Table 1.

Most common bacterial odorants.

Substance	Smell	Body Site	References
Hydrogen sulfide	Rotten eggs	Breath, Saliva, Flatus, Urine	[18,19,44,45]
Other volatile sulfur compounds (VSCs): ethanethiol, S-ethyl thioacetate, diethyl disulfide, dimethylsufide	Cooked onion or vegetables, ocean; musty, unpleasantly sweet smell	Breath, Saliva	[20,23,26]
Methanethiol	Putrid, barnyard; musty smell	Breath, Saliva, Flatus, Urine	[20,26,46,47,48]
Trimethylamine	Rotten fish	Breath, Urine, Sweat	[38,49,50,51,52,53]
Indole, Skatole	Fecal matter	Breath, Saliva	[28,30]
Short chain fatty acids (butyric, propionic, acetic, isovaleric, isocaproic acid)	Human vomit, sweat, goat-like, sweaty feet odor; cheesy smell	Sweat, Urine, Vaginal discharge	[54,55,56]
Putrescine, Cadaverine	Rotten meat, spoiled fish	Breath, Saliva, Vaginal fluid (in bacterial vaginosis)	[32,57,58,59]
Acetone	Acetone, fruity smell of rotten apple	Breath	[60,61,62]
Pyridine	Fishy odor	Breath, Saliva	[63,64]
(E)-3-methyl-2-hexenoic acid (E3M2H)	Peculiar pungent odor	Sweat	[65,66,67]
3-methyl-3-sulfanylhexan-1-ol ((R)/(S)-MSH)	Tropical fruit or grapefruit (enantiomer R), onion, clary sage, chicken-sulfury (enantiomer S)	Sweat	[65]
(R)/(S)-3-hydroxy-3-methylhexanoic acid ((R)/(S)-HMHA	Cheesy, rancid odor	Sweat	[68,69,70]
Ammonia	Urine-like, ammoniacal, fetid	Breath, Saliva, Urine, Stool, Sweat	[34,71,72,73,74,75]
Methionine (transformed into dimethylsulfide)	Boiled cabbage, rancid butter, oast house, rotten mushrooms	Breath, Sweat, Urine	[11,12,76]
Phenylacetate	Musty, mousy, sweaty	Urine, Infant skin	[77]
Branched-chain amino acids (leucine, isoleucine and valine)	Maple syrup, caramelized/burnt sugar, fenugreek, curry	Urine, Ear wax	[78,79]
3-hydroxyisovaleric acid	Male cat urine	Urine	[80,81]
Aldehydes (2-nonenal)	Foul, urine-like	Urine, Skin	[82,83,84]