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Comment on “Enumeration of Escherichia coli in Probiotic Products. Microorganisms 2019, 7, 437”

By February 12, 2020February 26th, 2020Publications

Wassenaar TM, von Bünau R, and Zimmermann

Microorganisms 2020, 8(2), 245;


Recently, Zimmer and Dorea published a communication on the enumeration of Escherichiaácoli in probiotic products containing this species [1]. They investigated the content of two commercial products, Mutaflor (produced by Pharma-Zentrale GmbH, Herdecke, Germany) and Symbioflor 2 (produced by SymbioPharm GmbH, Herborn, Germany). Mutaflor is available as viable, lyophilized E. ácoli bacteria inside an acid-resistant capsule, while Symbioflor 2 contains viable E. ácoliábacteria in a liquid suspension. The authors tested the viability of the bacteria for three batches of each product. They report that the products contained E. ácoli in numbers several orders of magnitude less than claimed on the product information [1].The authors assessed the number of viable bacteria by applying the methodology optimized for enumeration of coliform bacteria in surface waters. Serial dilutions were made in Ringers solution (the content of the Mutaflor capsules was resuspended for this) and these were enumerated in triplicate using a Colilert Quanti-train/2000 system, from which the most probable number (MPN) was obtained. This method is validated and recommended in multiple countries, including Germany [2], to estimate the number of coliform bacteria in samples expected to contain low numbers, for instance, surface water samples. For such samples the MPN methodology has been developed and optimized [3].

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