Morphological, genotypic, and physiological characterization of Acanthamoeba isolates from keratitis patients and the domestic environment in Vitoria, Espírito Santo, Brazil

Abstract

Amoebae of the genus Acanthamoeba are free-living protozoa that can cause granulomatous encephalitis and keratitis in humans. In this study, four clinical and three household dust isolates obtained in Vitória, Espírito Santo, Brazil were characterized by their morphological, genotypic, and physiological properties. All isolates belonged to group II according to Pussard and Pons' cyst morphology. Analysis of their 18S rDNA sequence identified one isolate from household dust as genotype T11 and the others six samples as genotype T4. Five T4 isolates presented a highly variable region (DF3) in 18S rDNA identical to those previously described. Physiological assays carried out with trophozoites in co-culture with bacteria or in axenic conditions showed all samples tolerated temperatures up to 37°C, regardless of culture method. One keratitis isolate grew at 42°C in co-culture with bacteria. Most isolates in co-culture survived at 1.0M, except a T11 isolate, which tolerated up to 0.5M. The isolates did not grow at 42°C and did not tolerate 0.5M and 1.0M under axenic condition. This is the first report of 18S rRNA gene genotyping applied to Acanthamoeba isolated from keratitis patients in Brazil. The results also indicated that osmo-tolerance is dependent on the culture system.

Acanthamoeba containing endosymbiotic chlamydia isolated from hospital environments and its potential role in inflammatory exacerbation

“…Consistent with PCR results, 21 of these amoebae had morphological features identical to those of Acanthamoeba cysts, such as arm-like structures [13] (See Additional file 2). These results indicated that the amoebal enrichment method was very accurate with high sensitively, despite being time consuming.…”

“…Plates were then incubated at 30 °C. After 7 days of incubation, crawling amoebae with arm-like structures characteristic of Acanthamoeba cysts were isolated, according to a morphological assessment procedure [13]. Amoebae picked under microscopic observation from non-nutrient agar plates were then continuously grown in PYG broth to achieve axenic cultures.…”

Acanthamoeba keratitis related to contact lens use in a tertiary hospital in China

“…The result of genotyping analysis was consistent with our previous study [9] and other study in China [26] . Although the subtypes were different, the genotype T4 is still the main AK-related genotype in China, furthermore, genotype T4 is the predominant genotype in other countries and areas [27][28][29][30] .…”

Acanthamoeba keratitis related to contact lens use in a tertiary hospital in China

“…Although the subtypes differ, genotype T4 is still the main AK-related genotype in China; furthermore, genotype T4 is the predominant genotype in other countries and areas [27][28][29][30].…”