Abstract
A study of the quantity and types of airborne bacteria and its correlation with human presence was conducted. Air samples were collected from different units for three days and three sessions (morning, afternoon and evening) for the enumeration and identification of bacterial isolates. Walk-through exercise was also conducted prior to every sampling to gather information on the number of occupants present, activities going on, and room characteristics. Isolation study revealed higher bacterial load in the afternoon and evening sessions; with Male Ward and Operating Theatre recording the highest and lowest bacterial loads respectively, as compared to the morning session that was done immediately after cleaning and before influx of people. The Spearman’s Correlation Coefficient showed a positively direct linear correlation between the bacterial load and occupant population irrespective of the three sessions (r = 0.84, 0.88 and 0.93). Identification study showed that the isolates are representatives of normal microflora of the skin, respiratory and gastro-intestinal tracts which includes the following; Staphylococcus aureus, Staphylococcus epidermidis, Micrococcus roseus, Klebsiella pneumoniae, Proteus mirabilis, Bacillus subtilis, Aspergillus, Penicillium, Mucor, Candida and Fusarium species. The study presents evidence of increased concentration of indoor airborne bacteria due to human presence, movement and activities.
Highlights
Air represents a vehicle for movement of microbes from one habitat to another
The microbial loads in hospital indoor air are influenced by the number of occupants, their activities and the ventilation (Ayliffe, 1999)
Occupants are a potential source of microorganisms or microbial vectors shaping the microbiome of indoor surfaces with which they come in contact with, as they shed microorganisms from the skin squames and the respiratory tract (Lax et al, 2014)
Summary
Air represents a vehicle for movement of microbes from one habitat to another. The study of indoor microbiome is of critical importance since humans spend the majority of their time indoors and regularly encounter microbes in this habitat (THMP Consortium, 2012). The microbial loads in hospital indoor air are influenced by the number of occupants, their activities and the ventilation (Ayliffe, 1999). Occupants are a potential source of microorganisms or microbial vectors shaping the microbiome of indoor surfaces with which they come in contact with, as they shed microorganisms from the skin squames and the respiratory tract (Lax et al, 2014). Dressings and beddings can act as the sources of airborne microorganisms. Sweeping of floors and changing of bed linens can cause suspension of bioaerosols in air. Fungal spores gain entry into the hospital buildings through crevices in the walls and ventilation ducts with inadequate filtration
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