Streptococcal Disease, Emergency Medicine

Basics

Description

Increase in frequency of aggressive streptococcal necrotizing skin infection noted in 1980s and dubbed "flesh-eating bacteria. "
Affects otherwise healthy patients aged 20 " 50 yr who did not have underlying predisposing diseases.
Rapid progression of shock and multiorgan dysfunction, with death occurring within 1 " 2 days.
Incidence is 3 " 4 per 100,000 in industrialized countries
Invasive infections caused by group A Streptococcus (GAS) include:
- Necrotizing fasciitis (NF):
  - Progressive, rapidly spreading soft tissue infection located within the deep fascia and subcutaneous fat
- Streptococcal toxic shock syndrome (STSS):
  - May occur in patients with GAS associated NF.
  - Portals of entry for streptococci include vagina, pharynx, mucosa, and skin.
  - Unknown cause in 50% of cases.
- "Other " invasive disease defined as isolation of GAS from a normally sterile body site (i.e., sepsis, bacteremic pneumonia, septic arthritis, etc.)
Occurs sporadically, with occasional outbreaks in long-term care facilities and hospitals.
Rate of invasive GAS disease 6 times the annual incidence of meningococcal disease.

STSS Case Definition

Isolation of GAS from sterile or nonsterile body site
Hypotension
2 or more of the following:
- Renal impairment
- Coagulopathy
- Liver abnormalities
- Acute respiratory distress
- Extensive tissue necrosis (NF)
- Erythematous rash

Etiology

NF:
- GAS is causative in 10% of cases. Blunt trauma is risk factor.
- Mixed anaerobic and aerobic organisms are found in 70% of cases.
- Staphylococcus aureus, Clostridium species, and other enteric organisms
Streptococcal toxic shock syndrome:
- Occurs when susceptible host is infected with virulent strain
- M protein types 1, 3, and 28 are most common.
- Pyrogenic exotoxins (e.g., A, B, and C) produce fever and shock via activation of tumor necrosis factor and interleukins.
- Nonsteroidal anti-inflammatory drugs appear to mask or predispose patients.
- Risk factors:
  - Age <10 or >60 yr
  - Cancer
  - Renal failure
  - Leukemia
  - Severe burns
  - Corticosteroids

Diagnosis

Signs and Symptoms

History

Pain:
- Most common initial symptom of NF:
  - Occurs in 85% of cases
- Out of proportion to physical findings
- Often abrupt in onset and severe
- Often requires palliative IV narcotics
- Usually involves an extremity
- May mimic peritonitis, pelvic inflammatory disease, pneumonia, acute MI, or pericarditis

Physical Exam

Fever most common sign:
- Can present with hypothermia, especially if patient is in shock
Altered mental status present in 55% of cases
Soft tissue infection (erythema and swelling) present in 80%:
- Indistinct borders, blisters, bullae
- No lymphangitis or lymphadenopathy
Influenza-like syndrome in 20%:
- Fever
- Chills
- Myalgias
- Nausea, vomiting
- Diarrhea
Shock:
- Present at admission or within 4 " 8 hr in all patients
- Frequently persists despite fluids, antibiotics, and vasopressors
Renal failure:
- Precedes onset of shock in many cases
- Dialysis often necessary
- Kidney function returns to normal within 4 " 6 wk in survivors.
ARDS:
- Occurs in 55% of patients

Essential Workup

Suspect NF when pain is out of proportion to exam.
Obtain plain films to search for presence of air in soft tissues.
Blood cultures should be obtained.

