Phage Consultants Issue New Warnings on Inconsistent Indicators and Ineffective Tests

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Phage Consultants Issue New Warnings on Inconsistent Indicators and Ineffective Tests

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AUGUST 24, 2013

Phage Consultants Issue New Warnings on Inconsistent Indicators and Ineffective Tests

One of Europe’s leading scientific experts in the detection and testing of bacteriophages has warned that researchers’ work is being made more difficult by indicator strains that lack consistency in resistance to some phages. He also criticises ineffective validated tests and lack of education in phage testing.

Dr. Marcin Los, who heads Gdansk-based specialist laboratory Phage Consultants, issues his warnings in an article for the July 2013 issue of the European Biopharmaceutical Review (EBR). He reveals the wide range of difficulties and dilemmas confronting phage detection researchers.

He explains that while most virulent phages are relatively easy to detect, some that produce the most evident contaminations can sometimes be elusive and challenging even for experienced researchers.

Lack of Training
Dr. Los says problems become even more pronounced in temperate phage detection, where the most common methods, such as triggering SOS regulon, often prove ineffective with the more dangerous P2 prophages groups. Recent studies have also shown that standard plating methods cannot detect some phages, even when properly induced.

“When one considers how few microbiology courses contain any phage handling and detection practice, it becomes easier to understand how even skilled microbiologists sometimes find phage detection difficult,” says Dr. Los.

“Paradoxically, the situation can be worse in facilities that do not suffer frequently from phage contamination, due to the fact that staff will not have worked enough with phage-contaminated samples and lack the necessary skills needed to perform the task correctly. Another frequent mistake is the wrong choice of indicator strain.”

Inconsistent Indicators
“To make the situation worse, some strains can gain resistance (partial or full) to individual or, occasionally, groups of phages. Our laboratory found that some bacterial strains, theoretically identical but obtained from different sources, possess widely varying phage resistance patterns. The reason for this is the inconsistent histories of sister strains between each lab. Some may even contain prophages which have been introduced accidentally, causing additional confusion and, in some cases, false negative results.”

Dr. Los also focuses on the dilemma that faces many researchers on whether to use validated or non-validated test methods. The former may have been proven to work in the chosen test, but non-validated methods sometimes work better.

Dr. Los explains: “With non-validated methods, the probability of phage detection is higher when two conditions are fulfilled: firstly, when the test is performed by a person who is experienced in detecting various types of phages; and secondly, when a test is constructed, it has been dedicated to particular bioprocess and situations. Where customised tests are concerned, the probability of making an error rises dramatically for unskilled personnel; however, in the correct hands the probability of phage detection also dramatically increases.”

Ineffective Validated Tests
In the end, he says, the choice of method is dictated by the situation. Validated tests are best for in-house phage testing, or when authority requires them “even if their performance is sub-optimal.”

But Dr. Los says customised test methods should be chosen when tests are to be provided for facilities utilising large amounts of different strains, such as contract manufacturing organisations. “In such cases, the idea that ‘one test fits all’ will not work,” says Dr. Los.

He also recommends that customised tests should be chosen in emergency scenarios, for example when identifying the source of a process failure, “as they provide greater accuracy, especially in the detection of low-level phage contamination.”

Critical Issues
Dr. Los concludes that errors can have critical consequences, both in failing to detect bacteriophages where they exist or of wrongly detecting non-existent phages.

“False negatives can allow for phage to spread within a facility and cause an outbreak, which in turn can paralyse productivity for an extended period. Another possibility is for undetected phage to contaminate the final product, which may cause the need for product recall. At first glance false positives do not seem so dangerous; however, they could trigger unnecessary and quite expensive decontamination procedures, which usually causes the temporary stop of production.”

EBR’s Editor, Dr. Deborah O’Neill, Chief Executive and Scientific Officer of NovaBiotics Ltd, commented: “Stricter regulatory controls on the quality of originator and biosimilar biopharmaceuticals are such that detection and prevention of process-related contaminants has never been more critical. Marcin Los focuses on the need for robust and appropriate means of phage detection, the challenges associated with devising and implementing the best methodologies to do so and the need to avoid any tests that are not specifically optimised for any particular process.”

About Dr. Marcin Los
Marcin Los is CEO of Phage Consultants. He has an MSc from the University of Bradford. Marcin spent one year at the Fraunhofer Institute for Silicon Technology in Itzehoe, Germany, as a researcher involved in the construction of novel virus detection methods, before obtaining a PhD in 2004 and a DSc in molecular biology from the University of Gdansk, Poland in 2011. He was Secretary of the Main Board of Polish Genetic Society and is currently an Associate Professor at both the University of Gdansk and the Institute of Physical Chemistry in Warsaw.

About Bacteriophages
Phages, viruses that infect bacteria, were first discovered around 1915 and have played a unique role in viral biology. While they have become perhaps the best understood viruses, their structure can be extraordinarily complex, with genomes that may encode many hundreds of genes. The use of bacteriophages has played a prominent role in elucidating DNA viral reproduction through lytic and lysogenic cycles. They have been used for almost a century as alternatives to antibiotics, particularly in Russia and Eastern Europe and are currently seen as a possible therapy against multi-drug-resistant strains of many bacteria.

About Phage Consultants
Phage Consultants specialise in bacteriophage infection and contamination control and assisting companies whose production is based on microbial activities with fighting and preventing phage, bacterial, fungal and viral contaminations.

Phage Consultants panel of experts are specialists in the field of bacteriophage biology with specific expertise on bacteriophages in bioprocessing. Its team provides a unique service for customers, offering a range of services from personal training to consulting and process optimisation in aspect of phage growth limitation as well as advising and assisting clients in the development of new production facilities. In addition, Phage Consultants also offer Contract Research Services, Contract Phage Manufacturing and Phage Purification Services.

For more information or to discuss Phage Consultants issue new warnings on inconsistent indicators and ineffective tests, please contact Phage Consultants directly.

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