making microbiology easy

Antimicrobial efficacy assessment

Determination of the efficacy of anti-infective compounds

Antibiotic resistance is the phenomenon of a bacterium becoming resistant to antibiotics, making these molecules ineffective against a bacterial infection. This phenomenon of bacterial defense involves genetic modifications that lead to various mechanisms such as the production of enzymes that inhibit the molecule, the impermeabilization of the bacterial membrane, the production of efflux systems or the modification of the antibiotic’s target. This antibiotic resistance can be natural or acquired. 

Antibiotic resistance is a natural phenomenon in the bacterial world, but the misuse of these drugs in human and veterinary medicine has greatly accelerated the process and contributed to the emergence of multi-resistant and highly resistant bacteria. Antibiotic resistance is now one of the most serious threats to global human and animal health, food safety and the environment.

The overall objective is therefore to limit the spread of bacterial resistance, in order to allow time for industries to deploy new therapeutic strategies. These solutions are based on the modification of existing antibiotics, the development of new compounds, the use of bacteriophages or other strategies complementary to antibiotic therapies.

Our offer

Smaltis assists you in the evaluation of antimicrobial properties of your compounds under development, whose mechanism of action and structure have been established. Standard or custom-developed tests are offered to determine the spectrum of action of antibiotic candidates, antimicrobial peptides, phages, and any antibacterial compound.

In addition, Smaltis can assist you in determining the sensitivity of bacterial strains (such as probiotics) to antibiotics.

Antimicrobial efficacy and susceptibility to antimicrobials

Smaltis delivers characterization services according to the recommendations of CLSI (Clinical & Laboratory Standards Institute), CA-SFM/EUCAST (European Committee on Antimicrobial Susceptibility Testing), or EFSA (European Food Safety Authority).

These tests can be performed in aerobic or anaerobic conditions. 

  • Antibiograms
  • Minimum Inhibitory Concentration (MIC, MIC50, MIC90). Depending on the mode of action of the compound, the determination of the MIC at different pH can be interesting, because it allows to analyze the efficiency of the molecule in intracellular pH conditions.
  • Minimum Bactericidal Concentration (MBC)
  • Fractionated Inhibitory Concentration (FIC) – to identify synergies or antagonisms of efficacy between several anti-infective molecules
    (dilution in liquid Broth or agar media)
  • Antimicrobial effect in cellular infection models
    T84 line (intestinal cells), A549 & NCI-H820 (lung cells), J774A.1 (macrophages)
  • Bactericidal curves
  • Co-cultures to determine the impact of a strain on the inhibition of the growth of a pathogenic bacterium
  • Probiograms

Supporting the development of bacteriophages

Bacteriophages, or phages, are viruses that infect only bacteria. Since lytic phages destroy bacteria, they can be used to fight bacterial infections: this is the principle of phage therapy or phagotherapy. The advantage of phages is that they are specific to a bacterium, with each virus infecting only a given subgroup within a bacterial species.

Phage therapy is still practiced in some countries of the former Soviet bloc and is regaining the attention of researchers worldwide following the problem of antibiotic resistance. The use and return to phage therapy seems to be one of the most proven, promising and sustainable ways to fight against this resistance phenomenon. Today, discussions are underway in Europe to define a specific regulatory framework for phage therapy and to conduct clinical studies and fundamental research projects on the biology of phages and their effects on the organism and the ecosystem.

Smaltis accompanies the actors of the development of bacteriophages, by proposing services allowing to characterize them and to evaluate their effects:

  • Screening by Spot Phage Assay
  • Titration of suspensions by Phage Plaque Assay
  • Search for lytic and lysogenic phages
  • Identification of phages by sequencing
  • Partnership for the visualization and quantification of phage particles by electronic microscopy

Example of achievement


The objective of this study was to compare the in vitro bactericidal activity of lipacid-containing ear hygiene products with a reference product, on 9 pathogenic strains isolated from dog ear infections: Malassezia pachydermatis, Pseudomonas aeruginosa and Staphylococcus pseudintermedius.

Bactericidal curves were performed for 32 minutes with 6 measuring points, on 3 strains of each pathogenic species, exposed to pure and diluted products. For each strain, a viability test was performed in parallel.

The results of the enumerations made it possible to conclude on the antiseptic activity of the products compared to the reference product, both in terms of their bactericidal kinetics and their spectrum of activity, and then to classify them according to their efficacy and speed of action.

Evolution of Log10 CFU/mL of Pseudomonas aeruginosa strain N° XX over time, in diluted products.