The investigation of antibiotic residues, antibiotic resistance genes and antibiotic-resistant organisms in a drinking water reservoir system in Germany.

Between August 2018 and June 2019, a river system in Germany that supplies a drinking water reservoir and is subject to the discharge from two sewage treatment plants was monitored for antibiotic residues via liquid chromatography-tandem mass spectrometry, antibiotic resistance genes (including blaNDM, blaVIM, blaOXA-48, blaKPC, blaGIM, blaSME, blaIMI, blaIMP, blaSPM, blaSIM, blaOXA-23, blaOXA-24, blaOXA-51, blaOXA-58, mcr) via qualitative real-time PCR and antibiotic-resistant bacteria [belonging to the ESKAPE-group (Enterococcus faecium, Staphyhlococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter ssp.; with resistance against Carbapenemases, Cephalosporines and Colistin) and Escherichia coli] based on cultivation methods followed by a characterization via MALDI-TOF MS and susceptibility testing applying microdilution. Residues of macrolide antibiotics such as clarithromycin (up to 0.60 µg/L) and residues of sulfamethoxazole (up to 0.40 µg/L) and trimethoprim (up to 0.39 µg/L) were detected downstream of the sewage treatment plants. In addition, no antibiotic residues were detected upstream the respective sewage treatment plants, except for anhydroerythromycin (n = 1,

Association between antibiotic residues, antibiotic resistant bacteria and antibiotic resistance genes in anthropogenic wastewater - An evaluation of clinical influences.

The high use of antibiotics in human and veterinary medicine has led to a wide spread of antibiotics and antimicrobial resistance into the environment. In recent years, various studies have shown that antibiotic residues, resistant bacteria and resistance genes, occur in aquatic environments and that clinical wastewater seems to be a hot spot for the environmental spread of antibiotic resistance. Here a representative statistical analysis of various sampling points is presented, containing different proportions of clinically influenced wastewater. The statistical analysis contains the calculation of the odds ratios for any combination of antibiotics with resistant bacteria or resistance genes, respectively. The results were screened for an increased probability of detecting resistant bacteria, or resistance genes, with the simultaneous presence of antibiotic residues. Positive associated sets were then compared, with regards to the detected median concentration, at the investigated sampling points. All results show that the sampling points with the highest proportion of clinical wastewater always form a distinct cluster concerning resistance. The results shown in this study lead to the assumption that ciprofloxacin is a good indicator of the presence of multidrug resistant P. aeruginosa and extended spectrum ß-lactamase (ESBL)-producing Klebsiella spec., Enterobacter spec. and Citrobacter spec., as it positively relates with both parameters. Furthermore, a precise relationship between carbapenemase genes and meropenem, regarding the respective sampling sites, could be obtained. These results highlight the role of clinical wastewater for the dissemination and development of multidrug resistance.

Antibiotic resistant bacteria and resistance genes in biofilms in clinical wastewater networks.

Increasing isolation rates of resistant bacteria in the last years require identification of potential infection reservoirs in healthcare facilities. Especially the clinical wastewater network represents a potential source of antibiotic resistant bacteria. In this work, the siphons of the sanitary installations from 18 hospital rooms of two German hospitals were examined for antibiotic resistant bacteria and antibiotic residues including siphons of showers and washbasins and toilets in sanitary units of psychosomatic, haemato-oncological, and rehabilitation wards. In addition, in seven rooms of the haemato-oncological ward, the effect of 24 h of stagnation on the antibiotic concentrations and MDR (multi-drug-resistant) bacteria in biofilms was evaluated. Whereas no antibiotic residues were found in the psychosomatic ward, potential selective concentrations of piperacillin, meropenem and ciprofloxacin were detected at a rehabilitation ward and ciprofloxacin and trimethoprim were present at a haemato-oncology ward. Antibiotic resistant bacteria were isolated from the siphons of all wards, however in the psychosomatic ward, only one MDR strain with resistance to piperacillin, third generation cephalosporins and quinolones (3MRGN) was detected. In contrast, the other two wards yielded 11 carbapenemase producing MDR isolates and 15 3MRGN strains. The isolates from the haemato-oncological ward belonged mostly to two specific rare sequence types (ST) (P. aeruginosa ST823 and Enterobacter cloacae complex ST167). In conclusion, clinical wastewater systems represent a reservoir for multi-drug-resistant bacteria. Consequently, preventive and intervention measures should not start at the wastewater treatment in the treatment plant, but already in the immediate surroundings of the patient, in order to minimize the infection potential.

