Isolation and molecular characterization of free-living amoebae from different water sources in Italy.

Margherita Montalbano Di Filippo,Federica Berrilli,Maristella Santoro,Carla Calia,Luciana Fumarola,Carmen Capolongo,David Di Cave,Rosa Monno,Piero Lovreglio,Rossella D'Alfonso

doi:10.3390/ijerph120403417

Abstract

Free-living amoebae (FLA) are protozoa ubiquitous in Nature, isolated from a variety of environments worldwide. In addition to their natural distribution, some species have been found to be pathogenic to humans. In the present study a survey was conducted in order to evaluate the presence and to characterize at molecular level the isolates of amoebic organisms collected from different water sources in Italy. A total of 160 water samples were analyzed by culture and microscopic examination. FLA were found in 46 (28.7%) of the investigated water samples. Groundwater, well waters, and ornamental fountain waters were the sources with higher prevalence rates (85.7%, 50.0%, and 45.9%, respectively). Identification of FLA species/genotypes, based on the 18S rDNA regions, allowed to identify 18 (39.1%) Acanthamoeba isolates (genotypes T4 and T15) and 21 (45.6%) Vermamoeba vermiformis isolates. Other FLA species, including Vahlkampfia sp. and Naegleria spp., previously reported in Italy, were not recovered. The occurrence of potentially pathogenic free-living amoebae in habitats related to human population, as reported in the present study, supports the relevance of FLA as a potential health threat to humans.

Highlights

Free-living amoebae (FLA) are widespread protozoa not requiring a host organism for survival, having their natural habitats in the environment.Some of them may occasionally infect and cause diseases in humans and other animals [1].Currently, the causative agents of diseases in humans are classified as belonging to two super-groups: Amebozoa, including the genera Acanthamoeba, Balamuthia, Sappinia and Hartmannella, and Excavata, including the genus Naegleria [2,3]
Naegleria fowleri is responsible for primary amoebic meningoencephalitis (PAM), while some species of Acanthamoeba and Balamuthia mandrillaris induce granulomatous amoebic encephalitis (GAE), mainly in immunocompromised patients
A lower rate of positivity was obtained from thermal water (T) (33.3%), tap water (TW) (17.8%) and bottled mineral water (M) (15.8%)

Summary

Introduction

Some of them may occasionally infect and cause diseases in humans and other animals [1]. The causative agents of diseases in humans are classified as belonging to two super-groups: Amebozoa, including the genera Acanthamoeba, Balamuthia, Sappinia and Hartmannella, and Excavata, including the genus Naegleria [2,3]. Naegleria fowleri is responsible for primary amoebic meningoencephalitis (PAM), while some species of Acanthamoeba and Balamuthia mandrillaris induce granulomatous amoebic encephalitis (GAE), mainly in immunocompromised patients. Acanthamoeba species may give rise to a severe corneal infections designated as amoebic keratitis (AK). Several genotypes are described as the causative agent of different diseases, the genotypes T4, T3, and T11 are the most often associated with keratitis [5,6]. The species Hartmannella vermiformis, rarely associated with AK [7,8], has been renamed as Vermamoeba vermiformis, because its significant differentiation from all other Hartmannella species [2]

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