Tag Archives: antibiotics

Bacteriophages: A Possible Alternative to Antibiotics?

What would happen if we ran out of antibiotics to use against bacteria? Antibiotic resistance is known to be one of the major concerns among doctors and scientists around the world since, it’s our primary defense against bacterial infections. Without these antibiotics, it’d be virtually impossible to treat many types of diseases or even perform surgeries.

The quality of healthcare has significantly improved over the centuries as more people have access to treatment, medicine, and antibiotics. However, it has also increased the risk of wrong applications of drugs, allowing the bacteria to develop defense mechanisms to different types of antibiotics. In fact, there has been a dramatic increase in the number of scientific reports about different drugs resistance cases.

Antibiotic resistance occurs through process known as ‘Natural Selection’, where the bacteria has evolved and is no longer affected by the antibiotics. A stand-out candidate as an alternative for antibiotics is known as bacteriophages.

‘Alternative treatments are urgently required and we are investigating one such treatment – the use of bacteriophage.’

  • Robert Atterbury, Phage Biotechnology, University of Nottingham.                             
Resistance bacteria survived the treatment of antibiotics, thus able to reproduce and increase in numbers.

Resistance bacteria survived the treatment of antibiotics, thus able to reproduce and increase in numbers. <http://www.reactgroup.org/toolbox/mutation-and-selection/>. Photo credit: Uppsala University

‘Bacteriophage, or phage is a virus that infects bacteria, so these don’t infect human cells- they are specialised and only infect bacteria’

  • Brent Gilpin, Science Leader, Environmental Science Group, New Zealand.
Bacteriophage attached itself to the bacteria before releasing its DNA inside.

Bacteriophage attached itself to the bacteria before releasing its DNA inside. <http://www.news-medical.net/news/20151202/Bacteriophage-therapy-an-alternative-to-antibiotics-An-interview-Professor-Clokie.aspx>. Photo credit: News-Medical.net team

Bacteriophage or phage infects the bacterial cell by first recognizing the bacteria and then attaching itself to the bacteria’s surface (cell wall). After the phage has penetrated the cell wall, entering the bacteria, and it releases its DNA inside. This DNA merges itself with the bacterial DNA causing the bacteria to produce proteins for the phage. Other chain reactions occur which causes the bacteria cell to produce more phages and eventually bust out, causing the bacteria to die. – This process is shown in the following video:

‘Bacteriophage Life Cycle’

This method is currently being adopted by many industries including food protection against food-borne disease, and medical treatment for both animal and humans. Furthermore, there are many advantages in using phage therapy; for example the phages are target specific, thus only attacking bacteria with a certain structure. With the right phage, it’s harmless to humans and since, phage is found naturally throughout the environment, there are several types of phages that can be studied and used. In addition to this, phage can be genetically modified to reduce their side effects, harmful abilities, or any unnecessary features. With this, it’s possible that phages can be used as an efficient and effective treatment against bacteria.

I strongly believe that bacteriophage is a potential alternative for antibiotics due to its ability to target specific bacteria, its harmless nature to humans, and its ability to be genetically engineered. Moreover, it can also be used in many industries as a safety precaution, in medical treatments, or even scientific research.

 

Poramat Sucharit

Researchers observe when bacteria develop resistance to drugs

Microbiologist Michael Baym and colleagues of Harvard Medical School has developed a new experimental setup  to watch how bacteria adapt the drug and evolve antibiotic resistance, reported in the Sept. 9 Science. The experimental setup pictures shows step by step how could those minute creatures found in gardens grow up to strong drug fighters.

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Fig. 1 An experimental device for studying microbial evolution in a spatially structured environment.

(A) Setup of the four-step gradient of trimethoprim (TMP). Antibiotic is added in sections to make an exponential gradient rising inward. (B) The four-step TMP MEGA-plate after 12 days. E. coli appear as white on the black background. The 182 sampled points of clones are indicated by circles, colored by their measured MIC. Lines indicate video-imputed ancestry. (C) Time-lapse images of a section of the MEGA-plate. Repeated mutation and selection can be seen at each step. Images have been aligned and linearly contrast-enhanced but are otherwise unedited.

It is very common for scientists to study bacteria in petri dishes or flasks, a small closed space which includes all experimental materials together, and see how bacteria develop mutant to face and overcome the new challenge of environment.

Although Baym and colleagues did something different as they said, “Inside that flask, in order for a new strain to evolve, the new mutant has to be more fit than everything around it. But in nature, we see a second dynamic: You don’t necessarily need to be more fit than everything around you. You just need to make it into a new environment.”

In order to simulate the natural environment better, they modeled a environment for diversity, an experimental device called the microbial evolution and growth arena (MEGA)–plate was used. By placing different concentrations of trimethoprim or ciprofloxacin (both are widely-used antibotics) in different parts, some of the Escherichia coli bacteria was then observed to have incredible ability to endure a thousand times concentrated antibiotics. However, this sometimes also makes the bacteria spread slowly, which means it may not make them become more competitive in nature selection.

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Fig. 2 Initial adaptation to low drug concentrations facilitates later adaptation to high concentrations.

(A) Frames from a section of the TMP intermediate-step MEGA-plate over time (TMP, movie S4; CPR, movie S5). The first frame showing a mutant in the highest band is indicated by a blue box. (B) Rates of adaptation in the intermediate-step experiments across TMP and CPR, showing the necessity of intermediate adaptation for the evolution of high levels of resistance. Error bars show the appearance times of multiple lineages in the highest concentration. Because the intermediate step with no drug puts the highest and lowest concentrations adjacent, it serves as both the highest and lowest intermediate steps (dashed line).

Sam Brown, a microbiologist at the Georgia Institute of Technology in Atlanta who was not in Baym’s group, believes that the bacteria are “climbing this impossible mountain of antibiotics.” Baym and his colleagues thinks this experimental setup could be useful for microbial researches interested in particular environment with special restrictions.

This research suggest that the traditional method is not always the best for new experimental conditions,  the new methodology can be developed and applied to fit the real situation. The relative simplicity and ability to visually demonstrate evolution makes the MEGA-plate a useful tool for science education.

Video:

Reference:

M. Baym et al. Spatiotemporal microbial evolution on antibiotic landscapes. Science. Vol. 353, September 9, 2016. doi:10.1126/science.aag0822