A former employee of a McDonald's outlet in Louisiana, identified only as Nick, recently caused a commotion online after posting pictures on Twitter of ice cream machines covered in mold and goo.

With many people around the world expressing concern over hygiene standards at the fast-food chain, Shanghai's food safety authorities inspected four McDonald's stores in the city this week.

Inspectors were faced with resistance from staff members at first, who alleged they cannot dismantle the machines as they were serving customers.

The workers eventually cooperated with the authorities, and the auditors were able to carry out the inspection.

Their findings came as a relief for both McDonald's and its customers as hygiene levels at the stores were at satisfactory levels.

In the wake of the US exposé, McDonald's China released a statement on its official account on Weibo, saying that its ice cream machines in the country are automatically disinfected every day to ensure food safety standards.