Highlights from the SFAM Conference on Antibiotic and Biocide Resistance 

The summer conference of the UK Society for Applied Microbiology took place 10–12 July, 2001 at University of Swansea. The title was "Antibiotic and Biocide Resistance in Bacteria: Perceptions and Realities for the Prevention and Treatment of Infection".

There were over 100 international delegates including academic researchers, health professionals and representatives from pharmaceutical companies, research institutions and industry associations. A series of renowned speakers from Europe, Australia, Canada and the US gave presentations in four sessions:

• Target sites for antibiotics and biocides
• Mechanisms of bacterial resistance to biocides and antibiotics
• Perceptions and realities of bacterial resistance to antibiotics and biocides for the medical, veterinary and food industries
• Biocide use and antibiotic resistance

During the first two sessions current knowledge on target sites for antibiotics and biocides and the mechanisms whereby organisms develop resistance to antimicrobial agents was reviewed. The sessions highlighted some of the major differences between biocides and antibiotics, many of which derive from the fact that antibiotics tend to be target specific whereas biocides are multi-target in nature. A number of speakers stressed the need to distinguish between “reduced susceptibility” to antimicrobials and “resistance”. It was argued that the term tolerance is more appropriate for describing reduced susceptibility to biocides where alterations in more sensitive target sites may produce an increase in MICs but may not affect susceptibility in practice where much higher concentrations are used.  The biocide tolerance of naturally occurring organisms compared with laboratory cultured organisms to physical or chemical inactivation was also discussed.

In the 3rd and 4th sessions, the benefits and risks of biocide and antibiotic use in hospital, manufacturing, community, domestic and other settings were evaluated by a range of appropriate speakers.

In his presentation on issues of resistance in the hospital environment, Ian Hosein (University of Wales, UK) evaluated both external sources of resistance, such as visiting staff and students, nursing homes and long-stay facilities and animal husbandry, and sources within the hospital such as patients, staff and visitors, the environment and internal transfer of patients from one area to another. He also presented data from a handwashing audit in six hospitals and found that 48% of staff had never been instructed in correct handwashing technique and 17% did not wash their hands before invasive techniques. The misuse of antibiotics in humans and animals was highlighted as an important contributor to the increase in antibiotic resistance. Professor Ian Gould (Aberdeen Royal Infirmary, UK) said that “20–50% of antibiotic use in humans is not necessary” and “40–80% of antibiotic use in animals is questionable”.

Colin Teale (Central Veterinary Agency, UK) discussed the spread of resistant genes and resistant organisms from animals to man via the food chain, illustrating his presentation with examples such as multi-resistant Salmonella typhimurium DT104. Antibiotics are used widely for therapeutic, prophylactic and growth promotion purposes in animal husbandry, the latter giving most concern in terms of the potential risk–benefit relationship.

Although the general view of the conference was that not only antibiotics, but also biocides, have, and will continue to have a vital role in the prevention and treatment of infections, the need to ensure prudent use of these agents was also strongly expressed.  Professor Stuart Levy (Tufts University, USA), supported by a number of other presenters, was particularly critical of the now widespread use of triclosan in plastics (e.g. toys, toothbrush handles, chopping boards). Several speakers, including Stuart Levy, supported the use of effective disinfectants that did not persist in the environment and hence were unlikely to give rise to resistance.

From his evaluation of the scientific evidence, Dr Peter Gilbert (University of Manchester, UK) argued that in fact there is no real evidence to suggest a link between biocide use and the development of antibiotic resistance in the real world. He stressed the need to view results of laboratory experiments which claim to show this in a proper perspective. As an example, he presented studies showing that not only does the biocide triclosan activate the multidrug efflux pumps which produce reduced susceptibility to antibiotics, but also spices such as mustard, chilli and garlic can. Despite this, and in view of our incomplete understanding of antimicrobial resistance, he also supported the need to avoid the overuse of biocidal products.

The need to develop hygiene strategies based on a risk assessment approach, not only for manufacturing settings but also hospital and other settings, was proposed by a number of speakers. During her presentation on “the significance of biocide use and antibiotic resistance in the home”, Professor Sally Bloomfield (IFH board member) outlined the risk assessment/risk prevention approach to home hygiene. The IFH also presented a poster “Development of guidelines for prevention of infection and cross infection in the domestic setting” which was on display during the conference. By reference to handwashing, Dr Joan Rose (University of South Florida, USA) showed how a quantitative risk assessment approach can be used to assess the relative benefits of different hygiene procedures in reducing infection risks.

The conference proceeding will be published in a conference supplement of the Journal of Applied Microbiology next year.