Antibiotics in the offshore waters of the Bohai Sea and the Yellow Sea in China: Occurrence, distribution and ecological risks

The ocean is an important sink of land-based pollutants. Previous studies showed that serious antibiotic pollution occurred in the coastal waters, but limited studies focused on their presence in offshore waters. In this study, eleven antibiotics in three different categories were investigated in offshore waters of the Bohai Sea and the Yellow Sea in China. The results indicated that three antibiotics dehydration erythromycin, sulfamethoxazole and trimethoprim occurred throughout the offshore waters at concentrations of 0.10-16.6 ng L-1 and they decreased exponentially from the rivers to the coastal and offshore waters. The other antibiotics all presented very low detection rates (<10%) and concentrations (<0.51 ng L-1). Although the concentrations were very low, risk assessment based on the calculated risk quotients (RQs) showed that sulfamethoxazole, dehydration erythromycin and clarithromycin at most of sampling sites posed medium or low ecological risks (0.01 < RQ < 1) to some sensitive aquatic organisms, including Synechococcus leopoliensis and Pseudokirchneriella subcapitata. (C) 2012 Elsevier Ltd. All rights reserved.The ocean is an important sink of land-based pollutants. Previous studies showed that serious antibiotic pollution occurred in the coastal waters, but limited studies focused on their presence in offshore waters. In this study, eleven antibiotics in three different categories were investigated in offshore waters of the Bohai Sea and the Yellow Sea in China. The results indicated that three antibiotics dehydration erythromycin, sulfamethoxazole and trimethoprim occurred throughout the offshore waters at concentrations of 0.10-16.6 ng L-1 and they decreased exponentially from the rivers to the coastal and offshore waters. The other antibiotics all presented very low detection rates (<10%) and concentrations (<0.51 ng L-1). Although the concentrations were very low, risk assessment based on the calculated risk quotients (RQs) showed that sulfamethoxazole, dehydration erythromycin and clarithromycin at most of sampling sites posed medium or low ecological risks (0.01 < RQ < 1) to some sensitive aquatic organisms, including Synechococcus leopoliensis and Pseudokirchneriella subcapitata. (C) 2012 Elsevier Ltd. All rights reserved

Different Concentrations of Doxycycline in Swine Manure Affect the Microbiome and Degradation of Doxycycline Residue in Soil

Antibiotic residues that enter the soil through swine manure could disturb the number, community structure and functions of microbiota which could also degrade antibiotics in soil. Five different concentrations of doxycycline (DOX) incorporated into swine manure were added to soil to explore the effects of DOX on microbiota in soil and degradation itself. The results showed that the soil microbiome evolved an adaptation to the soil containing DOX by generating resistance genes. Moreover, some of the organisms within the soil microbiome played crucial roles in the degradation of DOX. The average degradation half-life of DOX in non-sterile groups was 13.85 ± 0.45 days, which was significantly shorter than the 29.26 ± 0.98 days in the group with sterilized soil (P &lt; 0.01), indicating that the soil microbiome promoted DOX degradation. DOX addition affected the number of tetracycline resistance genes, depending on the type of gene and the DOX concentration. Among these genes, tetA, tetM, tetW, and tetX had significantly higher copy numbers when the concentration of DOX was higher. In contrast, a lower concentration of DOX had an inhibitory effect on tetG. At the same time, the microbial compositions were affected by the initial concentration of DOX and the different experimental periods. The soil chemical indicators also affected the microbial diversity changes, mainly because some microorganisms could survive in adversity and become dominant bacterial groups, such as the genera Vagococcus and Enterococcus (which were associated with electrical conductivity) and Caldicoprobacter spp. (which were positively correlated with pH). Our study mainly revealed soil microbiota and DOX degradation answered differently under variable concentrations of DOX mixed with swine manure in soil

Occurrence and risks of antibiotics in the Laizhou Bay, China: Impacts of river discharge

