Persistence of wastewater antibiotic resistant bacteria and their genes in human fecal material. - Related Documents




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708401.0000Persistence of wastewater antibiotic resistant bacteria and their genes in human fecal material. Domestic wastewater is a recognized source of antibiotic resistant bacteria and antibiotic resistance genes (ARB&ARGs), whose risk of transmission to humans cannot be ignored. The fitness of wastewater ARB in the complex fecal microbiota of a healthy human was investigated in feces-based microcosm assays (FMAs). FMAs were inoculated with two wastewater isolates, Escherichia coli strain A2FCC14 (MLST ST131) and Enterococcus faecium strain H1EV10 (MLST ST78), harboring the ARGs blaTEM, blaCTX, blaOXA-A and vanA, respectively. The FMAs, incubated in the presence or absence of oxygen or in the presence or absence of the antibiotics cefotaxime or vancomycin, were monitored based on cultivation, ARGs quantification and bacterial community analysis. The fecal bacterial community was dominated by members of the phyla Firmicutes, Bacteroidetes, Actinobacteria, Proteobacteria and Verrucomicrobia. The ARGs harbored by the wastewater isolates could be quantified after one week, in FMAs incubated under both aerobic and anaerobic conditions. These observations were not significantly different in FMAs incubated anaerobically, supplemented with sub-inhibitory concentrations of cefotaxime or vancomycin. The observation that ARGs of wastewater ARB persisted in presence of the human fecal microbiota for at least one week supports the hypothesis of a potential transmission to humans, a topic that deserves further investigation.202032239211
535310.9998The influence of the autochthonous wastewater microbiota and gene host on the fate of invasive antibiotic resistance genes. The aim of this study was to assess the fate of invasive antibiotic resistance genes (ARG) discharged in wastewater. With this objective, antibiotic resistant bacteria (ARB) known to harbor specific ARG were inoculated in wastewater (hospital effluent, or municipal raw and treated wastewater) and in ultra-pure sterile water microcosms. Two sets of wastewater ARB isolates were used - set 1, Enterococcus faecalis, Acinetobacter johnsonii, Klebsiella pneumoniae and set 2, Enterococcus faecium, Acinetobacter johnsonii, Escherichia coli. Non-inoculated controls were run in parallel. Samples were collected at the beginning and at the end (15days) of the incubation period and the abundance of the genes 16S rRNA, intI1, bla(TEM) and vanA and the bacterial community composition were analyzed. In general, the genes bla(TEM) and vanA had lower persistence in wastewater and in ultra-pure water than the genes 16S rRNA or the class 1 integron integrase intI1. This effect was more pronounced in wastewater than in ultra-pure water, evidencing the importance of the autochthonous microbiota on the elimination of invasive ARG. Wastewater autochthonous bacterial groups most correlated with variations of the genes intI1, bla(TEM) and vanA were members of the classes Gammaproteobacteria, Bacilli or Bacteroidia. For bla(TEM), but not for vanA, the species of the ARB host was important to determine its fate. These are novel findings on the ecology of ARB in wastewater environments.201727697350
708620.9997Detection of faecal bacteria and antibiotic resistance genes in biofilms attached to plastics from human-impacted coastal areas. Plastics have been proposed as vectors of bacteria as they act as a substrate for biofilms. In this study, we evaluated the abundance of faecal and marine bacteria and antibiotic resistance genes (ARGs) from biofilms adhered to marine plastics. Floating plastics and plastics from sediments were collected in coastal areas impacted by human faecal pollution in the northwestern Mediterranean Sea. Culture and/or molecular methods were used to quantify faecal indicators (E. coli, Enterococci and crAssphage), and the ARGs sulI, tetW and bla(TEM) and the 16S rRNA were detected by qPCR assays. Pseudomonas and Vibrio species and heterotrophic marine bacteria were also analysed via culture-based methods. Results showed that, plastic particles covered by bacterial biofilms, primarily consisted of marine bacteria including Vibrio spp. Some floating plastics had a low concentration of viable E. coli and Enterococci (42% and 67% of the plastics respectively). Considering the median area of the plastics, we detected an average of 68 cfu E. coli per item, while a higher concentration of E. coli was detected on individual plastic items, when compared with 100 ml of the surrounding water. Using qPCR, we quantified higher values of faecal indicators which included inactive and dead microorganisms, detecting up to 2.6 × 10(2) gc mm(-2). The ARGs were detected in 67-88% of the floating plastics and in 29-57% of the sediment plastics with a concentration of up to 6.7 × 10(2) gc mm(-2). Furthermore, enrichment of these genes was observed in biofilms compared with the surrounding water. These results show that floating plastics act as a conduit for both the attachment and transport of faecal microorganisms. In contrast, low presence of faecal indicators was detected in plastic from seafloor sediments. Therefore, although in low concentrations, faecal bacteria, and potential pathogens, were identified in marine plastics, further suggesting plastics act as a reservoir of pathogens and ARGs.202336596379
