# Exposure and Health Effects of Bacteria in Healthcare Units: An Overview
## 4 Discussion  
Numerous studies presented divergent points of view on how bacterial contamination can be observed in different locations within hospital facilities, how seasonal variations affect the concentration, and even how data regarding the most prevalent genera that can be found in healthcare environments and staff due to occupational activities. In the first presented study [34], concentrations of airborne bacteria reached a peak in November (436.3 CFU/m\({}^{3}\)), and the lowest value was identified in December (257.1 CFU/m\({}^{3}\)). However, the authors did not explain the decrease between these two months or between the other months of the year that were assessed. Another study, conducted in Portugal [45], described that most of the departments analyzed presented a high level of bacterial concentration (ranging from 12 to 170 CFU/m\({}^{3}\)) and concluded that the indoor bacterial concentration was not influenced by outdoor concentration but by indoor air. A higher bacterial concentration was identified in the mornings (267.1-505.6 CFU/m\({}^{3}\)), and even though the authors did not provide an explanation, we hypothesize that this could be due to increased human activity from visitors or workers [36; 46]. In another analyzed study [37], winter and autumn had the highest concentration levels of bacteria with the increased bioburden associated with the waiting room in autumn and children's ward in the winter. A possible explanation for the higher load in the waiting room can be attributed to an increase in the number of occupants (200 per day or more). The same hypothesis is suggested in the children's ward, with the additional factor of the increased number of infections in children during the wintertime. The fact that the rooms in that ward are small, and that more than one parent can accompany the child, is another factor that increases the concentration of bacteria such as airborne actinomycetes, which were the most prevalent in the children's ward [37]. The data from Portuguese studies revealed that _Staphylococcus epidermidis_[45] and _Microoccus_ spp. [45; 46; 47] were the most prevalent bacteria identified. However, _S. epidermidis_ is not considered to be a relevant risk of exposure due to its lower infections rates [34]. On the other hand, _Acintebacter_ (species not identified) was found in two studies [32; 34] as a prevalent genus in a university hospital from Ethiopia, justifying its persistence due to its great survival ability in the indoor environment [47], which can be a potential cause for hospital infections transmitted via the air [48]. Another relevant microorganism is _Pantoea agglomerants_, which is able to infect hospitalized individuals, particularly immunodeficient patients, through contaminated medical instruments [49]. A bacteria genus described in several studies considered of great interest is _Staphylococcus_ spp., which was identified at the highest concentration in a cardiology ward/intensive care room (hospital 5). Once the strains were analyzed, _S. saprophyticus_ was the most predominant, followed by _S. warneri_, being reported as an important opportunistic pathogen and associated with healthcare-acquired infections [37]. Cabo Verde et al. [45] also found _S. warneri_ to be a prevalent species in the hospital, but no data were reported regarding _S. saprophyticus_ in contrast to the findings of [PERSON] et al. [50]. _S. saprophyticus_ can infect an individual's blood through catheters, surgical prostheses, pneumonia, urinary tract infections and more [51; 52; 53]; therefore, this species is of particular relevance. Moreover, _Staphylococcus aureus_ is one of the most relevant nosocomial pathogens, described as one of the main pathogenic bacteria that cause osteomyelitisitis (including in children)[54; 55; 56; 57; 58; 59] septic arthritis [60; 61; 62; 63], and prosthetic joint infections [64; 65; 66; 67]. _S. aureus_ is a commensal bacterium and a human pathogen; about 30% of all humans are colonized with _S. aureus_[68].