Acanthamoeba keratitis: 8 years survey with Broad-range real-time PCR and culture

Abstract

 

Purpose

 

Protozoa are found in freshwater, swimming pools, thermal baths, air-conditioning filters, earth, contact lenses (CL) and in CL cleansing solutions. Misuse of CL solutions, lack of CL rubbing, showering with CL and ocular trauma or corneal abrasion are associated with Acanthamoeba keratitis (AK) pathogenesis, triggered by the loss of corneal epithelia integrity. Increased incidence of AK related to the Protozoa Acanthamoeba (A) has garnered much attention in the United States, Australia, New Zealand, Singapore and India. The majority of cases in emerging nations occurred in non-contact lens wearers. Specimens from patients with keratitis were tested with the broad-range Acanthamoeba Taqman real-time PCR (Br-rtPCR) in a survey performed between 2005 and 2012 in a referral eye-center in Paris. The results were confronted with cultures of CLC.

 

Methods

 

CL and CL cases (CLC) were co-cultivated with inactivated Enterobacteria not producing extracellular mucoid capsules (that impede phagocytosis). DNA was extracted after procedures validated for cyst lysis from scrapings and tested with the A Br-rtPCR using selected primers and highly specific fluorogenic probes.

 

Results

 

Table 1: CL and CLC A-cultures (c); Positive (+). Table 2: A Br-rtPCR; corneal scrapings (CS); Male (M); Female (F); Positive(+). For CL users with signs of K the rates + A CLC cultures (c) ranged between 4 and 7%. For the same population results of + Br-rtPCR range between 2 and 6% for M and 1 and 8.2% for F

 

Conclusions

 

The association between + A c (CLC) and + A Br-rtPCR (CS) is not statistically significant. A CLC c were positive in subjects with atypical AK lesions responding irreversibly to antibiotic treatments (72 h, fluoroquinolon+ aminoglycoside). Considering that + A CLC c do not warrant AK diagnosis, CS for Br-rtPCR should be held in higher consideration when facing CL users, trauma or patients exhibiting herpetic-like lesions associated with infiltrates, especially with disproportionate ocular pain in respect to the objective clinical picture.

 

 

Keywords: 402 Acanthamoeba • 573 keratitis • 477 contact lens