This study will determine the frequency of Staphylococcus aureus carriage in household contacts of individuals with clinical infection due to this pathogen. It will also assess the frequency of transmission events over the following three months. Finally it will aim to identify predisposing characteristics both on a demographic/social level as well virulence characteristics of the identified strains.
This is a prospective cohort study based at Anuradhapura Teaching Hospital (Sri Lanka). Potential index study participants will have clinical infection caused by Staphylococcus aureus and will be identified from hospital microbiology laboratory records within 48 hours of admission. With consent, the investigators will approach up to 4 household members for participation in the carriage study. With their consent, household members will have swabs collected on 2 occasions 3 months apart. All hospitalised patients will receive standard-of-care treatment in accordance with local practice and national guidance. Clinical, demographic and social/lifestyle data will be collected from index patients and households by scheduled interview performed by local investigators. Bacterial isolates from the initial index patient infection, and those identified through household member screening will be assessed for antimicrobial susceptibility, virulence factor repertoire and analysed by whole genome sequencing. While infection with the cc5 MRSA clone has been described in several hospital and hospital-associated settings in South Asia a major unresolved issue is whether transmission and circulation of this clone is occurring in community settings. In this study the investigators will investigate and characterise the household circulation of Staphylococcus aureus strains, exploring differences in bacterial virulence characteristics and host susceptibility factors associated with increased risk of carriage. Understanding these factors and estimating the burden of disease which may be occurring in the community setting will allow more accurate assessment of the risk posed by cc5 PVL-MRSA to similar Low and Middle Income Countries (LMIC) settings and signal potential routes to mitigation through treatment optimisation and disease prevention including infection control or vaccination.
Study Type
OBSERVATIONAL
Enrollment
300
Determine the baseline prevalence of Staphylococcus aureus carriage or infection in household contacts of hospital inpatients diagnosed with clinical infection due to Staphylococcus aureus.
Index cases will be identified by screening laboratory reports for samples obtained within 72 hours of hospital admission and where Staphylococcus aureus has been isolated from a skin or soft tissue infection or a normally sterile site and there is a clinical diagnosis of infection at that site. Up to 4 household contacts of this index case will be approached to participate in the study and will have bacterial swabs of the anterior nares and any incidental sites of infection at an initial assessment (as soon after identification and recruitment as possible). The swabs will be inoculated on to blood agar and MacConkey agar. Staphylococcus aureus will be identified by colonial morphology, Gram stain, catalase test and coagulase test. Methicillin resistant Staphylococcus aureus will be detected by disc diffusion method using a cefoxitin disc as per the CLSI protocol.
Time frame: First household visit and swabbing of household contacts will be as soon as possible after recruitment of the index case.
Measure the frequency of Staphylococcus aureus transmission events within households over a three month period.
Proportion of household individuals carrying same/similar strains, as determined by similarity in antimicrobial susceptibility profile and genotypic homology. This will be assessed over a three month time period to detect possible household transmission in contacts who are initially not detected as carriers.
Time frame: First visit and swabbing of the index and household contacts will be as soon as possible after recruitment of the index case. Both the index and household contacts will have a second visit 3 months later (window 2-4 months).
Characterise predisposing clinical, demographic or social characteristic differences of individuals/households with evidence of household transmission over a three month period by interview and completion of a proforma.
After consent is obtained, study investigators will visit the dwellings to assess up to 4 household contacts. A baseline interview using a proforma will be conducted to investigate each individual and their shared dwellings. This will include identification of: dwelling location, type of dwelling, number of other inhabitants, pet/animal ownership, occupations, duration of residence, recent illness/hospitalisations, recent courses of antimicrobial treatment. This will be repeated at the follow up visit to ensure there have not been any change in circumstances.
This platform is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional.
Time frame: The baseline interviews will occur as soon as possible after the index patient is recruited and the second interview will occur three months later (window 2-4 months).
Describe virulence characteristics of strains causing a) (invasive) infection and b) higher number of household transmission events
Analysis of whole genome sequencing and antimicrobial virulence data from isolates that are more associated with infection (in the index and household contacts) and where a high frequency of household transmission has been observed.
Time frame: Data analysis will occur throughout and beyond the study recruitment period, expected to take a minimum of 6 months.