535230.9997Microbiological characterization of aquatic microbiomes targeting taxonomical marker genes and antibiotic resistance genes of opportunistic bacteria. The dissemination of medically relevant antibiotic resistance genes (ARGs) (blaVIM-1, vanA, ampC, ermB, and mecA) and opportunistic bacteria (Enterococcus faecium/faecalis, Pseudomonas aeruginosa, Enterobacteriaceae, Staphylococcus aureus, and CNS) was determined in different anthropogenically influenced aquatic habitats in a selected region of Germany. Over a period of two years, four differently sized wastewater treatment plants (WWTPs) with and without clinical influence, three surface waters, four rain overflow basins, and three groundwater sites were analyzed by quantitative Polymerase Chain Reaction (qPCR). Results were calculated in cell equivalents per 100 ng of total DNA extracted from water samples and per 100 mL sample volume, which seems to underestimate the abundance of antibiotic resistance and opportunistic bacteria. High abundances of opportunistic bacteria and ARG were quantified in clinical wastewaters and influents of the adjacent WWTP. The removal capacities of WWTP were up to 99% for some, but not all investigated bacteria. The abundances of most ARG targets were found to be increased in the bacterial population after conventional wastewater treatment. As a consequence, downstream surface water and also some groundwater compartments displayed high abundances of all four ARGs. It became obvious that the dynamics of the ARG differed from the fate of the opportunistic bacteria. This underlines the necessity of an advanced microbial characterization of anthropogenically influenced environments.201525634736
535440.9997Cultivation-dependent and high-throughput sequencing approaches studying the co-occurrence of antibiotic resistance genes in municipal sewage system. During the past years, antibiotic-resistant bacteria (ARB) leading for the spreading of antibiotic resistance genes (ARGs) became a global problem, especially multidrug-resistant (MDR) bacteria are considered the prime culprit of antibiotic resistance. However, the correlation between the antibiotic-resistant phenotype and the ARG profiles remains poorly understood. In the present study, metagenomic functional screening and metagenomic analysis of coliforms were combined to explore the phenotype and genotype of the ARBs from municipal sewage. Our results showed that the ARG co-occurrence was widespread in the municipal sewage. The present study also highlighted the high abundance of ARGs from antibiotic resistance coliforms especially the MDR coliforms with ARG level of 33.8 ± 4.2 copies per cell. The ARG profiles and the antibiotic resistance phenotypes of the isolated antibiotic resistant coliforms were also correlated and indicated that the resistance to the related antibiotic (ampicillin, kanamycin, erythromycin, chloramphenicol, and tetracycline) was mostly contributed by the ARGs belonging to the subtypes of β-lactamase, aminoglycoside 3-phosphotransferase, phosphotransferase type 2, chloramphenicol acetyltransferase, tetA, etc.201729034431
342650.9997Detection of antibiotic-resistant bacteria and their resistance genes in wastewater, surface water, and drinking water biofilms. Abstract In view of the increasing interest in the possible role played by hospital and municipal wastewater systems in the selection of antibiotic-resistant bacteria, biofilms were investigated using enterococci, staphylococci, Enterobacteriaceae, and heterotrophic bacteria as indicator organisms. In addition to wastewater, biofilms were also investigated in drinking water from river bank filtrate to estimate the occurrence of resistant bacteria and their resistance genes, thus indicating possible transfer from wastewater and surface water to the drinking water distribution network. Vancomycin-resistant enterococci were characterized by antibiograms, and the vanA resistance gene was detected by molecular biology methods, including PCR. The vanA gene was found not only in wastewater biofilms but also in drinking water biofilms in the absence of enterococci, indicating possible gene transfer to autochthonous drinking water bacteria. The mecA gene encoding methicillin resistance in staphylococci was detected in hospital wastewater biofilms but not in any other compartment. Enterobacterial ampC resistance genes encoding beta-lactamase activities were amplified by PCR from wastewater, surface water and drinking water biofilms.200319719664
