In Vitro Models of Bacterial Biofilms: Innovative Tools to Improve Understanding and Treatment of Infections

Abstract

Bacterial infections are a growing concern to the health care systems. Bacteria in the human body are often found embedded in a dense 3D structure, the biofilm, which makes their eradication even more challenging. Indeed, bacteria in biofilm are protected from external hazards and are more prone to develop antibiotic resistance. Moreover, biofilms are highly heterogeneous, with properties dependent on the bacteria species, the anatomic localization, and the nutrient/flow conditions. Therefore, antibiotic screening and testing would strongly benefit from reliable in vitro models of bacterial biofilms. This review article summarizes the main features of biofilms, with particular focus on parameters affecting biofilm composition and mechanical properties. Moreover, a thorough overview of the in vitro biofilm models recently developed is presented, focusing on both traditional and advanced approaches. Static, dynamic, and microcosm models are described, and their main features, advantages, and disadvantages are compared and discussed.

Culture Shock: An Investigation into the Tolerance of Pathogenic Biofilms to Antiseptics in Environments Resembling the Chronic Wound Milieu

“…Interestingly, when contrasted with the data in Table 2, where SOHs was relatively effective in reducing staphylococcal biofilm, it appears that the introduction of a porous cellulosic mesh, which allows microorganisms to penetrate through (similarly to necrotic layers in chronic wounds [45]), significantly diminishes the efficacy of SOHs in exhibiting killing activity. Above shows the importance of application of different in vitro models to obtain the full insight into possible activities of applied antiseptic agents towards pathogenic biofilms in vitro and to obtain full insight before attempting to translate such data on the clinical conditions [17,46,47]. This comprehensive approach ensures that the nuances and complexities of biofilm behavior and antiseptic efficacy in different environments are adequately considered, leading to more accurate and applicable results in clinical settings.…”

Combined electrical-electrochemical phenotypic profiling of antibiotic susceptibility of in vitro biofilm models

“…11 However, in vivo modeling is not practical because it requires labor-, skill-, and cost-intensive procedures and a relatively long time for biofilm formation. [17][18][19] Furthermore, the procedures provide little control of bacterial environments, biofilm thickness, and the formation of multispecies communities. 16 Meanwhile, in vitro models have been widely used because they are practical, cost-effective, and easily controlled.…”

“…16 Meanwhile, in vitro models have been widely used because they are practical, cost-effective, and easily controlled. 17 Although small deviations can occur in exactly mimicking the natural environment, in vitro models have become a powerful tool to understand biofilm formation and development. Moreover, they have fewer ethical concerns than those using living animals.…”

“…16 Closed static methods such as the calgary biofilm device (CBD) and the microtiter plate assay, and continuous dynamic approaches such as the flow cell system and the Centers for Disease Control (CDC) biofilm reactor are the most popular in vitro biofilm models. [16][17][18][19] The static models provide more cost-effective, less equipmentdependent, and more voluminous throughput while the dynamic models can mimic more in vivo-like bacterial communities with continuous introduction of nutrient and waste removal. However, existing static and dynamic in vitro models do not fully reflect the advantages of both technologies to meet the demands of a rapid and simple biofilm simulation concomitantly replicating the 3-D in vivo environments.…”

Three dimensional printed biofilms: Fabrication, design and future biomedical and environmental applications

“…Not only is 3D bioprinting in the nascent stage for the fabrication of mammalian cell living materials but also for the development of 3D scaffolds composed of algae (Malik et al., 2020 ), bacteria (Schmieden et al., 2018 ) and plant cells (Seidel et al., 2017 ). While several reviews have been published recently on the topic of 3D bioprinting of microbes (Crivello et al., 2023 ; Hayta et al., 2021 ; Li et al., 2022 ), this review will focus on the importance of the material composition and printing parameters of 3D printed biofilms to highlight the importance of structure–function relation achieved through 3D printing, as well as highlight biomedical and environmental applications of biofilms. With further development of the spatial patterning of extracellular matrix (ECM) components 3D printing would allow for highly robust and biorelevant engineered biofilms.…”