Methods: All Care home residents and staff were screened in February/March 2015 for throat (and skin lesions if present) carriage of GAS using standard microbiological methods. Environmental sampling was also undertaken. Following screening, 21 isolates of GAS emm ST 5.23 were available from the Care Home for further analysis (11 residents, 9 staff members and 1 environmental isolate). Two additional isolates (1 staff & 1 resident) were excluded from further analysis as they were of different emm type. Genome sequence data was obtained (Illumina) for these and an additional 30 emm ST 5 lineage isolates from 2014 -2015 from varying geographical locations in England/Wales/Ireland, including invasive isolates. All isolates included in the study passed quality and coverage checks. The emm ST5 lineage reference strain Manfredo_M5 was used to map genomic sequence data
Results: All isolates from the care home located within the same phylogenetic clade in addition to isolates from other geographical UK regions sequenced. However all 2015 care home isolates co-located to a distinct phylogenetic sub-branch, proximal to the 2014 isolates. Strains from staff, patients and the environmental isolate were in some cases indistinguishable.
Conclusion: Several residents, staff and a chair in the clinical room were found to have indistinguishable GAS isolates suggesting persistence of the strain within the care home over a 10 month period. However local contemporaneous strains were not available for comparison so reintroduction into the home cannot be discounted. The outbreak was brought to an end by several outbreak control measures including environmental cleaning with steam and chlorine-based agents as well as antibiotic chemoprophylaxis for all staff and residents administered in March 2015.
G. Kapatai, None
J. Coelho, None
H. Mohamed, None
K. Martin, None
M. Tahir, None