Microbial image of the month This is a great image of a biofilm growing on a micro-fibrous material. Biofilms are aggregates of bacteria that are coated with a ‘slimy’ substance consisting of polysaccharide, DNA and proteins. Bacteria are very sociable; more than 90% live in biofilms because they confer many benefits, including resistance to antimicrobials and harsh environmental conditions. They are everywhere, including on our teeth, in our showers and down our sinks.  Image by Paul Gunning, Smith and Nephew from - http://www.fei.com/resources/image-gallery/bacterial-biofilm-7330.aspx
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 Microbial image of the month

This is a great image of a biofilm growing on a micro-fibrous material. Biofilms are aggregates of bacteria that are coated with a ‘slimy’ substance consisting of polysaccharide, DNA and proteins. Bacteria are very sociable; more than 90% live in biofilms because they confer many benefits, including resistance to antimicrobials and harsh environmental conditions. They are everywhere, including on our teeth, in our showers and down our sinks. 

Image by Paul Gunning, Smith and Nephew from - http://www.fei.com/resources/image-gallery/bacterial-biofilm-7330.aspx

Bugs eat bugs for brunch

Have you ever wondered what bacteria have for lunch? Just like us, bacteria are choosy in what they eat, picking certain sugars first and utilising nutrients in their environment. They also help us break down our own food; for example, Lactobacillus breaks down food we eat containing lactose. But apart from sugars and nutrients, bacteria may also eat other bacteria, and in some cases, even their own kind.

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Photo credit:David Wacey

There have been cases when humans have resorted to cannibalism in order to survive, so it is of no surprise that bacteria do the same. Bacteria cannot control their environment, so they have evolved to adapt to environmental extremes. When nutrient deprived, some bacteria, such as Bacillus and Clostridia, have evolved to withstand starvation by forming endospores. Endospores are resilient, dormant structures that do not require nutrients to survive. When nutrients become available again, sporulation occurs and the bacterium goes back to its normal state. However, this is an energy and time consuming process, so organisms such as B. subtilis resort to killing other bacteria in order to obtain more nutrients, or even cannabilism before it has to go through this process. This organism has been found to prefer killing other bacteria, such as Escherichia coli and Pseudomonas aeruginosa by secreting antimicrobial compounds, before it has to kill its siblings.

Evidence of bacteria preying on other bacteria dating back 1,900 million years has now been found by researchers at the University of Western Australia and Oxford University. The study, published in PNAS, found fossils capturing ancient organisms eating a cyanobacterium-like fossil called Gunflintia in preference to other bacteria. This is the first evidence showing bacteria have been preying on other bacteria in order to survive for nearly 2000 million years. The high abundance of bacteria on Earth back then combined with this choice of diet also suggests this planet smelt a lot like rotten eggs. Thank you evolution, for it not smelling like that now!

The Great Bacterial Bake Off!

If you’re a microbiologist and enjoy baking, then you’re going to love what the Bioscience department (@ICaMB_NCL) at Newcastle University did yesterday. Forget The Great British Bake Off, it’s all about The Great Bacterial Bake Off now! Phil Aldridge (@wragbags) organised a microbial cake competition for his students, and I very much enjoyed seeing what was produced on Twitter; here are some of my favourite creations:

I particularly love the use of various sweets for plasmids, flagella and supercolied DNA - some fantastic ideas! It’s a great way to get students enthused in microbiology, so, why not organize a Great Bacterial Bake off in your lab?  

World Immunisation Week: The fight against TB

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This week is ‘World Immunisation Week’, which aims to promote vaccinations, particularly amongst the 22 million infants which are not protected with routine immunisations. This campaign coincides with the measles outbreak currently occurring in Wales, which has highlighted the importance of getting children vaccinated. The infographic in my previous post shows the breakthroughs in vaccine research which have happened since the 1950s, demonstrating the plethora of infectious diseases which have been nearly eradicated through immunisation, including Polio. There is however an ancient disease that still remains a leading global killer due to the unavailability of a efficacious vaccine: Tuberculosis (TB).

