Poster Presentation Australian Society for Microbiology Annual Scientific Meeting 2016

Staphylococcus aureus colonisation and infection in a prospective cohort of dialysis clients and staff in the Northern Territory. (#220)

Deborah C. Holt 1 , Tegan M. Harris 1 , Rachael A. Lilliebridge 1 , Heather Hall 1 2 , Sian Graham 1 , David Crocker 1 , Steven Y. Tong 1 , Gregory Perry 2 , Jaqui T. Hughes 1 2 , Phillip M. Giffard 1
  1. Menzies School of Health Research, Charles Darwin University, Casuarina, NT, Australia
  2. Renal Services, Nothern Territory Government Department of Health, Darwin, NT, Australia

Rates of renal replacement therapy in the Indigenous population of the Northern Territory are among the highest in the world. Infections with Staphylococcus aureus, including bacteraemia and peritonitis, are a major cause of morbidity and mortality for renal replacement patients. The Staphylococcus aureus reservoirs in renal medicine study (STARRS) aimed to investigate S. aureus colonisation, transmission and infection in our cohort to identify any specific risk factors and inform possible infection control measures.

Dialysis clients (n=82, 95% Indigenous) and clinical and research staff (n=47) volunteered as participants in the study. Visits were conducted two monthly and participants consenting at each visit had swabs of the nose, axilla, dialysis access site, catheter, groin and any skin sores or wounds collected and cultured to detect S. aureus colonisation. In addition, S. aureus isolates from clinical infections were collected via the Royal Darwin Hospital Pathology Service. The feasibility of the study was underpinned by the involvement of two Indigenous clinical research assistants and strong engagement with the renal service clients and staff.

Participants had at least one and up to 12 rounds of swabs collected over a two year period, totalling over 2,000 swabs. S. aureus was cultured from 12.7% (73/573) of nasal swabs, 2.8% (16/573) of axilla swabs, 1.6% (5/311) of dialysis access site swabs, 7.1% (1/14) of catheter swabs, 6.2% (35/569) of groin swabs and 31.0% (9/29) of skin wound swabs. Fifty‑five of the 129 participants (42.6%) had at least one S. aureus positive swab.

Genotyping indicated that dialysis clients and staff were colonised with similar S. aureus strains, the most common being multi-locus sequence type 5. Isolates from clinical infections were more likely to possess lukSF-PV encoding for Panton-Valentine leucocidin than colonisation isolates (47% vs 17%). Whole genome sequence analysis is underway to investigate possible transmission patterns. Preliminary analysis provided no evidence to support the need to introduce nasal decolonisation to reduce infections in this dialysis cohort.