535560.9997Impact of wastewater treatment processes on antimicrobial resistance genes and their co-occurrence with virulence genes in Escherichia coli. An increase in the frequency of antimicrobial resistance genes (ARGs) in bacteria including Escherichia coli could be a threat to public health. This study investigated the impact of activated sludge and physicochemical wastewater treatment processes on the prevalence of ARGs in E. coli isolates. In total, 719 E. coli were isolated from the influent and effluent (prior to disinfection) of two activated sludge and two physicochemical municipal treatment plants, and genotyped using DNA microarrays. Changes in the abundance of ARGs in the E. coli population were different for the two treatment processes. Activated sludge treatment did not change the prevalence of ARG-possessing E. coli but increased the abundance of ARGs in the E. coli genome while physicochemical treatment reduced both the prevalence of ARG-carrying E. coli as well as the frequency of ARGs in the E. coli genome. Most E. coli isolates from the four treatment plants possessed ARGs of multiple antimicrobial classes, mainly aminoglycoside, β-lactams, quinolone and tetracyclines. In addition these isolates harboured DNA insertion sequence elements including integrase and transposase. A significant positive association was found between the occurrence of ARGs and virulence genotypes.201424380739
532370.9997Monitoring and assessing the impact of wastewater treatment on release of both antibiotic-resistant bacteria and their typical genes in a Chinese municipal wastewater treatment plant. Wastewater treatment plants (WWTPs) are important hotspots for the spread of antibiotic resistance. However, the release and impact factors of both antibiotic resistant bacteria and the relevant genes over long periods in WWTPs have rarely been investigated. In this study, the fate of bacteria and genes resistant to six commonly used antibiotics was assessed over a whole year. In WWTP effluent and biosolids, a high prevalence of heterotrophic bacteria resistant to vancomycin, cephalexin, sulfadiazine and erythromycin were detected, each with a proportion of over 30%. The corresponding genes (vanA, ampC, sulI and ereA) were all detected in proportions of (2.2 ± 0.8) × 10(-10), (6.2 ± 3.2) × 10(-9), (1.2 ± 0.8) × 10(-7) and (7.6 ± 4.8) × 10(-8), respectively, in the effluent. The sampling season imposed considerable influence on the release of all ARB. High release loads of most ARB were detected in the spring, while low release loads were generally found in the winter. In comparison, the ARG loads changed only slightly over various seasons. No statistical relevance was found between all ARB abundances and their corresponding genes over the long-term investigation period. This inconsistent behavior indicates that bacteria and genes should both be considered when exploring resistance characteristics in wastewater. A redundancy analysis was adopted to assess the impact of wastewater quality and operational conditions on antibiotic resistance. The results indicated that most ARB and ARG proportions were positively related to the COD and turbidity of the raw sewage, while negatively related to those of the effluent. DO and temperature exhibited strong negative relevance to most ARB prevalence.201424927359
709980.9997The impact of a freshwater fish farm on the community of tetracycline-resistant bacteria and the structure of tetracycline resistance genes in river water. The aim of this study was to assess the impact of a fish farm on the structure of antibiotic resistant bacteria and antibiotic resistance genes in water of Drwęca River. Samples of upstream river waters; post-production waters and treated post-production waters from fish farm; as well as downstream river waters were monitored for tetracycline resistant bacteria, tetracycline resistant genes, basic physico-chemical parameters and tetracyclines concentration. The river waters was characterized by low levels of pollution, which was determined based on water temperature, pH and concentrations of dissolved oxygen and tetracycline antibiotics. Culture-dependent (heterotrophic plate counts, counts of bacteria resistant to oxytetracycline (OTC(R)) and doxycycline (DOX(R)), minimum inhibitory concentrations for oxytetracycline and doxycycline, multidrug resistance of OTC(R) and DOX(R), qualitative composition of OTC(R) and DOX(R), prevalence of tet genes in resistant isolates) and culture-independent surveys (quantity of tet gene copies) revealed no significant differences in the abundance of antibiotic-resistant bacteria and antibiotic resistance genes between the studied samples. The only way in which the fish farm influenced water quality in the Drwęca River was by increasing the diversity of tetracycline-resistance genes. However, it should also be noted that the bacteria of the genera Aeromonas sp. and Acinetobacter sp. were able to transfer 6 out of 13 tested tet genes into Escherichiacoli, which can promote the spread of antibiotic resistance in the environment.201525698291
