Necrotizing fasciitis pathophysiology: Difference between revisions

Jump to navigation Jump to search
Line 29: Line 29:
'''Type 1 NF'''
'''Type 1 NF'''
*The exact pathogenesis of type 1 necrotizing fasciitis is not fully understood.
*The exact pathogenesis of type 1 necrotizing fasciitis is not fully understood.
*It is thought that type 1 NF is caused by [[polymicrobial]] species that work together to enhance the spread of infection ([[Synergistic]]).
*It is thought that type 1 NF is caused by polymicrobial species that work together to enhance the spread of infection ([[Synergistic]]).
*Synergistic NF is comparatively slow process evolving over days.
*Synergistic NF is comparatively slow process evolving over days.
*It usually develops in the area where [[gut flora]] breaches the [[mucosa]], entering the tissue planes.
*It usually develops in the area where [[gut flora]] breaches the [[mucosa]], entering the tissue planes.

Revision as of 19:24, 12 September 2016

Necrotizing fasciitis Microchapters

Home

Patient Information

Overview

Historical Perspective

Classification

Pathophysiology

Causes

Differentiating Necrotizing fasciitis from other Diseases

Epidemiology and Demographics

Risk Factors

Screening

Natural History, Complications and Prognosis

Diagnosis

Diagnostic Criteria

History and Symptoms

Physical Examination

Laboratory Findings

Electrocardiogram

X Ray

CT

MRI

Ultrasound

Biopsy

Other Diagnostic Studies

Treatment

Medical Therapy

Surgery

Primary Prevention

Secondary Prevention

Future or Investigational Therapies

Case Studies

Case #1

Necrotizing fasciitis pathophysiology On the Web

Most recent articles

Most cited articles

Review articles

CME Programs

Powerpoint slides

Images

American Roentgen Ray Society Images of Necrotizing fasciitis pathophysiology

All Images
X-rays
Echo & Ultrasound
CT Images
MRI

Ongoing Trials at Clinical Trials.gov

US National Guidelines Clearinghouse

NICE Guidance

FDA on Necrotizing fasciitis pathophysiology

CDC on Necrotizing fasciitis pathophysiology

Necrotizing fasciitis pathophysiology in the news

Blogs on Necrotizing fasciitis pathophysiology

Directions to Hospitals Treating Necrotizing fasciitis

Risk calculators and risk factors for Necrotizing fasciitis pathophysiology

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Yamuna Kondapally, M.B.B.S[2]

Overview

The pathophysiology of necrotizing fasciitis is common to all types but the speed of development and associated clinical features differs depending on the causative organisms. Following transmission, the bacteria uses the entry site to invade the fascial planes which causes the wide spread necrosis of superficial fascia, deep fascia, subcutaneous fat, nerves, arteries, and veins. Necrotizing fasciitis can be a serious complication of omphalitis in the neonate.The pathogenesis of necrotizing fasciitis is the result of bacterial and host factors. The exact pathogenesis of type 1 necrotizing fasciitis is not fully understood but polymicrobial species work together to enhance the spread of infection (Synergistic). Group A streptococcus is the most common causative agent of type 2 NF. Bacterial virulence factors, exotoxins, superantigens and host immune system plays a major role in the pathogenesis of type II NF. Recurrent NF is caused by MRSA. On gross pathology, the characteristic findings of NF include subcutaneous emphysema, skin sloughing, bulae and necrosis. Inflammatory changes are seen on microscopic histopathology.

Pathophysiology

The pathophysiology of necrotizing fasciitis is common to all types of NF but the speed of development and associated clinical features differs depending on the causative organisms.

  • The transmission of pathogens occurs through the following routes:

subcutaneous fat, nerves, arteries, and veins.

  • Superficial skin and deeper muscles are typically spared.
  • In late stages, lesions develop liquefactive necrosis at all tissue levels.

Neonate

  • Necrotizing fasciitis can be a serious complication of omphalitis in the neonate.
  • The omphalitis may progress resulting in purplish discoloration and periumbilical necrosis.
  • The necrosis may extend to the flanks and even onto the chest wall.

Pathogenesis

The pathogenesis of necrotizing fasciitis is the result of bacterial and host factors.

Type 1 NF

  • The exact pathogenesis of type 1 necrotizing fasciitis is not fully understood.
  • It is thought that type 1 NF is caused by polymicrobial species that work together to enhance the spread of infection (Synergistic).
  • Synergistic NF is comparatively slow process evolving over days.
  • It usually develops in the area where gut flora breaches the mucosa, entering the tissue planes.

Type 2 NF

  • Group A streptococcus is the most common causative agent of type 2 NF.[1]
  • Type 2 NF is initially insidious in onset but progress more rapidly.
  • The disease may appear spontaneously with no obvious focus. Hematogenous infection from many foci such as skin, throat, ascending vaginitis, primary peritonitis reaches the fascial layer or seeds vimentin exposed by muscle damage.
  • Direct inoculation of GAS through wounds or associated surgery is less common.
  • The pathogenesis of type 2 NF is the result of the following process:
  • Nerves supplying the necrotizing areas of skin die, the central areas become anaesthetic and peripheral areas remain tender.
  • In later stages, infection from deeper layers ascends, producing edema of epidermal and dermal layers (peau d'orange) and a woody firmness of the tissues
  • The fascial and nerve destruction results in sensory and motor deficits, which causes progression of hemorrhagic bullae to cutaneous gangrene.

Recurrent necrotizing fasciitis

Recurrent NF is seen in following conditions:

Gross pathology

On gross pathology the characteristic findings of necrotizing fasciitis include:[2]

Microscopic histopathological analysis

On microscopic histopathological analysis, the characteristic findings of necrotizing fasciitis are[2]

  • Early stages
  • Late stages

References

  1. Leitch HA, Palepu A, Fernandes CM (2000). "Necrotizing fasciitis secondary to group A streptococcus. Morbidity and mortality still high". Can Fam Physician. 46: 1460–6. PMC 2144855. PMID 10925760.
  2. 2.0 2.1 2.2 2.3 Librae pathology(2015) https://librepathology.org/wiki/Necrotizing_fasciitis Accessed on September 2,2016