Ensuring Cosmetic Safety: Tackling Pluralibacter gergoviae and Burkholderia cepacia

At in-cosmetics 2025, Dagmar Antoni-Zimmermann delivered an eye-opening talk on two often overlooked but critical microbial threats in cosmetic preservation: Pluralibacter gergoviae and Burkholderia cepacia.

These preservative-tolerant strains are increasingly linked to product recalls, consumer safety concerns, and brand reputation damage. Their ability to withstand preservatives and form persistent biofilms makes them particularly problemàtic, especially in formulations relying solely on organic acids.

To effectively address the rising risk of microbial contamination, the cosmetics industry must adopt a multi-layered strategy. Dagmar outlined three essential pillars to strengthen product safety and ensure long-term protection.

Go Beyond Standard Tests: Detect What Others Miss

Standard methods like ISO 11930 often do not detect resilient strains such as Pluralibacter gergoviae and Burkholderia cepacia. These organisms are not always included in standard microorganism panels, which means contaminated products may pass release testing unnoticed.

THOR’s TM206 Multichallenge Test addresses this critical gap by incorporating these hard-to-kill strains into the validation process. The result: a more realistic and accurate assessment of preservative performance, helping brands catch potential contamination risks before they reach the market.

pH Is Not Enough: Rethink Your Preservation Strategy

Relying solely on organic acids for preservation is risky. While commonly used, they are only effective at low pH (typically 4–5) and may not protect against tolerant strains.

A more robust approach involves using pH-independent actives like benzyl alcohol, phenoxyethanol, and phenylpropanol. These multifunctional ingredients:

• Provide broad-spectrum protection across a wide pH range

• Interfere with bacterial adaptation and resistance mechanisms

• Remain effective even in complex formulations

Combining these actives with glycols further boosts antimicrobial performance while enhancing skin compatibility and formulation stability.

Hygiene Starts at the Source: Audit Your Plant to Stop Recurring Contamination

Contamination often begins where products are made, not just in what goes into them. Persistent strains like B. cepacia can form biofilms inside equipment, pipes, and tanks, leading to repeated batch contamination.

THOR’s Plant Hygiene Audits help identify and eliminate these hidden risks by assessing:

• Water systems and quality

• Raw material handling procedures

• Personnel hygiene protocols

• Cleaning and sanitisation routines

By uncovering root causes and implementing targeted corrective actions, manufacturers can significantly reduce contamination risks and build long-term microbiological resilience.

Real-world case studies confirmed that these organisms are still being found in contaminated products, despite standard preservation systems. With our Microcare® range of cosmetic ingredients, THOR offers science-backed, adaptable preservation solutions that protect both your formulations and your reputation.

Future-proof your products against evolving microbial threats, because safety starts with smart preservation.