532990.9997Distribution of Antibiotic Resistance in a Mixed-Use Watershed and the Impact of Wastewater Treatment Plants on Antibiotic Resistance in Surface Water. The aquatic environment has been recognized as a source of antibiotic resistance (AR) that factors into the One Health approach to combat AR. To provide much needed data on AR in the environment, a comprehensive survey of antibiotic-resistant bacteria (ARB), antibiotic resistance genes (ARGs), and antibiotic residues was conducted in a mixed-use watershed and wastewater treatment plants (WWTPs) within the watershed to evaluate these contaminants in surface water. A culture-based approach was used to determine prevalence and diversity of ARB in surface water. Low levels of AR Salmonella (9.6%) and Escherichia coli (6.5%) were detected, while all Enterococcus were resistant to at least one tested antibiotic. Fewer than 20% of extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae (17.3%) and carbapenem-resistant Enterobacteriaceae (CRE) (7.7%) were recovered. Six ARGs were detected using qPCR, primarily the erythromycin-resistance gene, ermB. Of the 26 antibiotics measured, almost all water samples (98.7%) had detectable levels of antibiotics. Analysis of wastewater samples from three WWTPs showed that WWTPs did not completely remove AR contaminants. ARGs and antibiotics were detected in all the WWTP effluent discharges, indicating that WWTPs are the source of AR contaminants in receiving water. However, no significant difference in ARGs and antibiotics between the upstream and downstream water suggests that there are other sources of AR contamination. The widespread occurrence and abundance of medically important antibiotics, bacteria resistant to antibiotics used for human and veterinary purposes, and the genes associated with resistance to these antibiotics, may potentially pose risks to the local populations exposed to these water sources.202337998788
3423100.9997bla(TEM) and vanA as indicator genes of antibiotic resistance contamination in a hospital-urban wastewater treatment plant system. Four indicator genes were monitored by quantitative PCR in hospital effluent (HE) and in the raw and treated wastewater of the municipal wastewater treatment plant receiving the hospital discharge. The indicator genes were the class 1 integrase gene intI1, to assess the capacity of bacteria to be involved in horizontal gene transfer processes; bla(TEM), one of the most widespread antibiotic resistance genes in the environment, associated with Enterobacteriaceae; vanA, an antibiotic resistance gene uncommon in the environment and frequent in clinical isolates; and marA, part of a locus related to the stress response in Enterobacteriaceae. Variation in the abundance of these genes was analysed as a function of the type of water, and possible correlations with cultivable bacteria, antimicrobial residue concentrations, and bacterial community composition and structure were analysed. HE was confirmed as an important source of bla(TEM) and vanA genes, and wastewater treatment showed a limited capacity to remove these resistance genes. The genes bla(TEM) and vanA presented the strongest correlations with culturable bacteria, antimicrobial residues and some bacterial populations, representing interesting candidates as indicator genes to monitor resistance in environmental samples. The intI1 gene was the most abundant in all samples, demonstrating that wastewater bacterial populations hold a high potential for gene acquisition.201427873693
3678110.9997Abundance and dynamics of antibiotic resistance genes and integrons in lake sediment microcosms. Antibiotic resistance in bacteria causing disease is an ever growing threat to the world. Recently, environmental bacteria have become established as important both as sources of antibiotic resistance genes and in disseminating resistance genes. Low levels of antibiotics and other pharmaceuticals are regularly released into water environments via wastewater, and the concern is that such environmental contamination may serve to create hotspots for antibiotic resistance gene selection and dissemination. In this study, microcosms were created from water and sediments gathered from a lake in Sweden only lightly affected by human activities. The microcosms were exposed to a mixture of antibiotics of varying environmentally relevant concentrations (i.e., concentrations commonly encountered in wastewaters) in order to investigate the effect of low levels of antibiotics on antibiotic resistance gene abundances and dynamics in a previously uncontaminated environment. Antibiotic concentrations were measured using liquid chromatography-tandem mass spectrometry. Abundances of seven antibiotic resistance genes and the class 1 integron integrase gene, intI1, were quantified using real-time PCR. Resistance genes sulI and ermB were quantified in the microcosm sediments with mean abundances 5 and 15 gene copies/10(6) 16S rRNA gene copies, respectively. Class 1 integrons were determined in the sediments with a mean concentration of 3.8 × 10(4) copies/106 16S rRNA gene copies. The antibiotic treatment had no observable effect on antibiotic resistance gene or integron abundances.201425247418
