Invasive group A streptococcal disease: Management and chemoprophylaxis

Question 1

What are the most common clinical presentations of invasive GAS infections?

Answer 1

1. Necrotizing fascitis (NF)
2. Myositis
3. Bacteremia with no septic focus
4. Pneumonia
5. TSS

Question 2

What is the incidence of invasive GAS infections in Canada?

Answer 2

2. 7 per 100 000
3. 8 per 100 000 in infants <1yo
4. 6 per 100 000 in children 1-4yo
5. 9 per million in <5yo
6. 8 per million in 5-16yo

Question 3

What is a risk factor for invasive GAS in children?

Answer 3

Varicella

Question 4

What is the definition of a confirmed case of invasive GAS disease?

Answer 4

Laboratory confirmation (isolation of GAS Streptococcus pyogenes from a normally sterile site) with or without clinical evidence of invasive disease

Question 5

What is the definition of clinical evidence of invasive disease?

Answer 5

1. streptococcal TSS, which is characterized by hypotension (sBP <90 adults OR <5th %ile children) and at least two of the following signs:
   a) renal impairment (Cr>177 in adults)
   b) coagulopathy (Plt <100 or DIC)
   c) liver function abnormality (AST, ALT or bili >2x UL of normal)
   d) adult respiratory distress syndrome
   e) generalized erythematous macular rash that may desquamate;
2. soft-tissue necrosis, including NF, myositis or gangrene;
3. meningitis; or
4. a combination of the above.

Question 6

What is the definition of a severe case?

Answer 6

1. Streptococcal TSS
2. Soft tissue necrosis (NF, myositis, or gangrene)
3. Meningitis
4. GAS pneumonia (GAS from sterile site or BAL)
5. Other life-threatening conditions
6. Confirmed case resulting in death

Question 7

What is the definition of a probable case?

Answer 7

Invasive disease in the absence of another identified etiology and with isolation of GAS from a nonsterile site.

Question 8

What cases are notifiable to public health?

Answer 8

Confirmed cases of invasive GAS are reportable at the national level

Question 9

What is the definition of close contacts?

Answer 9

1. Household contacts who have spent at least 4 h per day on average in the previous seven days or 20 h per week with the case.
2. Non-household persons who share the same bed with the case or had sexual relations with the case.
3. Persons who have had direct mucous membrane contact with the oral or nasal secretions of a case (eg, mouth-to-mouth resuscitation, open mouth kissing) or unprotected direct contact with an open skin lesion of the case.
4. Injection drug users who have shared needles with the case.
5. Selected contacts of long-term care facilities.
6. Selected contacts in child care settings.
7. Selected hospital contacts.

Question 10

What are the Canadian guidelines with respect to chemoprophylaxis for invasive GAS disease?

Answer 10

1. Chemoprophylaxis should only be offered to close contacts of a confirmed case of severe GAS, and to close contacts who have been exposed to the case during the period from seven days before the onset of symptoms in the case to 24 h after the initiation of antimicrobial therapy in the case.
2. Chemoprophylaxis of close contacts should be administered as soon as possible and preferably within 24 h of case identification, but chemoprophylaxis is still recommended for up to seven days after the last contact with an infectious case.
3. Close contacts of all confirmed cases (ie, regardless of whether the case is a severe one) should be alerted to signs and symptoms of invasive group A streptococcal disease, and be advised to seek medical attention immediately should they develop febrile illness or any other clinical manifestations of group A streptococcal infection within 30 days of diagnosis in the index case.
4. Provincial/territorial protocols for prophylaxis may vary; clinicians should become familiar with local policies.

Question 11

What is the recommendation regarding chemoprophylaxis for children and staff in family or home daycare settings?

Answer 11

Chemoprophylaxis should be provided to all children and staff who have spent at least 4 h per day on average in the previous seven days or 20 h per week with the confirmed case in the 7d prior to onset of symptoms or 24h after initiation of treatment

Question 12

What is the recommendation for chemoprophylaxis in group or institutional child care centres and preschools?

Answer 12

Not recommended but consider if >1 case of invasive GAS within 1m or if concurrent varicella outbreak

Question 13

What agent should be used for chemoprophylaxis?

Answer 13

First line: Cephalexin (1st gen cephalosporin) 25-50mg/kg/d (max 1g/day) PO BID-QID x 10d
Use in pregnancy

Second-line:
1. Erythromycin 5-7.5mg/kg PO q6h OR 10-15mg/kg PO q12h x 10d (max 500mg q12h)
Cannot use during pregnancy or liver disease

2. Clarithromycin 15mg/kg/day (max 250mg) PO q12h x 10d
   Cannot use during pregnancy
3. Clindamycin: 8-16mg/kg/day PO TID-QID x 10d (max 150mg per dose)

Question 14

What are the recommendations regarding follow up cultures in close contacts?

Answer 14

Not recommended

Question 15

What is the recommended management of severe invasive GAS disease?

Answer 15

1. Supportive treatment with IVF and electrolytes
2. Penicillin + Clindamycin IV
3. IVIG 150-400mg/kg/day x 5d OR 1-2g/kg single dose if TSS or severe toxin-mediated disease
4. Surgical debridement of necrotic tissue if applicable

Question 16

What is the recommended infection control for invasive GAS in health care settings?

Answer 16

Consult PHAC guidelines