Thursday 31 January 2019

Special magnetic coating used to kill bacteria, an antibiotic alternative

The problems and limitations of antibiotics and antimicrobial substances have received a great deal of attention in the press. The main concern is bacterial resistance. As an alternative, a science group have developed a special coating which can destroy bacteria on contact.

A research team based at the Nanyang Technological University (NTU), Singapore, have developed a special coating which has a magnetic-like feature. The magnetic nature is used to attract bacteria and then kills them. The application could lead to an antibiotic 'alternative'.

According to an NTU press release, the special sponge-like coating is made from Dimethyldecylammonium Chitosan methacrylate. The coating is a type of polymer which holds a positive charge. The charge acts like a type of magnet which generates a force. The force draws bacteria, which possess a negative charge on their cell walls, towards the surface. When the bacterium comes in contact with the coating, the cell walls are 'sucked' into the nanopores, causing the cell to rupture, thus killing the bacterium.

The Alpha Galileo Foundation notes that the coating has been tested against bacteria like Pseudomonas aeruginosa, which can cause infections in the upper respiratory tract, gastrointestinal tract and the urinary tract; and Staphylococcus aureus, which can cause infections ranging from skin boils or abscesses to deadly diseases such as pneumonia and meningitis.

The research was led by Professor Mary Chan, Acting Chair of NTU's School of Chemical and Biomedical Engineering. The research findings were published in the journal Nature Materials.

Chan is quoted by the Meridian Institute as saying, in relation to the research:

"The coating can also be applied on biomedical objects, such as catheters and implants to prevent bacterial infections, which is a serious cause of concern as many bacteria are now developing resistance to antibiotics - currently our main source of treatment for infections. By developing novel materials which uses physical interaction to kill bacteria cells, we envisage this can be an alternative form of treatment for bacterial infections in the near future."

A key advantage with the coating is that it is harmless to human cells.

The application is thus far being used by two companies: a contact lens manufacturer and a company specializing in animal care products. The next wave of developments is likely to be with implants and surgical instruments.

Posted by Dr. Tim Sandle, Pharmaceutical Microbiology

Friday 25 January 2019

Examining the reliability of manual plate colony counts in environmental monitoring

An interesting essay has been published on-line about colony counting by R. Hutchinson:

Plate counts of colony forming units (CFUs) are the gold standard of microbial enumeration and therefore essential to environmental monitoring in the pharmaceutical industry. There are strict regulations regarding bioburden at each stage of pharma production, from raw materials to finished products, but we often fail to question whether current methods are rigorous enough to fulfil these requirements.

The article can be accessed here.

Posted by Dr. Tim Sandle, Pharmaceutical Microbiology

Wednesday 16 January 2019

Real-time Mycoplasma Contamination Detection for Biomanufacturing

Aseptic and Sterile Processing: Control, Compliance and Future Trends

Here is the most important text discussing aseptic and sterile manufacturing to be published in the last decade that looks at both today and tomorrow in regard to these two vital processing procedures.

The Editors realized that there was an urgent imperative for the relevant subjects to be reassessed and represented. To achieve this objective, along with many subject matter experts, they produced a book that is foremost practical. It has been designed for those involved with aseptic and sterile processing to take away many learning points and apply these principles to aseptic and sterile processing within the pharmaceutical and healthcare sectors.

Drawing on experience, they made every effort to incorporate sound science into the practices described, not least to emphasize why new paradigms are required but to provide wide-ranging guidance and offer depth and scope. This is why chapters on human error, risk assessment, depyrogenation, bioburden testing and so on, are extensively covered. It is the aim of the Editors to help readers reassess legacy definitions and historical understandings and move them toward concepts that will help them think in new ways about equipment and processes that will reach the highest standards and evaluate them through science-based risk assessments.

Available from the PDA Bookstore:

Posted by Dr. Tim Sandle, Pharmaceutical Microbiology

Sunday 13 January 2019

How to Choose and Validate Your Ready-to-Use (RTU) Media

Media that is bought into labs in a ready to go or Ready to Use (RTU) format goes by many different descriptions such as Ready Prepared Media, Pre-Plated Media/Pre-Poured Media (PPM), Ready-to-Rehydrate;  there's no shortage of terms just as there is an almost limitless choice of presentations from broths in bags, ready to rehydrate media in bags and film plates, solid agar in bottles for melting and prepoured plates. But how to choose a supplier that will be best for your lab?

Rapid Microbiology are carrying an exclusive interview with Barbara Gerten, Senior Scientist Traditional Microbiology with Merck KGaA we find out what makes a good media supplier and how to introduce a new RTU media into your lab's schedule.

