infeccion necrotizante de tejidos blandos

7/28/2019 Infeccion Necrotizante de Tejidos Blandos

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INFECCION NECROTIZANTE DE

TEJIDOS BLANDOS


2/17

ANTECEDENTES

Jones 1871 and were termed hospital

gangrene.

In 1951,Wilson coined the term necrotizing

fasciitis.

infections of any of the layers within the soft

tissue compartment (dermis, subcutaneous

tissue, superficial fascia, deep fascia, or

muscle) that are associated with necrotizing

changes.


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ANTECEDENTES

incidence of NSTI in the United States is

estimated to be 5001500 cases per year.

0.04 cases per 1000 person-years.

Establishing the diagnosis of NSTI is probably

the greatest challenge in managing these

infections.


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DIAGNOSTICO

Delay of diagnosis leads to delayed surgical

debridement, which leads to higher mortality.

The first and most important tool for early

diagnosis of NSTI is to have a high index of

suspicion.


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FACTORES DE RIESGO

injection drug use

chronic debilitating comorbidities (e.g.,

diabetes mellitus, immune suppression, and

obesity).

most large published series

show that, in 20% of patients with NSTI, theetiology is unknown, and the patients are

considered to have idiopathic NSTI


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We have also observed that cases of NSTI

without a recognized precipitating factor are

more likely to be caused by group A

streptococcal and community-acquired

methicillin-resistant staphylococcal infection.


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Initial signs and symptoms swelling, erythema, pain,and tachycardia.

once the infection progresses: tense edema outsidethe area of compromised skin, pain disproportionate to

appearance, skin, discoloration (ecchymosis),blisters/bullae and necrosis, crepitus and/orsubcutaneous gas.

Systemic findings include: fever, tachycardia,hypotension, and shock (sensitivity is low, 1040%.

Progression of these signs and symptoms is usuallyrelatively fast, particularly if group A Streptococcus orClostridium species are involved.


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Even in the most experienced hands, clinical

findings are not accurate enough for

diagnosis, and both clinical clues and

diagnostic tools should be used in

combination to help make an early diagnosis.


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PRUEBAS DE LABORATORIO

Wall et al. WBC count

115,400 cells/mm3 or a

serum sodium level 135

mmol/L was associated

with NSTI.

NPV of 99%, but not very

specific, PPV of only 26%.

Wong et al.

PPV of 92% and a NPV of

96%.


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ESTUDIOS DE IMAGEN

Radiography: identify subcutaneous gas

Ultrasonography: increased thickness of

the fascial layer with or without enhancement MRI

CT: deep abscesses


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OTROS METODOS

Biopsy specimen from the compromised site

that includes deep fascia and possibly muscle.

These findings include gray necrotic tissue,

lack of bleeding, thrombosed vessels,

dishwater pus, noncontracting muscle, and

a positive finger test result, which is

characterized by lack of resistance to fingerdissection in normally adherent tissues.


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MICROBIOLOGIA

A wide spectrum of

organisms are

commonly recovered.

2/3polymicrobial; 1/3Monomicrobial. gram-

positive cocci.


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TRATAMIENTO

source control, antimicrobial therapy, support,

and monitoring.

when treatment is only based on antimicrobial

therapy and support, mortality approaches

100%.


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TRATAMIENTO

Broad-spectrum antimicrobial therapy shouldbe started early to include coverage for gram-positive, gram-negative, and anaerobic

organisms. Special consideration for group A Streptococcus

and Clostridium species should be taken.

Acceptable regimens include monotherapyagents, such as imipenem, meropenem,ertapenem, piperacillin/tazobactam andtigecycline.


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TRATAMIENTO

Multidrug regimens have also been described,including triple-drug therapy regimens, suchas high-dose penicillin, high-dose clindamycin,

and a fluoroquinolone or an aminoglycosidefor coverage of gram-negative organisms.

Vancomycin, daptomycin, or linezolid shouldbe included in the regimen until methicillin-resistant staphylococcal infection has beenexcluded.


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MORTALIDAD

Since the first description by Jones [1], mortality

in patients with NSTI remains high. He reported a

mortality rate of 46%, and a recent pooled

analysis determined it to be34%. More recent series have reported mortality rates

with a range of 16%24%a rate that, although

lower than the rate 100 years ago, still accountsfor high mortality associated with NSTI

infeccion necrotizante de tejidos blandos

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