I am a veteran nursery school teacher and have always frequently washed my hands with soap and water during the workday, especially when preparing food and changing diapers. Most of my colleagues, however, have switched to liquid antibacterial soap. Is this more effective against germs than ordinary liquid or solid soap, or could it possibly be harmful to the environment, leading to antibiotic resistance? S.M., JerusalemAssociate Prof. Colin Block, a senior expert on clinical microbiology at Hadassah University Medical Center in Jerusalem’s Ein Kerem and chairman of the steering committee for medical education at the Hebrew University Medical Faculty, comments:The idea of hand hygiene has increasingly penetrated public awareness in recent years and for good reason. Starting with the AIDS era in the early 1980s and progressing through successive dramatic episodes of SARS, bird flu and now MERS chest infections, among others, we have witnessed the appearance first of gloves (and sometimes masks) and now the ubiquitous alcohol-based solutions, gels and sprays one finds in so many places, from restaurants to your local clinic, from hospitals to handbags.The first question essentially asks if adding antibacterial properties to soap or detergent actually enhances effectiveness against bacteria, while the second raises issues of unintended consequences.As you have practiced over the years, hand washing has been – and still is – the essential basic element of hand hygiene. In order to answer your questions, we should consider what it is that we are trying to achieve by adding antibacterial capacity. What germs are we trying to neutralize? What kind of infections are we trying to prevent? To keep this manageable, let’s look at this in the context of nursery schools or any other childcare facility.Diarrhea, respiratory infections and skin infections are among the chief nuisances, and they all can result in outbreaks in childcare facilities. “Childhood diseases” like measles and chicken pox, which should by now be memories, are unfortunately still around to some extent, partly due to parents’ fear of vaccination, which is fueled mainly by inaccurate information that’s all too accessible these days.Those are the diseases, more or less. What of the critters that cause them? We’re mostly concerned here with bacteria and, let’s not forget, viruses. Both these types of “beasties” can often be killed by commonly used disinfectants, but not always with equal ease. For example, among the viruses that cause diarrhea, some, such as noroviruses, are extremely difficult to kill with chemical agents (despite what may be written on some product labels). So, while the antibacterial soap might contribute something to preventing the spread of Shigella or Campylobacter (two of the main diarrhea bacteria), it adds nothing to neutralizing some viruses.All this notwithstanding, there is much evidence that antimicrobial chemicals can contribute to the reduction of pathogens (germs that cause diseases) on the hands of people who use them when washing their hands. This would include child carers, food handlers, hospital staffers and other professionals and even regular folk. So we might infer that the informed use of such agents in soap or other detergent products should theoretically contribute to actually preventing infections.So does this actually happen? It’s complicated. On the one hand there is good evidence that hand washing with soap and water goes some way to reducing diarrheal disease in advanced as well as less-advanced countries. This was summarized this year in a systematic Cochrane Review (the Cochrane Collaboration publishes reviews of the combined results of many studies, according to strict criteria).On the other hand, a very sophisticated Dutch study published just last month found that a hand-hygiene intervention had no significant benefit over regular hand-washing practice in preventing both upset stomachs and the common cold.And here’s the rub: The Dutch study compared an intensive program, conducted in “test” daycare centers, in which regular hand washing was supplemented by the addition of an alcohol-based hand sanitizer and special training, with unsupplemented regular hand washing practice in “control” daycare centers.If we assume that regular good (Dutch) hand washing is effective, then the alcohol and the intensive intervention may not be needed. Can some of this be explained otherwise? Maybe it has something to do with how germs get around. Not all are spread on the hands of carers.Contact between kids, their sharing of secretions (and sometimes excretions) directly or on toys and other items handled or touched, all complicate the interpretation of such research.Thorough and frequent hand washing with soap results in the physical removal of germs (though not their total elimination), including “unkillable” viruses, from the hands of carers. Whether antibacterial additions really make a difference in reducing infections in settings such as yours is not clear.Potentially negative effects of these disinfectants and other chemicals and drugs on the environment has mainly been inferred from their presence in sometimes large concentrations in hospital wastewater, for example. Much of the research in this area has centered on treating this waste. It would be reasonable to assume that the amount of pollution generated by hand washing with antimicrobial substances in a nursery-school setting would be negligible by comparison. Let’s not forget, too, the contribution of the detergents in liquid and solid hand washing formulations to messing up the environment.These materials are there whether disinfectants are used or not.Concerns about the effect of antimicrobial chemicals in engendering the resistance of bacteria to antibiotics have been addressed several times over the past few years. There is some evidence for certain mechanisms that may reduce the susceptibility of bacteria to both disinfectants and some antibiotics, though the effect of this is more likely to be significant in settings where the use of such chemicals is much more intense, and not only for hand hygiene, such as in hospitals.So to sum up, the short answers are: The evidence says that hand washing is the core, and common sense dictates that doing it properly is the secret. The addition of antimicrobial chemicals may contribute, but this question is not fully settled in settings outside of hospitals. Using these chemicals in the narrow context of childcare is unlikely to have significant negative consequences in the environment.Rx for Readers welcomes queries from readers about medical problems. Experts will answer those we find most interesting. Write Rx for Readers, The Jerusalem Post, POB 81, Jerusalem 9100002, fax your question to Judy Siegel-Itzkovich at (02) 538-9527, or email it to firstname.lastname@example.org, giving your initials, age and place of residence.