Poikilothermic Animals as a Previously Unrecognized Source of Fecal Indicator Bacteria in a Backwater Ecosystem of a Large River

Abstract

Quantitative information regarding the presence of , intestinal enterococci, and in poikilotherms is notably scarce. Therefore, this study was designed to allow a systematic comparison of the occurrence of these standard fecal indicator bacteria (SFIB) in the excreta of wild homeothermic (ruminants, boars, carnivores, and birds) and poikilothermic (earthworms, gastropods, frogs, and fish) animals inhabiting an alluvial backwater area in eastern Austria. With the exception of earthworms, the average concentrations of and enterococci in the excreta of poikilotherms were equal to or only slightly lower than those observed in homeothermic excreta and were 1 to 4 orders of magnitude higher than the levels observed in the ambient soils and sediments. Enterococci reached extraordinarily high concentrations in gastropods. Additional estimates of the daily excreted SFIB ( and enterococcus) loads (DESL) further supported the importance of poikilotherms as potential pollution sources. The newly established DESL metric also allowed comparison to the standing stock of SFIB in the sediment and soil of the investigated area. In agreement with its biological characteristics, the highest concentrations of were observed in carnivores. In conclusion, the long-standing hypothesis that only humans and homeothermic animals are primary sources of SFIB is challenged by the results of this study. It may be necessary to extend the fecal indicator concept by additionally considering poikilotherms as potential important primary habitats of SFIB. Further studies in other geographical areas are needed to evaluate the general significance of our results. We hypothesize that the importance of poikilotherms as sources of SFIB is strongly correlated with the ambient temperature and would therefore be of increased significance in subtropical and tropical habitats and water resources. The current fecal indicator concept is based on the assumption that the standard fecal indicator bacteria (SFIB) , intestinal enterococci, and multiply significantly only in the guts of humans and other homeothermic animals and can therefore indicate fecal pollution and the potential presence of pathogens from those groups. The findings of the present study showed that SFIB can also occur in high concentrations in poikilothermic animals (i.e., animals with body temperatures that vary with the ambient environmental temperature, such as fish, frogs, and snails) in an alluvial backwater area in a temperate region, indicating that a reconsideration of this long-standing indicator paradigm is needed. This study suggests that poikilotherms must be considered to be potential primary sources of SFIB in future studies.

Viral and Bacterial Fecal Indicators in Untreated Wastewater across the Contiguous United States Exhibit Geospatial Trends

“…Many water quality authorities rely on methods using general fecal indicator bacteria (FIB), such as culture-based Escherichia coli and enterococci, to determine if surface waters impacted by sewage are safe for swimming and other recreational activities. However, these cultivation-based procedures have several limitations, e.g., they typically require 18 h or more to yield results, making it challenging to ascertain water safety on the same day of use (7), the methods target bacteria when viral pathogens are thought to be the dominant public health risk in sewage pollution (8), and FIB are present in fecal waste across a broad range of animal groups (9), making it impossible to determine if sewage or another pollution source is the cause of water contamination.…”

Hazard assessment and categorization of microbiological risk in a water treatment and distribution system located in a municipality in the interior of Minas Gerais, Brazil

“…However, recent studies have shown that E. coli can survive for long periods of time in soil, sand, sediment and water, in tropical, subtropical and temperate climates, which facilitates its dissemination in water supply systems and explains the increased contamination during rainy periods (Jang et al, 2017). In addition, Frick et al (2018) evaluated the abundance of E. coli in several groups of animals (homeothermic and poikilothermic), in an alluvial backwater in Austria, whose results showed the average concentrations of this bacterium in poikilothermic excreta, close to those found in homeothermic plants, confirming that its occurrence it is not exclusive to warm-blooded animals.…”

Microbial faecal pollution of river water in a watershed of tropical Ethiopian highlands is driven by diffuse pollution sources

“…After incubation, FIB colonies were identified according to the agar manufacturer's protocol, in which dark blue colonies on CCA were scored as E. coli (Byamukama et al 2000), while fluorescing black colonies growing on F-TSC plates (Byamukama et al 2005) and round pink to dark maroon-coloured colonies on mENT plates were scored as CP and ENT, respectively. Of note, the detection limit (DL) for the considered faecal indicator bacteria in this study was 10 cfu/g for soil and 1 cfu/100 ml for water as determined according to the formula described by Frick et al (2018). The numbers of E. coli, ENT and CP colonies were separately quantified from their respective plates and were expressed as colony-forming units per 100 ml or gram for water or soil samples, respectively.…”