Effect of oxytetracycline-medicated feed on antibiotic resistance of gram-negative bacteria in catfish ponds. - Related Documents




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342801.0000Effect of oxytetracycline-medicated feed on antibiotic resistance of gram-negative bacteria in catfish ponds. The effect of oxytetracycline-medicated feeds on antibiotic resistance in gram-negative bacteria from fish intestines and water in catfish ponds was investigated. In experiments in the fall and spring, using ponds with no previous history of antibiotic usage, percentages of tetracycline-resistant bacteria in catfish intestines obtained from medicated ponds increased significantly after 10 days of treatment. In the fall, resistance of the intestinal and aquatic bacteria returned to pretreatment levels within 21 days after treatment. In the spring, resistance declined after treatment but remained higher than pretreatment levels for at least 21 days in intestinal bacteria and for 5 months in aquatic bacteria. Plesiomonas shigelloides, Aeromonas hydrophila, and Citrobacter freundii were isolated frequently in both spring and fall; Escherichia coli, Klebsiella pneumoniae, Edwardsiella tarda, and Enterobacter spp. were isolated primarily in the spring. Oxytetracycline treatment did not affect the distribution of bacterial species in the fall but may have accelerated a shift toward greater prevalence of members of the family Enterobacteriaceae in the spring. Multiple antibiotic resistance did not appear to be elicited by oxytetracycline treatment.19957793953
353210.9998Transfer of Antibiotic Resistance Plasmid from Commensal E. coli Towards Human Intestinal Microbiota in the M-SHIME: Effect of E. coli dosis, Human Individual and Antibiotic Use. Along with (in) direct contact with animals and a contaminated environment, humans are exposed to antibiotic-resistant bacteria by consumption of food. The implications of ingesting antibiotic-resistant commensal bacteria are unknown, as dose-response data on resistance transfer and spreading in our gut is lacking. In this study, transfer of a resistance plasmid (IncF), harbouring several antibiotic resistance genes, from a commensal E. coli strain towards human intestinal microbiota was assessed using a Mucosal Simulator of the Human Intestinal Ecosystem (M-SHIME). More specifically, the effect of the initial E. coli plasmid donor concentration (10(5) and 10(7) CFU/meal), antibiotic treatment (cefotaxime) and human individual (n = 6) on plasmid transfer towards lumen coliforms and anaerobes was determined. Transfer of the resistance plasmid to luminal coliforms and anaerobes was observed shortly after the donor strain arrived in the colon and was independent of the ingested dose. Transfer occurred in all six simulated colons and despite their unique microbial community composition, no differences could be detected in antibiotic resistance transfer rates between the simulated human colons. After 72 h, resistant coliform transconjugants levels ranged from 7.6 × 10(4) to 7.9 × 10(6) CFU(cefotaxime resistant)/Ml colon lumen. Presence of the resistance plasmid was confirmed and quantified by PCR and qPCR. Cefotaxime treatment led to a significant reduction (85%) in resistant coliforms, however no significant effect on the total number of cultivable coliforms and anaerobes was observed.202133670965
351920.9998Fate of chlortetracycline- and tylosin-resistant bacteria in an aerobic thermophilic sequencing batch reactor treating swine waste. Antibiotics have been added to animal feed for decades. Consequently, food animals and their wastes constitute a reservoir of antibiotic-resistant bacteria. The objective of this work was to characterize the impact of an aerobic thermophilic biotreatment on aerobic, antibiotic-resistant bacteria in swine waste. The proportion of tylosin- and chlortetracycline-resistant bacteria grown at 25 degrees C, 37 degrees C, and 60 degrees C decreased after treatment, but they were still abundant (10(2) to 10(8) most probable number ml(-1)) in the treated swine waste. The presence of 14 genes conferring resistance to tylosin and chlortetracycline was assessed by polymerase chain reaction in bacterial populations grown at 25 degrees C, 37 degrees C, and 60 degrees C, with or without antibiotics. In 22 cases, genes were detected before but not after treatment. The overall gene diversity was wider before [tet(BLMOSY), erm(AB)] than after [tet(LMOS), erm(B)] treatment. Analysis by denaturing gradient gel electrophoresis of amplified 16S ribosomal DNA (rDNA) fragments generally showed a reduction of the bacterial diversity, except for total populations grown at 60 degrees C and for tylosin-resistant populations grown at 37 degrees C. The latter were further investigated by cloning and sequencing their 16S rDNA. Phylotypes found before treatment were all closely related to Enterococcus hirae, whereas six different phylotypes, related to Pseudomonas, Alcaligenes, and Pusillimonas, were found after treatment. This work demonstrated that the aerobic thermophilic biotreatment cannot be considered as a means for preventing the dissemination of aerobic antibiotic-resistant bacteria and their resistance genes to the environment. However, since pathogens do not survive the biotreatment, the effluent does not represent an immediate threat to animal or human health.200919125305
