These party crashers love food and drinks, but you won't see them eating and imbibing. You likely won't even know they're at your table because they're invisible. What are they? They're three common undesirable bacteria: salmonella, campylobacter and E. coli O157.

Any of these bacteria can cause illness and sometimes even death if victims are young children, elderly or sick. Poor hygiene, sloppy food handling, improper food storage or lax preparation let them into the party. Jim Chan, the manager of food safety for the City of Toronto Public Health, shares tips on how to keep your gathering safe from food-borne illnesses.

1. Food safety starts with your shopping list.
• Only buy pasteurized milk and juices to ensure all disease bacteria are killed. If you enjoy gourmet cheeses that are made from raw milk, buy only those that are aged more than 60 days and that say so on the package. The aging process kills the disease-causing bacteria.

2. Thoroughly wash your hands and all preparation surfaces.
• Wash your hands with soap under warm water before handling any food, especially raw poultry or meat. After handling, wash your hands again before touching anything else.

• To prevent cross-contamination of foods, use separate cutting boards and utensils: one for meat or poultry and another for raw foods. Wash these in a sink of hot soapy water. Rinse well with clean water that has about four capfuls of bleach added to it.

• Clean countertops and surrounding areas using a similar bleach solution and a clean dish cloth. Machine-wash the cloth with hot soapy water and bleach before you use it again.

• Sponges are not as easy to clean as cloths. Either don't use them, or, if you do, wash them then put them in the microwave at high for about 10 seconds after each use.

3. Monitor how long buffet foods have been out.
• Keep hot food hot (60 C or above) and cold food cold (below 4 C). Temperatures between these ranges are in the danger zone.

• When you entertain don't let perishable foods linger in the temperature danger zone for longer than one hour.

• Use small serving dishes and platters and keep replacement dishes of food hot in the oven or cold in the refrigerator. Replenish with new full dishes, rather than adding to ones that have been sitting.

• As for the vitamin-rich raw vegetables and fruits, remember to wash them thoroughly before putting them out. Many people use a bath of water and a few spoonfuls of vinegar to a litre of clean water on lettuce or other salad greens that are eaten raw. The slightly acidic vinegar helps remove dirt and most remaining microorganisms.

4. Store foods properly.
• Remove leftover turkey from the bone and refrigerate meat, stuffing and gravy separately.

• If food is hot, let it cool for no more than 30 minutes, then put it in the refrigerator, uncovered in a shallow container, for quick cooling. Once it's cold, cover it.

• Keep raw foods away from cooked foods; safely cooked food can become contaminated through even the slightest contact with raw food or an unwashed utensil.

• Use leftovers within two to three days or freeze them for up to one month.

• Before serving leftovers, reheat them so all parts reach at least 74 C, and bring gravy to a full boil, stirring while reheating. This will kill any bacteria that might have developed during refrigeration.

BONUS: Play it safe when cooking a turkey
• A frozen turkey can take up to one week to thaw completely. Allow five hours per pound (500 grams) thawing time.

• Thaw the bird in the refrigerator. Keep it in its protective plastic wrap and in a pan deep enough to contain any drips.

• Cook the turkey until its internal temperature rises to at least 75 C as registered on a thermometer inserted into the thickest part of the thigh. If the cooked bird shows any pink juice or flesh, put it back in the oven.

• It's preferable to cook the stuffing separately to avoid growth of bacteria. If you want to put an all-dressed turkey on the table, add cooked stuffing to the bird's cavity when it's done.

• If you do cook stuffing with the bird, don't stuff it until just before you're ready to put the turkey into the oven.