Protecting Yourself from Germs and Bacteria

In the US, peak flu season occurs from late November through March. With cold and flu season coming up soon, everyone is typically concerned about germs and bacteria. Here's a transcript of an interview between our medical director, Dr. Patricia David, and a local reporter regarding germs, bacteria, and viruses in our homes.

Q. What is the difference between germs, bacteria, and viruses?

Dr. Patricia David: “Germs” is a general term. There are actually 4 categories of “germs”: Bacteria, viruses, fungi, and protozoa.

Bacteria are one-celled living animals with a complete genetic code. They are able to self-reproduce. Viruses are not much more than a section of RNA or DNA covered by a protein shell. A virus can’t reproduce without a living host – so it must first find a suitable host, penetrate the cell wall and, once inside, replace the cells’ original genetic commands with its own (usually to make as many copies of the virus as possible). Once the cell has outlived its usefulness, it explodes and sends out thousands of copies of the original virus to other cells.


Q: Which germs are most common in the home?

Dr. Patricia David: Germs are continually introduced in the home via people, food/water, insects, and air. Most are really of little consequence, but you can encounter several dangerous organisms in your home. As far as bacteria, the most commonly found are E. coli from undercooked beef, raw milk, Salmonella from raw/undercooked eggs, undercooked poultry, fruits/veggies, Staphylococcus from cooked high-protein or dairy-containing foods that are kept at room temp for a long time (such as chicken salad), and Listeria from deli meats and soft cheeses. The viruses we can encounter in our home are rotavirus, hepatitis A, the "common cold" viruses rhinovirus and coronavirus, influenza virus, and adenovirus.


Q: Where are they commonly found in the home?

Dr. Patricia David: Everyone’s first thought is obviously the bathroom, but that's actually not true. The kitchen is the dirtiest place in the home, with the sink being dirtier than the bathroom toilet. You can find the most dangerous sources of virulent bacteria (E. coli, Salmonella, Staphylococcus and others) in a typical kitchen sponge and dish cloth. They provide a source of moisture, a ready food supply in the form of food particles, and little pockets where bacteria can cling. A sponge that’s been in use for no more than 2 or 3 days in a kitchen harbors MILLIONS of bacteria.

The sink itself, as well as refrigerator door handles, are also breeding grounds for bacteria. Another source is plastic cutting boards; wood cutting boards have received some bad press – even the FDA says that plastic is less likely to harbor bacteria than wood – however, experimenters at UC-Davis showed that the wood absorbs bacteria but won’t release it. Bamboo may actually be the best choice, since its properties are presumably similar to wood but is more environmentally friendly.

Poorly cooked food is another source. Microbes multiply in rare or even medium steaks, raw or lightly steamed shellfish, poached eggs and unwashed fruit. An estimated 76 million cases of food-borne illnesses in the United States each year are contracted in the home – and many of these can be prevented.


Q: So the bathroom isn't the dirtiest place?

Dr. Patricia David: That's correct. The kitchen sink is the dirtiest place in the house. The bathroom is still obviously a dirty area – but it’s not the toilet, where you'd think it would be. In the bathroom, it's the sink drain that harbors the most germs.


Q: What are some tips to combat germs/bacteria in the kitchen, bathroom, bedroom, carpeting/flooring?

Dr. Patricia David: First, always wash your hands thoroughly. The biggest obstacle seems to be simply getting people to wash their hands. Washing hands in hot soapy water for at least 20 seconds rinses off surface bacteria and makes it difficult for bacteria to cling to skin. In an experiment by Utah State University, a raw chicken was covered with “GloGerm,” which is invisible in daylight but visible when exposed to ultraviolet light. This chicken was given to a home cook, who was asked to prepare it. By the time the chicken was done, the ultraviolet light revealed chicken juice everywhere - on the counter, in the sink, on cabinet handles, and even on the sippy cup of the cook's 2-year-old child.

If you use cellulose sponges, make sure you wash them well and then microwave them for a minute. Experimenters at UC-Davis Dept of Food Safety soaked sponges in bacteria-laden concoctions, and a one minute nuke eliminated them.

If you use dishcloths, change them often. By the way, it's interesting to note that studies of bacteria in home kitchens have found that people who had the cleanest-looking kitchens were often the dirtiest – and it’s because these "clean" people wipe up frequently using the same cloth, so they often end up spreading bacteria all over the place. The cleanest kitchens were in the homes of those who never wiped up, and just put their dirty dishes in the sink.

If you stick to plastic cutting boards, you can wash them in the dishwasher but make sure the water gets hotter than 140 degrees or it will only spread the bacteria around, and the bacteria in the cracks will remain.

An environmentally-safe cleaner to use in your kitchen and bathrooms is 5% vinegar (such as that found in the supermarket). This kills 99 percent of bacteria, 82 percent of mold, and 80 percent of viruses. You can also try 1 cup water + 1 tsp pure essential oil of lavender – lavender is more antiseptic than phenol (the industry standard for disinfectants) – and it smells much better! To clean floors and carpet, the very best way is steam cleaning – the high heat kills bacteria.


Q: Do homes with pets have an increased risk for higher germ levels? What germs to pets tend to carry?

Dr. Patricia David: Yes, homes with pets have this additional source for bringing in germs. Cats tend to carry Bartonellosis (cat scratch disease) and Toxoplasma (toxoplasmosis). Dogs harbor roundworms, Campylobacter, and Pasterella multocida (a bacteria found in dogs’ mouths). Both of these pets also can carry rabies, Giardia, Cryptosporidium, and ringworm.

Even the more unusual pets still carry some germs that can be harmful to their owners. For example, reptiles can have Salmonella, birds carry Psittacosis, and deer mice can carry Hantavirus.


Q: Is it true thousands of droplets from a sneeze may contain millions of virus particles that can be infectious for hours or even several days and that a sneeze sends 10,000 virus-filled droplets into the air at 200mph? What should people do when they're in close proximity to a cougher/sneezer? Does holding your breath work?

Dr. Patricia David: Yes - when you sneeze, 40,000 droplets containing several thousand particles fly out of your mouth and nose (mostly the mouth). They’ve been clocked at 103.6 miles per hour, and can potentially land up to 12 feet away. If the person sneezing has the flu and doesn’t cover up, everything in the room is covered with the droplets.

The germs in those droplets can thrive for a few hours on hard dry surfaces (faucet handles, doorknobs, credit cards, telephones, etc.). They can thrive for a day (perhaps longer) in skin folds, under fingernails, in creases in your palms.

The most likely way for those germs to make you ill is for you to touch an infected surface, then touch your eyes, mouth, etc. If you’re in close proximity to a sneezer, holding your breath and leaving the area of the sneeze may help keep you from breathing in the particles – but you still have to remember to wash your hands, since the sneeze particles can be sitting on your skin or clothing. And, when you go back in the room, make sure you wash up again if you touch anything.


Q: So what's your best advice for us?

Dr. Patricia David: Our best protection is to wash your hands well, and wash them often. Each washing should involve vigorous scrubbing with soap – all surfaces, including between the fingers and underneath the fingernails – for at least 20 seconds. Antibacterial soap isn't necessary -- just plain old soap is fine, as long as you follow the instructions for vigorous scrubbing of all surfaces for at least 20 seconds. Wearers of fake fingernails should be aware that germs are embedded in those false fingernails -- and can still be there even after you wash your hands.