In Silico Modeling of Antibiotics Treatment Combined with Corticosteroids for Septic Arthritis

Septic arthritis is a bacterial infection in the joint fluid and joint tissues. Although it is rare, septic arthritis is a serious condition—it can cause permanent damage to the affected joint and lead to further severe complications. Quick medical diagnosis and therapy are of key importance in order to prevent irreversible cartilage destruction in the joint: treatment protocol comprises antibiotics therapy and joint fluid drainage. While there is general medical consensus regarding the use of adequate antibiotics and surgical joint lavage, the potential application of corticosteroids is debated. Corticosteroids are traditionally contraindicated for bacterial infections, but several recent studies suggest that, whenever the infection is appropriately treated by antibiotics, then the additional use of corticosteroids may be safe and pronouncedly beneficial. We propose a hybrid mathematical model to simulate, analyze, and assess the outcome of in silico septic arthritis infections. Our multiscale approach describes the infection itself (i.e., the local concentration of bacteria) by means of a partial differential equation, while chondrocytes and immune cells are grasped by a discrete stochastic agent-based model. The system becomes complete by the natural effects and counter-effects taking place between interacting entities. Experiments with varying treatment options (i.e., which drugs are administered and when) and their respective outcome are discussed in our work. While actual in vivo clinical experiments would be virtually impossible for obvious ethical reasons, our rudimentary system allows for safe in silico experimenting in connection to the open question: are corticosteroids a promising option for complementary treatment of septic arthritis?