Abstract
Purpose :
The Boston Keratoprosthesis (B-KPro) is an artificial cornea that can restore vision in patients with severe corneal diseases. Prophylactic low dose antibiotics drops postoperatively have greatly reduced bacterial infection rates. Thus, polymyxin B (PMB)/trimethoprim (TMP), fluoroquinolones (FQ), vancomycin (VAN), or chloramphenicol (CAF), with or without addition of benzalkonium chloride (BAK), have been the leading choices. However, there is still an unmet need for a similar prophylaxis against fungi. We have earlier found that on a regimen of Polytrim® (PMB 10,000 units/mL, TMP 1mg/mL, BAK 0.004%), one drop daily indefinitely, no fungal infections occurred in a cohort of KPro patients, whereas FQs allowed several infections (Behlau et al, 2014). Our aim is to explore the antifungal properties of antibiotics that are already being used to prevent bacterial endophthalmitis.
Methods :
Experiments were based on the Clinical and Laboratory Standards Institute methods for testing fungal species. ATCC strains of Candida albicans, Candida parapsilosis, Fusarium solani, and Aspergillus fumigatus were tested. Time kill tests and MIC’s were determined for the antibiotics and the preservative mentioned above. Growth and sterility controls were included.
Results :
Polytrim®, PMB, Zymaxid® (gatifloxacin with BAK), and BAK alone all exhibited some antifungal activity in vitro, with the exception that PMB had little effect against A. fumigatus. Of the brand name preparations, Polytrim® and Zymaxid® had similar antifungal effect. PMB and BAK seem to have additive effect against molds when combined. Vigamox® (moxifloxacin without BAK), TMP, VAN, and CAF had no effect.
Conclusions :
Polytrim® and Zymaxid® have antifungal killing effect that is mainly conferred by their BAK content. PMB also exhibited some antifungal effect, which may not be true for gatifloxacin alone. Polytrim® is by far the least expensive alternative and is therefore preferable. The results are consistent with our observations in B-KPro patients on a Polytrim® regimen, and suggest that this drug may suffice to prevent not only bacterial infections but also fungal ones. A clinical study of B-KPro with Polytrim® prophylaxis will be conducted in a country with high incidence of fungal infections.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.