That claim as commonly made doesn't mean a blind thing. It is SO nonsensical that for my part I think it should be a matter for advertising authorities. Does it mean 99.9% of the germs on your hand or the medium treated? Does it mean after a second or an hour? Does it mean 99.9% of all species investigated at one time or another? Does it mean at concentrations that can safely, easily, effectively and harmlessly will work where the need applies? Does it mean that the "germs" in question are harmful or not? Are we speaking of bacteria, fungi, protoctists, or viruses, and in particular hether they are hiding in each other or in our own cells, tissues or dirt?

It is enough to make any biologist's, never mind microbiologist's, stomach turn.

Does it work on the marketroids who perpetrate that sort of of suckerbabble? Now, THAT sounds like a more attractive proposition!

Jon

Sorry Jon, but it actually DOES mean something, and it's to do with the standard tests that are used to measure the antibacterial effectiveness of a product. Tests such as EN1276 are used - this is a suspension test where a known concentration of bacteria are treated with a given product for a given contact time (usually 5 minutes). The before and after (after neutralisation) figures are measured and expressed as a log reduction. The TVC (Total viable counts) to start with of each bacterium are usually so huge that they are expressed as powers of 10; for instance, you may start off with 5 x 10 to the power of 6 bugs per ml of test solution, and, after treatment with a product, end up with 5 x 10 to the power of 2 bugs per ml of test solution - this is a reduction of 10 to the power of 4, commonly expressed by those in the field as a log4 reduction. For the EN1276 test 4 bacteria are used - two Gram positive, and two Gram negative. These bugs are used as they give a good represntation as to what will happen when you test against other bugs (obviously it is impractical to test ALL bacteria). The bugs used in EN1276 (a disinfectant and antiseptics standard) are Esherichia coli, Staphylococcus aureus, Enterococcus hirae and Pseudomonas aeruginosa. When a bottle of product claims it kills 99.9% of bugs, it means that in a test like EN1276 it achieved a log3 reduction in TVC of all bugs tested against. In reality, if you have a heavily contaminated surface (say, a Log6 challenge to start with), and you kill 99.9% of bugs, you still have a log3 concentration left, so it has only killed half the bugs present! The product is only as good as the challenge it meets, and if it is a tough challenge, it won't perform very well. By the way, I am not a Marketroid, I am a scientist, and in my opinion, bleach and soap kill more bugs than any proprietary product you can buy.

Peter Finan, Haworth, West Yorkshire

And for the sake of getting back to the root of the issue (now that we know that advertisers use the truth to lie), what exactly are the kinds of generally universal, omnipresent germs that are unaffected by common cleaners?

PP & GCC,

 Nice comments chaps! A few thoughts:

PP, Doomed it is? Well, in some senses yes, but our global demise demands more than our being unable to kill every germ. As long as we can keep our pitifully dwindling global population to more than a few tens of millions, suitably genetically assorted and outbred, it would take a formidable combination of pathogens to wipe us out.

Mind you, we have no written guarantee of indefinite survival. Probably millions of species (including germs)  have been exterminated in interspecific strife, probably most of them in unequal combat with microbes. Why should humanity be different?

Meanwhile, from the optimistic point of view, there are two factors to begin with: selective breeding and competition. Selective breeding means that, much as happened most dramatically with rabbits in Australia, we get selected to survive the worst of our pathogens, and they get selected not to kill us off too quickly for their own good. Now, before you pedantically, but correctly, point out all sorts of complications to those relationships, I hasten to add that it is a large subject with many complications (and a very interesting subject at that!) but that as a rule this sort of thing does happen remarkably effectively with a remarkable range of diseases in a remarkable range of circumstances. The Black Death (which, together with some epidemiologists, I suspect was a viral disease, and not Yersinia at all) went away within a few centuries after possibly a few million deaths. Syphilis, which was a horror almost beyond description when it struck Europe in the wake of the rape of the Americas, was merely a disgrace and a threat on a par with say, measles, in the late 19th century.  TB to this day is less virulent in ethnic groups that were heavily exposed in past centuries, and complementarily, yellow fever has long been drastically more deadly among colonialistic peoples than equatorial indigenes, a fact that has had enormous historical consequences. These are just a few examples.

Make no mistake, the abuses that you describe are genuine, and some of them, when I am elected global president, I shall take steps to wipe out, probably starting by putting triclosan and a few associated compounds on the prohibited list, along with heroin.   

GCC, good question of course, but not as easy to answer as to ask (not that questioning skills are to be sniffed at in science, to be sure!) As a rule of thumb the strains chosen for testing are pretty helpful; the microbiologists concerned were not being particularly stupid. If those strains are controlled by a particular treatment, then you can reasonably assume that most others would be as well. This said, there are very important reservations. For one thing, each of the four species that Peter mentioned occur in many strains, ranging from practically harmless (even useful as probiotics or normal flora) to dangerously infectious or nosocomial, with horrific degrees of multiple microbicidal resistance. However, none of them is spore forming. I wonder how some of our marvellous commercial products would perform in challenging, say a partly sporulated population of certain Clostridum strains. (Peter? Any ideas?)

Then again, every time anyone begins to explore the environment for evidence of how many unknown bacteria there are in a given environment, they generally retrieve mind-numbing counts. We don’t know what those bugs are, or even whether they are good, bad or indifferent.

Sometimes it really is no easier to answer the questions than to ask.

Cheers,

Jon

It's because, we're not sure whether all bacteria has been discovered yet. Also things aren't always 100% affective, on a game you don't always acheive 100%.