Toxicological impacts of antibiotics on aquatic micro-organisms: A mini-review

Abstract

Antibiotics are found globally in the environment at trace levels due to their extensive consumption, which raises concerns about the effects they can have on non-target organisms, especially environmental micro-organisms. So far the majority of studies have focused on different aspects of antibiotic resistance or on analyzing the occurrence, fate, and removal of antibiotics from hospital and municipal wastewaters. Little attention has been paid to ecotoxicological effects of antibiotics on aquatic micro-organisms although they play a critical role in most ecosystems and they are potentially sensitive to these substances. Here we review the current state of research on the toxicological impacts of antibiotics to aquatic micro-organisms, including proteobacteria, cyanobacteria, algae and bacteria commonly present in biological wastewater treatment processes. We focus on antibiotics that are poorly removed during wastewater treatment and thus end up in surface waters. We critically discuss and compare the available analytical methods and test organisms based on effect concentrations and identify the knowledge gaps and future challenges. We conclude that, in general, cyanobacteria and ammonium oxidizing bacteria are the most sensitive micro-organisms to antibiotics. It is important to include chronic tests in ecotoxicological assessment, because acute tests are not always appropriate in case of low sensitivity (for example for proteobacteria). However, the issue of rapid development of antibiotic resistance should be regarded in chronic testing. Furthermore, the application of other species of bacteria and endpoints should be considered in the future, not forgetting the mixture effect and bacterial community studies. Due to differences in the sensitivity of different test organisms to individual antibiotic substances, the application of several bioassays with varying test organisms would provide more comprehensive data for the risk assessment of antibiotics. Regardless of the growing concerns related to antibiotics in the environment, there are still evident knowledge gaps related to antibiotics, as there is only limited or no ecotoxicological data on many potentially harmful antibiotics.

Effect of sulfadiazine and trimethoprim on activated sludge performance and microbial community dynamics in laboratory‐scale membrane bioreactors and sequencing batch reactors at 8°C

“…Antibiotics removal rates were left out of the scope of this study because of low biodegradation potential of both SDZ and TMP, especially under given temperature conditions. 3,11…”

“…TMP and sulfonamide sulfadiazine (SDZ) are two globally known heavily used antibiotics in both human and veterinary medicine . These two antibiotics were detected worldwide in wastewater effluents (up to 3.05 and 0.56 μg L −1 respectively) as well as in natural waters (up to 2.65 and 0.11 μg L −1 , respectively) . Their toxicological impact was proven for marine bacteria as well as for the activated sludge bacteria and in particular for AOBs, resulting in inhibition of nitrogen and organic carbon removal in WWTPs .…”

“…In particular, low temperature significantly affects activated sludge bacterial community, slows down metabolic processes and, as consequences, decreases biological removal of pharmaceutically active compounds. 6,7 At the same time, in Nordic countries, the wastewater temperature during more than 5 months of winter season is around 8 AE 1 C. [8][9][10] As nitrifiers are reported among the most sensitive microorganisms to both antibiotics and lowtemperature conditions, 5,11 the efficient nitrogen removal in WWTPs of cold regions may be challenging under pressure of these two factors. Wastewater treatment processes operated with longer sludge retention time (SRT) such as membrane bioreactors (MBRs) were proposed as beneficial for activated sludge performance in presence of pharmaceutically active compounds at low temperatures.…”

“…11 Their toxicological impact was proven for marine bacteria as well as for the activated sludge bacteria and in particular for AOBs, resulting in inhibition of nitrogen and organic carbon removal in WWTPs. 11,18 However, most of the data reported for subtherapeutic concentrations of antibiotics and the experiments were conducted at room temperature. Thus, there are no clear data on the effect of these antibiotics in environmentally relevant concentrations on activated sludge of WWTPs under lowtemperature conditions.…”

<i>Cis-Trans</i> Isomerization Reaction of Sulindac Induced by UV Irradiation in the Aqueous Media

“…Furthermore, pharmaceuticals are now considered as important environmental contaminants on account of the growing number of reports focused on not only the persistence of them in the aquatic environment but also their possible ecotoxicological effects on aquatic organisms due to their nature as bioactive substances. Many ecotoxicological tests are utilized for examination of the influence of pharmaceuticals on the aquatic organisms such as cyanobacteria, green algae and marine proteobacteria [9][10][11], but data on the toxicological impacts of many potentially harmful pharmaceuticals are still lacking [12]. Evaluation of the persistence and influence of the pharmaceutical in the aquatic environment has become an important issue.…”