Table 1.

Microbial groups reportedly active in coinfection of COVID-19 patients

Microbial group	Microbe(s)	Origin	Endogenous/exogenous	Found in	References
Virus	C. pneumoniae, parainfluenza 3, influenza A, M. pneumoniae, rhinovirus, non-SARS-CoV-2	Environment/birds/animals	Exogenous	Upper/lower respiratory tract	[26]
	Other coronavirus, hRV, influenza (H3N2)	Environment/birds/animals	Exogenous	Upper/lower respiratory tract, intestine	[27]
	RSV, entero/rhinovirus, non-SARS-CoV-2	Environment/birds/animals	Exogenous	Upper/lower respiratory tract, intestine	[28]
	Hepatitis virus	Human	Endogenous/exogenous	Blood, tissues, body secretions	[29]
	HIV	Human	Endogenous/exogenous	Blood, tissues, body secretions	[30]
	hMPV, hRV, PIV2, HKU1	Human, animals	Exogenous	Upper/lower respiratory tract	[29, 30]
Bacteria	Veillonella, Capnocytophaga,	Human	Endogenous	Oral cavity	[23, 31–33]
	Neisseria, Streptococcus pneumoniae, Corynebacterium, Leptotrichia, Prevotella, Fusobacterium periodonticum	Human	Endogenous	Oral cavity	[34, 35]
	Pseudomonas aeruginosa, Streptococcus pneumoniae, Fusobacterium periodonticum, Veillonella, Prevotella, Capnocytophaga	Human	Endogenous/exogenous	Upper/lower respiratory tract	[23, 31–33]
	Staphylococcus aureus, Haemophilus influenza, Escherichia coli	Human/environment	Endogenous/exogenous	Respiratory tract, skin, and intestines	[36]
	Coprobacillus, Clostridium hathewayi, C. ramosum	Human, environment	Endogenous/exogenous	Gut	[37]
	Clostridium, Veillonella, Actinomyces, Streptococcus pneumoniae, Rothia	Human, environment	Endogenous/exogenous	Gut	[25, 37–40]
	Mycobacterium tuberculosis	Human, environment	Endogenous/exogenous	Lower respiratory tract, other organs of the body	[41–43]
Fungi	Candida tropicalis, C. albicans, C. glabrata, C. dubliniensis, C. krusei	Human	Endogenous	Upper/lower respiratory tract, intestine	[44]
	Aspergillus fumigatus	Human, environment	Endogenous/exogenous	Upper/lower respiratory tract	[45]
	Aspergillus fumigatus, Rhizopus oryzae, Absidia mucor	Human, environment	Endogenous/exogenous	Respiratory tract, other organs of the body	[46]
	Black fungus (Rhizomucor species, Syncephalastrum species, Cunninghamella bertholletiae, Apophysomyces, Lichtheimia, Saksenaea, Rhizomucor)	Environment	Majorly exogenous	Respiratory tract, eye, broken skin and its appendages, sinuses, and brain	[47–49]