Evaluation of vitreous Procalcitonin as a diagnostic biomarker in infectious endophthalmitis

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.

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.

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^-1, 100.24 ± 12.9 pg mL^-1, and 126.41 ± 26.47 pg mL^-1 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^-1(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^-1) and gram-positive (175.09 ± 45 pg mL^-1) (p = 0.02) bacterial infections; the sensitivity and specificity were 70%, with a cut-off of ≤ 82.3 pg mL^-1.

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.