Fig. 5

Bacterial composition at the level of genera in nasopharyngeal samples. Each column represents one sample. Two major clusters (I and II) were identified; the first cluster included particularly participants working at NEO, the other cluster consisted of participants working at RCX. Nasopharyngeal samples from ENT workers were distributed equally between both major clusters Samples were collected in the morning and in the afternoon (after an 8 h exposure to the workplace environment) from participants working at the maternity hospital (NEO; n = 8), pediatric hospital (ENT; n = 6), and a research center (RCX; n = 8). Only the 20 most abundant genera from each workplace were included in the heatmap. One nasopharyngeal sample collected in the afternoon was excluded from the analysis due to the low DNA conent in the sample