Biofilm antimicrobial susceptibility testing: where are we and where could we be going?

Abstract

SUMMARY Our knowledge about the fundamental aspects of biofilm biology, including the mechanisms behind the reduced antimicrobial susceptibility of biofilms, has increased drastically over the last decades. However, this knowledge has so far not been translated into major changes in clinical practice. While the biofilm concept is increasingly on the radar of clinical microbiologists, physicians, and healthcare professionals in general, the standardized tools to study biofilms in the clinical microbiology laboratory are still lacking; one area in which this is particularly obvious is that of antimicrobial susceptibility testing (AST). It is generally accepted that the biofilm lifestyle has a tremendous impact on antibiotic susceptibility, yet AST is typically still carried out with planktonic cells. On top of that, the microenvironment at the site of infection is an important driver for microbial physiology and hence susceptibility; but this is poorly reflected in current AST methods. The goal of this review is to provide an overview of the state of the art concerning biofilm AST and highlight the knowledge gaps in this area. Subsequently, potential ways to improve biofilm-based AST will be discussed. Finally, bottlenecks currently preventing the use of biofilm AST in clinical practice, as well as the steps needed to get past these bottlenecks, will be discussed.

Died or Not Dyed: Assessment of Viability and Vitality Dyes on Planktonic Cells and Biofilms from Candida parapsilosis

“…Different challenges are observed in the assessment of biofilm susceptibility. Although conventional methods are high throughput, these in vitro models poorly represent the in vivo situation, leading to susceptibility data that may disagree with clinical output [ 36 ]. Dynamic models allows media flow above the biofilm surface, mimicking better in vivo conditions and providing more reliable outcomes when evaluating antimicrobial compounds [ 37 ].…”

Multimodal evaluation of drug antibacterial activity reveals cinnamaldehyde analog anti-biofilm effects against Haemophilus influenzae

“…Biofilm-related infections are difficult to treat, making the development and testing of new effective therapeutics needed. Also, there is a pressing need for standardized methods that appreciate the biological variability of bacterial biofilms while also able of reproducibly assess the potential of anti-biofilm drugs [ 15 ]. Here, we detail simple protocols that can be performed routinely in numerous laboratories worldwide.…”

“…In this context, anti-biofilm drug development should contribute to expanding the global antibacterial pipeline. Moreover and closely related, standardized guidelines for anti-biofilm drug testing should be made available to parallel standard minimal inhibitory concentration (MIC) testing against planktonic cells [ [13] , [14] , [15] ].…”

Nanomedicine against biofilm infections: A roadmap of challenges and limitations

“…Despite the existing guidelines regularly published by the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) and the Infectious Disease Society of America (IDSA), there is no standardized protocol for biofilm diagnosis in clinical practice (Coenye, 2023;Høiby et al, 2015;Paul et al, 2022;Tamma et al, 2023). Biofilm-associated infections are often subclinical for long periods and are only detectable in the case of bacteremia.…”