Introduction

The antibiotic-resistance profiles used to define microbial susceptibility to drugs are performed in-vitro and do not provide information on the resistances that microorganisms are able to develop by growing protected within a biofilm matrix. As a result, conventional antibiograms are often inadequate to determine bacterial susceptibility to antimicrobial drugs. New procedures to assess the susceptibility of biofilm-producing microorganisms to antimicrobial drugs are required. The proposed invention provides a system for evaluating the susceptibility of pathogenic bacteria to antibiotics taking into account their ability to form biofilms.

Technical features

The method called “Anti-Biofilm Test” (ABT) is based on setting up bacteriological plates containing standard micro-dilutions of antibiotics. This set-up allows to measure the efficacy of different antibiotics against biofilm producing bacteria and offers specifications on the susceptibility profile expressed in “biofilm minimal inhibitory concentration (BMIC)”. ABT can also be used for combinations of antibiotics. By introducing gram-positive (Staphylococcus aureus) and gram-negative (Pseudomonas aeruginosa, Klebsiella pneumoniae) laboratory strains with known biofilm production characteristics, it is possible to standardize ABT and evaluate the effectiveness of antimicrobial treatments in different conditions of growth and with specific culture media. To reduce variability and ensure the accuracy of the results, internal system controls (positive and negative) are introduced to evaluate the reliability parameters of the result.

Possible Applications

• Clinical microbiological diagnostics;
• Microbiological controls and environmental sanitation;
• Pharmaceutical industry: development of new molecules and/or drug formulations capable of attacking the microbial biofilm;
• Food industry, sanitation and food preservation.

Advantages

• Requires reduced manual skills and equipment commonly found in clinical microbiology laboratories;
• Ideal test for clinical routine;
• Can be used in a non-clinical setting due to its simplicity, speed of implementation and low costs.