The presence of thirteen antibiotics categorized into four different groups (fluoroquinolones, macrolides, sulfonamides and trimethoprim) was investigated in the rivers discharging to the Laizhou Bay and the seawater of the bay, and the impacts of river discharge on the marine environment were assessed. The results revealed that the same antibiotics predominated in both the river water and the seawater. Additionally, the detected antibiotics in the river water were generally higher than those in the inner bay and in the open bay, reflecting the importance of the riverine inputs as a source of antibiotics. Risk assessment based on the calculated risk quotients (RQ) showed that enoxacin, ciprofloxacin, and sulfamethoxazole in the two aquatic environments both posed high ecological risks (RQ > 1) to the most sensitive aquatic organisms Vibrio fischeri, Microcystis aeruginosa and Synechococcus leopoliensis, respectively. (C) 2012 Elsevier Inc. All rights reserved.The presence of thirteen antibiotics categorized into four different groups (fluoroquinolones, macrolides, sulfonamides and trimethoprim) was investigated in the rivers discharging to the Laizhou Bay and the seawater of the bay, and the impacts of river discharge on the marine environment were assessed. The results revealed that the same antibiotics predominated in both the river water and the seawater. Additionally, the detected antibiotics in the river water were generally higher than those in the inner bay and in the open bay, reflecting the importance of the riverine inputs as a source of antibiotics. Risk assessment based on the calculated risk quotients (RQ) showed that enoxacin, ciprofloxacin, and sulfamethoxazole in the two aquatic environments both posed high ecological risks (RQ > 1) to the most sensitive aquatic organisms Vibrio fischeri, Microcystis aeruginosa and Synechococcus leopoliensis, respectively. (C) 2012 Elsevier Inc. All rights reserved

Levels, spatial distribution and sources of selected antibiotics in the East River (Dongjiang), South China

Eleven selected antibiotics in the East River, South China, were measured using high performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-EI-MS-MS). Erythromycin, roxitromycin, azithromycin, clarithromycin, sulfadimidine, sulfamethoxazole, sulfadiazine and trimethoprim were detected with frequencies of more than 75%, and average concentrations ranging from 0.9 to 67.4 ng l(-1). The other three compounds' (sulfathiazole, sulfacetamide and spiramycin) concentrations were below detection limits. In general, the concentrations of sulfonamides and trimethoprim were higher than those of macrolides. The concentrations of macrolides showed a spatial distribution pattern of delta > lower reach > middle reach (or urban area > agriculture area), while sulfonamides and trimethoprim did not have a significant spatial pattern. Principal component analysis and comparison with wastewater were further used to explore source information of the antibiotics. The results suggested that macrolides in the East River were mainly associated with domestic sewage, while sulfonamides and trimethoprim may be more related to agriculture wastewater, especially livestock industrial wastewater. It is suggested that to ensure/improve the drinking water quality in the region, a better pollution control of livestock industry in the lower and middle reaches is of critical importance.Eleven selected antibiotics in the East River, South China, were measured using high performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-EI-MS-MS). Erythromycin, roxitromycin, azithromycin, clarithromycin, sulfadimidine, sulfamethoxazole, sulfadiazine and trimethoprim were detected with frequencies of more than 75%, and average concentrations ranging from 0.9 to 67.4 ng l(-1). The other three compounds' (sulfathiazole, sulfacetamide and spiramycin) concentrations were below detection limits. In general, the concentrations of sulfonamides and trimethoprim were higher than those of macrolides. The concentrations of macrolides showed a spatial distribution pattern of delta > lower reach > middle reach (or urban area > agriculture area), while sulfonamides and trimethoprim did not have a significant spatial pattern. Principal component analysis and comparison with wastewater were further used to explore source information of the antibiotics. The results suggested that macrolides in the East River were mainly associated with domestic sewage, while sulfonamides and trimethoprim may be more related to agriculture wastewater, especially livestock industrial wastewater. It is suggested that to ensure/improve the drinking water quality in the region, a better pollution control of livestock industry in the lower and middle reaches is of critical importance

Doxycycline Attenuates Pig Intestinal Microbial Interactions and Changes Microbial Metabolic Pathways

Doxycycline is a therapeutic veterinary antibiotic commonly used in pig breeding. In this study, 27 fattening pigs of 33.5 ± 0.72 kg were divided equally into 3 groups. Doxycycline at 0, 3, and 5 mg/kg body weight was added to the feed in groups CK, L and H. The medication and withdrawal periods were set at 5 and 28 days. The results showed that the doxycycline average concentrations in groups L and H during the medication period were 117.63 ± 13.54 and 202.03 ± 24.91 mg/kg dry matter, respectively. Doxycycline levels were lower than the detection limit after 20 days. Doxycycline did not affect the diversity of the intestinal microbial community structure. The relative abundances of Streptococcus were significantly higher in treatment groups than that in group CK, and Alishewanella, Vagococcus, Cloacibacterium, and Campylobacter abundances were significantly positively correlated with doxycycline concentration. Interestingly, the microbiota cooccurrence network suggested that high doxycycline concentration weakened the interactions among bacteria until day 33. Functional prediction showed that doxycycline significantly altered metabolic pathways related to the cell membrane. The results revealed that the use of doxycycline during pig breeding can affect bacterial abundance during the withdrawal period, and it may affect interactions among bacteria and change the intestinal metabolic pathways