The Microbiological Profile of Bicanalicular Silicone Tubes Placed During External Dacryocystorhinostomy

Objectives To identify microbiological growth on bicanalicular silicone tubes (BST) placed during dacryocystorhinostomy (DCR) surgery and to analyze the association between culture results and surgical outcomes and BST removal time. Materials and methods A total of 80 lacrimal drainage systems of 68 patients who had external DCR with bicanalicular silicone intubation were included the study. Twenty-five tubes (31.3%) were removed up to 8 weeks, 28 tubes (35.0%) were removed between 9 and 11 weeks, and the remaining 27 tubes (33.7%) were removed 12 weeks or more after surgery. The tubes were transferred to Stuart medium and sent for microbiologic examination. The disc diffusion method was used to determine antibiotic resistance. Results Culture positivity was observed for 96.2% of the tubes. Among a total of 109 isolates, 63 were gram-positive bacteria (57.8%), 37 were gram-negative bacteria (34%), and 9 were fungi (8.2%). The most commonly isolated gram-positive and gram-negative bacteria were Staphylococcus aureus (66.6%) and Enterobacter spp. (29.7%), respectively. Penicillin, clindamycin, erythromycin, and tetracycline resistances were higher among gram-positive pathogens. Cephalothin, amoxicillin-clavulanic acid, and ampicillin resistances were higher among gram-negative pathogens. There was no significant difference in terms of the microbiological profile between the three groups of removed tubes. Haemophilus influenzae was isolated at a significantly higher rate in patients with surgical failure (p=0.04). Conclusion Although a variety of agents were isolated from removed BST, gram-positive organisms were more frequent than gram-negatives and fungi. S. aureus and Enterobacter were the most common gram-positive and gram-negative isolates. Later BST removal was associated with the isolation of significantly more bacterial strains per tube. There was no correlation between multiple infections and surgical failure. H. influenzae was more common in failed DCR cases.