Evaluation of vitreous Procalcitonin as a diagnostic biomarker in infectious endophthalmitis.

Background: Endophthalmitis is a potentially blinding intraocular infection following intraocular surgery or trauma. Prompt diagnosis and treatment are important in preventing devastating visual complications. Procalcitonin (PCT) is a promising biomarker for diagnosing bacterial infections. The aim of the study was to measure vitreous PCT in infectious endophthalmitis and assess its utility as a biomarker.

Methods: In this prospective study, vitreous was collected from patients with non-infectious retinal disorders and infectious endophthalmitis. PCT was measured using the Human Procalcitonin ELISA Kit. The diagnostic performance of PCT was calculated via receiver operating characteristic curves.

Results: The study included three groups: patients with non-infectious retinal conditions, culture-positive endophthalmitis, and culture-negative endophthalmitis. The average PCT was 75.74 ± 26.8 pg mL, 100.24 ± 12.9 pg mL, and 126.41 ± 26.47 pg mL in control, culture-negative, and culture-positive endophthalmitis, respectively. There was a significant difference in the vitreous PCT in the study and control groups (p = 0.04), but not between culture-positive and culture-negative endophthalmitis (p = 0.65). The sensitivity (66.7%) and specificity (65%) for PCT with a cut-off of ≤ 54.88 pg mL(p = 0.31) implied that its diagnostic accuracy was not significant. But there was a significant difference in gram-negative (68.2 ± 16.5 pg mL) and gram-positive (175.09 ± 45 pg mL) (p = 0.02) bacterial infections; the sensitivity and specificity were 70%, with a cut-off of ≤ 82.3 pg mL.

Conclusions: This study showed that vitreous procalcitonin concentration might not be a suitable biomarker for diagnosing culture-negative endophthalmitis though it could help distinguish between gram-positive and gram-negative infections.