3681120.9997A closer look at the antibiotic-resistant bacterial community found in urban wastewater treatment systems. The conventional biological treatment process can provide a favorable environment for the maintenance and dissemination of antibiotic-resistant bacteria and the antibiotic resistance genes (ARG) they carry. This study investigated the occurrence of antibiotic resistance in three wastewater treatment plants (WWTP) to determine the role they play in the dissemination of ARGs. Bacterial isolates resistant to tetracycline were collected, and tested against eight antibiotics to determine their resistance profiles and the prevalence of multiple antibiotic resistance. It was found that bacteria resistant to tetracycline were more likely to display resistance to multiple antibiotics compared to those isolates that were not tetracycline resistant. Polymerase chain reaction (PCR) was used to identify the tetracycline resistance determinants present within the bacterial communities of the WWTPs and receiving waters, and it was found that ARGs may not be released from the treatment process. Identification of isolates showed that there was a large diversity of species in both the tetracycline-resistant and tetracycline-sensitive populations and that the two groups were significantly different in composition. Antibiotic resistance profiles of each population showed that a large diversity of resistance patterns existed within genera suggesting that transmission of ARG may progress by both horizontal gene and vertical proliferation.201829484827
5326130.9997The presence of antibiotic-resistant bacteria at four Norwegian wastewater treatment plants: seasonal and wastewater-source effects. Wastewater treatment plants receive low concentrations of antibiotics. Residual concentrations of antibiotics in the effluent may accelerate the development of antibiotic resistance in the receiving environments. Monitoring of antimicrobial resistance genes (ARGs) in countries with strict regulation of antibiotic use is important in gaining knowledge of how effective these policies are in preventing the emergence of ARGs or whether other strategies are required, for example, at-source treatment of hospital effluents. This study evaluates the presence of certain common resistance genes (bla (SHV-1), bla (TEM-1), msrA, ermA, ermC, tetM, tetL, tetA, vanA, and vanC) in the influent, sludge, and effluent of four wastewater treatment plants (WWTPs) in the North Jæren region of Norway at two different sampling times (January and May). These WWTPs vary in drainage area and wastewater composition and were selected based on their differing wastewater characteristics. Randomly selected colonies from the activated sludge samples were used to determine the minimum inhibitory concentration (MIC) for ampicillin, vancomycin, and tetracycline. In addition, variations in the bacterial composition of the wastewater were characterized via 16S rRNA sequencing and were analyzed in terms of bacterial host taxa that explain the presence of the ARGs in wastewater. The MIC tests revealed MIC(90) values of >128 µg/mL for ampicillin, ≥128 µg/mL for vancomycin, and 32 µg/mL for tetracycline. In addition, the three resistance genes, ermB, tetA, and tetM, that were present in the influent and activated sludge were still present in the effluent. These results indicate that WWTPs represent a direct route into the environment for resistance genes and do not significantly reduce their abundance. Hence, the development of treatment methods for the removal of these genes from WWTPs in the future is of utmost importance.202439816252
7115140.9997Antibiotics, antibiotic resistance and associated risk in natural springs from an agroecosystem environment. This study investigates the occurrence, transport, and risks associated to antibiotic residues, antibiotic resistance genes (ARGs) and antibiotic resistant Escherichia coli (AR-E. coli) in eleven natural springs in an agroecosystem environment with intense livestock production, where groundwater nitrate concentration usually sets above 50 mg L(-1). Out of 23 multiple-class antibiotics monitored, tetracycline and sulfonamide residues were the most ubiquitous, and they were detected at concentrations ranging from ng L(-1) to μg L(-1). Five ARGs were monitored, conferring resistance to the antibiotic classes of major use in livestock production. Thus, genes conferring resistance to sulfonamides (sul1 and sul2) and tetracyclines (tetW) as well as a gene proxy for anthropogenic pollution (intI1) were present in most springs. sul1 was the most abundant, with absolute concentrations ranging from 4 × 10(2) to 5.6 × 10(6) gene