Diagnostic Performance of Leukocyte Count in Direct Microscopic Examination in the Diagnosis of Septic Arthritis

Abstract

In this study, the value of leukocyte count in the differential diagnosis of culture-negative septic arthritis was investigated. The study was designed retrospectively. Syno- vial fluid samples sent to Turhal State Hospital Microbiology Laboratory between July 2018 and November 2019 for direct microscopic examination for the differential diagnosis of arthritis were evaluated. In this study, patients who were admitted to Turhal State Hospital between July 2018 and November 2019 and were prediagnosed with septic arthritis and whose synovial fluid samples were sent to the microbiology laboratory for leukocyte count were examined. Synovial fluid samples were counted without centrifugation at 400X magnification under a light microscope in the cell counting chamber. For bacteria isolation, samples were planted on plates of 5% Sheep Blood agar (RDS, Turkey), Chocolate agar (RDS, Turkey) and Eosin Methylene Blue agar (RDS, Turkey) and incubated at 37°C for 24-48 hours. Twenty three (43.3%) of 53 patients included in the study with a pre-diagnosis of septic arthritis were accepted as septic arthritis. Leukocyte was not detected in four (7.5%) and were counted for less than 20,000 in 24 (45.3%), between 20,000-50,000 in nine (17%), between 50,000-100,000 in seven (13.2%), over 100,000 in nine (17%) of the samples. Only three (13%) patients were diagnosed with bacteria isolation. The correlation between high leukocyte count and bacterial isolation was statistically significant (p=0.031). Also, the correlation between the high leukocyte count and the decision to initiate empirical antibiotherapy was statistically significant (p<0.001). Microscopic synovial leukocyte count is a valuable diagnostic parameter for the diagnosis of septic arthritis in secondary healthcare institutions where diagnostic possibilities are limited and where automated culture systems are not available, especially in cases if the pathogen microorganism cannot grown in cultures.