Advantages of using mitochondrial 16S rDNA sequences to classify clinical isolates of Acanthamoeba.

Purpose: This work was intended to test the classification of Acanthamoeba into genotypes based on nuclear ribosomal RNA gene (18S rDNA, Rns) sequences. Nearly all Acanthamoeba keratitis (AK) isolates are genotype RnsT4. This marked phylogenetic localization is presumably either due to an innate potential for pathogenicity or to a peculiarity of the gene sequences used.

Use of subgenic 18S ribosomal DNA PCR and sequencing for genus and genotype identification of acanthamoebae from humans with keratitis and from sewage sludge.

This study identified subgenic PCR amplimers from 18S rDNA that were (i) highly specific for the genus Acanthamoeba, (ii) obtainable from all known genotypes, and (iii) useful for identification of individual genotypes. A 423- to 551-bp Acanthamoeba-specific amplimer ASA.S1 obtained with primers JDP1 and JDP2 was the most reliable for purposes i and ii.

Unusual case of Acanthamoeba polyphaga and Pseudomonas aeruginosa keratitis in a contact lens wearer from Gauteng, South Africa.

Acanthamoeba species can cause a chronic, progressive ulcerative keratitis of the eye which is not responsive to the usual antimicrobial therapy and is frequently mistaken for stromal herpes keratitis. An unusual case of coinfection with Acanthamoeba polyphaga and Pseudomonas aeruginosa as causes of corneal keratitis in a contact lens wearer from Gauteng, South Africa, is reported. These two pathogens have previously been assumed to be selectively exclusive.

Anti-Acanthamoeba activity of contact lens solutions.

Aims: This study was undertaken to investigate the effects of contact lens disinfecting solutions on strains of Acanthamoeba from the United Kingdom and southern Africa and to compare the results with those of other researchers. No information was previously available for southern African isolates.

Methods: 11 contact lens solutions were tested on cysts of 10 strains of Acanthamoeba.

Cytopathogenicity of clinical and environmental Acanthamoeba isolates for two mammalian cell lines.

The cytopathic effect (CPE) of southern African, British, and an Asian strain of Acanthamoeba was assessed using a system developed around 2 different mammalian cell (MC) lines. The time taken by the amebae to destroy cell cultures completely was shown to be dependent largely on the size of the amebic inoculum and the cell type. This highlights the need to assess carefully the behavior of cell lines prior to using them for cytopathic testing.

Anti-Mastigina activities of eight contact lens solutions.

The effects of eight contact lens solutions on a Mastigina sp., which was associated with the infected eye of a patient, were studied. The solutions which killed the organism promptly were those which are used for gas-permeable and hard contact lenses.