copies L(-1) water. AR-E. coli showing resistance to sulfonamides and tetracyclines was also detected, with a prevalence up to approximately 40 % in some sites but with poor correlations with the concentration of antibiotic residues and ARGs. The occurrence of antibiotics, ARGs and AR-E. coli was characterized by large seasonal variations which were mostly associated to both hydrological factors and reactive transport processes. Finally, a risk assessment approach pointed out towards low risk for both the groundwater environment and human health, when spring water is used for direct human consumption, associated with the occurrence of antibiotics, ARGs and AR-E. coli. However, long-term effects cannot be neglected, and proper actions must be taken to preserve groundwater quality.202336208750
7098150.9997Antibiotic resistance along an urban river impacted by treated wastewaters. Urban rivers are impacted ecosystems which may play an important role as reservoirs for antibiotic-resistant (AR) bacteria. The main objective of this study was to describe the prevalence of antibiotic resistance along a sewage-polluted urban river. Seven sites along the Zenne River (Belgium) were selected to study the prevalence of AR Escherichia coli and freshwater bacteria over a 1-year period. Culture-dependent methods were used to estimate E. coli and heterotrophic bacteria resistant to amoxicillin, sulfamethoxazole, nalidixic acid and tetracycline. The concentrations of these four antibiotics have been quantified in the studied river. The antibiotic resistance genes (ARGs), sul1, sul2, tetW, tetO, blaTEM and qnrS were also quantified in both particle-attached (PAB) and free-living (FLB) bacteria. Our results showed an effect of treated wastewaters release on the spread of antibiotic resistance along the river. Although an increase in the abundance of both AR E. coli and resistant heterotrophic bacteria was observed from upstream to downstream sites, the differences were only significant for AR E. coli. A significant positive regression was also found between AR E. coli and resistant heterotrophic bacteria. The concentration of ARGs increased from upstream to downstream sites for both particle-attached (PAB) and free-living bacteria (FLB). Particularly, a significant increase in the abundance of four among six ARGs analyzed was observed after crossing urban area. Although concentrations of tetracycline significantly correlated with tetracycline resistance genes, the antibiotic levels were likely too low to explain this correlation. The analysis of ARGs in different fractions revealed a significantly higher abundance in PAB compared to FLB for tetO and sul2 genes. This study demonstrated that urban activities may increase the spread of antibiotic resistance even in an already impacted river.201829453174
3432160.9997Insights into the amplification of bacterial resistance to erythromycin in activated sludge. Wastewater treatment plants are significant reservoirs for antimicrobial resistance. However, little is known about wastewater treatment effects on the variation of antibiotic resistance. The shifts of bacterial resistance to erythromycin, a macrolide widely used in human medicine, on a lab-scale activated sludge system fed with real wastewater was investigated from levels of bacteria, community and genes, in this study. The resistance variation of total heterotrophic bacteria was studied during the biological treatment process, based on culture dependent method. The alterations of bacterial community resistant to erythromycin and nine typical erythromycin resistance genes were explored with molecular approaches, including high-throughput sequencing and quantitative polymerase chain reaction. The results revealed that the total heterotrophs tolerance level to erythromycin concentrations (higher than 32 mg/L) was significantly amplified during the activated sludge treatment, with the prevalence increased from 9.6% to 21.8%. High-throughput sequencing results demonstrated an obvious increase of the total heterotrophic bacterial diversity resistant to erythromycin. Proteobacteria and Bacteroidetes were the two dominant phyla in the influent and effluent of the bioreactor. However, the prevalence of Proteobacteria decreased from 76% to 59% while the total phyla number increased greatly from 18 to 29 through activated sludge treatment. The gene proportions of erm(A), mef(E) and erm(D) were greatly amplified after biological treatment. It is proposed that the transfer of antibiotic resistance genes through the variable mixtures of bacteria in the activated sludge might be the reason for the antibiotic resistance amplification. The amplified risk of antibiotic resistance in wastewater treatment needs to be paid more attention.201525957255
