Bacterial flora of the ocular fornix in patients with lacrimal silicone tubes

O R I G I N A L A R T I C L E ANN OPHTHALMOL. 2001;33(1):31–34 31 Reprints: Riad Ma’luf, MD, Department of Ophthalmology, American University of Beirut Medical Center, 113-6044, Beirut, Lebanon. Drs. Ma’luf and Noureddin are from the Department of Ophthalmology, Dr. Dbaibo is from the Department of Pediatrics, and Dr. Araj is from the Department of Pathology and Laboratory Medicine, American University of Beirut Medical Center, Beirut, Lebanon. Acknowledgment Supported in part by a grant from the Lebanese National Council for Scientific Research. The traditional management to acquired naso-lacrimal duct obstruction requires a dacryocys- torhinostomy (DCR), in which the lacrimal sac is directly fistulized to the nasal cavity. This is done using either the external approach or the intranasal endoscopic approach. Most of the time, both tech- niques are supplemented by the use of a silicone tube. The insertion of a silicone tube into the lacrimal drainage system during a DCR may prevent postoper- ative obstructions by securing an open pathway dur- ing the healing process.1 Some authors also find that silicone intubation facilitates surgery in cases with excessive intraoperative bleeding or nasal mucosal tears and also simplifies postoperative follow-up.2 The tube is kept in place for an average of 6 months. Some of these patients might need intraocular surgery dur- ing the 6-month period. For example, they may have initially presented because of cataract and decreased visual acuity but were found to have an additional obstruction in the nasolacrimal duct that had to be corrected first. The tube, which is inserted with a regular DCR, acts as a foreign body and a direct conduit between the nasal cavity and the ocular fornix. Elective intraoc- ular surgery is generally postponed until after tube removal because of concern about an increased risk of infectious complications due to possible colonization with potential pathogens. Riad Ma’luf, MD, Ghassan Dbaibo, MD, George F. Araj, PhD, & Baha’ Noureddin, MD Bacterial Flora of the Ocular Fornix in Patients With Lacrimal Silicone Tubes We assessed the impact of a lacrimal silicone tube inserted during dacryocystorhinostomy on the bacterial flora of the ocular fornix in 20 patients. At the time of tube removal we cultured the ipsilateral and contralateral fornices in addition to the part of the tube adja- cent to the fornix. Coagulase-negative staphylococci were isolated from the fornices containing the tube in 18 out of 20 patients (90%). These findings indicate that the presence of the silicone tube does not result in colonization by new bacteria. A B S T R A C T ANN OPHTHALMOL. 2001;33(1)32 This study was aimed at examining the impact of silicone tube placement on the bacterial flora of the conjunctiva in order to determine whether this con- cern is justified. Patients & Methods Twenty patients who underwent a unilateral DCR and insertion of a silicone tube were studied at the 6-month postoperative follow-up, when the tube was removed. All patients enrolled in the study were free of tearing and discharge. None of the patients had been using any topical medication for the past 3 months. Topical anesthesia was not used upon sampling for culture to avoid an inhibitory effect on bacterial growth. A 1-cm piece of the tube adjacent to the fornix was cut using a sterile forceps and scissors. A sample was obtained by passing a sterile, moistened cotton swab back and forth twice along each of the following sites: the external part of the cut piece of tube, the ipsilateral fornix, and the contralateral fornix. Care was taken to avoid the eyelid margin and the eyelash- es during sampling from the fornices. The cut piece of tube and the 3 cotton swabs were placed in separate thioglycolate media and were sent to the laboratory. Processing of the specimens was done within 1 hour of sampling. All handling, process- ing of cultures, recovery, and identification of aerobic and anaerobic bacteria were done according to estab- lished procedures.3 Results A total of 80 cultures were taken from 40 eyes of 20 patients. The bacterial species recovered from each sampled site are listed in Table 1. The predominant bacteria isolated from the fornices containing the tube were coagulase-negative staphylococci in 18 (90%) of 20 cultures. Diphtheroids were isolated from the fornix culture of 1 patient. Nonenterococcal group D streptococci also were isolated from the culture of 1 of the patients. Results of the tube cultures were all iden- tical to the ipsilateral fornix cultures except in 1 patient, whose tube culture yielded Serratia marcescens and Streptococcus viridans, whereas the ipsilateral fornix culture showed coagulase-negative staphylococci. From this same patient, the swab taken from the tube revealed no bacterial organisms. In most cases, the cultures taken from the con- tralateral fornix of the eye without the tube were iden- tical to the cultures taken from the fornix adjacent to the tube. Discussion Different studies have shown that the types of microorganisms recovered from the conjunctiva of healthy individuals are consistent and similar throughout the world.4-6 The microorganisms recov- ered from the conjunctival cultures in these studies were also identical to those recovered from the sur- rounding skin. This suggests that the eye has no true microflora of its own but that the organisms present are contaminants from the skin of the adjacent eye- lid.5,7 Generally, the most common bacterial species isolated from these sites were Staphylococcus epider- midis and diphtheroids, with Propionibacterium species being the predominant anaerobic bacteria.5,6 In neonates, Escherichia coli and Streptococcus