-40%
 Skin findings
• May be erythematous, edematous, cyanotic, bronzed,
indurated, blistered, or frankly gangrenous.
• Generally the appearance of the skin underestimates
the degree of underlying disease.

14.  Diabetes mellitus (present in up to 60% of cases)
 Drug use
 Obesity
 Immunosuppresion
 Malnutrition
 HIV infection
 Alcoholism

15. 13/10/2010
Established by making a small skin incision and passing a haemostat or probe
through the subcutaneous tissues.
In necrotizing fasciitis the subcutaneous and fascial layers lack resistance to this
manoeuvre, a feature that indicates widespread tissue necrosis underneath seemingly
viable skin.
Gas may or may not be present in the soft tissues
HISTOLOGY
Shows widespread necrosis of subcutaneous fat and fascia, with relative sparing of
muscle.
An acute inflammatory reaction, with many Polymorphonuclear cells,
 Thrombosis of blood vessels and abundant Bacteria

16. 1. Blood samples-for TLC,DLC
2. Testing for elevated or lowered creatinine, glucose, CPK,
bicarbonate, albumin, and calcium levels.
3. X-ray
4. CT, and MRI scanning in advanced cases
5. And most importantly antibiotic culture and sensitivity tests

17. 13/10/2010

18. 13/10/2010
This score allows early classification of patients according to disease severity
identify patients at high risk of death
Identify a high-risk patients in whom surgical decision making debridement vs
amputaion.
Control or attempts at limb salvage with repeat operative debridements.
A prognostic score which allow weigh the relative risks and benefits of an
intervention better
Score can be used for comparisons across institutions and over time, providing a
more formal means to assess the impact of interventions

19. 13/10/2010

20.  Early and aggressive surgical exploration and debridement
 This should be done in the first 24 hours of symptoms
 Surgical mortality 6% (<24hrs), 24% (>24hrs)
 Repeat debridement should be repeated daily until all necrotic tissue
has been removed (typically 2-4 times)
 Fourneir’s Gangrene may require cystostomy, colostomy, or
orchiectomy (although this is rare).

21. • Virtually 100% of patients will die on antibiotics without
surgical debridement
• Antibiotics should be broad-spectrum until cultures return
• Type 1- ampicillin or ampicillin-sulbactam and clindamycin
or metronidazole. For patients with prior hospitalization
substitute ticarcillin-clavulanate or piperacillin-tazobactam
for ampicillin-sulbactam
• Type 2- penicillin group + clindamycin. Add vancomycin to
cover for MRSA

22. • Type 2
• In the case of streptococcal toxic shock massive amounts of fluid (10-20
L/day) may be necessary to maintain perfusion. Pressors such as
dopamine may also be required
• IV Ig has also been used to neutralize the streptococcal superantigens,
however no studies have been done to support this use

23. • NF can progress rapidly leading to amputation or death
• A degree of suspicion is necessary to get a patient to surgery for
diagnosis and treatment
• Treatment primarily involves surgery ,surgery , and only surgery and
antibiotics
• Even with rapid treatment mortality remains high

24. 13/10/2010

25. 13/10/2010