Riboflavin and ultraviolet A as adjuvant treatment against Acanthamoeba cysts

Abstract

Background Experimental studies have shown that the standard dose of R or R+UVA as solo treatment are not able to exterminate Acanthamoeba cysts or even trophozoites. The purpose of this study is to determine whether the application of R+UVA can enhance the cysticidal effects of cationic antiseptic agents in vitro. Methods The log of either polyhexamethylene biguanide (PHMB) or chlorhexidine minimal cysticidal concentration (MCC) in solutions containing riboflavin (concentrations 0.1 %; 0.05% and 0.025 %) plus either Acanthamoeba castellanii cysts or Acanthamoeba polyphaga cysts was determined and compared in groups treated with UVA 30 mW/cm2 for 30 min and in control groups (with no exposure to UVA). A permutation test was used to determine the P-value associated with treatment. Results Regardless of the riboflavin concentration and UVA treatment condition, no trophozoites were seen in plates where the cysts were previously exposed to cationic antiseptic agents concentrations ≥ 200 µg/mL for Acanthamoeba castellanii samples and ≥ 100 µg/mL for Acanthamoeba polyphaga samples. There was no statistical evidence that R+UVA treatment was associated with MCC (P = 0.82). Conclusion R+UVA in doses up to 10 times higher than recommended for corneal crosslinking does not enhance the cysticidal effect of either polyhexamethylene biguanide or chlorhexidine in vitro.

Acanthamoeba keratitis: a review of biology, pathophysiology and epidemiology

“…13 The combination of riboflavin (R) with ultraviolet-A radiation (UVA) should inactivate isolates of virus and bacteria, but the standard dose is not sufficient to eradicate Acanthamoeba cysts or trophozoites. 149 The success of this treatment depends on the depth at which the microorganisms lie, as if they are located at depths greater than 300 lm, then treatment is unsuccessful. 19 Photorefractive surgery has been used to remove a large corneal stromal abscess with laser phototherapeutic keratectomy.…”

High fluence PACK-CXL as adjuvant treatment for advanced Acanthamoeba keratitis

“…Despite these observations, there are reports of both in vivo and in vitro failure to eradicate Acanthamoeba with PACK-CXL given both as monotherapy 5 , 29 , and adjuvant to anti-amoebic treatment 30 , 31 . The former report, however, concerned an animal model, did not use PACK-CXL as adjuvant to medical therapy, and used the standard 5.4 J/cm 2 dose.…”

“…In our case, deterioration seemingly first came to a halt when 7.2 J/cm 2 was utilized adjuvant to the topical anti-amoebic therapy. An earlier study 30 , which came to the conclusion that the anti-amoebic properties solely relied on the concentrations of different anti-amoebic agents without any effect attributed to PACK-CXL, was performed in an in vitro setting. Although current anti-amoebic drugs show low minimal cysticidal concentrations (MCC) in vitro , the clinical correlation between MCC in vitro and those required in a clinical setting seems poor.…”

Treatment of corneal ulcers by local ultraviolet crosslinking (an experimental study)

“…Действительно, показано, что высокий индуцированный уровень оксидативного стресса -интенсивное Treatment of corneal ulcers by local ultraviolet crosslinking (an experimental study) Vladimir V. Neroev 1 , Elena V. Yani 1 , Elena N. Iomdina 1 , Inna P. Khoroshilova-Maslova 1 , Viktoriya A. Golikova 1  , Anton V. Kiryukhin 2 образование активных форм кислорода при УФА-кросслинкинге -необратимо разрушает ДНК и клеточные мембраны патогенных микроорганизмов, присутствующих в роговице, и останавливает их репликацию [19,20]. Антимикробная эффективность УФА (365 нм) в комбинации с рибофлавином была выявлена in vitro в отношении бактерий и грибов, Acanthamoeba (цист и трофозоитов), а также S. aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, S. aureus (MRSA), P. aeruginosa, Streptococcus pneumoniaе [20][21][22][23][24][25][26].…”