Communicable Diseases Deren > Invasive Group A Streptococcus > Flashcards

Invasive Group A Streptococcus Flashcards

(28 cards)

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1
Q

Is iGAS nationally notifiable?

A

Yes, since 1 July 2022.

Notifiable in QLD (2005), NT (2011), SA (2021), WA (2021).

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2
Q

What organism causes iGAS?

A

Group A Streptococcus (S. pyogenes)

Gram +, B-haemolytic bacteria. >240 strains

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

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3
Q

What is iGAS?

A

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.

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4
Q

What is the reservoir of iGAS?

A

Humans only

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5
Q

What is the mode of transmission for iGAS?

A
  • 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.

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6
Q

What is the clinical presentation of GAS (not iGAS)?

A

Spectrum of disease (mild to severe):

  • ASx carriage (common: 5-30%)
  • Scarlet fever, tonsilitis, pharyngitis
  • Impetigo or cellulitis
  • Complications: ARF, PSGN
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7
Q

What is the clinical presentation of iGAS?

A
  • 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%.

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8
Q

Who is at increased risk of disease?

A
  • 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

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9
Q

What is the case definition for iGAS?

A

Confirmed cases - lab definitive: culture/PCR from normally sterile site.

Probable case - lab suggestive + clinical suggestive

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10
Q

How is iGAS diagnosed?

A

Culture or PCR from normally sterile site.

Typing at reference lab e.g. MDU/VIDRL

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11
Q

What is the iGAS incubation period?

A

Not well-defined.

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

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12
Q

What is the iGAS infectious period?

A

7 days before onset to 24 hours after appropriate antibiotic

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13
Q

What is the outbreak definition for iGAS?

A

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.

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14
Q

What is the definition of an institutional cluster for iGAS?

A

Confirmed: 2 + epi linked cases in 3 months + identical molecular type where cases not HH contacts.

Suspected: as above without typing.

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15
Q

What are the routine prevention activities?

A

No vaccine

Primordial prevention - social determinants - reduce overcrowded housing, improve health hardware, education on hygiene practices.

Primary prevention - improve skin health,

Secondary prevention - early detection and treatment of sore throat/impetigo in high-risk people.

Institutional settings - follow IPC practices, encourage basic hygiene practices

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16
Q

What resources are available for iGAS management?

Study These Flashcards
A

SoNG, DH guidelines.

17
Q

What is the case management for iGAS?

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A
  • 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
18
Q

What are the types of contacts for iGAS?

Study These Flashcards
A
  • Birthing person-neonate pairs
  • Household or household-like
  • Institutional
  • Airway exposed healthcare workers
19
Q

How are iGAS contacts managed?

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A
  • 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
20
Q

How are iGAS outbreaks managed?

Study These Flashcards
A

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
21
Q

What are considerations for iGAS clusters in First Nations households / communities?

Study These Flashcards
A
  • 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
22
Q

What is the antimicrobial sensitivity of GAS?

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A

Universally penicillin sensitive.

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

23
Q

What environmental controls are required for iGAS?

Study These Flashcards
A

Not routinely required.

24
Q

For which contacts are chemoprophylaxis routinely provided?

Study These Flashcards
A

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.

25
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 > > non-urgent medical attention * If symptoms of iGAS > > immediate medical attention
26
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
27
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
28
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
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