Abstract
Free-living amoebae (FLA) are ubiquitous in nature, whereas amoeba-resistant bacteria (ARB) have evolved virulent mechanisms that allow them to resist FLA digestion mechanisms and survive inside the amoeba during hostile environmental conditions. This study assessed the prevalence of FLA and ARB species in borehole water before and after a ceramic point-of-use intervention in rural households. A total of 529 water samples were collected over a five-month period from 82 households. All water samples were subjected to amoebal enrichment, bacterial isolation on selective media, and molecular identification using 16S PCR/sequencing to determine ARB species and 18S rRNA PCR/sequencing to determine FLA species present in the water samples before and after the ceramic pot intervention. Several FLA species including Acanthamoeba spp. and Mycobacterium spp. were isolated. The ceramic pot filter removed many of these microorganisms from the borehole water. However, design flaws could have been responsible for some FLA and ARB detected in the filtered water. FLA and their associated ARB are ubiquitous in borehole water, and some of these species might be potentially harmful and a health risk to vulnerable individuals. There is a need to do more investigations into the health risk of these organisms after point-of-use treatment.
Highlights
A total of 529 water samples consisting of 398 stored household water samples which were collected over the 5-month period and a total of 131 filtered water samples from the Potters for Peace (PFP) ceramic pot filter which were collected over the 3-month intervention period were included in the study for assessment
Electrical conductivity (EC) is a measure of the ability of water to conduct electricity, and this is directly dependent on the concentration of dissolved ions, which establishes a direct relationship between electrical conductivity (EC) and total dissolved salts (TDS) [63]
Several studies have shown that V. vermiformis is not just a pathogen on its own, it has been associated with numerous amoeba-resistant bacteria (ARB) species, including Mycobacteriae [157,158,159,160], Pseudomonas aeruginosa [161], and S. maltophilia [77,161], amongst others
Summary
Free-living amoebae (FLA) are ubiquitous in the natural environment (in biofilm; in water–soil, water–air, and water–plant interfaces) where they play an important part in nutrient and energy turnover by acting as bacterial population-controlling predators [1]. Free-living amoebae are part of a large polyphyletic group, with organisms ranging from non-pathogenic to pathogenic in humans [2,10]. Pathogenic FLA often lead to brain pathologies [11,12], such as granulomatous amoebic encephalitis (GAE) caused by Acanthamoeba spp. and Balamuthia mandrillaris, and primary amoebic meningoencephalitis (PAM) caused by Naegleria fowleri—many of these infections are fatal [13,14]. Acanthamoeba spp. and B. mandrillaris have been isolated from both skin and lung infections [11], Entamoeba histolytica (an enteric parasite) can cause amebiases, or liver abscesses [17] and is
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