Differential Antimicrobial Efficacy of Preservative-Free Contact Lens Disinfection Systems against Common Ocular Pathogens

Abstract

Understanding the most efficacious products will allow clinicians to best communicate to patients and consumers the safest products on the market to reduce adverse events, including microbial keratitis, during contact lens use.

Acanthamoeba spp. aggregate and encyst on contact lens material increasing resistance to disinfection

“…To determine MPS disinfection efficacy of Acanthamoeba in different cellular formations ( Figure 7 ), Acanthamoeba were assessed for biocide resistance in either trophozoite, cyst, or spheroid forms after cells had been allowed to adhere (or aggregate) in plates for 12 or 24 h ( Figure 11 ). Consistent with published findings ( Gabriel et al, 2019 ; Walters et al, 2022 ), cells in the trophozoite form were the most susceptible to MPS biocides while cysts were significantly more challenging to disinfect. PAPB/PQ showed little ability to kill any form, with 100% survival for spheroids and cysts across all cell concentrations.…”

“…As previously described ( Walters et al, 2022 ), trophozoites were axenically cultured in AC6 media (axenic culture medium, containing 20 g biosate peptone, 5 g glucose, 0.3 g KH 2 PO 4 , 10 μg vitamin B12, and 15 mg L-methionine per liter of distilled deionized water). Media was adjusted to a pH of 6.6–6.95 with 1 M NaOH and autoclaved at 121°C for 20 min before storing at room temperature for use within 3 months.…”

“…Spheroid age was between 2 and 72 h depending on the images. Prior to aggregation experiments, control trophozoites and cysts [pre-generated separately via starvation ( Walters et al, 2022 )] were stained to verify stain response to cells. No control cells were added to aggregation experiments.…”

“…Acanthamoeba exists either in the motile, infective trophozoite form or as the more resistant, persistent cyst form, which can remain viable for years ( Mazur et al, 1995 ; Siddiqui and Khan, 2012 ). Cysts are notoriously difficult to eradicate versus the trophozoite form, and have been shown to be impervious to most disinfection methods that do not involve hydrogen peroxide or povidone iodine ( Johnston et al, 2009 ; Coulon et al, 2010 ; Ahearn et al, 2012 ; Walters et al, 2022 ). While not generally considered a social amoebae like Dictyostelium , which can become a multicellular structure during their lifecycle, Acanthamoeba has been shown in the literature as forming clumps of cysts.…”

The Activity of PHMB and Other Guanidino Containing Compounds against Acanthamoeba and Other Ocular Pathogens

“…However, in commercially available MPS, activity is variable even in solutions containing similar formulations of antimicrobial agents [ 6 , 7 , 8 , 9 ]. To overcome this issue, there are newer formulations of MPS, including ACUVUE™ RevitaLens (JnJvision, Jacksonville, FL, USA), which combines the biguanide alexidine with the quaternary ammonium compound polyquaternium-1 (PQ-1), and Biotrue ® (Bausch & Lomb, Rochester, NY, USA), which combines the polyaminopropyl-biguanide (PAPB) with PQ-1 to increase antimicrobial activity.…”