Acanthamoeba spp. in Contact Lenses from Healthy Individuals from Madrid, Spain
Thiago Dos Santos Gomes1,2, Angela Magnet1, Fernando Izquierdo1
1Facultad de Farmacia, Universidad San Pablo CEU, Urbanización Montepríncipe, Alcorcón, Madrid, Spain.
Purpose:
Acanthamoeba keratitis (AK) is a painful and potentially blinding corneal infection caused by Acanthamoeba spp. In Madrid, environmental studies have demonstrated a high presence of these free-living amoebae in tap water. Since most of AK cases occur in contact lenses (CL) wearers with inadequate hygiene habits, the presence of Acanthamoeba in discarded CL has been studied and compared with other common etiological agents of keratitis, such as Pseudomonas aeruginosa and Staphylococcus aureus.
Methods:
One hundred and seventy-seven healthy individuals from Madrid contributed their discarded CL and answered a questionnaire on hygiene habits. DNA was extracted from the CL solution and analyzed by real-time PCR for Acanthamoeba, Pseudomonas aeruginosa and Staphylococcus aureus. These CL and their solutions were also cultured on non-nutrient agar to isolate Acanthamoeba.
Results:
Among the 177 samples, Acanthamoeba DNA was detected in 87 (49.2%), P. aeruginosa DNA in 14 (7.9%) and S. aureus DNA in 19 (10.7%). Cultivable amoebae, however, were observed in only one sample (0.6%). This isolate was genotyped as T4. The habits reported by this CL owner included some recognized risk factors for AK, but in this study only the practice of "not cleaning the CL case" presented some statistical significant association with Acanthamoeba DNA presence. Detection of the investigated bacterial DNA did not demonstrate statistical significant association with the studied practices, but the presence of P. aeruginosa revealed a possible inhibition of Acanthamoeba in these samples.
Conclusions:
The PCR results suggest a high presence of Acanthamoeba spp. in healthy CL wearers from Madrid, but we can assume that CL solutions are properly disinfecting the CL since only 1.1% of the positive PCR samples correspond to viable amoebae and, after four years, only one participant reported stronger ocular problems. Nevertheless, more studies are necessary to corroborate this hypothesis.
Insights
Acanthamoeba DNA is common in discarded contact lenses (CL) in Madrid, but viable amoebae are rare, suggesting CL solutions may prevent infection. Poor CL case hygiene is linked to Acanthamoeba presence.
Area of Science:
- Ophthalmology
- Microbiology
- Public Health
Background:
- Acanthamoeba keratitis (AK) is a severe eye infection linked to Acanthamoeba species.
- Environmental studies in Madrid show high Acanthamoeba presence in tap water.
- Contact lens wearers with poor hygiene are at increased risk for AK.
Purpose of the Study:
- To investigate the presence and prevalence of Acanthamoeba in discarded contact lenses (CL) from Madrid wearers.
- To compare Acanthamoeba detection with common keratitis pathogens like Pseudomonas aeruginosa and Staphylococcus aureus.
- To identify potential associations between CL hygiene habits and Acanthamoeba presence.
Main Methods:
- 177 healthy CL wearers in Madrid provided discarded CL and hygiene data.
- Real-time PCR was used to detect DNA of Acanthamoeba, P. aeruginosa, and S. aureus.
- CL solutions were cultured for Acanthamoeba isolation and genotyping.
Main Results:
- Acanthamoeba DNA was detected in 49.2% of samples, P. aeruginosa in 7.9%, and S. aureus in 10.7%.
- Cultivable Acanthamoeba was found in only 0.6% of samples (T4 genotype).
- Not cleaning the CL case showed a significant association with Acanthamoeba DNA presence.
Conclusions:
- High Acanthamoeba DNA prevalence in CL wearers suggests environmental exposure.
- Low viable amoeba counts indicate effective disinfection by CL solutions.
- Further research is needed to confirm the protective role of CL disinfection against AK.
