Co-aggregation of bacterial flora isolated from the human skin surface

Human hands play a prominent role in the intra and interpersonal transmission of microbes that constantly connect one's microbiome to other individuals and the environment. Along with beneficial bacteria, an individual may harbor pathogenic organisms which may get transferred to others. Thus, understanding the transmission mechanism and interaction among microbiota is crucial in preventing infection. In the present study, the ability of skin microbes, isolated from different individuals, to physically interact (coaggregate) intergenically was assessed. The bacterial flora from the hands (palm area) of similar age group students was isolated. The predominant isolates were selected and identified using 16s rRNA gene sequencing. Further, these isolates were subjected to visual coaggregation assay. A total of 27 bacteria were isolated from the human skin (palm area-fingers) of 10 individuals. These isolates belong to seven bacterial genera and 10 different species. Among 123 combinational visual coaggregation positive reactions; 53.66% showed a reaction score of +1, while 32.52%, 11.38% and 2.44% showed a score of +2, +3, and +4 respectively. Among 27 isolates, Staphylococcus haemolyticus had highest coaggregation partners of 17 followed by Acinetobacter spp. and Pseudomonas spp. with 15 partners each. The present study is the first report demonstrating the coaggregation potential of microbiota harboring the skin surface of the human hand. The study indicates that few microbes have high potential to influence coaggregation among distinct genera isolated from the skin. However, further studies are needed to understand the ability of these bacteria to coaggregate, their influence in interpersonal transmission and shaping of microbial ecology of the host skin.