23 -153 - NECROTIZING FASCIITIS, NECROTIZING CELLULITIS AND MYONECROSIS

Question 1

What are the components of necrotizing fasciitis score?

Answer 1

Question 2

Factors Found in Literature to Be Associated with a High Mortality Risk in Patients with Necrotizing Fasciitis

Answer 2

Question 3

T/F Antibiotics are the first line of treatment of necrotizing fasciitis

Answer 3

False

Question 4

In necrotizing fasciitis, until when should antibiotics be continued?

Answer 4

Antibiotics should be continued until final surgical debridement has been completed, patient is afebrile for 48 to 72 hours, and patient has clinically stabilized.

Question 5

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

Answer 5

Necrotizing or gangrenous cellulitis

Question 6

Bacteria that are known more widely for causing severe crepitant myonecrosis or “gas gangrene”

Answer 6

Clostridium spp.

Question 7

Aside from the Clostridium spp., gas can also be produced by other anaerobic of facultative bacterial species. What are those?

Answer 7

Peptostreptococcus spp., Bacteroides spp., Enterobacteriaceae, and Klebsiella spp.

Question 8

Marineassociated necrotizing skin infections are most commonly caused by

Answer 8

Vibrio spp. or Aeromonas spp.,

Question 9

Question 10

Causes of Marine-Based Necrotizing Cellulitis

Answer 10

Question 11

Comorbids with highest risk of necrotizing fasciitis

Answer 11

Cardiovascular disease and diabetes

Question 12

Most common isolate found in community acquired necrotizing aoft tissue infections

Answer 12

S. Pyogenes

Question 13

MC isolates in hospital-acquired necrotizing soft tissue necrosis

Answer 13

S.aureus
E. coli
Pseudomonas spp.

Question 14

In diabetic patients, this isolate is frequently isolated in necrotizing infection

Answer 14

Klebsiella pneumoniae

Question 15

Identify the cutaneous variant of Necrotizing fasciitis:

• Fungal cases caused by candidal necrotizing fasciitis
• very rare

Answer 15

Type IV necrotizing fasciitis

Question 16

Identify the cutaneous variant of Necrotizing fasciitis:

■ Vibrio subspecies

■ Result of puncture wound caused by fish or marine insect

Answer 16

Type III necrotizing fasciitis

Question 17

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

Answer 17

TYPE II necrotizing fasciitis

Question 18

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

Answer 18

Type I

Question 19

. describes a very rare subtype of disease that has an anatomic predilection for the head and neck region

Answer 19

Cervical and craniofacial necrotizing fasciitis

Question 20

refers to necrotizing fasciitis localized to the genitalia, perineum, anus, and, occasionally, skin of the lower abdomen

Answer 20

Fournier gangrene

Question 21

gold standard for diagnosis of necrotizing soft-tissue infection

Answer 21

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

Question 22

remains the mainstay of therapy for patients with necrotizing fasciitis

Answer 22

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

Question 23

Infectious Diseases Society of America (IDSA) guidelines on antimicrobial selection for patients with necrotizing infections of the skin, fascia, and muscle

Answer 23

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

Question 24

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

Answer 24

Necrotizing or gangrenous cellulitis

Question 25

known more widely for causing severe crepitant myonecrosis or “gas gangrene”

Answer 25

Clostridium spp

Question 26

- 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

Answer 26

clostridial crepitant cellulitis infections

Question 27

other gas-forming anaerobic of facultative bacterial species

Answer 27

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.

Question 28

Marineassociated necrotizing skin infections are most commonly caused by what spp?

Answer 28

Vibrio spp. or Aeromonas spp., Vibrio vulnificus is the most virulent of this group of curved Gram-negative bacilli found in coastal waters

Question 29

What primary lesion is a common defining feature found in patients with infection secondary to Vibrio spp

Answer 29

Bullae

Question 30

cornerstone of therapy of gangrenous or necrotizing cellulitis

Answer 30

Surgical debridement, in conjunction with antimicrobial therapy as outlined by the IDSA guidelines

Question 31

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.

Answer 31

MYONECROSIS

Question 32

infection characterized by bacterial infection leading to collections of purulent material within the body of 1 or more muscles in affected patients

Answer 32

Pyomyositis

Question 33

Population or condition in which pyomyositis occurs with increased frequency

Answer 33

immunosuppressed (eg, HIV) or have diabetes mellitus

Question 34

Area of predilection of pyomyositis

Answer 34

Lower extremities and pelvic girdle occur more commonly following localized trauma or muscle overuse

Question 35

A majority of pyomyositis infections (90%) are caused by what bacteria?

Answer 35

S.aureus

Question 36

Nonstaphylococcal infections that can cause pyomyositis

Answer 36

S. pneumoniae or Gram-negative enteric bacteria

Question 37

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

Answer 37

Stage I

Question 38

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

Answer 38

Stage II

Question 39

Stage of pyomyositis characterized by progression to systemic disease with septic physiology, shock, and multifocal abscess formation

Answer 39

Stage III

Question 40

gold standard for pyomyositis diagnosis

Answer 40

MRI will demonstrate muscle inflammation and intramuscular abscess formation on MRI.

Question 41

Antimicrobial treatment of pyomyositis

Answer 41

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

Question 42

Patients with pyomyositis whose cultures are positive for methicillin-sensitive S. aureus should be narrowed to what antibiotics?

Answer 42

cefazolin or an antistaphylococcal penicillin (eg, nafcillin or oxacillin)

Question 43

most common causative organisms of clostridial myonecrosis

Answer 43

Clostridium perfringens, Clostridium novyi, Clostridium histolyticum, and Clostridium septicum

Question 44

Clostridial myonecrosis related to trauma are most commonly caused by what bacteria?

Answer 44

C. perfringens

Question 45

This Clostridium can be found in myonecrotic infections of the uterus and perineum in the postpartum and postabortive periods

Answer 45

Clostridium sordellii

Question 46

spontaneous non–trauma-related cases of Clostridium myonecrosis are most commonly caused by what bacteria?

Answer 46

C. septicum

Question 47

Clostridial myonecrosis in IV drug users is most commonly caused by what subspecies?

Answer 47

C. sordellii and C. novyi

Question 48

the cardinal feature of clostridial myonecrosis as it is in clostridial crepitant cellulitis

Answer 48

Gas collection in tissue manifests as overlying crepitus

Question 49

A brownish discharge with a foul smell, described as “dishwater exudate,” can be noted Seen in what infection?

Answer 49

clostridial myonecrosis

Question 50

Triad of clostridial myonecrosis

Answer 50

The triad of soft-tissue crepitus, severe pain, and tachycardia disproportionate to the fever is thought to be diagnostic of clostridial myonecrosis

Question 51

Gram stain findings of Tissue or exudate retrieved during surgical exploration of clostridial myonecrosis

Answer 51

large Gram-positive or Gram-variable “blunt-end” rods

Question 52

mainstay of therapy for patients with clostridial myonecrosis

Answer 52

surgical debridement

Question 53

antibiotics of choice for clostridial myonecrosis

Answer 53

clindamycin plus high-dose penicillin

Question 54

Patients with clostridial myonecrosis with penicillin allergy can be treated with what antibiotics?

Answer 54

clindamycin monotherapy or with metronidazole