Antimicrobial activity testing: measuring, understanding, and anticipating resistance

The skin microbiome is not mere scenery. It is a functional component of the skin, involved in protection against pathogens, immune dialogue, and the modulation of inflammation. It is a dynamic ecosystem shaped by subtle interactions between bacteria, yeasts, the host, and the environment.

Our approach is grounded in a simple conviction: understanding a microbiome is not merely about identifying it. It is about knowing how to culture it, interrogate it, and generate scientifically defensible data.

This is precisely how we approach the skin microbiome: as a complex ecosystem whose actors, dynamics, and mechanisms must be mastered before attempting to modulate its balance.

Once upon a time, in the hospitals of the twenty-first century, there was an infection that even antibiotics could no longer silence. An opportunistic infection caused by a bacterium called Clostridioides difficile, it often appeared in patients who were already vulnerable… and, above all, already heavily treated. Let us look back at the history of this infection, which gave rise to new therapeutic approaches.

Probiotics are often presented as a simple category. In reality, their characterization has become a demanding scientific and regulatory exercise. It is no longer enough to identify a species or to invoke a favorable history of use: the demonstration must now be conducted at the strain level, in a way that is consistent with the intended use, the target population, and the applicable regulatory framework. In the main reference frameworks, a microorganism can be qualified as a probiotic in the strict sense only if it is sufficiently characterized, safe for its intended use, alive at a relevant dose until the end of the product’s shelf life, and associated with a documented health benefit. [1,5,7,8]

The key question therefore becomes: what can we robustly demonstrate about its identity, safety, and functional activity? This is particularly true for new or poorly documented strains, for which taxonomy alone is not sufficient. The EFSA, GRAS, and Canadian frameworks converge on one central point: useful characterization is strain-level characterization interpreted in light of the final use. [1-6]

The construction of bacterial mutants is a cornerstone of microbiology. Historically used to decipher gene function, it now plays an equally strategic role in bioproduction, biotechnology, and the development of therapeutic bacteria, where the engineered strain itself may ultimately become the final product.

This shift has profoundly changed how mutagenesis projects are approached. Today, the objective is no longer simply to modify a gene, but to design a strain aligned with its final application, operational constraints, and regulatory expectations.

Once upon a time, an invisible battle was raging deep inside our noses. A microscopic battlefield, where bacteria fought relentlessly to defend their territory. Picture a small village of indomitable Gauls, surrounded on all sides… but instead of Romans, it’s microbes. And in this surprisingly strategic setting, a most unexpected antibiotic was discovered: lugdunin.

As we step into 2026, the entire Smaltis team sends you our warmest wishes. May this new year bring clarity, creativity, meaningful collaborations — and a few scientific breakthroughs that get the attention they deserve.

Every day, antimicrobials face their natural adversaries: bacteria.
But in this silent war, nothing remains static — bacteria learn, adapt, defend themselves… and develop increasingly sophisticated resistance mechanisms.
Smaltis is a microbiology CRO specialized in the study of antimicrobial resistance and the preclinical development of antimicrobials.
We support the developers of new antibiotics, peptides, biocides, and other anti-infective agents with a comprehensive panel of in vitro assays designed to meet the most demanding R&D challenges.

Smaltis at the Key Industry Events of Autumn 2025! From medical devices to biotherapies, from fundamental research to industrial production, we meet project leaders to better understand microbiology needs and build new collaborations.

At Smaltis, our ambition remains unchanged: bringing microbiological excellence to your innovations.
To better address the diversity of your needs, we have structured our offer around 2 complementary Business Units, true pillars of our scientific and technical commitment.

Some yeasts are particularly resistant… especially Malassezia restricta.

This lipophilic yeast, naturally present on human skin, is involved in various imbalances of the skin microbiota, notably those linked to dandruff or seborrheic dermatitis. But cultivating it in the laboratory is no easy task!