Efficiency of Hichrome Enterococcus faecium Agar in the Isolation of Enterococcus spp. and other Associated Bacterial Genera from Water

Abstract

Members of the genus Enterococcus are intestinal microorganisms that have been used as indicators for recreational water fecal contamination. They are opportunistic pathogens that have been associated with nosocomial infections, therefore, their isolation and identification is important for proper estimation of their count. Accordingly, this study was conducted to identify the efficiency of Hichrome Enterococcus faecium agar in isolating enterococci to better monitor their presence in recreational water samples. Ten water samples were collected, filtered, and spread on the chromogenic Hichrome Enterococcus faecium agar in an attempt to isolate Enterococcus spp. depending on its ability to grow on this medium and produce color as illustrated by Himedia company. Results showed the ability of this medium to select for Enterococcus spp., however, other non-enterococci genera were also capable of growing on this medium producing different colors that were not mentioned by Himedia company. Interestingly, some of these bacterial colonies were found to be Gram negative. Colonies were diagnosed by VITEK-2 system then further diagnosed by 16S rRNA gene sequencing. Our results, showed major differences in diagnosis between the two methods suggesting 16S rRNA gene sequencing for more precise identification. Antibiotic resistance of our environmentally isolated bacteria revealed the threat of antibiotic resistance spread among environmental bacteria with streptomycin being the highly resistant (64.2%) and chloramphenicol being the lowest (35.7%).