“The [septic arthritis] diagnosis is based on the cytobacteriological examination of the synovial fluid, but direct bacteriological examination is insensitive and the result of the culture is obtained only after several days,” the researchers explained. “Therefore, there is still a need for a rapid, simple, and reliable method for the positive diagnosis of septic arthritis. Such method must allow avoiding both unrecognized septic arthritis leading to major functional consequences, and overdiagnosis that will induce unnecessary expensive hospitalization and unjustified treatment with consequences in term of health and social costs.”
The purpose of the study, according to the investigators, was to verify the interest of mid-infrared spectroscopy to identify synovial fluid samples from patients with septic arthritis vs other causes of joint effusion. A total of 402 patients with suspected arthropathies were enrolled in the study. Investigators obtained synovial fluids from each patient and used a chalcogenide fiber sensor to acquire the infrared absorption spectrum from each sample. Spectral variables, which allowed determination of septic and nonseptic arthritis, were used to develop an algorithm that was later validated with non-frozen synovial fluids from a different research center.
Researchers used 16S polymerase chain reaction analysis and a synovial fluid bacteriologic analysis and culture to classify synovial fluid samples as having septic arthritis (n=30) or nonseptic arthritis (n=372). A sensitivity of 97% and specificity of 71% were observed for the developed algorithm. Additionally, investigators found a positive predictive value of 21% and a negative predictive value of 99% for the algorithm (area under the curve, 0.91).
“The high negative predictive value and the very short time (about 10 minutes) required to obtain the result makes it possible to quickly rule out an infection diagnosis, which could make it possible to avoid unnecessary hospitalization and antibiotic therapy,” the researchers concluded.
Reference
Albert JD, Le Corvec M, Martin A, et al. Septic arthritis screening with a fast diagnostic tool using mid infrared spectroscopy: a multi-centric study. Presented at: European League Against Rheumatism (EULAR) Congress 2018; June 13-16, 2018; Amsterdam, The Netherlands. Abstract FRI0642.