The Limitations of In Vitro Experimentation in Understanding Biofilms and Chronic Infection

We have become increasingly aware that, during infection, pathogenic bacteria often grow in multicellular biofilms that are often highly resistant to antibacterial strategies. In order to understand how biofilms form and contribute to infection, many research groups around the world have heavily used in vitro biofilm systems such as microtitre plate assays and flow cells. Whilst these methods have greatly increased our understanding of the biology of biofilms, it is becoming increasingly apparent that many of our in vitro methods do not accurately represent in vivo conditions. Here we present a systematic review of the most widely used in vitro biofilm systems, and we discuss why they are not always representative of the in vivo biofilms found in chronic infections. We present examples of methods that will help us to bridge the gap between in vitro and in vivo biofilm work so that we can ultimately use our benchside data to improve bedside treatment. [Display omitted] •We found microbial biofilms in many types of infection, and especially in chronic infections. They contribute to antimicrobial resistance and result in difficult to treat infections.•Most of our knowledge about biofilms comes from studying them with the use of well-established in vitro methods. However, there are significant differences that exist between in vitro biofilms grown in the laboratory, as well as in vivo biofilms found during infection.•There is a need to bridge the gap between in vitro work and in vivo observations. New methodologies and ways of thinking are required so that our future laboratory work better represents conditions found during infection.