7123170.9997Presence and fate of antibiotic residues, antibiotic resistance genes and zoonotic bacteria during biological swine manure treatment. The presence and dissemination of antibiotic residues, antibiotic resistance genes and zoonotic bacteria in the environment is of growing concern worldwide. Manure management practices, such as biological removal of nitrogen from swine manure, may help to decrease levels of antibiotic residues, antibiotic resistance genes and zoonotic bacteria present in manure before fertilization, thereby reducing environmental contamination. Therefore, the aim of this study was to monitor the presence and fate of seven antibiotic residues (colistin, sulfadiazine, trimethoprim, doxycycline, oxytetracycline, ceftiofur and tylosin A), nine antibiotic resistance genes (tet(B), tet(L), tet(M), tet(O), tet(Q), tet(W), erm(B), erm(F) and sul2) and two zoonotic bacteria (Salmonella Typhimurium and Campylobacter coli) during biological nitrogen removal from swine manure over time. Samples from the raw manure, the solid fraction, the liquid fraction and the storage lagoon were analyzed on two farms at six time points with an interval of two weeks. Only the antibiotics which were used during the three months preceding the first sampling could be detected before and after biological nitrogen removal from swine manure. Of all the antibiotics studied, doxycycline was recovered in all of the samples and sulfadiazine was recovered in most samples on both farms. For both antibiotics, there appears to be a reduction of the amount of residues present in the storage lagoon compared to the liquid fraction, however, this reduction was not statistically significant. A significant reduction of the relative abundances of most of the antibiotic resistance genes studied was observed when comparing the liquid fraction and the storage lagoon. For tet(L), no differences were observed between the fractions sampled and for sul2 and erm(F), a significant increase in relative abundances was observed on the second farm sampled. For the zoonotic bacteria, a reduction of at least 1 log was observed after biological nitrogen removal from swine manure. The results indicate that the concentration of certain antibiotic residues and several antibiotic resistance genes and the amount of zoonotic bacteria present in the manure may be reduced in the end product of the biological nitrogen removal from swine manure.201930878661
3676180.9997Diversity of antibiotic resistance genes and encoding ribosomal protection proteins gene in livestock waste polluted environment. The rapid development and increase of antibiotic resistance are global phenomena resulting from the extensive use of antibiotics in human clinics and animal feeding operations. Antibiotics can promote the occurrence of antibiotic resistance genes (ARGs), which can be transferred horizontally to humans and animals through water and the food chain. In this study, the presence and abundance of ARGs in livestock waste was monitored by quantitative PCR. A diverse set of bacteria and tetracycline resistance genes encoding ribosomal protection proteins (RPPs) from three livestock farms and a river were analyzed through denaturing gradient gel electrophoresis (DGGE). The abundance of sul(I) was 10(3) to 10(5) orders of magnitude higher than that of sul(II). Among 11 tet-ARGs, the most abundant was tet(O). The results regarding bacterial diversity indicated that the presence of antibiotics might have an evident impact on bacterial diversity at every site, particularly at the investigated swine producer. The effect of livestock waste on the bacterial diversity of soil was stronger than that of water. Furthermore, a sequencing analysis showed that tet(M) exhibited two genotypes, while the other RPPs-encoding genes exhibited at least three genotypes. This study showed that various ARGs and RPPs-encoding genes are particularly widespread among livestock.201829469609
7085190.9997Occurrence and antibacterial resistance of culturable antibiotic-resistant bacteria in the Fildes Peninsula, Antarctica. Quantifying the occurrence of Antarctic antibiotic-resistant bacteria (ARB) is essential for assessing the level of pollution and assessing the "baseline" or background level of ARB in human uninhabited environments. Animal feces, soil, and sediments were sampled from Fildes Peninsula. The abundance of sulfamethazine- and ciprofloxacin-resistance bacteria and antibotic resistance genes (ARGs) within ARB were investigated. The results showed Ciprofloxacin- and Sulfamethazine-resistant bacteria isolated from samples accounted for the highest abundances of 30 CFU/g and 79.8 CFU/g, respectively. The dominant genus of Sulfamethazine-and quinolone-resistance bacteria was Pseudomonas and Arthrobacter, respectively. 106 ARGs were detected from ARB. Strong positive correlations between mobile genetic elements (MGEs) and ARGs were found, what is relatively novel observation that the mechanism is confirmed to also occur in the Antarctic. This study reveals the compositional characteristics of ARGs of strains in Antarctic, providing support for the source of Antarctic antibiotic resistance and drug resistance mechanisms.202133243441