This may come as news to all the parents out there (including me) who’ve trained our kids to slather their hands with sanitizing gels or wipes to protect themselves against nasty germs such as MRSA. According to a consumer update issued Wednesday by the FDA, none of the sanitizing gels, wipes or creams available over the counter have FDA approval for killing that potentially deadly pathogen. The update was issued on the same day the agency sent warning letters out to four companies who claim their products combat MRSA.

The FDA’s message to consumers notes that no over-the-counter products have been approved for killing the E. coli or Salmonella bacteria or the H1N1 influenza virus, either. Still, it doesn’t outright advise avoiding hand sanitizers altogether, just those that make unsubstantiated claims about the pathogens they can kill. Here’s the agency’s advice to consumers:

Don’t buy over-the-counter hand sanitizers or other products that claim to prevent infection from MRSA, E. coli, Salmonella, flu, or other bacteria or viruses.

Ask your pharmacist or other health care professional for help in distinguishing between reliable and questionable information on product labels and company Web sites.

In general, wash hands often, especially before handling food, to help avoid getting sick. Wash hands with warm water and soap for 20 seconds. For children, this means the time it takes to sing the “Happy Birthday” song twice.

When it comes to fighting germs with hand sanitizers, though, the federal government sends a slightly confusing message. Here’s an excerpt from the CDC’s H1N1 Web page:

Washing your hands often will help protect you from germs. CDC recommends that when you wash your hands — with soap and warm water — that you wash for 15 to 20 seconds. When soap and water are not available, alcohol-based disposable hand wipes or gel sanitizers may be used. You can find them in most supermarkets and drugstores. If using gel, rub your hands until the gel is dry. The gel doesn’t need water to work; the alcohol in it kills the germs on your hands .... If soap and water are not available and alcohol-based products are not allowed, other hand sanitizers that do not contain alcohol may be useful.

The CDC’s more general Web page about hand cleanliness, updated in February, explains that washing with soap and water is the best defense against germs, but that when soap and water aren’t available, a sanitizer containing at least 60 percent alcohol can substantially reduce the number of germs on your hands, thus lessening the chance of infection.

The upshot seems to be that hand sanitizers may or may not help protect against certain infections, but that since the FDA hasn’t approved any specifically to fight MRSA, E. coli, Salmonella or H1N1, we should be wary of products that claim to combat those pathogens.