Microbiological quality control tests to ensure the quality of dermatological products: a critical review and perspectives

Abstract

Maintaining the microbiological quality of dermatological products is crucial for ensuring consumer safety and meeting regulatory requirements. Although these products are non-sterile, they can become contaminated during manufacturing, handling, and storage, potentially causing microbiota dysbiosis and skin infections. Microbiological Quality Control involves traditional tests, such as plate counts, pathogen-specific assays, and preservative efficacy testing (challenge tests), as per pharmacopeial guidelines (USP < 51>) or other standards (ISO 11930, PCPC). Current culture-based methods remain the regulatory standard; however, they have limitations, including slow turnaround times and an inability to detect non-culturable cells. Modern alternatives, such as molecular assays (qPCR, RT-PCR) and AI-driven systems, offer increased sensitivity, speed, and real-time monitoring capabilities. At the same time, developing new formulations (prebiotic, probiotic, and postbiotic products) introduces new challenges, requiring risk-based strategies, validated rapid methods, and hurdle preservation systems. Frameworks such as Quality by Design (QbD) and ICH Q9 risk management principles incorporate microbiological considerations into product design, while regulatory harmonization and digitalization accelerate global standardization. This review summarizes traditional and emerging approaches to microbiological quality control in dermatological products, highlights current regulatory expectations, and explores future perspectives to support safe, effective, and innovative formulations.