When we look at policy for Twitter, the same considerations as we discussed for other platforms are important.
Point-of-Contact: Your company should determine one person or a team internally who can handle all of Twitter interaction.
Content: Your company should determine a policy stating which employees post on behalf of the company, so there is no confusion on who can represent the company's interests. This should also include a policy on whether or not employees are allowed to respond to posts through their personal accounts.
Comment Response: Your company should create a protocol on who responds to tweets and how negative tweets are handled. Some companies will not respond to negative tweets; others see negative tweets as opportunities to engage in a discussion that can change mindsets by posting and responding appropriately.
You may also wish to address how employees portray themselves on their personal Twitter accounts. In the example of the Price Chopper tweet, the employee responded to the negative comment from a personal Twitter account. Price Chopper also responded by contacting the customer's employer, Syracuse University. Consider the expectations you might like to set forth for employees who have personal Twitter accounts.