Invasive Group A Streptococcus Flashcards
Is iGAS nationally notifiable?
Yes, since 1 July 2022.
Notifiable in QLD (2005), NT (2011), SA (2021), WA (2021).
What organism causes iGAS?
Group A Streptococcus (S. pyogenes)
Gram +, B-haemolytic bacteria. >240 strains
Classified by emm-typing (variable region of the emm gene)
What is iGAS?
Invasive Group A Streptococcus. I.e. GAS disease that is invasive - detected in normally sterile site.
Blood, CSF, pleural fluid, peritoneal fluid, pericardial fluid, joint fluid, bone, bone marrow.
Internal organs excluding lungs.
What is the reservoir of iGAS?
Humans only
What is the mode of transmission for iGAS?
- 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.
What is the clinical presentation of GAS (not iGAS)?
Spectrum of disease (mild to severe):
- ASx carriage (common: 5-30%)
- Scarlet fever, tonsilitis, pharyngitis
- Impetigo or cellulitis
- Complications: ARF, PSGN
What is the clinical presentation of iGAS?
- Septicaemia
- Pneumonia/empyema
- Osteomyelitis
- Septic arthritis
- Pericarditis
- Peritonitis
- Meningitis
- Puerperal sepsis
- Streptococcal toxic shock syndrome (STSS)
- Necrotising fasciitis.
High CFR with invasive disease - 7%.; TSS 23%; Nec fasc 70%.
Who is at increased risk of disease?
- Elderly, infants, young children
- Birthing person-neonate pairs
- Chronic disease (diabetes, heart dz, haemodialysis)
- Immunocompromised
- Household contacts of a case
- Institutional settings (CC, RACF etc)
- Overcrowded houses (First Nations, Pasifika)
- PWID
- Poor hygiene environments
PWID = people who inject drugs
What is the case definition for iGAS?
Confirmed cases - lab definitive: culture/PCR from normally sterile site.
Probable case - lab suggestive + clinical suggestive
How is iGAS diagnosed?
Culture or PCR from normally sterile site.
Typing at reference lab e.g. MDU/VIDRL
What is the iGAS incubation period?
Not well-defined.
Pharyngitis - 1-3 days
Impetigo - 7-10 days
What is the iGAS infectious period?
7 days before onset to 24 hours after appropriate antibiotic
What is the outbreak definition for iGAS?
2 + epi linked cases within 30 days.
If identical typing then confirmed outbreak, otherwise suspected.
An outbreak is a cluster with a suspected common source.
What is the definition of an institutional cluster for iGAS?
Confirmed: 2 + epi linked cases in 3 months + identical molecular type where cases not HH contacts.
Suspected: as above without typing.
What are the routine prevention activities?
No vaccine
Primordial prevention - social determinants - reduce overcrowded housing, improve health hardware, education on hygiene practices.
Primary prevention - improve skin health, early detection and treatment of sore throat/impetigo in high-risk people.
Institutional settings - follow IPC practices, encourage basic hygiene practices
What resources are available for iGAS management?
SoNG, DH guidelines.
What is the case management for iGAS?
- Liaise with treating clinician
- Isolation/restriction - standard/droplet precautions until 24 hours after appropriate ABx
- Identify if high-risk person, group or in a high-risk facility
- Determine if part of neonate-maternal pair or institutional / HH cluster
- Education re: disease and transmission
What are the types of contacts or iGAS?
- Birthing person-neonate pairs
- Household or household-like
- Institutional
- Airway exposed healthcare workers
How are iGAS contacts managed?
- Education re: transmission and preventative measures
- Routine screening and clearance ABx not recommended
- Clearance ABx for mother-neotnate pair
- No clearance ABx for HH, institutional or airway-exposed healthcare contacts (case-by-case basis)
- Restriction not routinely recommended
How are iGAS outbreaks managed?
HH clusters as above.
Institutional outbreak (RACF, CC, maternity ward):
* Inform contacts
* Arrange typing at ref lab (MDU)
* If confirmed offer clearance ABx for all residents and staff
* Review IPC (esp. cleaning and hand hygiene)
* Active surveillance for new cases
* Screening not usually indicated
What are considerations for iGAS clusters in First Nations households / communities?
- Refer to ACCHO/AMS for culturally appropriate Ax and F/U
- Develop & implement health education program with culturally appropriate governance structure
- Active participation in decisions by AHWs/AHPs, ACCHOs, community members
What is the antimicrobial sensitivity of GAS?
Universally penicillin sensitive.
Other agents can be used due to allergies - vanc, macrolides, trimethoprim/sulfamethoxazole, clindamycin
What environmental controls are required for iGAS?
Not routinely required.
For which contacts are chemoprophylaxis routinely provided?
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.
What education should be provide to contacts?
- Close contacts at higher risk up to 30 days following contact with case
- Symptoms to monitor for
- If symptoms of GAS»_space; non-urgent medical attention
- If symptoms of iGAS»_space; immediate medical attention
What are special situations where chemoprophylaxis may be required?
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
What are some facts about Aboriginal and Torres Strait Islander people in relation to iGAS?
- Higher rates compared to non-Indigenous
- Increased risk of tranmission due to overcrowding, inadequate housing, barriers to care
- Higher burden of comorbid conditions
How should clusters of iGAS be managed in Aboriginal and Torres Strait Islander communities?
- Aboriginal Community Controlled Health Service / Aboriginal Medical Service
- Culturally approriate follow-up, care, educational resources