342530.9998Horizontal transfer of antibiotic resistance genes among gram negative bacteria in sewage and lake water and influence of some physico-chemical parameters of water on conjugation process. Transfer of antibiotic resistance genes among gram negative bacteria in sewage and lake water and easy access of these bacteria to the community are major environmental and public health concern. The aim of this study was to determine transfer of the antimicrobial resistance genes from resistant to susceptible gram negative bacteria in the sewage and lake water by conjugation process and to determine the influence of some physico-chemical parameters of sewage and lake water on the transfer of these resistance genes. For this reason, we isolated 20 liter of each sewage and lake water from coconut area within university campus and Lingambudi lake respectively in Mysore city, India, during monsoon season and studied different physical parameters of the water samples like pH, temperature, conductivity turbidity and color as well as chemical parameters like BOD, COD, field DO and total chloride ion. The gram negative bacteria were isolated and identified from the above water samples using microbiological and biochemical methods and their sensitivity to different antibiotics was determined by disc diffusion break point assay. Conjugation between two multiple antibiotic resistant isolates Pseudomonas aeuginosa and E. coli as donor and E. coli Rif(r) (sensitive to antibiotics) as recipient were carried out in 5ml sterile sewage and lake water. All isolates were resistant to Am, moderately resistant to Te and E, while majority were sensitive to Cip, Gm and CAZ antibiotics. Horizontal transfer of antibiotic resistance genes by conjugation process revealed transfer of Gm, Te and E resistant genes from Ps. aeruginosa to E. coli Rif(r) recipient with mean frequency of +/- 2.3 x 10(-4) in sewage and +/- 2.6 x 10(-6) in lake water respectively Frequency of conjugation in sewage was two fold more as compared to lake water (p< or =0.05). Co- transfer study revealed simultaneous transfer of above resistant markers together to the recipient cells. As the above results indicate, due to selective pressure in sewage (presence of antibiotics), the isolates from sewage were more resistant to different antibiotics as compared to those from lake water. Furthermore, these resistance genes can transfer to sensitive bacteria by conjugation. Physico-chemical parameters of water may play role in this process.200920112862
528940.9998Examination of the Aerobic Microflora of Swine Feces and Stored Swine Manure. Understanding antibiotic resistance in agricultural ecosystems is critical for determining the effects of subtherapeutic and therapeutic uses of antibiotics for domestic animals. This study was conducted to ascertain the relative levels of antibiotic resistance in the aerobic bacterial population to tetracycline, tylosin, and erythromycin. Swine feces and manure samples were plated onto various agar media with and without antibiotics and incubated at 37°C. Colonies were counted daily. Randomly selected colonies were isolated and characterized by 16S rRNA sequence analyses and additional antibiotic resistance and biochemical analyses. Colonies were recovered at levels of 10 to 10 CFU mL for swine slurry and 10 to 10 CFU g swine feces, approximately 100-fold lower than numbers obtained under anaerobic conditions. Addition of antibiotics to the media resulted in counts that were 60 to 80% of those in control media without added antibiotics. Polymerase chain reaction analyses for antibiotic resistance genes demonstrated the presence of a number of different resistance genes from the isolates. The recoverable aerobic microflora of swine feces and manure contain high percentages of antibiotic-resistant bacteria, which include both known and novel genera and species, and a variety of antibiotic resistance genes. Further analyses of these and additional isolates should provide additional information on these organisms as potential reservoirs of antibiotic resistance genes in these ecosystems.201627065407