species may be present in large numbers but usually cause no localized infection.8 These are replaced in a few months by the bacterial pattern seen in adults. Studies performed on the normal flora revealed no dif- ference between males and females or between the right and left eyes.5 No statistically significant season- al variation was found; however, both the climate and the geographic area are important factors.9 Other fac- tors that also appear to influence the conjunctival flora include hospitalization,10 severe burns,4 or immunocompromised states,11 and these conditions result in colonization with Staphylococcus aureus and/or gram-negative bacilli. Soft contact lens wear was not found to result in colonization by new flora.7 In the event that silicone tubes, regularly inserted after DCR, should have any effect on the conjunctival bacterial flora, one would expect a change toward the flora of the nose and the nasopharynx. Studies have shown that the most commonly isolated organisms from the nose and the nasopharynx of healthy sub- jects are Staphylococcus aureus and hemolytic strep- tococci.12,13 The cultures of the conjunctiva obtained in our study are compatible with the normal conjunctival flora as described in the literature, with the predomi- nance of coagulase-negative staphylococci, namely, S epidermidis.5 This suggests that the presence of the tube for 6 months and its significance as a direct con- duit between the nasal cavity and the ocular fornix does not appear to result in colonization by new flora. In addition, the presence of the tube on 1 side did not result in a difference between the cultures obtained from the 2 opposite fornices. This fact also supports the observation that the tube plays no role in altering the flora. However, it does not exclude the possibility of hand-eye contact and contamination from the ipsi- lateral fornix. In only 1 of our patients, cultures of the tube and not the conjunctiva yielded S marcescens and S viri- dans. The latter is commonly isolated in cultures of the nose and nasopharynx in healthy subjects.12,13 In this isolated case, the most likely route of colonization of the catheter appears to be from the nose via the length of the tube. However, despite colonization of the tube, the conjunctiva was not affected. The volume of culture material was not determined in this study, and hence, the results cannot be consid- ered quantitative. This would have been necessary had we observed any qualitative shiftin the conjuncti- val flora. In conclusion, the above findings suggest that the presence of a lacrimal silicone tube does not result in colonization by new bacteria, which might have increased the risk of any intraocular procedure if done during the period when the tube was in place. Thus, ANN OPHTHALMOL. 2001;33(1) 33 the preoperative preparation of a conjunctival fornix with a lacrimal tube, in case an intraocular procedure is to be done, should not be different from the routine preparation. T A B L E 1 Culture Results Obtained From Silicone Tube and Conjunctival Fornices Patient No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Coagulase-neg. staph. indicates coagulase-negative staphylococci. Tube Coagulase-neg. staph. Coagulase-neg. staph. Coagulase-neg. staph. Nonenterococcal group D streptococci Coagulase-neg. staph. Coagulase-neg. staph., diphtheroids Coagulase-neg. staph. Coagulase-neg. staph. Coagulase-neg. staph. Coagulase-neg. staph. Coagulase-neg. staph. Serratia marcescens, Streptococcus viridans Coagulase-neg. staph. Coagulase-neg. staph. Coagulase-neg. staph. Coagulase-neg. staph. Coagulase-neg. staph. Coagulase-neg. staph. Coagulase-neg. staph. Coagulase-neg. staph. Swab From Tube No growth Coagulase-neg. staph. Coagulase-neg. staph. Nonenterococcal group D streptococci Coagulase-neg. staph. Diphtheroids No growth Coagulase-neg. staph. Coagulase-neg. staph. Coagulase-neg. staph. Coagulase-neg. staph. No growth Coagulase-neg. staph. Coagulase-neg. staph. Coagulase-neg. staph. Coagulase-neg. staph. No growth Coagulase-neg. staph. Coagulase-neg. staph. Coagulase-neg. staph. Ipsilateral Fornix Coagulase-neg. staph. Coagulase-neg. staph. Coagulase-neg. staph. Nonenterococcal group D streptococci Coagulase-neg. staph. Diphtheroids Coagulase-neg. staph. Coagulase-neg. staph. Coagulase-neg. staph. Coagulase-neg. staph. Coagulase-neg. staph. Coagulase-neg. staph. Coagulase-neg. staph. Coagulase-neg. staph. Coagulase-neg. staph. Coagulase-neg. staph. Coagulase-neg. staph. Coagulase-neg. staph. Coagulase-neg. staph. Coagulase-neg. staph. Contralateral Fornix Coagulase-neg. staph. Coagulase-neg. staph. Coagulase-neg. staph., Proteus vulgaris Nonenterococcal group D streptococci, coagulase-neg. staph. Coagulase-neg. staph. Coagulase-neg. staph., diphtheroids Coagulase-neg. staph. Coagulase-neg. staph. Coagulase-neg. staph. Coagulase-neg. staph. Coagulase-neg. staph. Coagulase-neg. staph. Coagulase-neg. staph. Coagulase-neg. staph. Coagulase-neg. staph. Coagulase-neg. staph. Coagulase-neg. staph. Coagulase-neg. staph. Coagulase-neg. staph. Coagulase-neg. staph. ANN OPHTHALMOL. 2001;33(1)34 References 1. Older JJ. Routine use of silicone stent in dacryocystorhinostomy. Ophthalmic Surg 1982;3:911–915. 2. Rosen N, Sharir M, Moverman D, et al. Dacryocystorhinostomy with silicone tubes: evaluation of 253 cases. Ophthalmic Surg. 1989;20:115–119. 3. Balows A, Hausler WJ, Herrmann K, et al. Manual of Clinical Microbiology. 5th ed. Washington, DC: American Society for Microbiology; 1991. 4. Pramhus C, Runyan T, Lindberg R. Ocular flora in the severely burned patient. Arch Ophthalmol. 1978; 96:1421–1424. 5. Tabbara K, Hyndiuk R. Infections of the Eye. 2nd ed. Boston, Mass: Little Brown & Co; 1996:69–151. 6. 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