Assessment of airborne bacteria from a public health institution in Mexico City

In this work, the composition of the bacterial community in the air of a hospital in Mexico City was evaluated using metabarcoding and proteomics approaches, along with the assessment of environmental factors such as temperature, humidity, and suspended particles. Two types of aerobiological samplers were used: Andersen One-Stage Viable Particle Sampler (AVPS) and Coriolis μ sampler (CμS-Sampler). Sampling was performed in four areas of the hospital: Floor 1 (F1), Floor 2 (F2), and Emergency Unit (EU), as well as outdoors (OH). The use of both samplers showed variations in diversity and composition. Bacterial abundance was 89.55% with the CμS-Sampler and 74.00% with the AVPS. The predominant phyla with the AVPS were Firmicutes, Proteobacteria and Actinobacteria, while with the CμS-Sampler, the main phyla were Proteobacteria, followed by Actinobacteria and Firmicutes. The highest diversity and richness of bacteria was recorded in F1 and F2, with 32 species identified, with a greater number within the hospital. Potentially pathogenic bacteria such as Bacillus spp., B. cereus, B. pumilus, Clostridium spp., Enterococcus gallinarum, Micrococcus luteus and Staphylococcus spp. were detected. Furthermore, a high concentration of particles between 2.5 μm and 10 μm, and Total Particulate Matter (TPM) was observed, with values of TPM, 303 μg/m3 in F1, 195 μg/m3 in F2, 235 μg/m3 in EU and 188 μg/m3 in OH. Temperatures averaged between 26 and 27°C, and relative humidity ranged between 39.8 and 43.5%. These environmental conditions and particulate matter can promote bacterial growth and their dispersion in the air, constituting a continuous risk of exposure to pathogens, mainly in indoor areas of the hospital. This study provides a framework for air monitoring, where the results of different samplers complement the detection of potential pathogens.