Isolation of amoebae of the genera Naegleria and Acanthamoeba from public fountains in Galicia (N.W. Spain)

Abstract

Tests for free-living amoebae in water from 11 public fountains in Galicia were conducted at two seasons of the year, winter and summer. Only one fountain gave a negative result for the presence of amoebae in both samples. Twenty five strains were isolated, 14 belonging to the genus Acanthamoeba and 10 to the genus Naegleria. The Acanthamoeba strains were made up of the species A. polyphaga, A. quina, A. castellanii and A. paradivionensis. No relation was found between temperature, presence of free chlorine in the water and whether the water was drinkable and the presence or absence of amoebae, nor with the number of strains present in the water samples. The pathogenic capacity of the strains isolated from the genera Naegleria and Acanthamoeba was tested in vivo. It was found that of the 22 strains that would grow at 37 °C, 4 (3 strains of Acanthamoeba and 1 of Naegleria) caused the death of a statistically significant number of mice that had been inoculated intracerebrally, and the presence of amoebae was confirmed in the brains of all the animals inoculated. Intranasal inoculation caused less mice deaths than intracerebral inoculation, and less organs were found containing amoebae.