In vitro antimicrobial efficacy of riboflavin-UVA for common bacteria in ophthalmology / 中华实验眼科杂志

ABSTRACT

Background Staphylococcus aureus,Staphylococcus epidermidis and Pseudomonas aeruginosa are common pathogenic bacteria in ophthalmology.To seek an optimal antimicrobial method is critical for the prevention of infection.Objective This study was to investigate the antimicrobial efficacy of riboflavin-ultraviolet A (UVA) on Staphylococcus aureus,Staphylococcus epidermidis and Pseudomonas aeruginosa.Methods Ten strains of frozen Staphylococcus aureus,Staphylococcus epidermidis and Pseudomonas aeruginosa were incubated to culture dishes and resuscitated for 2 times.The bacteria were put into bacterial dilution to prepare the suspension of 0.5 Mclntosh concentration and then the suspension was diluted 10-folds.UVA was used to irradiate the culture dishes added 0,0.1％,0.5％ riboflavin for 10,20,30 minutes with the exposure intensities of 1,2,3 mW/cm2,and the optimal bacteriostatic condition was evaluated by measuring the diameters of inhibition zone.Staphylococcus aureus,Staphylococcus epidermidis and Pseudomonas aeruginosa were divided into normal control group,riboflavin group,UVA group and photodynamic therapy (PDT) group (riboflavin+UVA),and colony forming unit was compared among the groups.Results The optional experimental conditions of PDT inactivating microorganisms were determined as UVA wavelength 370 nm,UVA exposure rate 3 mW/cn2,UVA exposure time 30 minutes and riboflavin 0.1％.The colony forming units were decreased in turn in the normal control group,riboflavin group,UVA group and PDT group (F =110.990,190.841,118.197,all at P =0.000).Compared with the normal control group,the colony forming units were significantly decreased in the UVA group (t =14.640,7.550,5.320,all at P＜0.05),and the colony forming units were significantly decreased in the PDT group (t =25.480,14.750,12.920,all at P＜0.05).The colony forming units decreased by 46.4％-50.2％ in the UVA group and 91.6％-96.7％ in the PDT group.There was no significant difference in colony forming units between the normal control group and the riboflavin group(t =0.660,0.470,0.510,all at P＞0.05).Conclusions PDT can effectively inactivate common bacteria in ophthalmology.This result suggests that PDT has a potential in the treatment of microbial keratitis.