NEW YORK (GenomeWeb News) – Researchers from San Diego State University and the University of Arizona have taken a crack at characterizing the bacterial communities found in US city offices, identifying differences in bacterial abundance and diversity related to geography, gender, and the office surface sampled.
As reported online last night in PLoS ONE, the team sampled multiple surfaces in 90 offices from three American cities — New York, San Francisco, and Tucson — using a combination of culture-based cell counting methods and ribosomal RNA sequencing to get a peek at the numbers and diversity of bacteria on oft-touched surfaces in dozens of men's and women's offices.
The analysis uncovered differences in the types of bacteria found in different cities, with New York and San Francisco sites sharing more similar diversity patterns than surfaces sampled from offices in Tucson.
Even so, sites tested in San Francisco offices generally showed lower bacterial abundance than those from the other two cities, researchers reported. And while bacterial diversity was comparable in men's offices and women's office, they noted that women's offices typically yielded lower bacterial counts.
Those involved in the effort emphasized that it represents a preliminary step in deciphering the bacterial communities in office buildings and the factors influencing them. Nevertheless, they argued that the use of molecular methods in other office settings could help to tease apart the range of microbial diversity in such indoor spaces that is compatible with human health.
"The baseline information we gathered in this study on nominally 'healthy' buildings could prove useful down the road for identifying causes of various building sickness syndromes," San Diego State University biologist Scott Kelley, the study's senior author, and colleagues noted.
"For instance," they explained, "the microbial diversity of samples collected in 'sick' buildings could be analyzed for meaningful departures from otherwise healthy buildings, possibly identifying the sources of building-related health problems."
Kelley and his co-workers tested 30 randomly selected offices each in New York, San Francisco, and Tucson, using double-tipped swabs to swipe samples from five common, frequently touched surfaces: chairs, phones, desktops, computer keyboards, and computer mice.
Bacteria from one end of sampling swabs were then subjected to 16S rRNA sequencing with the Roche 454 GS FLX at the University of South Carolina's Environmental Genomics Core Facility. Meanwhile, researchers did culture-based testing with bugs from the other end of the swab to count numbers of viable bacteria from the sites tested.
From 16S rRNA sequence data on 54 of the samples, representing 18 chair and phone surfaces per city, the researchers found representatives from 20 bacterial divisions and more than 500 bacterial genera.
These included some soil bacteria and bacteria believed to have originated in the human mouth, nose, skin, and/or intestinal tract. More rarely, the team also found sequences believed to be from bugs normally found in hot springs and other hot locales.
Across all of the samples, the most common bacteria were those from the Proteobacteria, Firmicutes, and Actinobacteria phyla, researchers reported, though bugs from the Bacteroidetes phylum were also quite common.
The team did not detect bacterial diversity differences between men's offices and women's offices or between samples taken at offices in New York and San Francisco. In contrast, Tucson samples typically had more variable bacterial diversity patterns than those collected in the other two cities and tended to contain more soil bacteria.
On the other hand, when researchers looked at the overall abundance of bacteria at various sampling sites, they found that the samples they'd taken from men's offices yielded higher numbers of viable bacteria than those from women's offices.
Bacterial abundance also appeared to be higher in the New York and Tucson offices compared to those in San Francisco.
As for sites within the offices, the phone and chair appeared to be the most highly colonized sites, followed by the computer keyboard, mouse, and desk.
While their study focused primarily on office spaces that had not been implicated in any health problems, the researchers noted that similar approaches may eventually prove useful in studies of indoor environments that have been associated with illness.