Trends in viable microbial bioburden on surfaces within a paediatric bone marrow transplant unit.

INTRODUCTION: Despite their role being historically overlooked, environmental surfaces have been shown to play a key role in the transmission of pathogens causative of healthcare-associated infections (HCAI). To guide infection prevention and control (IPC) interventions and inform clinical risk assessments, more needs to be known about microbial surface bioburden.

AIMS: To identify the trends in culturable bacterial contamination across communal touch sites over time in a hospital setting.

METHODOLOGY: Swab samples were collected over nine weeks from 22 communal touch sites in a paediatric bone marrow transplant unit. Samples were cultured on Columbia blood agar and aerobic colony counts (ACC) per 100cm2 were established for each site. Individual colony morphologies were grouped and identified by Matrix Assisted Laser Desorption Ionisation - Time of Flight Mass Spectrometry or 16s rDNA sequencing.

RESULTS: Highest mean counts were observed for sites associated with ward management activity and computer devices (3.29 and 2.97 ACC/100cm2 respectively). A nurses' station keyboard had high mean ACC/100cm2 counts (10.67) and diversity, while laundry controls had high mean ACC/100cm2 counts (4.70) and low diversity. Micrococcus luteus was identified in all sampling groups. Clinical staff usage sites were contaminated with similar proportions of skin and environmental flora (52.19% - 46.59% respectively), but sites associated with parental activities were predominantly contaminated by environmental microflora (86.53%).

CONCLUSION: The trends observed suggest patterns in microbial loading based on site activities, surface types and user groups. Improved understanding of environmental surface contamination could help support results interpretation and IPC interventions, improving patient safety.