Characterization of enterococci populations collected from a subsurface flow constructed wetland

Abstract

Aims: The aim of this study was to identify and characterize the population of Enterococcus sp. in domestic wastewater as it flows through a constructed wetland. Methods and Results: Four hundred and eighty‐four Enterococcus isolates were collected from the inlet, various sites within and from the outlet of a plastic lined constructed wetland in College Station, TX. The wetland treated septic tank effluent that passed sequentially through two 1·89 m3 septic tanks and a 1·89 m3 pump tank allowing 48 l doses at a 24 l min−1 rate. The Enterococcus isolates were identified to species using the commercial Biolog system. The 484 Enterococcus isolates were comprised of ten different species, including Enterococcus faecalis (30·6%), Enterococcus pseudoavium (24·0%), Enterococcus casseliflavus (12·8%), Enterococcus faecium (11·2%), Enterococcus mundtii (7·9%), Enterococcus gallinarum (6·2%), Enterococcus dispar (3·7%), Enterococcus hirae (2·1%), Enterococcus durans and Enterococcus flavescens both 0·8%. Of the 88 isolates collected from the inlet, only 9·1% of the isolates were identified as Ent. faecalis and Ent. pseudoavium (36·4%) was identified as the predominant species. Whereas of the 74 isolates collected from the outlet, the predominant species were identified as Ent. faecalis (29·7%). Species identification varied among sites within the wetland, but often Ent. faecalis was the predominant species. Conclusions: Our data suggest that while Ent. faecalis is the predominant species of Enterococcus found in domestic wastewater, the populations may shift during treatment as the wastewater flows through the constructed wetland. Significance and Impact of the Study: We found that shifts in Enterococcus species composition occurred during domestic wastewater treatment. This has implications for the identification of faecal pollution based on the presence of specific bacterial types associated with domestic wastewater.

Multiple antibiotic-resistance of Enterococcus isolated from coastal water near an outfall in Brazil

“…In this study, the species E. faecalis and E. faecium were the most frequently isolated. This result is similar to those obtained by Graves and Weaver (2010), who reported a diversity of ten species of Enterococcus (E. faecalis -30.6%; Enterococcus pseudoavium -24%, Enterococcus casseliflavus -12.8%; E. faecium -11.2%, E. mundtii 7.9%, Enterococcus gallinarum -6.2%; E. dispar -3.7%; Enterococcus hirae -2.1%, Enterococcus durans -0.8% and Enterococcus flavescens -0.8%) in water samples in a wetland close to College Station, Texas. According to the authors, the distribution of these species depends on environmental factors and specific points and sources of the sewer system.…”

Occurrence, diversity, and persistence of antibiotic resistant enterococci in full-scale constructed wetlands treating urban wastewater in Sicily

“…An increase of enterococci counts was observed, both in CW2 and CW3 effluents sampled in May. The observed slight decrease in all effluents is in agreement with previous studies (Graves and Weaver, 2010;Martins da Costa et al, 2006), confirming that conventional wastewater treatments are not able to efficiently remove these microorganisms. Furthermore different persistence rates (calculated as percentage ratio between inlet and outlet loads) were detected in the three effluents, with values ranging from 86% to 67% in the CW1; from 86% to 50% in CW2 and; from 79% to 72% in CW3 effluents (data not shown).…”

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

“…Enterococci emerged in the last decade of the twentieth century as one of the primary causes of hospital-acquired infections, although enterococci can also cause human infections in the community [1]. Enterococci can survive in a variety of environments, such as soil, water, food, plants, and animals [2], [3], [4]. In humans, as well as in other mammals and birds, these microbes are mainly found in the gastrointestinal tract as commensals but may become opportunistic pathogens in individuals with serious diseases whose immune systems are compromised and in patients who have been hospitalized for prolonged periods or who have received broad-spectrum antimicrobial therapy.…”