Select Committee on Science and Technology Written Evidence

Memorandum by the Association of Clinical Oral Microbiologists

1.   What are the main problems facing the surveillance, treatment and prevention of human infectious disease in the United Kingdom?

  Oral infectious diseases rarely obtain a high profile as a distinct disease entity. However, oral diseases caused either directly or indirectly by micro-organisms contribute to a significant degree of morbidity within the population of the UK. Dental caries, caused in part by cariogenic micro-organisms, such as Streptococcus mutans, results in millions of episodes of dental treatment throughout the country on an annual basis[7] A common sequel of dental caries is a dental abscess which may, even today, lead to life threatening infections despite the use of antibiotic treatment. Antibiotics are frequently prescribed for oral diseases and there is compelling evidence to suggest that the majority of these prescriptions are unnecessary[8], [9] However, there is little in the way of surveillance of the micro-flora involved in oral infections and their susceptibility to various antimicrobial agents. A recent multi-centre study funded by the Scottish Executive Health Department (Grant No. CZG/4/2) highlighted the difficulties in obtaining sufficient high quality specimens for microbiological analysis, particularly from primary care. There is evidence to suggest that antibiotic resistant determinants from members of the oral flora have been transmitted to other more virulent relatives. This is best demonstrated by the spread of penicillin resistance genes from Streptococcus oralis to Streptococcus pneumoniae[10] illustrating the importance of surveillance of micro-organisms in the oral cavity.

  Periodontal disease, in its many guises, also affects a large proportion of the UK population, and is caused in part by a wide variety of anaerobic micro-organisms. Recent research has suggested a possible link between periodontal disease and a number of systemic conditions, such as heart disease and in the induction of pre-term birth and low birth weight children. Much research has been performed on the microbiology of periodontal disease but the prevention and treatment of periodontal disease has changed very little over the last decade. Considerable use of the antibiotic metronidazole is made in the treatment of periodontal disease and this probably accounts for the reason why dental prescriptions of metronidazole represent the largest number of prescriptions for this antibiotic in the community. The widespread use of metronidazole may have contributed to the increased burden of metronidazole resistance in Helicobacter pylori, a well documented aetiological agent in stomach cancer.

  Candida (yeast) infections of mucosal surfaces (thrush) are extremely common, debilitating, distressing and often recurring. Candida albicans is carried as a common commensal fungus at low levels in the oral cavities of approximately 50 per cent of healthy individuals but candidosis can result when host conditions allow the organism to express virulence factors and proliferate to high numbers. Infection of the mouth by Candida albicans can be problematic, particularly in denture wearing patients and is commonly underdiagnosed and mistreated. Oral infections particularly in the more vulnerable members of society, such as the terminally ill and nursing home residents, frequently cause considerable morbidity and can be difficult to treat. Antifungal agents can produce clinical improvement but relapses are common. New treatments and vaccines are thus desperately needed.

  The relationship between oral micro-organisms and systemic disease is classically illustrated by infection with oral micro-organisms of damaged heart valves following dental treatment. A few cases have been reported highlighting problems with increased antimicrobial resistance in these types of infections. Of interest is the increasing body of evidence to suggest that the oral cavity may be the source of other micro-organisms, such as Staphylococcus aureus, that are well documented pathogens, particularly in implanted devices such as prosthetic joints[11].

  In summary, oral infectious diseases contribute significant morbidity to the UK population, but the surveillance of these infections, particularly in the community, has received scant attention from public health bodies. Improvements in the detection, monitoring, treatment and prevention of oral infectious diseases would not only impact on the quality of oral health but are also likely to lead to improvement in general health.

2.   Will these problems be adequately addressed by the government's recent infectious disease strategy, "Getting Ahead of the Curve?"

  There is no strategy to address the issues highlighted for combating oral infectious diseases.

3.   Should the United Kingdom make greater use of vaccines to combat infection and what problems exist for developing new, more effective or safer vaccines?

  Yes. UK immunology is very strong and has been at the forefront of development of the new generation of vaccines at mucosal surfaces which allow for ingestion or nasal inoculation of the vaccine rather than by injection, for example, influenza. Indeed the first vaccine to be engineered in plants was against Streptococcus mutans. The potential for locally delivered immunotherapeutics is undoubted but what the microbial targets of such treatments should be remains unclear. Although some bacterial species are strongly associated with oral infection, we remain largely ignorant of the composition of the bacterial communities in oral health and disease. Much fundamental work is required to comprehensively describe the oral microflora and investigate which species are associated with disease. It is recognised that oral infections result from a complex interaction between the host and the normal microflora. Better understanding of this interaction will lead to novel prevention and treatment options. Other problems include financial support to maintain the UK at the forefront of vaccine technology and establishing long term efficacy of vaccines.

4.   Which infectious diseases pose the biggest threats in the foreseeable future?

  The Department of Health risk assessment for the potential transmission of variant Creutzfeldt-Jakob disease (vCJD) via surgical instruments has highlighted the potential for transmission via this route. Dental treatment accounts for the most common healthcare intervention involving surgical instruments in the UK. It has already been suggested that reductions in dental disease would play a role in reducing the number of these interventions and therefore use of dental instruments[12].

  Strategies to improve the decontamination of dental instruments would do much to reduce the risk of onward transmission not only of vCJD but of other infectious diseases such as hepatitis C. However, despite the large number of dental treatment episodes there is no on-going surveillance of infection following dental treatment, making it difficult to provide pragmatic advice on the decontamination of dental instruments.

5.   What policy interventions would have the greatest impact on preventing outbreaks of and damage caused by infectious disease in the United Kingdom?

  In order to reduce the impact of oral infectious diseases a considerable effort must be devoted to improving the oral health of the nation.

October 2002

7   Dental Practice Board Eastbourne, Digest of Statistics 2000-01 Back

8   Palmer N A O, Pealing R, Ireland R S, Martin M V. A study of therapeutic antibiotic prescribing in National Health Service general dental practice in England British Dental Journal 188, 554-558. Back

9   Palmer N A O, Pealing R, Ireland R S, Martin M V study of prophylactic antibiotic prescribing in National Health Service general dental practice in England. British Dental Journal 189, 43-46. Back

10   Coffey T J Dowson, C G Daniels, M Spratt, BG (1993) Horizontal spread of an altered penicillin binding protein 2B gene between Streptococcus pneumoniae and Streptococcus oralis. FEMS Microbiol Lett. 110: 335-340. Back

11   Smith A J, Jackson M S, Bagg J. The ecology of staphylococci in the oral cavity: a review. Journal of Medical Microbiology 2001; 50, 940-946. Back

12   A Report of the Working Group on Decontamination of Instruments in Dental Services in Scotland ( Back

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