Evaluate the culture positivity of Acanthamoeba in contact lenses, lens cases, lens cases solutions and plungers as potentials sources for Acanthamoeba keratitis investigation

Abstract

Purpose : To investigate the culture positivity of Acanthamoeba in contact lenses, lens cases, lens cases solutions, and plungers to determine whether these would be potential sources for Acanthamoeba investigation in patients suspected of Acanthamoeba keratitis.

Methods : Scleral contact lenses (ScCL), non-scleral contact lenses (NScCL), lens cases, lens cases solutions, plungers, and cornea scrapings collected from patients suspected of Acanthamoeba keratitis (AK) underwent culture. The culture was carried out in 1.5% non-nutrient agar with a drop of heat-inactivated Escherichia coli (DH5a). Contact lenses were deposited onto the agar with an optical zone upwards, and the lens cases and plungers were washed with sterile phosphate-buffered saline (PBS) which was also placed in agar. Any additional solution stored in the case was also cultured. The samples were incubated at 28°C to 30°C for 20 days, and the cultures were checked for positivity through optical microscopy.

Results : Data of 724 cultures from 279 patients (173 females and 106 males, average age of 34 years) collected between July 1988 and April 2022 were analyzed. From the total, 400 were contact lenses and paraphernalia (338 NScCL, 14 ScCL, 13 lens cases, 29 lens cases solutions, and 6 plungers), and 324 were corneal scraping. We observed positive cultures in 31.4% of NScCL, 35.8% of ScCL, 46.2% of the lens case, 41.4% of the lens cases solutions, 16.7% of plungers, and 26.3% of corneal cultures (figure 1). Of these, 22.3% were positive for both cornea and contact lenses/paraphernalia; 46.2% were negative for both; 14.7% were negative for contact lenses/paraphernalia and positive for cornea scraping, and 17% were positive for contact lenses/paraphernalia and negative for cornea scraping (figure 2).

Conclusions : The present study suggests that the culture of contact lenses and paraphernalia may be helpful to further investigate Acanthamoeba keratitis since it revealed a high culture positivity for Acanthamoeba and was determinant to detect Acanthamoeba in almost 17% of the cornea scraping negative culture.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.

 

Figure 1. Acanthamoeba percentage in contact lenses, contact lenses paraphernalia, and cornea samples.

 

Figure 2. Acanthamoeba percentage in contact lenses/paraphernalia and cornea samples.