"Fomites is derived from Latin and in the original Latin the singular form is fomes, and this has been directly transplanted to modern English. Therefore the form "fomite" is a linguistically-incorrect back-formation and should not be used. However articles will be seen where it is used, often by people, e.g. microbiologists, who should really know better 5,6!"
"Fomites (singular: fomes) are used in medicine to refer to inanimate porous or non-porous objects, or surfaces colonised with microbes (viruses, bacteria, fungi) and serve as vehicles for transmitting many pathogenic microorganisms 1-3. Some examples of fomites are clothing, mobile phones, handrails, doorknobs, light switches, medical equipment, countertops, computer mice, computer keyboards 1-3."