Dissolvable alginate hydrogel-based biofilm microreactors for antibiotic susceptibility assays
Le Hoang Phu Pham,
Khanh Loan Ly,
Mariliz Colon-Ascanio,
Jin Ou,
Hao Wang,
Sang Won Lee,
Yi Wang,
John S. Choy,
Kenneth Scott Phillips,
Xiaolong Luo
Affiliations
Le Hoang Phu Pham
Department of Mechanical Engineering, The Catholic University of America, Washington, DC, 20064, USA
Khanh Loan Ly
Department of Biomedical Engineering, The Catholic University of America, Washington, DC, 20064, USA
Mariliz Colon-Ascanio
Department of Biology, The Catholic University of America, Washington, DC, 20064, USA
Jin Ou
Department of Biology, The Catholic University of America, Washington, DC, 20064, USA
Hao Wang
Division of Biology, Chemistry, and Materials Science, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, White Oak, MD, 20993, USA
Sang Won Lee
Division of Biology, Chemistry, and Materials Science, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, White Oak, MD, 20993, USA
Yi Wang
Division of Biology, Chemistry, and Materials Science, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, White Oak, MD, 20993, USA
John S. Choy
Department of Biology, The Catholic University of America, Washington, DC, 20064, USA; Corresponding author.
Kenneth Scott Phillips
Division of Biology, Chemistry, and Materials Science, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, White Oak, MD, 20993, USA; Corresponding author.
Xiaolong Luo
Department of Mechanical Engineering, The Catholic University of America, Washington, DC, 20064, USA; Corresponding author.
Biofilms are found in many infections in the forms of surface-adhering aggregates on medical devices, small clumps in tissues, or even in synovial fluid. Although antibiotic resistance genes are studied and monitored in the clinic, the structural and phenotypic changes that take place in biofilms can also lead to significant changes in how bacteria respond to antibiotics. Therefore, it is important to better understand the relationship between biofilm phenotypes and resistance and develop approaches that are compatible with clinical testing. Current methods for studying antimicrobial susceptibility are mostly planktonic or planar biofilm reactors. In this work, we develop a new type of biofilm reactor—three-dimensional (3D) microreactors—to recreate biofilms in a microenvironment that better mimics those in vivo where bacteria tend to form surface-independent biofilms in living tissues. The microreactors are formed on microplates, treated with antibiotics of 1000 times of the corresponding minimal inhibitory concentrations (1000 × MIC), and monitored spectroscopically with a microplate reader in a high-throughput manner. The hydrogels are dissolvable on demand without the need for manual scraping, thus enabling measurements of phenotypic changes. Bacteria inside the biofilm microreactors are found to survive exposure to 1000 × MIC of antibiotics, and subsequent comparison with plating results reveals no antibiotic resistance-associated phenotypes. The presented microreactor offers an attractive platform to study the tolerance and antibiotic resistance of surface-independent biofilms such as those found in tissues.