Posted by Dr. Tim Sandle, Pharmaceutical Microbiology

Monday 7 January 2019

Effective training for keeping cleanrooms clean

Controlled environments required for the manufacture of pharmaceutical products are cleanrooms and they are assigned a class through meeting a set standard for airborne particles. Once a grade is assigned, a series of other physical and microbial parameters need be met: HEPA filtration, control of the air through air changes and pressure differentials; staff wearing appropriate garments; adequate cleaning and disinfection. While such measures can be introduced through the Quality by Design approach and good procedures, to achieve ongoing control requires effective training.

In relation to these important issues, Tim Sandle has written an new article. The introduction reads:

“Traditional training has served the industry well, but it does not always deliver expected outcomes. Moreover, classroom-style training can be expensive and where it is not sufficiently engaging; the message does not always sink in. For these reasons, many pharmaceutical companies are turning to e-learning.”

The link to the article is:

Posted by Dr. Tim Sandle, Pharmaceutical Microbiology

Thursday 3 January 2019

Recording device for cell history

Different "events" such as infections by viruses, as well as the exposure to environmental toxins or other forms of stress, change the activity of genes thereby leaving molecular traces inside the cell. These changes happen mainly at the level of messenger RNA (mRNA). These are molecules that encode genetic information when genes become activated and read, a process known as transcription. Researchers can accurately investigate the activity of a gene by measuring the mRNA molecules present in a cell. However, the traces of gene transcription disappear rapidly: mRNA is highly instable, and cells often degrade it after a short time.

ETH researcher Randall Platt and his colleagues in the Department of Biosystems Science and Engineering have now developed a molecular recording system that writes transcriptional events into DNA where they can be permanently stored and later accessed to by sequencing.

To create their "recording device," Platt's doctoral students Florian Schmidt and Mariia Cherepkova employed the CRISPR-Cas system. CRIPSR-Cas is an adaptive immune system in bacteria and archaea. The system functions like an immunological memory device by recording genetic information about pathogens infecting the cell. This genetic information is recorded in a specific stretch of DNA known as a CRISPR array -- a process called acquisition.

CRISPR arrays are capable of storing short sequences of DNA, known as 'spacers', originating from a pathogen. Spacers are separated from each other by short identical DNA sequence called direct repeats, just like pearls on a string.

The researchers worked with the gut bacterium Escherichia coli, introducing the genes for the CRISPR-Cas system from a different bacterial species. One of those Cas genes is fused to a reverse transcriptase, an enzyme that uses an RNA molecule to produce DNA encoding the same information -- in other words, it transcribes RNA back into DNA.

The Escherichia coli cells supplied with the foreign genes for this CRISPR-Cas were able to produce a protein complex that binds short mRNA molecules. The reverse transcriptase translates these RNA spacers into DNA, containing the same information as the original RNA, and subsequently storing them in the CRISPR array. This process can occur multiple times such that new spacers are added to the CRISPR array in reverse chronological order, so the most recently acquired piece of DNA is always first.

In principle, this makes it possible to record any number spacers within a CRISPR array. Since DNA is very stable, the information recorded in them is stored for a long time and is also passed on from one generation of bacteria to the next.

"Our system is a biological data logger. It records the genetic response of bacteria to external influences and enables us to access that information even after many bacterial generations" says Florian Schmidt, the lead author of the study, which was recently published in the journal Nature.

ETH Professor Randall Platt says, "Researchers have been working on creating forms of synthetic cellular memory for a long time, but we are the first to develop one that can record information about the expression of each gene in a cell over time." The researchers have spent over two years working on this system.

Until now, researchers were limited to measuring mRNA at only a single snapshot in time. Taking these snapshots generally means destroying the cell, extracting its mRNA, and then quantifying them. In contrast, the new CRISPR-Cas RNA recording system records the history of cell, allowing researchers to effectively access the entire cellular log book rather than just a single point in time.

As part of their study, the ETH researchers recorded the reaction of E. coli bacteria equipped with the data logger to the herbicide paraquat. This substance provokes changes in mRNA transcription within the cells, and the scientists could read out this response from the CRISPR arrays even days after the herbicide exposure. Without the data logger, any molecular traces of the bacteria's contact with the herbicide would have long since been broken down and the information lost.

Biological data loggers like this, in addition to being interesting for research purposes, could also conceivable be used as a kind of sensor, to measure environmental toxins such as the herbicide, or in diagnostics. The present study intriguingly demonstrates the feasibility of such an approach, however practical applications are still a long way off. Randall Platt's research team in Basel is already working on transferring the system to other cell types and paving the way for its effective use as a diagnostic tools.


Florian Schmidt, Mariia Y. Cherepkova, Randall J. Platt. Transcriptional recording by CRISPR spacer acquisition from RNA. Nature, 2018; DOI: 10.1038/s41586-018-0569-1

Posted by Dr. Tim Sandle, Pharmaceutical Microbiology

Tuesday 1 January 2019

Happy New Year

Happy New Year to all readers of Pharmaceutical Microbiology - let's look forward to lots of exciting microbiology news for 2019.

Posted by Dr. Tim Sandle, Pharmaceutical Microbiology

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