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Brian Duerden CBE

Abstract: Man and Microbes: the battle goes on

The relationship between man and microbes is a fascinating balance between our human biology (individual and population) and the bacterial biology, with a huge overlay of our human (individual and political) behaviour. Each one of us plays host to 500 million million (5 x 1013) bacteria – most are living in harmony with us and in fact essential to our health. A few microbes are the ones we pay most attention to – the ones that can cause disease in us. Even here, the same bacteria can be both normal ‘commensals’ and potential pathogens.

The microbial world comprises bacteria, viruses (not really living organisms in themselves), fungi and some protozoa, but the major threats to our health are generally bacteria and viruses and four examples from the front pages of the tabloid press show the different intricacies of their capacity to damage us, aided and abetted by our own behaviour. Two are classical infectious diseases that affect healthy people (influenza and Escherichia coli O157) and two are healthcare associated infections that mostly affect vulnerable and compromised patients already in our healthcare system (MRSA and Clostridium difficile).

In April 2009, the headlines screamed ‘swine flu’. A new influenza strain had arisen in Mexico, a genetic reassortment between human, swine and avian flu virus genes that was spreading rapidly in the human population – a true pandemic. It affected predominantly young people – probably because those over 60 years old had some residual immunity from infection with closely related flu viruses circulating before the Asian flu pandemic of 1957. How virulent (i.e. able to cause severe illness or death) would it be?? Activate the pandemic flu plan!! Treat those who were ill (‘Tamiflu’) and try to slow its spread (school closures) while a vaccine was developed. Many youngsters were ill, a few sadly died; we later found many more had been infected but were not ill. Transmission slowed with the summer holidays and restarted with the school term. The vaccine came on stream in October (how to define priorities? – pregnant women especially). A dip in cases over half term, and then a continued fall in November. Had it run out of vulnerable victims? Would it come back? What about vaccination?

MRSA (meticillin resistant Staphylococcus aureus). In 2004 our headlines screamed of ‘dirty hospitals’ and ‘killer bugs’, but it was not new. S. aureus has lived with man (30% of us carry it in our noses), and occasionally killed him, for ever. Penicillin was magic, but by 1959, 95% were resistant and the meticillin group of antibiotics then gave reassurance, but even by 1961 we had the first MRSA, but only a minor problem. In the early 1990s, two epidemic (E) strains appeared; we failed to control them and they spread through our hospitals. Reporting of blood stream (the most serious and life threatening) infections was made compulsory in 2001 and by 2004 we had 7,700 cases in England. The result was a political response – a top priority for a 50% reduction by 2008 – and it worked! How? – political and management will and a re-establishment of proper infection prevention and control activities in the clinical practice of doctors and nurses. We had forgotten the importance of the pre-antibiotic basics. We have turned the corner, but there is still much to do because MRSA has become embedded in our population and can still bite back.

C. difficile. While MRSA concern was at its height, headlines turned to a new ‘superbug’, C. difficile – a spore-forming anaerobic bacterium that could cause devastating diarrhoea and colitis in patients whose normal gut flora was upset by antibiotics, allowing CD to grow and produce its disease-causing toxins. By 2006 we had 56,000 cases in patients over 65 years old (extrapolated to 70,000 in all age groups). Time for another target! – a 30% reduction by 2010-11, achieved within the first year by stopping the obvious outbreaks: Isolate those infected, stop transmission by good hygiene practice, limit the use of antibiotics. Again, this was modern medical practice having to re-learn the old lessons and also be careful with those most marvellous and life-saving drugs – antibiotics.

Finally E. coli O157. This is a disease that appeared from nowhere in the early 1980s – a variant of the E. coli that we all carry in large numbers in our gut, but now with a virulent kick that lets it produce a potent toxin that causes severe diarrhoea and in some cases kidney failure – the haemolytic uraemic syndrome. Where did it come from? It can be found harmlessly in cattle, sheep etc, but if it spreads to humans, especially young children, it causes dramatic and severe illness. The 1980s outbreaks were linked to undercooked burgers, sometimes with added child to child transmission in nurseries. Then we had the surge in popularity of open farms with petting areas. How do you maintain good hygiene on a farm visit? – with difficulty. Hands are contaminated from the animals, from the environment around the animals, from the shoes that have walked across the farmyard – and hands go into mouths, and pick up sandwiches for lunch. Personal hygiene has to be scrupulous to address this risk from something that we want to be part of modern life – bringing children into contact with nature, animals, farming.......

So, we live in a constant state of flux with our microbial population. It is dynamic and exciting, but we can never afford to be complacent.

We will explore the latest ideas about the structure of the universe and the possible theories which might explain it, including the idea of cosmological 'inflation' and the astronomical evidence for it, dark energy, the future of the universe and the possibility that other universes exist.

Professor Brian Duerden is the Inspector of Microbiology and Infection Control at the Department of Health. He is responsible for ensuring the quality and consistency of clinical and public health microbiology services and is the clinical director for the Healthcare-associated Infections programme. He is emeritus Professor of Medical Microbiology at Cardiff University.

He qualified in medicine and microbiology at Edinburgh University in 1972.  He was a Lecturer in Edinburgh and Lecturer (1976), Senior Lecturer (1979) and then Professor (1983) of Medical Microbiology in Sheffield University. He was also Consultant Medical Microbiologist to the Sheffield Children’s Hospital.  In 1991 he moved to the Chair of Medical Microbiology in the University of Wales College of Medicine, Cardiff, coupled with the Directorship of the Cardiff Public Health Laboratory.

He was Deputy Director and Medical Director of the Public Health Laboratory Service (PHLS) for England and Wales 1995-2002 and was Director and Chief Executive of the PHLS from August 2002 until it became part of the Health Protection Agency in April 2003. In the HPA, he was Director for Clinical Quality until moving to DH in 2004. His major interests are in anaerobic microbiology, healthcare associated infection and antibiotic resistance. He has published over 140 scientific papers, edited and contributed to several textbooks and served for 20 years (1982-2002) as Editor in Chief of the Journal of Medical Microbiology. He was awarded CBE for services to medicine and charity in 2008.



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