Superbugs, MRSA, Phages and Bdellovibrio

12 December 2004
Presented by Adel Fattah, Chris Smith


This week the world of bacteria, fungi, viruses and superbugs goes under the microscope. Microbiologist Dr Mark Farrington discusses the worsening issue of antibiotic resistance and the MRSA problem. He is joined by Nottingham University bacteriologist Dr Liz Sockett who works on Bdellovibrio, a predatory bacterium that hunts down other bacteria and might be useful as a living antibiotic, and Professor Nick Mann, from Warwick University, who is developing bacteriophages (viruses that can attack bacteria including MRSA) that can safely be applied to wounds, in a dressing or as a nose-spray, to eliminate the carriage of bacteria, or infection.

In this episode

Ant-i Fungus

A newly-identified fungus discovered by scientists in the US may provide the perfect Trojan Horse for getting rid of ant and termite infestations without needing to resort to pesticides or dangerous chemicals. Previous attempts to use fungi to wipe out unwanted nests of ants and termites have failed because the animals normally avoid fungi like the plague, because the spores can proove lethal to the colony. They even post guards to sniff out and bar infected individuals from the nest. But before it produces any lethal spores, the newly discovered fungus secretes a substance which ants and termites find irrestible. They collect it and carry it back to the nest, and have even been known to turn it into a bed for the queen. Shortly afterwards, however, the fungus begins to produce spores which infect and kill every member of the nest. Even better, once the nest has been wiped out, the smell of the residual spores deters re-infestations by fresh colonies of insects. Paul Stamets, who made the discovery and has now set up a company to commercialise his green means of pest control, is currently screening different strains of the fungus to find specimens which are slower to begin spore production, which would provide sufficient time for nests to become loaded with fungus to ensure efficient and complete destruction of the occupants.

Laptops Bad For your Fertility

A New York-based urologist warned this week that laptops could be bad for mens' sperm counts. Dr. Yefim Sheynkin studied 29 men in their 20s and 30s and found that using a laptop for an hour increased the temperature of the average scrotum by over 2.5 degrees celsius, potentially affecting fertility. Previous studies have found that raising scrotal temperature by as little as 1 degree celsius is sufficient to affect sperm formation, but the volunteers in the laptop study achieved this rise in temperature after just 15 minutes on the computer. The effects of temperature on sperm formation are well known. A 1999 study showed that American mens' sperm production can drop by over 40% during the summer, compared to the winter, and that in hotter temperatures sperm speed drops and the number of defective sperms increases. On the basis of their findings Sheynkin and his team argue that regular daily laptop use could lead to chronically low sperm counts and advise users to put their laptop on a table whenever possible. They are now planning a follow up study to find out to what extent regular laptop use can affect mens' fertility.

Capture The Moment

Have you ever waited ages for the perfect picture and then missed the moment because you were a fraction of a second too slow hitting the button ? If this sounds like you then Kodak may have the solution with a new invention to be added to their future digital camera range, called BLILO, short for "burst last in last out". Once the BLILO button is pressed the camera continuously shoots pictures at the rate of 2 a second, storing them to a separate 32 megabyte memory card. Once 30 pictures have been shot, the camera starts overwriting the old images with new ones, indefinitely. Once the button is released the last 4 frames taken, one of which hopefully contains the crucial moment, are transferred to the camera's main memory.

- The MRSA (methicillin-resistant Staphylococcus Aureus) Problem

The Naked Scientists spoke to Dr Mark Farrington Chris - We are told that MRSA kills 5000 people per year. What is MRSA and where did it come from?

The MRSA (methicillin-resistant Staphylococcus Aureus) Problem
with Dr Mark Farrington Chris - We are told that MRSA kills 5000 people per year. What is MRSA and where did it come from?

Mark - MRSA, or Methicillin Resistant Staphylococcus aureus, is a special variety of a very common bacterium. We come into contact with it every day, and a third of us have Staphylococcus aureus up our noses all the time! MRSA is just a small group of this bacterium that has become resistant to a common type of antibiotics. The bacteria itself isn't particularly nasty; it is just more resistant to treatment, which has implications when trying to find ways of preventing and treating infection. The problems Staphylococcus would cause on a day to day basis are wide ranging, and are one of the commonest causes of infection in normal healthy people. When we have a cut, it is usually our own Staphylococcus that infects us. The MRSA strain was first found early 1960s, which was the same time that the antibiotic methycillin was introduced. The reason there were a few isolates of the resistant strain so early on is probably due to methicillin being related to beta-lactin. Beta-lactin is a natural antibiotic produced by fungi; probably used as defence against bacteria. Therefore, Staphylococcus has been in contact with the antibiotic for a long time, allowing a few resistant strains to evolve. It is only since people have been repeatedly prescribed antibiotics that problems have arisen. The non-resistant strains die out, leaving the resistant strains behind.

