Friday, 27 May 2022

Bacteria and temperatures of growth


Microorganisms are adept at surviving extreme environments (both physical and geochemical), including ultracentrifugation, hypervelocity, shock pressure, high temperature variations, vacuums, and different ultraviolet and ionizing radiation intensities. On Earth, microorganisms are found to thrive at 6.7 kilometres depth inside the Earth’s crust, and

more than 10 kilometres deep inside the ocean at pressures of up to 110 Megapascals (the piezophiles); from extreme acid, even at pH 0 (acidophiles) to extreme basic conditions, with up to pH 12.8 recorded (alkaliphiles); and from hydrothermal vents at 122 °C to frozen sea water at −20 °C (in the case of Psychrobacter cryopegella).


Understanding temperature variations is of importance of assessing microbial risk in pharmaceutical processing, in terms of whether microorganisms may be present.


(such as a cold room or hot water system); whether they might survive and pose a problem to a non-sterile product; and as part of the process of establishing their origins for root cause analysis.


This article assesses the core differences with bacterial growth and survival at different temperatures. The article also explains why organisms that are often generally associated with cold environments might survive, potentially elevating the risks to pharmaceutical facility cold rooms.


Sandle, T. (2022) Bacteria and temperatures of growth: Cold comfort?, Pharmig News, Issue 87, pp12-16 (see:


Posted by Dr. Tim Sandle, Pharmaceutical Microbiology Resources (

Monday, 23 May 2022

Improving Microbiological Control Of Non-Sterile Pharmaceuticals: Unlocking The FDA Guidance


The document is the first time that the FDA has pieced together a compliance framework for non-sterile medicines, and, in some ways, the document stands as a companion piece to the Aseptic Processing Guidance (issued in 2004, although in clear need of an update). The trigger for the non-sterile document was based on the pattern of non-sterile product recalls involving microbial contamination, based on the period 2014 to 2017 when 197 bacterial and fungal contamination events, associated with either the manufacture, packaging, shipping, or storage of the drug, were recorded.



This paper critically assesses the regulatory text.


For details, see:


Sandle, T. (2021) Improving Microbiological Control Of Non-Sterile Pharmaceuticals: Unlocking The FDA Guidance, Journal of GxP Compliance, 25 (6). DOI:


Posted by Dr. Tim Sandle, Pharmaceutical Microbiology Resources (

Monday, 16 May 2022

Alternative method for sterilisation: X-rays

Compared with gamma, X-rays used for sterilisation have the highest potential penetration depth in a product. This advantage is off-set by the few number of X-ray generators available and less product validation or compatibility data being available. While the decontamination of products and materials with high-energy X-rays was developed during the 1970s, the first application of the technology for sterilisation (medical devices) did not begin until the early-2000s. 



The lower take-up may be about to change since interest in X-rays for sterilisation has increased in the 2020s following advances with higher beam power ratings of industrial electron accelerators. Along with e-beam and gamma radiation, three related-yet-different technologies are available.




Sandle, T. (2021) Alternative method for sterilisation: X-rays, Staxs article,


Posted by Dr. Tim Sandle, Pharmaceutical Microbiology Resources (

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