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

Abstract

We have become increasingly aware that during infection, pathogenic bacteria often grow in multicellular biofilms which are often highly resistant to antibacterial strategies. In order to understand how biofilms form and contribute to infection, in vitro biofilm systems such as microtitre plate assays and flow cells, have been heavily used by many research groups around the world. 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 our bench-side data can ultimately be used to improve bedside treatment.

Phage Inhibit Pathogen Dissemination by Targeting Bacterial Migrants in a Chronic Infection Model

“…Microfluidic devices, in particular, have been used to study slime-enclosed communities, or biofilms, which are thought to be a major contributor to the persistence of chronic infections. This persistence has been hypothesized to be due to the ability of biofilm bacteria to tolerate host immune functions and antimicrobial therapies (9, 10). However, most in vitro biofilm systems lack several important aspects of chronic infections, including the following.…”

Clinical potential of engineered cationic antimicrobial peptides against drug resistant biofilms

“…Though small animal models have been used to demonstrate the efficacy of eCAPs for acute infections[23], most small animals are not amenable to the chronic or recurrent infection that is critical to the development of relevant model biofilms[29]. Porcine models are more reflective chronic human infections, though the relative lack of ability to manipulate the host, the inability for some human pathogens to cause infection, and the cost associated with such models make this option inaccessible for many studies.…”

Antimicrobial efficacy against Pseudomonas aeruginosa biofilm formation in a three-dimensional lung epithelial model and the influence of fetal bovine serum

“…Accurately predicting the efficacy of antimicrobial agents for treatment of bacterial infections will be improved by the availability of model systems that replicate both the bacterial and host in vivo phenotypes111213. In the present study, we developed a novel approach to study interactions between P. aeruginosa biofilms and biotic surfaces, by generating biofilms associated with in vivo -like 3-D lung epithelial cells.…”

“…Therefore, novel antimicrobial approaches that target bacterial virulence factors (such as those regulating biofilm formation) or host factors (such as immune stimulation) represent promising alternatives to antibiotics, especially given the global problem of antibiotic resistance910. When assessing the clinical potential of novel antimicrobial agents, mimicking the in vivo bacterial phenotype and incorporating key aspects of host tissues are essential111213. Indeed, the more closely in vivo host-pathogen interactions are reflected in a model system, the more relevant the experimental outcome will be to the patient.…”