Invasive Group A Streptococcus

Question 1

What is iGAS?

Answer 1

Invasive Group A Streptococcus. I.e. GAS disease that is invasive - detected in normally sterile site.

Normally sterile sites include:
* blood, CSF, pleural fluid, peritoneal fluid, pericardial fluid, joint fluid, bone, bone marrow
* internal organs including: lymph node, brain, heart, liver, spleen, vitreous fluid, kidney, pancreas, ovary, vascular tissue

Lung tissue is not a normally sterile site.

Question 2

What is the infectious agent?

Answer 2

Streptococcus pyogenes also known as group A Streptococcus, Gram +, B-haemolytic bacteria.

Classified by emm-typing (variable region of the emm gene)

Question 3

What is the reservoir of iGAS?

Answer 3

Humans only

Question 4

What is the mode of transmission?

Answer 4

• Direct person-person
• Droplet spread
• Direct contact with patients/carriers (saliva, wound discharge, nasal secertions
• Fomites (rarely)

People with GAS disease (e.g. impetigo, pharyngitis) are much more likely to transmit the bacteria to others than asymptomatic carriers.

Question 5

What is the iGAS incubation period?

Answer 5

Not well-defined

Pharyngitis - 1-3 days
Impetigo - 7-10 days

Question 6

What is the iGAS infectious period?

Answer 6

7 days before onset to 24 hours after appropriate antibiotic

Question 7

What is the clinical presentation?

Answer 7

Mild to severe.

• Scarlet fever, tonsilitis, pharyngitis
• Impetigo or cellulitis
• Invasive disease (blood, CSF, bone marrow) - bacteraemia, sepsis, empyema, osteomyelitis, septic arthritis, meningitis, puerperal sepsis, streptococcal toxic shock syndrome (STSS), necrotising fasciitis.

High case fatality ratio with invasive disease.

Question 8

Who is at increased risk of disease?

Answer 8

• birthing person-neonate pairs
• chronic disease
• immunocompromised
• elderly contacts
• household contacts of a case
• residents or attendees of institutional settings (childcare, aged care, prisons/jails, hospitals, schools, military barracks, hostels/shelters)
• overcrowded houses (First Nations, Pasifika)
• shared needle use
• poor hygiene environments

Question 9

When did iGAS become nationally notifiable in Australia?

Answer 9

1 July 2022

Question 10

What are the routine prevention activities?

Answer 10

Primordial prevention - social determinants (housing, health hardware, education on hygiene practices)

Institutional settings - follow infection prevention and control practices, encourage basic hygiene practices

Primary prevention - early detection and treatment.

No vaccine

Question 11

What is the public health urgency?

Answer 11

Respond in:
* 1 day for birthing-person neonate pairs
* 3 days for all other cases

Question 12

What is the case definition?

Answer 12

Confirmed case - lab only (culture of NAAT from normally sterile site

Probable case - lab suggestive + clinical suggestive

Question 13

What is the antimicrobial sensitivity?

Answer 13

Universally penicillin sensitive.

Other agents can be used due to allergies - vanc, macrolides, trimethoprim/sulfamethoxazole, clindamycin

Question 14

What is the case management for iGAS?

Answer 14

• Identify if high-risk person, group or in a high-risk facility
• Liaise with treating clinician
• Identify contacts&raquo_space; provide factsheet
• Treat cases with appropriate ABx
• Isolation/restriction - standard/droplet precautions until 24 hours after appropriate ABx

Question 15

How are contacts managed?

Answer 15

Aim is to:
* Identify source contact
* Identify those at increased risk
* Provide information and risk level
* Chemoprophylaxis if indicated

Question 16

What environmental controls are required?

Answer 16

Not routinely required.

Question 17

What are the types of contacts?

Answer 17

• Birthing person-neonate pairs
• Household or household-like
• Institutional
• Airway exposed healthcare workers

Question 18

For which contacts are chemoprophylaxis routinely provided?

Answer 18

Birthing person-neonate pairs - where the birthing person or neonate develop iGAS disease during the first 28 days after birth.

Routine provision of ABx for chemoprophylaxis to all close contacts of a single case is generally not recommended due to limited evidence of its efficacy.

Chemoprophylaxis can be considered for contacts with additional risk factors on a case-by-case basis.

Question 19

Which groups are at higher risk at baseline for iGAS infection?

Answer 19

• Aboriginal and Torres Strait Islander people
• elderly people (particularly aged >75 years)
• children < 5 years
• chronic disease
• immunocompromise
• haemodialysis
• injecting drug users
• homeless
• residence or attendance at institutions pron to poor hygiene, body fluid contact, overcrowing (prisons, hospitals, military barracks etc.)
• other special risk groups unique to states/territories

Question 20

What education should be provide to contacts?

Answer 20

• Close contacts at higher risk up to 30 days following contact with case
• Symptoms to monitor for
• If symptoms of GAS&raquo_space; non-urgent medical attention
• If symptoms of iGAS&raquo_space; immediate medical attention

Question 21

What are special situations where chemoprophylaxis may be required?

Answer 21

Household clusters and institutional settings.

Household cluster = 2 or more cases within 30 days of symptoms in initial case

Institutional cluster = 2 or more epidemiologically linked cases within 3 months

Question 22

What are some facts about Aboriginal and Torres Strait Islander people in relation to iGAS?

Answer 22

• Higher rates compared to non-Indigenous
• Increased risk of tranmission due to overcrowding, inadequate housing, barriers to care
• Higher burden of comorbid conditions

Question 23

How should clusters of iGAS be managed in Aboriginal and Torres Strait Islander communities?

Answer 23

• Aboriginal Community Controlled Health Service / Aboriginal Medical Service
• Culturally approriate follow-up, care, educational resources