Table 1.

Results of bacterial culture in different zones of Clinic A and Clinic B from Hermosillo, Sonora.

Sample area	Filtration unit	CFU	Isolation	Biochemical characteristics
Emergency room Clinic A	Filter 3	9	Streptococcus spp.	Gram-positive cocci in short chains, anaerobic and lactose fermentative, catalase (-), motility (-), nitrate reductase (+) and alpha-hemolysis (+)
			Bacillus spp.	Gram-positive aerobic rods in single and short chains, catalase (+), motility (+) and nitrate reductase (+)
Internal Medicine Clinic A	Filter 3	35	Staphylococcus spp.	Gram-positive cocci in clusters, facultative anaerobic, lactose fermentation (+), catalase (+), motility (-), coagulase (+)
			Micrococcus spp.	Gram-positive aerobic non-fermentative cocci in irregular clusters, catalase (+), motility (-) and nitrate reductase (-)
COVID-19 patient room Clinic A	Filter 2	40	Bacillus spp.	Gram-positive aerobic rods in single and short chains, catalase (+), motility (+) and nitrate reductase (+)
			Micrococcus spp.	Gram-positive aerobic non-fermentative cocci in irregular clusters, catalase (+), motility (-) and nitrate reductase (-)
	Filter 6	10	Streptococcus spp.	Gram-positive cocci in short chains, anaerobic and lactose fermentative, catalase (-), motility (-), nitrate reductase (+) and alpha-hemolysis (+)
			Staphylococcus spp.	Gram-positive Cocci in clusters, facultative anaerobic, lactose fermentation (+), catalase (+), motility (-), coagulase (+)
COVID-19 patients care room Clinic B	Filter 2	15	Streptococcus spp.	Gram-positive cocci in short chains, anaerobic and lactose fermentative, catalase (-), motility (-), nitrate reductase (+) and alpha-hemolysis (+)

CFU, colony forming units.