Patients who have septic arthritis show significantly higher white blood cell count compared with patients who have gout, according to presented results. In a retrospective case series, Amer and colleagues studied the significant differences in the knee aspirate white blood cell count (WBC), ESR and C-reactive proteins (CRP) in patients with a potential diagnosis of septic knees that also had crystal arthropathies.
Researchers included patients who were suspected of having septic arthritis of the knee and had data on knee joint aspirates during a 10-year period. Patient records were used for age, gender, diagnosis, joint aspiration WBC count, ESR, CRP and procalcitonin, when available. If multiple aspirates were available, researchers analyzed the values from the first encounter. Patients with non-native knees and those younger than 18 years were excluded from the study. Investigators defined the presence of septic arthritis as growth of any organism cultured from knee aspirates.
Overall, 98 knee aspirates were included, with 69% of the cohort being from male patients. Patients with septic arthritis showed significantly higher synovial fluid WBC counts (55,591.2 cells/mm3) compared to patients with gout (32,420.9 cells/mm3). Staphylococcus aureus was the most common pathogen cultured as it was seen in 25% of patients.
Amer said analysis for procalcitonin could not be performed as there were no patients with a non-zero procalcitonin value. Additionally, no patients in the database had concomitant crystal arthropathy and septic arthritis.
Source: Amer KM, et al. Paper 2856. Presented at: Virtual EFORT Congress; Oct. 28-30, 2020, Healio