Chris - When did MRSA become a big problem in hospitals?

Mark - it actually took quite a long time. For many years, the bacteria were only found occasionally, and only slightly more often in people in hospital than people not in hospital. MRSA started to appear in clusters of people in nearby beds, but the outbreaks were still small. The problem has increased as the resistant bacteria has been passed from patient to patient. The most significant method of transmission is via the hands of healthcare workers in general, not just doctors. If a patient has MRSA on their skin and receives care from a member of staff who forgets to wash their hands, the next patient they treat will have the bacteria passed onto them. It is important to distinguish between being colonised by bacteria and being infected by bacteria. Studies have shown that people visiting hospital acquire a range of bacteria different from those they came in with. However, they do not develop a similar range of infections: having MRSA on your skin does not necessarily mean that you will become ill.

- Bdellovibrio

The Naked Scientists spoke to Bdellovibrio are natural, tiny predatory bacteria that have other bacteria as their main food. Their strategy is to break into bacterial...

with Liz Sockett, University of Nottingham

Bdellovibrio are natural, tiny predatory bacteria that exploit other bacteria as their main food. Their strategy is to break into bacterial cells, close up the hole behind them suck their guts out! Having dissolved the inside of their victim, they burst out in search of fresh prey. Dr Liz Sockett studies Bdellovibrio at the University of Nottingham...

Chris - What has the genetic information told you, and how can they be used in fighting infection?

Liz - We found that Bdellovibrio have lots of genes that make bacteria-dissolving enzymes. They also secrete a juice that breaks down chromosomes. These will both kill bacteria. Bdellovibrio don't look for any specific target sites on their bacteria prey, so there is no way for the bacteria to hide. Unfortunately, Bdellovibrio can't get into MRSA, but they can get into many others. We hope to use them on things like burns and leg ulcers, although more testing needs to be carried out. We might even be able to take genes and put them in the bacteria so they can attack MRSA.

Chris - What happens when the infection has cleared up?

Liz - If the Bdellovibrio burst out of the dead bacterium and can't find any more food, they just die. This makes it a self-terminating therapy that leaves no residue. They are likely to be best for wound infections, as eating them will kill good and bad stomach bacteria, and they also end up going down the loo [with unforeseen consequences].

- Bacteriophage (phage) Therapy

An inhaler laden with bacteriophages could be a new weapon to tackle MRSA infections in future...

Bacteriophage (phage) Therapy
with Nick Mann, University of Warwick

An inhaler laden with viruses called bacteriophages, which prey selectively on bacteria, could be a new weapon to tackle MRSA infections. Nick Mann, from the University of Warwick, has been developing ways to use phages to combat hospital superbugs, as he explains to Chris Smith...

Nick - Bacteriophages are viruses that infect bacterial cells and kill them. The word bacteriophage literally means 'bacteria eater.'

Chris - How do they grow?

Nick - Phages attach to bacteria and inject their genetic material into the cell. The genetic material makes more copies of itself, bursts the cell open and goes into the environment. One phage gives rise to, say, 100 new phages, which inject their genetic material into 100 more bacteria and so on. This amplifying process is one of the great benefits to phage therapy. Putting one phage into an infected wound will lead to a chain reaction that expands until all the bacteria are dead. This is in contrast to antibiotics, which become less concentrated and less effective the longer and further they travel into the body.

Chris - How would you give the phage to the patient?

Nick - More trails are needed before we can start administering phages to patients, but we will probably start by putting them on surface wounds. This could be achieved by impregnating wound dressings with the phages. Once the bacteria have gone, the phages also die out. Another avenue we are exploring with regards to MRSA is trying getting rid of it in the nose. The phages will be delivered through a plastic inhaler. So far, it has been tried out on a couple of student volunteers which remained negative for MRSA for the few days we looked at them. We are going to do longer controlled trails and are desperately trying to get it into hospitals. If the nasal inhaler is given to visitors, staff, and patients, the levels of MRSA in hospitals will hopefully decrease.

Chris - Will the bacteria become resistant to the phages like they have to some antibiotics?

Nick - The bacteria will become resistant, but phages are living and can mutate too. Therefore, the bacteria and phages will fall into an evolutionary arms race whereby both bacteria and bacteriophages will evolve methods to outwit the other. As long as phages can keep up, they will always be a threat to the bacteria.

