Biofilm formation and its effect on the management of culture-positive bacterial endophthalmitis

ABSTRACT

Purpose: To compare the clinicomicrobiological features and outcomes in patients with infectious endophthalmitis caused by biofilm?positive (BP) and biofilm?negative (BN) bacteria. Methods: This was a prospective, interventional, comparative, nonrandomized, consecutive case series. Culture?positive bacterial endophthalmitis cases from August 1, 2018 to July 31st 31, 2019 were included. All vitreous samples were tested for biofilm using crystal violet plate and XTT (2,3?bis?(2?methoxy?4?nitro?5?sulfophenyl)?2H?tetrazolium?5?carboxanilide) methods and classified as BN and BP. The antibiotic susceptibility of all organisms was determined. Anatomic and functional success was defined as intraocular pressure >5 mm Hg and final best?corrected vision ?20/400, respectively, at last visit. Results: There were 50 eyes in the BN group and 33 eyes in the BP group. BN group eyes required 2.86 ± 1.45 surgical interventions, and BP group eyes needed surgical 6.36 ± 2.89 interventions, P < 0.0001, 95% Confidence Interval, CI 2–4. Median follow?up was 6 and 5 months, respectively (P = 0.33). Final logMAR vision was a median of 1.2 and 1.9 respectively; P = 0.0005, 95% C.I. 0.4–1.7. Functional success was achieved in 44% and 21.2% (P = 0.03, 95% C.I. 1.86%–40.08%) and anatomic success was achieved in 68% and 42.42%, respectively (P = 0.02, 95% C.I. 3.85%–45.47%). The antimicrobial resistance patterns between the two groups were comparable. Conclusion: Endophthalmitis caused by the biofilm?forming bacteria needs a greater number of surgical interventions. The anatomic and functional outcomes are poorer than non?biofilm?forming bacterial endophthalmitis. The increased virulence and poorer outcomes can be hypothesized to be due to the physical barrier effect of the biofilm on the antibiotics