The occurrence of antimicrobial substances in toilet, sink and shower drainpipes of clinical units: A neglected source of antibiotic residues.

Antibiotics represent one of the most important drug groups used in the management of bacterial infections in humans and animals. Due to the increasing problem of antibiotic resistance, assurance of the antibacterial effectiveness of these substances has moved into the focus of public health. The reduction in antibiotic residues in wastewater and the environment may play a decisive role in the development of increasing rates of antibiotic resistance. The present study examines the wastewater of 31 patient rooms of various German clinics for possible residues of antibiotics, as well as the wastewater of five private households as a reference. To the best of our knowledge, this study shows for the first time that in hospitals with high antibiotic consumption rates, residues of these drugs can be regularly detected in toilets, sink siphons and shower drains at concentrations ranging from 0.02 µg·L-1 to a maximum of 79 mg·L-1. After complete flushing of the wastewater siphons, antibiotics are no longer detectable, but after temporal stagnation, the concentration of the active substances in the water phases of respective siphons increases again, suggesting that antibiotics persist through the washing process in biofilms. This study demonstrates that clinical wastewater systems offer further possibilities for the optimization of antibiotic resistance surveillance.

Long-term effects of a binary mixture of perfluorooctane sulfonate (PFOS) and bisphenol A (BPA) in zebrafish (Danio rerio).

Previous in vitro studies have reported the potential of perfluorooctane sulfonate (PFOS) to increase the toxicity of other compounds. Given the complex nature of mixtures of environmental pollutants in aquatic systems together with the persistent and bioaccumulative properties of PFOS, this study aimed at evaluating the long-term effects and toxicity-increasing behavior of PFOS in vivo using the zebrafish (Danio rerio). Fish were maintained in flow-through conditions and exposed to single and binary mixtures of PFOS and the endocrine disruptor bisphenol A (BPA) at nominal concentrations of 0.6, 100 and 300 µg/L and 10, 200 and 400 µg/L, respectively. F1 and F2 generations were evaluated from 0 to 180 days post-fertilization (dpf) and F3 generation was evaluated from 0 to 14 dpf. Survival was documented in all generations, whereas growth, fecundity, fertilization rate, histological alterations (in liver, thyroid and gonads) and vitellogenin (Vtg) induction in males were evaluated for F1 and F2 generations. Data for growth were collected at 30, 90 and 180 dpf and data for histological evaluations and Vtg induction were analyzed at 90 and 180 dpf. No significant effects on survival were seen in the F1 generation in any treatment following 180 d exposure; however, in the F2 generation, 300 µg/L PFOS both alone and in combination with BPA (10, 200 and 400 µg/L) induced 100% mortality within 14 dpf. PFOS (0.6 and 300 µg/L) did not increase the Vtg-inducing potential of BPA (10, 200 and 400 µg/L) in a binary mixture. In contrast, binary mixtures with 300 µg/L PFOS suppressed the Vtg levels in F1 males at 90 dpf when compared to single BPA exposures. Whereas the lowest tested PFOS concentration (0.6 µg/L) showed an estrogenic potential in terms of significant Vtg induction, Vtg levels were generally found to decrease with increasing PFOS-exposure in both F1 and F2 generations. In F1 generation, BPA-exposure was found to increase Vtg levels in a concentration-dependent manner. Histological analyses of F1 and F2 fish revealed hepatocellular vacuolization, predominantly in males, following PFOS-exposure both alone and in combination with BPA. Hepatotoxicity by PFOS might explain the suppressed Vtg response seen in PFOS-exposed F1 and F2 males. PFOS-exposed fish also showed granulomas, mainly in the liver. Given previous reports of the immunosuppressive potential of PFOS, the granulomas could be a consequence of a PFOS-induced reduction of the immune response potential. In conclusion, the hypothesis that the presence of PFOS increases the endocrine potential of BPA could not be confirmed in zebrafish. Adverse effects on liver structure and survival were only seen at concentrations well above ecologically relevant concentrations; however, the decline in survival rates following PFOS-exposure seen over generations again documents the importance of long-term studies for the investigation of persistent environmental pollutants.