Nelken advises against storing meats and takeout foods on the top shelf of the fridge, lest they drip on produce such as salad and contaminate it. Leave meats in their plastic grocery bags and keep takeout containers in their bags to contain any leakage.

It's important to get perishable foods to the fridge as soon as possible after buying them. Take food home from the grocery store within 20 minutes and refrigerate perishables to stop the spread of bacteria. Or keep perishable foods in thermal bags with ice packs. Keep in mind that food can reach that danger zone of 41-135 degrees very quickly in a hot car.

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Speaking of bags… For those of us who bring our own reusable bags to the grocery store, Nelken is finding that they pose a surprising bacteria risk.

"For people who bring their own bags to the market, we're finding that bags left in cars have high bacteria counts. Cloth bags are a perfect medium for growing high bacteria levels. To avoid bacteria buildup and transmission to other foods, throw the bags in the washing machine or sanitize the inside of the bag once a week," he says.