This from the BBC:
Out of 33 keyboards swabbed, four were regarded as a potential health hazard and one harboured five times more germs than one of the office’s toilet seats.
Microbiologist Dr Peter Wilson said a keyboard was often “a reflection of what is in your nose and in your gut”.
During tests in January this year, a microbiologist deemed one of the office’s keyboards to be so dirty he ordered it to be removed, quarantined and cleaned.
It had 150 times the recommended limit for bacteria — five times as filthy as a lavatory seat tested at the same time, the research found.