314350.9998Impact of colistin sulfate treatment of broilers on the presence of resistant bacteria and resistance genes in stored or composted manure. The application of manure may result in contamination of the environment with antimicrobials, antimicrobial-resistant bacteria, resistance genes and plasmids. The aim of this study was to investigate the impact of the administration of colistin and of manure management on (i) the presence of colistin-resistant Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa and (ii) the prevalence of various antimicrobial resistance genes in feces and in composted or stored manure. One flock of chickens was treated with colistin at the recommended dosage and a second flock was kept as an untreated control. Samples of feces, litter and stored or composted manure from both flocks were collected for isolation and determination of the colistin-susceptibility of E. coli, K. pneumoniae and P. aeruginosa and quantification of genes coding for resistance to different antimicrobials. The persistence of plasmids in stored or composted manure from colistin-treated broilers was also evaluated by plasmid capturing experiments. Results revealed that colistin administration to chickens had no apparent impact on the antimicrobial resistance of the dominant Enterobacteriaceae and P. aeruginosa populations in the chicken gut. Composting stimulated an apparently limited decrease in genes coding for resistance to different antimicrobial families. Importantly, it was shown that even after six weeks of composting or storage, plasmids carrying antimicrobial resistance genes could still be transferred to a recipient E. coli. In conclusion, composting is insufficient to completely eliminate the risk of spreading antimicrobial resistance through chicken manure.201626616601
709960.9998The 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
529170.9998Low-Concentration Ciprofloxacin Selects Plasmid-Mediated Quinolone Resistance Encoding Genes and Affects Bacterial Taxa in Soil Containing Manure. The spread of antimicrobial resistance in environment is promoted at least in part by the inappropriate use of antibiotics in animals and humans. The present study was designed to investigate the impact of different concentrations of ciprofloxacin in soil containing manure on the development of plasmid-mediated quinolone resistance (PMQR) - encoding genes and the abundance of soil bacterial communities. For these studies, high-throughput next-generation sequencing of 16S rRNA, real-time polymerase chain reaction and standard microbiologic culture methods were utilized. We demonstrated that the dissipate rate of relative abundances of some of PMQR-encoding genes, such as qnrS, oqxA and aac(6('))-Ib-cr, were significantly lower with ciprofloxacin 0.04 and 0.4 mg/kg exposure as compared to no-ciprofloxacin control and ciprofloxacin 4 mg/kg exposure during 2 month. Also, the number of ciprofloxacin resistant bacteria was significantly greater in ciprofloxacin 0.04 and 0.4 mg/kg exposure as compared with no-ciprofloxacin control and the ciprofloxacin 4 mg/kg exposure. In addition, lower ciprofloxacin concentration provided a selective advantage for the populations of Xanthomonadales and Bacillales in orders while Agrobacterium, Bacillus, Enterococcus, and Burkholderia in genera. These findings suggest that lower concentration of ciprofloxacin resulted in a slower rate of PMQR-encoding genes dissipation and selected development of ciprofloxacin-resistant bacteria in soil amended with manure.201627847506
529380.9997Tetracycline-Resistant Bacteria Selected from Water and Zebrafish after Antibiotic Exposure. The emergence of antibiotic-resistant pathogens due to worldwide antibiotic use is raising concern in several settings, including aquaculture. In this work, the selection of antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) was evaluated after exposure of zebrafish to oxytetracycline (OTC) for two months, followed by a recovery period. The selection of ARB in water and fish was determined using selective media. The abundance of tetA genes was estimated through qPCR. Higher prevalence of ARB was measured in all samples exposed to the antibiotic when compared to control samples, although statistical significance was only achieved five days after exposure. Isolates recovered from samples exposed to the antibiotic were affiliated with Pseudomonas and Stenotrophomonas. Various antibiotic susceptibility profiles were detected and 37% of the isolates displayed multidrug resistance (MDR). The selection of the tetA gene was confirmed by qPCR at the highest OTC concentration tested. Two MDR isolates, tested using zebrafish embryos, caused significant mortality, indicating a potential impact on fish health and survival. Overall, our work highlights the potential impact of antibiotic contamination in the selection of potential pathogenic ARB and ARGS.202133804606
