The Healthcare Workers' Hand Microbiome: Community Structure and Dynamics.

Abstract

The complex microbial communities that inhabit our bodies, our microbiota, profoundly influence human health. Alterations in microbiota profiles occur as a result of host and environmental factors, and can lead to increased microorganism transmission, pathogen susceptibility, and disease. This interdisciplinary dissertation investigates hand microbiota dynamics over a 3-week period among 34 surgical intensive care unit healthcare workers (HCWs), while accounting for technical sources of variation. We also assess the role hand microbiota play in specific nosocomial pathogen carriage. An accurate profile of the human microbiota requires assessment of the variation in biological patterns between individuals and within individuals over time, while considering technical variation due to (i) specimen collection method, (ii) DNA extraction technique, and (iii) sequencing. Analysis of the HCWs' hand microbiota showed that only sampling collection method appeared to have a significant impact on the observed microbial community structure. Samples collected using the glove-juice method showed that individuals' hands were slightly more similar to each other in microbial composition over time than between individuals. Using the swab method, however, samples from a single individual were no more similar to each other than to other individuals. After HCW hand microbiota characterization, we assessed its role in nosocomial pathogen carriage. The proportion of pathogens detected using qPCR varied by collection visit: Staphylococcus aureus ranged from 41.2%-52.9%; Enterococcus spp. ranged from 52.9%-61.8%; Candida albicans ranged from 2.9%-8.8%; and, MRSA from 2.9%-5.9%. HCWs with lower microbiota diversity were more likely to carry a pathogen on their hands than those with higher diversity. HCWs took a self-administered questionnaire regarding basic demographics, overall health, hand health, hand hygiene practices, and patient contact levels, to explore possible associations with pathogen carriage. Risk factors for pathogen carriage were pathogen specific. Hand microbiota may have mediated the relationship between hand hygiene and pathogen carriage; and, acted as effect modifiers in the relationships between a) age and Enterococcus spp. carriage, and b) work shift and Staphylococcus aureus carriage. Understanding risk factors for pathogen carriage and its relationship to HCW hand microbiota has significant implications for pathogen transmission and hospital infection control policies.