Comparison of Enterococcus faecium and Enterococcus faecalis Strains Isolated from Water and Clinical Samples: Antimicrobial Susceptibility and Genetic Relationships

Abstract

Enterococci are part of the normal intestinal flora in a large number of mammals, and these microbes are currently used as indicators of fecal contamination in water and food for human consumption. These organisms are considered one of the primary causes of nosocomial and environmental infections due to their ability to survive in the environment and to their intrinsic resistance to antimicrobials. The aims of this study were to determine the biochemical patterns and antimicrobial susceptibilities of Enterococcus faecalis and E. faecium isolates from clinical samples and from water (groundwater, water from the Xochimilco wetland, and treated water from the Mexico City Metropolitan Area) and to determine the genetic relationships among these isolates. A total of 121 enterococcus strains were studied; 31 and 90 strains were isolated from clinical samples and water (groundwater, water from the Xochimilco wetland, and water for agricultural irrigation), respectively. Identification to the species level was performed using a multiplex PCR assay, and antimicrobial profiles were obtained using a commercial kit. Twenty-eight strains were analyzed by pulsed-field gel electrophoresis (PFGE). E. faecium strains isolated from water showed an atypical biochemical pattern. The clinical isolates showed higher resistance to antibiotics than those from water. Both the enterococci isolated from humans, and those isolated from water showed high genetic diversity according to the PFGE analysis, although some strains seemed to be closely related. In conclusion, enterococci isolated from humans and water are genetically different. However, water represents a potential route of transmission to the community and a source of antimicrobial resistance genes that may be readily transmitted to other, different bacterial species.

Horizontal transfer of antibiotic resistance from Enterococcus faecium of fermented meat origin to clinical isolates of E. faecium and Enterococcus faecalis

“…These results are consistent with previous work by Descheemaeker et al (1999) and Kim et al (2010) where a high level of genetic heterogeneity was observed between E. faecium strains from humans and animals. Similarly Castillo-Rojas et al (2013) also showed that enterococci isolated from humans and those isolated from the environment had high genetic diversity according to PFGE analysis. Thus it can be concluded that in spite of their heterogeneity there are some close relationships, and food might be a potential route for antibiotic resistance transfer to humans.…”

Carriage of Multidrug Resistant Enterococcus Faecium and Enterococcus Faecalis Among Apparently Healthy Humans

“…In our case, all the isolates exhibited typical metabolic reaction to key phenotypic characteristics investigated. For instance, the E. faecalis isolates were able to utilize sorbitol unlike the E. faecium strains, contrary to some reports (Teixeira et al, 1995;Castillo-Rojas et al, 2013). Typically, strains of E. faecium would not produce acid from sorbitol but Day et al (2001) showed that 16 out of 18 E. faecium isolates utilized sorbitol.…”

La evolución de la resistencia bacteriana en México, 1973-2013

“…Más recientemente, se estudió la relación entre Enterococcus spp. aislados de agua y de pacientes, y se observó que no existía similitud entre ellos y que los aislamientos clínicos presentaron mayor resistencia a los antibióticos que los provenientes del agua (63)(64)(65).…”