TB is the second biggest microbial killer, second to HIV; in 2011, there were 8.7 million cases of TB of which 1.4 million died. Caused by Mycobacterium Tuberculosis, the disease can be treated with antibiotics, but this can take several months due to the slow growing nature of the organism. In addition, this slow replicating nature allows resistance to arise and many cases are becoming more to difficult to treat with currently available antibiotics; now we are seeing a worrying number of extensively resistant TB cases (XDR-TB), with some cases being completely untreatable. This makes the development of an effective vaccine vital.

I remember the day I received the vaccination against TB at school, absolutely terrified by the horror stories of it leaving a ‘huge’ scar by my peers (I actually struggle to see the scar now). This Bacille Calmette-Guérin (BCG) immunization is the only available vaccine for protecting against TB which was developed in 1921. Although BCG protects children against many forms of pediatric TB, it has many drawbacks. It does not protect against pulmonary TB, which is responsible for most deaths and it’s efficacy in adults is poor.

The development of a vaccine that protects against TB in both children and adults is therefore paramount in reducing the burden of this disease. So, what is being done and what are the World Health Organisations’s (WHO) aims in combating the disease? The WHO’s goal is to reduce the global burden of TB by 2015, halving the number of deaths caused by the disease and to eliminate the disease as a global health burden by 2050. To do this, scientists are currently working to develop a new, more effective vaccination strategy, including the following approaches (see the WHO’s website for more details):

  • Priming TB vaccines to replace BCG in infants.  
  • Early booster TB vaccines to improve the immune response induced by the priming vaccine.
  • Late booster TB vaccines for those who are potentially infected without any symptoms. These vaccines are intended to reduce progression from latent to active disease.
  • Vaccines for those with active TB, to be given alongside drug therapy to shorten duration of treatment.

There has been some success in developing new vaccines, with two in Phase IIa trials. There are also two in Phase IIb trials which will provide an estimation of protection. Both of these comprise of a virus expressing TB antigens. This gives us hope that a better vaccine is on the horizon, and that the WHO’s aims can be achieved.  

To find out more on the WHO’s immunisation goals, including more on TB vaccine candidates, check out their website. What are your thoughts on combating TB? 

A Brief History of Vaccine Triumphs Ahead of World Immunisation Week, here is a great infographic showing some of the successful vaccinations licensed since the 1950s, saving 2-3 millions lives each year; including Smallpox which still remains the only  eradicated infectious disease in humans. Hopefully Polio will be the second in the not-so-distant future.  Created by http://www.bcdcideas.com/2012/08/bringing-infographics-to-real-life/ for http://vaxnorthwest.org/
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A Brief History of Vaccine Triumphs

Ahead of World Immunisation Week, here is a great infographic showing some of the successful vaccinations licensed since the 1950s, saving 2-3 millions lives each year; including Smallpox which still remains the only  eradicated infectious disease in humans. Hopefully Polio will be the second in the not-so-distant future. 

Created by http://www.bcdcideas.com/2012/08/bringing-infographics-to-real-life/ for http://vaxnorthwest.org/

Microbial image of the month I’ve previously posted an image of a single phage, but this month’s image shows phages in action, infecting a bacterial cell. With their tail fibres and capsid heads, I find the structure of phages simple yet exquisite, so when I come across a phage image as great as this one, I have to share it! Enjoy! Lee D. Simon/Photo Researchers. Source- http://www.popsci.com/science/article/2013-03/bacteria-virus-arms-race-just-got-tiny-bit-hotter
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Microbial image of the month

I’ve previously posted an image of a single phage, but this month’s image shows phages in action, infecting a bacterial cell. With their tail fibres and capsid heads, I find the structure of phages simple yet exquisite, so when I come across a phage image as great as this one, I have to share it! Enjoy!