529290.9997Antibiotic-Resistant Bacteria in Hydroponic Lettuce in Retail: A Comparative Survey. Hydroponic produce is gaining popularity due to its suitability for urban agriculture. The general public also considers that hydroponic produce is free from microbiological contamination. In this study, we compared the frequency and abundance of tetracycline-resistant and sulphadiazine-resistant bacteria and the minimal inhibitory concentration (MIC) of these isolates in conventional, organic, and hydroponic lettuce sold in retail. We also determined the frequency of samples carrying tetB, tetX, sul1, sul2, and int1 genes by PCR and further quantified the copy number of tetX, sul1, and int1 genes in samples positive for these genes using qPCR. As expected, the number of resistant bacteria and the MICs of these isolates were lowest in hydroponic lettuce and highest in organic lettuce. All tested resistant genes, except int1, were detected in samples of all three production methods, but no significant difference was observed between the three groups in the frequency of samples carrying the resistance genes examined or in their copy number. To the best of our knowledge, it is the first study directly reporting the existence of antibiotic-resistant bacteria and resistance genes in hydroponic vegetables sold in retail. The result highlights that the risk of antibiotic-resistant bacteria contamination in hydroponic produce should be further investigated.202032967196
3433100.9997Effect of subinhibitory concentrations on the spreading of the ampicillin resistance gene bla(CMY-2) in an activated sludge microcosm. As the problem of multi-resistant bacteria grows a better understanding of the spread of antibiotic resistance genes is of utmost importance for society. Wastewater treatment plants contain subinhibitory concentrations of antibiotics and are thought to be hotspots for antibiotic resistance gene propagation. Here we evaluate the influence of sub-minimum inhibitory concentrations of antibiotics on the spread of resistance genes within the bacterial community in activated sludge laboratory-scale sequencing batch reactors. The mixed communities were fed two different ampicillin concentrations (500 and 5000 µg/L) and the reactors were run and monitored for 30 days. During the experiment the β-lactamase resistance gene bla(CMY-2) was monitored via qPCR and DNA samples were taken to monitor the effect of ampicillin on the microbial community. The relative copy number of bla(CMY-2) in the reactor fed with the sub-minimum inhibitory concentration of 500 µg/L ampicillin was spread out over a wider range of values than the control and 5000 µg/L ampicillin reactors indicating more variability of gene number in the 500 µg/L reactor. This result emphasises the problem of sub-minimum inhibitory concentrations of antibiotics in wastewater. High-throughput sequencing showed that continuous exposure to ampicillin caused a shift from a Bacteroidetes to Proteobacteria in the bacterial community. The combined use of qPCR and high-throughput sequencing showed that ampicillin stimulates the spread of resistance genes and leads to the propagation of microbial populations which are resistant to it.202539215485
3531110.9997Commensal E. coli rapidly transfer antibiotic resistance genes to human intestinal microbiota in the Mucosal Simulator of the Human Intestinal Microbial Ecosystem (M-SHIME). Food-producing animals are indicated as a reservoir of antibiotic resistance genes and a potential vector for transmission of plasmid-encoded antibiotic resistance genes by conjugation to the human intestinal microbiota. In this study, transfer of an antibiotic resistance plasmid from a commensal E. coli originating from a broiler chicken towards the human intestinal microbiota was assessed by using a Mucosal Simulator of the Human Intestinal Microbial Ecosystem (M-SHIME). This in vitro model mimics the human intestinal ecosystem and received a single dose of 10(9)E. coli MB6212, which harbors a plasmid known to confer resistance towards several antibiotics including tetracycline, sulfamethoxazole and cefotaxime. Since the degree of stress imposed by stomach pH and bile acids vary with the consumed meal size, the effect of meal size on E. coli donor survival and on plasmid transfer towards lumen and mucosal coliforms and anaerobes was determined. The administered commensal E. coli strain survived stomach acid and bile salt stress and was able to grow in the colon environment during the timeframe of the experiment (72 h). Transfer of antibiotic resistance was observed rapidly since cultivable transconjugant coliforms and anaerobes were already detected in the lumen and mucosa after 2 h in the simulated proximal colon. The presence of the resistance plasmid in the transconjugants was confirmed by PCR. Differences in meal size and adapted digestion had neither a detectable impact on antibiotic resistance transfer, nor on the survival of the E. coli donor strain, nor on short chain fatty acid profiles. The median number of resistant indigenous coliforms in the lumen of the inoculated colon vessels was 5.00 × 10(5) cfu/ml [min - max: 3.47 × 10(4)-3.70 × 10(8) cfu/ml], and on the mucosa 1.44 × 10(7) cfu/g [min-max: 4.00 × 10(3)-4.00 × 10(8) cfu/g]. Exact quantification of the anaerobic transconjugants was difficult, as (intrinsic) resistant anaerobic background microbiota were present. QPCR data supported the observation of plasmid transfer in the simulated colon. Moreover, inoculation of E. coli MB6212 had no significant impact on the microbial diversity in the lumen as determined by 16 S ribosomal gene based next generation sequencing on lumen samples. This study demonstrates that a commensal, antibiotic resistant E. coli strain present in food can transfer its antibiotic resistance plasmid relatively quickly to intestinal microbiota in the M-SHIME. The spread and persistence of antibiotic resistance genes and resistant bacteria in our intestinal system is an alarming scenario which might present clinical challenges, since it implies a potential reservoir for dissemination to pathogenic bacteria.201931536878
7123120.9997Presence 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
3696130.9997Assessment of Tetracyclines Residues and Tetracycline Resistant Bacteria in Conventional and Organic Baby Foods. Children are very vulnerable to bacterial infections and they are sometimes subject to antimicrobials for healing. The presence of resistance genes may counteract effects of antimicrobials. This work has thereby compared the amount of tetracycline resistance genes, tet(A) and tet(B), between conventional and organic meat-based or vegetable-based baby foods and used the quantification of these genes to assess the presence of tetracycline residues in these samples. Counts of bacteria harboring the tet(A) gene were higher than those containing tet(B), and there was no difference between the organic and the conventional samples. Samples with detectable amounts of tetracycline residues were also positive for the presence of tet genes, and when the presence of the genes was not detected, the samples were also negative for the presence of residues. The percentages of tetracycline residues were higher in organic samples than in conventional ones. It cannot be concluded that organic formulas are safer than conventional ones for the studied parameters.201528231206
7121140.9997Fate of fluoroquinolones in field soil environment after incorporation of poultry litter from a farm with enrofloxacin administration via drinking water. The practice of incorporating animal manure into soil is supported within the European Circular economy as a possible substitute for mineral fertilizers and will become crucial for the sustainability of agriculture. However, this practice may indirectly contribute to the dissemination of antibiotics, resistance bacteria, and resistance genes. In this study, medicated drinking water and poultry litter samples were obtained from a broiler-chick farm. The obtained poultry litter was incorporated into the soil at the experimental field site. The objectives of this research project were first to develop analytical methods able to quantify fluoroquinolones (FQs) in medicated drinking water, poultry litter, and soil samples by LC-MS; second to study the fate of these FQs in the soil environment after incorporation of poultry litter from flock medicated by enrofloxacin (ENR); and third to screen the occurrence of selected fluoroquinolone resistance encoding genes in poultry litter and soil samples (PCR analysis). FQs were quantified in the broiler farm's medicated drinking water (41.0 ± 0.3 mg∙L(-1) of ENR) and poultry litter (up to 70 mg∙kg(-1) of FQs). The persistence of FQs in the soil environment over 112 days was monitored and evaluated (ENR concentrations ranged from 36 μg∙kg(-1) to 9 μg∙kg(-1) after 100 days). The presence of resistance genes was confirmed in both poultry litter and soil samples, in agreement with the risk assessment for the selection of AMR in soil based on ENR concentrations. This work provides a new, comprehensive perspective on the entry and long-term fate of antimicrobials in the terrestrial environment and their consequences after the incorporation of poultry litter into agricultural fields.202438367114
7100150.9997Spread of tetracycline resistance genes at a conventional dairy farm. The use of antibiotics in animal husbandry contributes to the worldwide problem of increasing antibiotic resistance in animal and human pathogens. Intensive animal production is considered an important source of antibiotic resistance genes released to the environment, while the contribution of smaller farms remains to be evaluated. Here we monitor the spread of tetracycline resistance (TC-r) genes at a middle-size conventional dairy farm, where chlortetracycline (CTC, as intrauterine suppository) is prophylactically used after each calving. Our study has shown that animals at the farm acquired the TC-r genes in their early age (1-2 weeks), likely due to colonization with