Single-Temperature Incubation in Ambient Monitoring – Is it Permissible and Advisable?

Background

In most cases, microbiological samples from environmental monitoring are currently incubated at two temperatures. Annex 1 (2022) of the EU GMP Guide requires that the selection of sampling sites, sampling frequency, methods and incubation conditions be based on a risk assessment that takes into account the process, the facility and the typical flora. Some interpret this requirement as an explicit recommendation of two incubation temperatures for microbiological monitoring samples. However, the text of EU GMP Annex 1 does not specify concrete incubation temperatures or incubation times for environmental monitoring samples.

Current discussion

For some time, incubation at a single temperature has been investigated as an alternative to sequential incubation, which typically takes place at 20–25 °C and 30–35 °C. This could simplify workflows and reduce transfer and handling errors. Current findings suggest that the optimal temperature depends on the location, the medium and the microbial flora. A multicenter study found no significant differences between the incubation regimes after five days and recommended 32.5 °C for the sites investigated. Another study reported good recovery rates for most of the microorganisms tested when using TSA at 25–30 °C over three to four days. Exceptions were Cutibacterium acnes and certain moulds, which require specific conditions or culture media. A single-temperature strategy therefore appears practicable, provided it is supported by site-specific, risk-based comparison and validation data. How should such an approach be implemented?

The survey

To clarify this question, ECA has launched a survey to collect contributions from regulatory authorities, pharmaceutical and biotechnology companies, contract laboratories and subject-matter experts on single-temperature incubation of environmental monitoring plates. The survey follows a risk-based, validation-oriented approach consistent with EU GMP Annex 1, USP <1116> and USP <1223>. Estimated completion time: 5–7 minutes. Responses may be evaluated in aggregated form to support industry benchmarking and discussions on validation, regulatory acceptance and expectations regarding implementation.

Sources and literature

• Multicenter Study on Incubation Conditions for Environmental Monitoring and Aseptic Process Simulation , https://pubmed.ncbi.nlm.nih.gov/27593691/
• Comparison of different incubation conditions for microbiological environmental monitoring, https://pubmed.ncbi.nlm.nih.gov/25336415/
• The Rules Governing Medicinal Products in the European Union Volume 4 EU Guidelines for Good Manufacturing Practice for Medicinal Products for Human and Veterinary Use Annex 1 Manufacture of Sterile Medicinal Products
  https://www.gmp-compliance.org/files/guidemgr/20220825_gmp-an1_en_0.pdf
• Validierung der Inkubationsbedingungen In-situ-Studie zu Abklatschplatten aus dem mikrobiologischen Umgebungsmonitoring https://www.ecv.de/suse_search.php?index=search&suseMode=form&form_section_all=X&form_autor=Goverde+M