23 -153 - NECROTIZING FASCIITIS, NECROTIZING CELLULITIS AND MYONECROSIS Flashcards
What are the components of necrotizing fasciitis score?
Factors Found in Literature to Be Associated with a High Mortality Risk in Patients with Necrotizing Fasciitis
T/F Antibiotics are the first line of treatment of necrotizing fasciitis
False
In necrotizing fasciitis, until when should antibiotics be continued?
Antibiotics should be continued until final surgical debridement has been completed, patient is afebrile for 48 to 72 hours, and patient has clinically stabilized.
necrotizing infections with or without gas formation localized to the skin and subcutaneous tissue but not extending deep enough to involve the underlying fascia or muscles
Necrotizing or gangrenous cellulitis
Bacteria that are known more widely for causing severe crepitant myonecrosis or “gas gangrene”
Clostridium spp.
Aside from the Clostridium spp., gas can also be produced by other anaerobic of facultative bacterial species. What are those?
Peptostreptococcus spp., Bacteroides spp., Enterobacteriaceae, and Klebsiella spp.
Marineassociated necrotizing skin infections are most commonly caused by
Vibrio spp. or Aeromonas spp.,
Causes of Marine-Based Necrotizing Cellulitis
Comorbids with highest risk of necrotizing fasciitis
Cardiovascular disease and diabetes
Most common isolate found in community acquired necrotizing aoft tissue infections
S. Pyogenes
MC isolates in hospital-acquired necrotizing soft tissue necrosis
S.aureus
E. coli
Pseudomonas spp.
In diabetic patients, this isolate is frequently isolated in necrotizing infection
Klebsiella pneumoniae
Identify the cutaneous variant of Necrotizing fasciitis:
- Fungal cases caused by candidal necrotizing fasciitis
- very rare
Type IV necrotizing fasciitis
Identify the cutaneous variant of Necrotizing fasciitis:
■ Vibrio subspecies
■ Result of puncture wound caused by fish or marine insect
Type III necrotizing fasciitis
Identify the cutaneous variant of Necrotizing fasciitis:
■ Often monomicrobial
■ Hemolytic Streptococcus
■ Group A Streptococcus (S. pyogenes)
■ Rarely hemolytic Streptococcus group C or group G
■ ± Coinfection (or monoculture) with Staphylococcus aureus
TYPE II necrotizing fasciitis
Identify the cutaneous variant of Necrotizing fasciitis:
■ 1 or more anaerobic species
■ 1 or more facultative anaerobic streptococci (streptococci other than Streptococcus pyogenes)
■ Members of the aerobic Gram-negative rod grouping Enterobacteriaceae
Type I
. describes a very rare subtype of disease that has an anatomic predilection for the head and neck region
Cervical and craniofacial necrotizing fasciitis
refers to necrotizing fasciitis localized to the genitalia, perineum, anus, and, occasionally, skin of the lower abdomen
Fournier gangrene
gold standard for diagnosis of necrotizing soft-tissue infection
surgical consultation and exploration of the concerning site
defining feature of necrotizing fasciitis is notable easy dissection along the superficial fascial planes in attempts made to probe along the edge of an open wound
remains the mainstay of therapy for patients with necrotizing fasciitis
rapid surgical intervention
Surgical interventions include radical debridement of necrotic tissue at baseline with possible amputation for severe limb disease.
Ultimately, full surgical debridement of all necrotic areas involved in the underlying infection is essential to achieving therapeutic success
Infectious Diseases Society of America (IDSA) guidelines on antimicrobial selection for patients with necrotizing infections of the skin, fascia, and muscle
The IDSA recommends initial broad-spectrum antimicrobial therapy with either vancomycin, linezolid, or daptomycin used in conjunction with either piperacilling-tazobactam, carbapenem, ceftriaxone plus metronidazole, or fluoroquinolone plus metronidazole while awaiting culture data.
Antibiotics should be continued until final surgical debridement has been completed, patient is afebrile for 48 to 72 hours, and patient has clinically stabilized
accounts for necrotizing infections with or without gas formation localized to the skin and subcutaneous tissue but not extending deep enough to involve the underlying fascia or muscles
Necrotizing or gangrenous cellulitis
known more widely for causing severe crepitant myonecrosis or “gas gangrene”
Clostridium spp
- describe cases of limited, superficial, and focal infections of the skin, often without severe systemic symptoms and caused by this same bacterial subgroup
- characterized by extensive subcutaneous emphysema with often minimal overlying skin changes
clostridial crepitant cellulitis infections
other gas-forming anaerobic of facultative bacterial species
Peptostreptococcus spp., Bacteroides spp., Enterobacteriaceae, and Klebsiella spp.
