The evidence came after research undertaken for cleaning firm Initial tested more than 158 different office items, the Daily Express reported.
The growing trend for workers to eat lunch while browsing the internet is responsible for the infestation that makes toilets cleaner than people's workstations.
Men are the worst offenders with their desks being 40 per cent dirtier than those of women.
Warm conditions coupled with grease and crumbs provide the essential breeding ground for a whole host of bugs as computer equipment often goes for months without being cleaned properly.
Potentially infectious bacteria are transferred from computer mice to people's mouths as they touch their faces and eat lunch.
Some of the most commonly found bacterium included the virulent MRSA-causing staphy- lococcus germ and streptococcus, a cause of throat infections.
The survey's results showed that keyboards ran a close second to computer mice.
"Mice and keyboards are not cleaned as regularly or as thoroughly as other parts of the office," said Peter Barratt, from Initial.