- Is it normal for you to have a body temperature lower than 36.7 celsius?

Is it normal for you to have a body temperature lower than 36.7celsius ?

Is it normal for you to have a body temperature lower than 36.7 celsius?

Normal body temperature is 37?C. This is set by part of your nervous system and the hypothalamus, which is found in the brain stem. The hypothalamus monitors your body temperature and changes it if it becomes too hot or too cold. Your body temperature doesn't have to be exactly 37?C: exercise can make you hotter, while going outside on an icy day can make you cooler. The place in which you measure your temperature is very important. Putting a thermometer under your armpit will show you your peripheral temperature, and this can be quite a bit lower than your 'real' body temperature called your core temperature, or the temperature at the centre of your body. This varies very little at all in day to day life. It can best be measured by putting a thermometer in your bottom! You have to get very cold to change your core temperature, such as being stuck in freezing weather for a long time. People who have a drop in core body temperature have what is known as hypothermia. This makes them drowsy, and if left untreated, they will eventually become unconscious. When the body is cold, the chemical reactions that provide your cells with energy don't work as well. This makes cells function abnormally and, if prolonged, can be fatal.

- Does copper kill plants and algae?

Some roofs have clean lines across them caused by copper cables that have been lain across them in the past. Why?

Does copper kill plants and algae?

Plants make food for themselves via photosynthesis. This process involves a number of chemicals, enzymes and pigments, including green chlorophyll. Copper stops the photosynthetic process from working, which is why copper is toxic to plants and algae.

The lines on the roof are likely to have been caused by copper: some builders purposely build copper strips into roofs to stop them going green.

As for killing a tree with a copper nail, I'm not sure that that is true: trees are very large and contain lots of water to dilute any copper particles put into it. Therefore, lots of copper would be needed to kill a tree.

Metallic copper (which a nail would be made from) does not go into solution easily and would find it hard to get into the tree's food and water transport systems.

In terms of humans, I think copper poisoning is unlikely in this area. The east of England has very hard water, which makes the water pipes fur up. This makes it hard for our drinking water to come into contact with the pipes.

Copper in small amounts is actually important for humans as it helps some of our enzymes work. Only in the genetic 'Wilson's disease' can copper be a problem where sufferers accumulate too much of the metal in their brains.

- What causes thyroid problems?

I have a thyroid problem and have to take thyroxin. What causes thyroid problems?

What causes thyroid problems?

Thyroxin is given to people with an under-active thyroid that can't make enough thyroxin by themselves. People with low levels of thyroxin in their blood often have a slower heart rate, have a tendency to put on weight, and feel lethargic. Interestingly, only one in five of all cases of thyroid under-activity will be in men. Doctors tailor the amount of thyroxin given to patients to ensure that the patient's body is working at the right level. Without knowing exactly what is wrong with your thyroid, it is hard to say what caused it to become under-active. Sometimes its caused by insufficient iodine in the diet. Historically underactive thyroids were common in Derbyshire causing people to develop a neck 'goitre' (swollen thyroid) - termed 'Derbyshire neck' - because their diets were deficient in iodine. However, most cases are caused by an autoimmune response, whereby the body starts attacking its own tissues. The reasons for thyroid problems can therefore be partly genetic, and partly environmental.

- What ingredients go into antibiotics, and how do they work ?

What ingredients go into antibiotics, and how do they work?

What ingredients go into antibiotics, and how do they work ?

Tablets taken by mouth contain a lot of the actual antibiotic. They also contain lots of other substances which enable the manufacturer to produce a tablet that can be kept in packets and are easy to swallow. For example, the smooth outer coatings of some tablets are often made out of vegetable products. Once the tablet is in your stomach, the active bits distribute around the body through the bloodstream, reach the site(s) of infection, and kill the offending bacteria. There are three different ways antibiotics kill bacteria. Some stop bacteria from growing by stopping their protein production; others stop them from making chromosomes; and the third type stop bacteria from making cell walls. Without a proper cell wall, the bacteria explode and die.

- Which bacteria or viruses cause ear infections ?

Which bacteria or viruses cause ear infections?

Which bacteria or viruses cause ear infections ?

The ears have the same linings and are connected to the nose and throat through the eustacian tube. This means that any of the viruses that cause colds and sore throats can get through into your ears. Viruses are the main invaders, but bacteria can cause secondary infection. They seize the opportunity to invade after a virus has caused the initial problem - such as damaging the protective lining of the airway, or blocking up the eustacian tubes in your ears with mucus


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