- The defining feature for infections caused by each of these gas-forming bacteria is subcutaneous emphysema and each of these bacterial species can cause infection confined to the skin or extending more deeply into the muscle or fascia.
Marineassociated necrotizing skin infections are most commonly caused by what spp?
Vibrio spp. or Aeromonas spp.,
Vibrio vulnificus is the most virulent of this group of curved Gram-negative bacilli found in coastal waters
What primary lesion is a common defining feature found in patients with infection secondary to Vibrio spp
Bullae
cornerstone of therapy of gangrenous or necrotizing cellulitis
Surgical debridement, in conjunction with antimicrobial therapy as outlined by the IDSA guidelines
these infections can involve the more superficial structures—fascia, skin, and subcutaneous soft tissue—the focus of the infection and associated necrosis is located within the confines of the muscle itself.
MYONECROSIS
infection characterized by bacterial infection leading to collections of purulent material within the body of 1 or more muscles in affected patients
Pyomyositis
Population or condition in which pyomyositis occurs with increased frequency
immunosuppressed (eg, HIV) or have diabetes mellitus
Area of predilection of pyomyositis
Lower extremities and pelvic girdle
occur more commonly following localized trauma or muscle overuse
A majority of pyomyositis infections (90%) are caused by what bacteria?
S.aureus
Nonstaphylococcal infections that can cause pyomyositis
S. pneumoniae or Gram-negative enteric bacteria
Stage of pyomyositis that involves inflammation and pain surrounding the infected muscle with associated leukocytosis.
At this point there may be mild induration of the subcutaneous tissue structures; however, cutaneous changes are typically absent
Stage I
Stage of pyomyositis characterized by suppuration with abscess formation within the muscle belly; this stage is associated with severe focal pain, fever, and swelling overlying the affected muscle.
This stage generally lasts 1 to 3 weeks
Stage II
Stage of pyomyositis characterized by progression to systemic disease with septic physiology, shock, and multifocal abscess formation
Stage III
gold standard for pyomyositis diagnosis
MRI
will demonstrate muscle inflammation and intramuscular abscess formation on MRI.
Antimicrobial treatment of pyomyositis
Antimicrobial treatment of pyomyositis should also start broadly with vancomycin.
Piperacillin-tazobactam, ampicillin-tazobactam, or carbapenem should be added to vancomycin empirically for patients who have multiple comorbidities, are immunocompromised, or developed infection as the result of a penetrating wound
Patients with pyomyositis whose cultures are positive for methicillin-sensitive S. aureus should be narrowed to what antibiotics?
cefazolin or an antistaphylococcal penicillin (eg, nafcillin or oxacillin)
most common causative organisms of clostridial myonecrosis
Clostridium perfringens,
Clostridium novyi,
Clostridium histolyticum,
and Clostridium septicum
Clostridial myonecrosis related to trauma are most commonly caused by what bacteria?
C. perfringens
This Clostridium can be found in myonecrotic infections of the uterus and perineum in the postpartum and postabortive periods
Clostridium sordellii
spontaneous non–trauma-related cases of Clostridium myonecrosis are most commonly caused by what bacteria?
C. septicum
Clostridial myonecrosis in IV drug users is most commonly caused by what subspecies?
C. sordellii and C. novyi
the cardinal feature of clostridial myonecrosis as it is in clostridial crepitant cellulitis
Gas collection in tissue manifests as overlying crepitus
A brownish discharge with a foul smell, described as “dishwater exudate,” can be noted
Seen in what infection?
clostridial myonecrosis
Triad of clostridial myonecrosis
The triad of soft-tissue crepitus, severe pain, and tachycardia disproportionate to the fever is thought to be diagnostic of clostridial myonecrosis
Gram stain findings of Tissue or exudate retrieved during surgical exploration of clostridial myonecrosis
large Gram-positive or Gram-variable “blunt-end” rods
mainstay of therapy for patients with clostridial myonecrosis
surgical debridement
antibiotics of choice for clostridial myonecrosis
clindamycin plus high-dose penicillin
Patients with clostridial myonecrosis with penicillin allergy can be treated with what antibiotics?
clindamycin monotherapy or with metronidazole