TC-resistant bacteria from their mothers and/or the farm environment. The relative abundance of the TC-r genes tet(W), tet(Q), and tet(M) in fresh excrements of calves was about 1-2 orders of magnitude higher compared to heifers and dairy cows, possibly due to the presence of antibiotic residues in milk fed to calves. The occurrence and abundance of TC-r genes in fresh excrements of heifers and adult cows remained unaffected by intrauterine CTC applications, with tet(O), tet(Q), and tet(W) representing a "core TC-resistome" of the farm, and tet(A), tet(M), tet(Y), and tet(X) occurring occasionally. The genes tet(A), tet(M), tet(Y), and tet(X) were shown to be respectively harbored by Shigella, Lactobacillus and Clostridium, Acinetobacter, and Wautersiella. Soil in the farm proximity, as well as field soil to which manure from the farm was applied, was contaminated with TC-r genes occurring in the farm, and some of the TC-r genes persisted in the field over 3 months following the manure application. Concluding, our study shows that antibiotic resistance genes may be a stable part of the intestinal metagenome of cattle even if antibiotics are not used for growth stimulation, and that smaller dairy farms may also contribute to environmental pollution with antibiotic resistance genes.201526074912
3423160.9997bla(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
3427170.9997Annual changes in the occurrence of antibiotic-resistant coliform bacteria and enterococci in municipal wastewater. Wastewater contains subinhibitory concentrations of different micropollutants such as antibiotics that create selective pressure on bacteria. This phenomenon is also caused by insufficient wastewater treatment technology leading to the development and spread of antibiotic-resistant bacteria and resistance genes into the environment. Therefore, this work focused on monitoring of antibiotic-resistant coliform bacteria and enterococci in influent and effluent wastewaters taken from the second biggest wastewater treatment plant (Petržalka) in the capital of Slovakia during 1 year. Antibiotic-resistant strains were isolated, identified, and characterized in terms of susceptibility and biofilm production. All of 27 antibiotic-resistant isolates were identified mainly as Morganella morganii, Citrobacter spp., and E. coli. Multidrug-resistance was detected in 58% of isolated strains. All tested isolates could form biofilm; two strains were very strong producers, and 74% formed biofilm by strong intensity. The flow rate of the influent wastewater had a more significant impact on the number of studied bacteria than the temperature. Graphical abstract.201931049859
5290180.9997Antibiotic resistance of bacteria isolated from heavy metal-polluted soils with different land uses. OBJECTIVES: The main objective of this study was to determine the relationship between the antibiotic and heavy metal tolerance of culturable bacteria isolated from mining waste, pasture, and agricultural soils containing different levels of heavy metals. MATERIALS AND METHODS: The populations of total culturable bacteria, and heavy metal- and antibiotic-tolerant bacteria in the soils were enumerated on nutrient agar, nutrient agar amended with metals, and Mueller-Hinton agar amended with antibiotics, respectively. The multiple antibiotic resistance index, and patterns of antibiotic resistance and heavy metal-antibiotic co-resistance were determined for 237 isolates. RESULTS: Among all the samples, those of the tailings of mines with higher levels of heavy metals had the lowest number of bacteria, but a relatively higher abundance of heavy metal- and antibiotic-resistant bacteria. A high degree of resistance was observed for ampicillin and amoxicillin in the isolates from all soils. The agricultural soil isolates had a high prevalence of resistance towards vancomycin, tetracycline, and streptomycin. Among all the tested antibiotics, gentamicin was the most potent. The most frequent pattern of multiple antibiotic resistance in the isolates from agricultural soils was amoxicillin, ampicillin, streptomycin, vancomycin, tetracycline, and doxycycline. The percentage of isolates with multiple antibiotic resistance was considerably higher in the agricultural soils than in the mining waste soils. A high rate of co-resistance towards Hg and antibiotics was observed among the gram-negative isolates, and towards Zn, Ni, Hg, and the beta-lactam antibiotics among the gram-positive isolates. CONCLUSIONS: The higher percentage of isolates with multiple antibiotic resistance in the agricultural soils that in the mining waste soils may be related to (1) the level of soil heavy metals, (2) the population and diversity of soil bacteria, (3) the application of manures, and (4) other factors affecting gene transfer between bacteria.201728732786
5353190.9997The 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