An in-depth survey of the microbial landscape of the walls of a neonatal operating room.

Bacteria found in operating rooms (ORs) might be clinically relevant since they could pose a threat to patients. In addition, C-sections operations are performed in ORs that provide the first environment and bacterial exposure to the sterile newborns that are extracted directly from the uterus to the OR air. Considering that at least one third of neonates in the US are born via C-section delivery (and more than 50% of all deliveries in some countries), understanding the distribution of bacterial diversity in ORs is critical to better understanding the contribution of the OR microbiota to C-section- associated inflammatory diseases. Here, we mapped the bacteria contained in an OR after a procedure was performed; we sampled grids of 60x60 cm across walls and wall-adjacent floors and sequenced the V4 region of 16S rRNA gene from 260 samples. The results indicate that bacterial communities changed significantly (ANOSIM, p-value < 0.001) with wall height, with an associated reduction of alpha diversity (t-test, p-value <0.05). OR walls contained high proportions of Proteobacteria, Firmicutes, and Actinobacteria, with Proteobacteria and Bacteroidetes being the highest in floors and lowest in the highest wall sites. Members of Firmicutes, Deinococcus-thermus, and Actinobacteria increased with wall height. Source-track analysis estimate that human skin is the major source contributing to bacterial composition in the OR walls, with an increase of bacteria related to human feces in the lowest walls and airborne bacteria in the highest wall sites. The results show that bacterial exposure in ORs varies spatially, and evidence exposure of C-section born neonates to human bacteria that remain on the floors and walls, possibly accumulated from patients, health, and cleaning staff.