Genetic Susceptibility to Severe Streptococcal Infections

Sponsor

University of Oxford (Other)

Overall Status

Unknown status

CT.gov ID

NCT01911572

Collaborator

Public Health England (Other), Imperial College London (Other)

200

Enrollment

Location

Duration (Months)

2.8

Patients Per Site Per Month

Study Details

Study Description

Brief Summary

Invasive bacterial infection is a dangerous but relatively uncommon disease where bacteria spread deep into the body causing diseases like blood poisoning ('bacteraemia'), pneumonia, meningitis and others. The various bacteria of the streptococcus family are an important cause, often leading patients to require intensive care despite which, for some strains, one in five patients die. One notable form is called necrotising fasciitis, a condition where bacteria rapidly spreads through and destroys the layers of tissue just under the skin.

As individuals vary greatly in their risk of developing such serious infections, investigating how the genome, the inherited blueprint of our bodies, of these patients differs from that of healthy volunteers can help to explain why the disease develops in some and not others. For some streptococcal bacteria such as Streptococcus pneumoniae this approach is already proving successful; for others such as the "Group A" strain (Streptococcus pyogenes) it has yet to be explored but carries excellent potential.

The investigators have secured the support of the Lee Spark Necrotising Fasciitis Foundation to recruit from their membership survivors of streptococcal infections and some of their family members. The investigators will also ask infection specialists from NHS hospitals to invite patients they have looked after. The investigators also have a small existing collection. Taking part would involve registering information on a website, discussing the study on the telephone and then providing us with a sample of saliva from which the investigators can isolate DNA. The investigators would prepare the sample for analysis of the genome and compare the patients with both their family and an existing reference collection from healthy volunteers using technology that reads the DNA code.

Our study will be a first key step in renewing efforts to understand the determinants of invasive streptococcal infection, which is important for developing better treatments and vaccines.

Condition or Disease	Intervention/Treatment	Phase
Invasive Streptococcal Infection Invasive Group A Streptococcal Disease Invasive Group B Streptococcal Disease Necrotising Fasciitis

Study Design

Study Type:

Observational

Anticipated Enrollment :

200 participants

Observational Model:

Family-Based

Time Perspective:

Other

Official Title:

Genetic Susceptibility to Invasive Streptococcal Disease

Study Start Date :

Dec 1, 2013

Actual Primary Completion Date :

Dec 1, 2017

Anticipated Study Completion Date :

Dec 1, 2019

Arms and Interventions

Arm	Intervention/Treatment
Survivors Individuals who have previously experienced an episode of invasive streptococcal infection or necrotising fasciitis.
Family members Parents of those survivors aged less than forty years without risk factors for streptococcal disease (forming mother-father-child trios), or first and second degree relatives of survivors from a family in which two or more individuals have been affected.

Outcome Measures

Primary Outcome Measures

Number of genetic variants at which cases of invasive streptococcal infection (as defined in inclusion criteria 1) differ from their family members (inclusion criteria 2-4) [The outcome is measured once by genetic testing using a sample collected on enrolment ('baseline'). There is no follow-up period.]
This is an observational study comparing genetic data from cases (inclusion criteria 1) vs unaffected family members (inclusion criteria 2-4) and publically available genetic data from health volunteers in existing reference databases (e.g. UK10K - http://www.uk10k.org/). The case's illness (as defined in inclusion criteria 1) may have occurred anytime between 1st January 1980 and enrolment. The outcome is measured by genetic testing using a sample collected on enrolment. There is no follow-up period.

Eligibility Criteria

Criteria

Ages Eligible for Study:

N/A and Older

Sexes Eligible for Study:

All

Accepts Healthy Volunteers:

Yes

Participants for the genetics study are divided into cases/survivors and family members (relatives and parents).

To participate as a survivor, the individual must meet criteria 1A. Their illness can have occurred anytime from birth up until enrolment, providing it happened after 1st January 1980. Family members can only take part if invited to do so by the survivor from their family at the request of the research team.

In families in which two or more survivors are identified, all the remaining first- and second-degree relatives of the survivors will be eligible to participate. The recruitment team subdivide those relatives on enrolment into healthy (Criteria 2) or intermediate (Criteria 3) phenotype.

In families in which there is only a single survivor, the recruitment team will assess whether the survivor meets criteria 1B. If so the parents of that survivor are eligible to participate if they have a healthy phenotype (Criteria 4).

Inclusion Criteria:

Cases/Survivors

All Cases (survivors in pedigree, trio or as simplex case; existing serum samples from Imperial College London collection)

Either of:
Isolation of Streptococcus species from a normally sterile site (e.g. blood, joint fluid, etc.) during an acute illness since 1st January 1980
Severe clinical presentation - streptococcal toxic shock, necrotising fasciitis, pneumonia, puerperal sepsis, meningitis - since 1st January 1980 plus concurrent Streptococcus species isolated from non-sterile site (e.g. abscess, wound swab, pus)
And:
Admitted to an NHS hospital in England or Wales or Northern Ireland

Trio case (survivor in trio)

All of:
Meets criteria for 1A
Less than 40 years of age at the time of illness
None of at the time of the illness: heart disease, diabetes mellitus, cancer, steroid use, chronic lung disease, immunocompromise, intravenous drug use and alcoholism
Plus one of:
More than one episode of illness meeting criteria for 1A
Admission to high dependency or intensive care unit
Requirement for surgical procedure (including drainage of abscess or collection)
And:
Both parents alive at time of recruitment

Unaffected phenotype family member in multi-case pedigree

All of:
Biological first or second degree relative of a survivor meeting criteria 1A in a family in which two or more members meet those criteria
None of: severe streptococcal illness requiring hospital illness, recurrent tonsillitis or recurrent impetigo (recurrent is defined as more than one episode in two consecutive years)

Intermediate phenotype family member in multi-case pedigree

All of:
Biological first or second degree relative of a survivor meeting criteria 1A in a family in which two or more members meet those criteria
History of severe bacterial illness requiring hospital admission, recurrent tonsillitis or recurrent impetigo (recurrent is defined as more than one episode in two consecutive years)

Parent in mother-father-child trio

All of:
Biological parent of case meeting criteria for 1B
None of: severe bacterial illness requiring hospital admission, recurrent tonsillitis or recurrent impetigo (recurrent is defined as more than one episode in two consecutive years)