When Chipotle was linked to outbreaks of E. coli and norovirus that sickened hundreds of customers, it took more than two years and required a thorough management shakeup – including a new CEO – to repair the brand’s image and pull its stock out of the gutter.

As McDonald’s readies for its third-quarter earnings report Tuesday, Wall Street is focused on demand from lower-income diners, as well as a recent E. coli outbreak.

The U.S. Food and Drug Administration continues to believe that slivered onions from a single supplier are the likely source of contamination, McDonald’s said in a statement. It said it will