Diagnosis Tests & Interpretation

Lab

CBC with differential:
- Mild leukocytosis with left shift initially
Electrolytes, BUN, and creatinine
Calcium level:
- Hypocalcemia in association with fat necrosis from NF
Urinalysis:
- Hemoglobinuria if renal involvement
Serum creatine phosphokinase:
- An elevated or rising level correlates with NF or myositis.
Aerobic and anaerobic blood cultures
Wound cultures
PT/PTT/INR/DIC panel

Imaging

Plain films:
- Gas in soft tissues in 25 " 75% of cases of NF, but not as frequently associated with group A ²-hemolytic streptococcal infection
- More common in mixed anaerobic infections
CT scan:
- Asymmetric thickening of deep fascia
- Gas
MRI:
- High signal intensity of the fascia in T2-weighted images associated with NF

Diagnostic Procedures/Surgery
Aspiration of involved areas with Gram stain and culture may be useful

Differential Diagnosis

Sepsis
Cellulitis
Erysipelas
NF/myositis secondary to infection by another pathogen

Treatment

Pre-Hospital

Stabilize as appropriate

Initial Stabilization/Therapy

Maintain ABCs.
Treat shock with fluids and vasopressors as needed:
- Hypotension is often intractable, and up to 10 " 20 L/day may be required.
Intubation and mechanical ventilation for:
- ARDS
- Severe shock
- Ventilatory failure

Ed Treatment/Procedures

Broad-spectrum antibiotics immediately after cultures until the presence of GAS has been confirmed:
- Clindamycin is a potent suppressor of GAS bacterial toxin synthesis and inhibits M protein synthesis
Early surgical consultation. Most patients will require an operative procedure (e.g., fasciotomy, surgical debridement, exploratory laparotomy, intraocular aspiration, amputation, or hysterectomy):
- Immediate surgery is indicated if there is:
  - Extensive necrosis or gas
  - Compartment syndrome
  - Profound systemic toxicity
Droplet precautions for the 1st 24 hr of antibiotic therapy
Reports of successful use of IV immunoglobulin
Hyperbaric oxygen therapy still controversial

Medication

NF due to invasive streptococcal disease (NOTE: In the ED, empiric treatment should be initiated until monomicrobial NF caused by GAS has been confirmed):
- Clindamycin: 900 mg IV (peds: 40 mg/kg/d), and
- Penicillin G: 4 million U IV (peds: 250,000 U/d), or
- Vancomycin: 15 mg/kg IV (peds: 10 mg/kg q6h) if patient has penicillin allergy
Empiric treatment of NF from all causes (Clostridium perfringens, GAS, methicillin-resistant S. aureus [MRSA], mixed anaerobes/aerobes):
- Piperacillin/tazobactam 3.5 g IV and
- Clindamycin 900 mg IV and
- Vancomycin 1 g IV
- For patients with a penicillin allergy treat with aztreonam 2 g IV, clindamycin 900 mg IV, vancomycin 1 g IV, and metronidazole 500 mg IV

Follow-Up

Disposition

Admission Criteria
ICU admission required for all patients with suspected invasive streptococcal infection. Mortality from GAS NF ¢ ¼20%, but with both NF and STSS, mortality rate increases to 70%.
Discharge Criteria
None

Pearls and Pitfalls

Hypotension and shock may require large volumes of IV fluids and vasopressors.
Broad-spectrum antibiotics should be administered until the presence of GAS can be confirmed.
Surgical consultation should be obtained for debridement.

Additional Reading

Martin JM, Green M. Group A streptococcus. Semin Pediatr Infect Dis. 2006;17:140 " 148.
Nuwayhid ZB, Aronoff DM, Mulla ZD. Blunt trauma as a risk factor for group A streptococcal necrotizing fasciitis. Ann Epidemiol. 2007;17:878 " 881.
Steer AC, Lamagni T, Curtis N, et al. Invasive group A streptococcal disease: Epidemiology, pathogenesis, and management. Drugs. 2012;72(9):1213 " 1227.

Codes

ICD9

040.82 Toxic shock syndrome
041.01 Streptococcus infection in conditions classified elsewhere and of unspecified site, streptococcus, group A
728.86 Necrotizing fasciitis

ICD10

A48.3 Toxic shock syndrome
B95.0 Streptococcus, group A, causing diseases classd elswhr
M72.6 Necrotizing fasciitis

SNOMED

302809008 Streptococcus pyogenes infection (disorder)
449900006 necrotizing fasciitis due to Streptococcus pyogenes (disorder)
240451000 Streptococcal toxic shock syndrome (disorder)

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