Lee D. Simon/Photo Researchers. Source- http://www.popsci.com/science/article/2013-03/bacteria-virus-arms-race-just-got-tiny-bit-hotter

H7N9: bird flu strain infects humans for the first time

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This week, there has been much in the news on the Swansea measles epidemic, with concern that the epidemic could now spread across Britain. Further afield, another virus poses a potentially more serious threat; influenza A(H7N9). 

There are three types of influenza virus: influenza A, B and C. Influenza A usually infects birds and occasionally can cross species barriers, including humans. These viruses are the most virulent against humans and can cause huge pandemics, including the Spanish flu in 1918 and ‘Swine’ flu in 2009. Now H7N9, previously only able to infect birds, has crossed the species barrier and has now killed five people in China (to date).

Influenza viruses have two proteins, hemagglutinin and neuraminidase, that are involved in causing disease. Hemagglutinin binds a protein called sialic acid on epithelial cells of the host; some can bind only those in humans whilst others can bind only those in birds. H7N9, previously only able to bind sialic acid in birds, has acquired the ability to bind the protein in humans; something referred to as an antigenic shift. 

Why this has happened is being investigated, but one possibility is that the virus underwent a change in pigs, which can be infected by both avian and human influenza strains at the same time, allowing them to share genes.  This is what is thought to have happened with both the 2009 Swine flu (H1N1) and bird flu (H5N1). H5N1 is highly virulent, killing 60% of its infected hosts, but luckily it has not yet evolved to efficiently transmit between humans.

There is currently no evidence that H7N9 can do this either, but until we know this for sure with further epidemiological investigation and research, the risk of a pandemic cannot be ruled out. 

For more information on H7N9, check out WHO’s FAQ which is updated regularly.

Are you worried about H7N9? Share your thoughts. 

A belated Happy Birthday John Snow!

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Over the past couple of weeks, there has been quite a few blogs on John Snow; not the channel 4 presenter or the character from Game of Thrones, but the father of epidemiology. This is because it was his 200th birthday on the 15th March, so to celebrate his work there have been various posts on how he started the field of modern epidemiology by tracing the source of an outbreak of cholera. Before his work, it was believed ‘bad air’ and pollution caused cholera, of which Snow was a skeptic. In 1854, Snow identified the Broad Street pump in Soho was the source of an outbreak of cholera. He used statistics to correlate water quality with the number of cases and found there was a fecal-oral cause. This work founded the field of epidemiology, and much of his methods are still used today.

So, since Snow discovered Cholera was caused by contaminated water consumption, what have we learned about the disease?

1. It’s caused by Vibrio Cholerae. Whilst Snow was busy in London identifying the source of an outbreak, Filippo Pacini was identifying the cause of cholera in Italy. He found that cholera is caused by the bacterium V. Cholerae, which secretes cholera toxin during infection, causing severe diarrhoea.

2. It’s actually caused by a bacteriophage. Not all V. cholerae strains cause cholera; it is the serotypes 01 and 0139 that cause all epidemics. In 1996, Waldor and his colleagues found these pathogenic serotypes contain the genes for cholera toxin due to a temperate bacteriophage, called CTXΦ. Without this phage incorporated into its genome, V. cholerae does not cause cholera.

3. V. cholerae is environmental. Infection by V. cholerae was thought to be due solely to faecal contamination of water until the work of Rita Colwell who was able to isolate the organism in between epidemics. She found that the organism lives in zooplankton; pandemics can now be more accurately predicted, especially during changing temperature climates. Its environmental presence means the risk of infection can never be eliminated.

4. V. cholerae can live in a viable but non-culturable state. Rita Colwell also found V. cholerae can go into a non-culturable state, explaining why no one had succeeded in isolating the organism in between epidemics before her.

5. It can be vaccinated against. Two oral vaccines are currently available against cholera; one is licensed by WHO in over 60 countries, and another is licensed in India.

For more on John Snow, check out the PLoS Public Health blog for a number of posts.