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348100.9853Antibiotics and Antibiotic Resistance Genes in Sediment of Honghu Lake and East Dongting Lake, China. Sediment is an ideal medium for the aggregation and dissemination of antibiotics and antibiotic resistance genes (ARGs). The levels of antibiotics and ARGs in Honghu Lake and East Dongting Lake of central China were investigated in this study. The concentrations of eight antibiotics (four sulfonamides and four tetracyclines) in Honghu Lake were in the range 90.00-437.43 μg kg(-1) (dry weight (dw)) with mean value of 278.21 μg kg(-1) dw, which was significantly higher than those in East Dongting Lake (60.02-321.04 μg kg(-1) dw, mean value of 195.70 μg kg(-1) dw). Among the tested three sulfonamide resistance genes (sul) and eight tetracycline resistance genes (tet), sul1, sul2, tetA, tetC, and tetM had 100 % detection frequency in sediment samples of East Dongting Lake, while only sul1, sul2, and tetC were observed in all samples of Honghu Lake. The relative abundance of sul2 was higher than that of sul1 at p < 0.05 level in both lakes. The relative abundance of tet genes in East Dongting Lake was in the following order: tetM > tetB > tetC > tetA. The relative abundance of sul1, sul2, and tetC in East Dongting Lake was significantly higher than those in Honghu Lake. The abundance of background bacteria may play an important role in the horizontal spread of sul2 and tetC genes in Honghu Lake and sul1 in East Dongting Lake, respectively. Redundancy analysis indicated that tetracyclines may play a more important role than sulfonamides in the abundance of sul1, sul2, and tetC gens in Honghu Lake and East Dongting Lake.201627418176
775710.9852Removal of antibiotics and antibiotic resistance genes from domestic sewage by constructed wetlands: Effect of flow configuration and plant species. This study aims to investigate the removal of antibiotics and antibiotic resistance genes (ARGs) in raw domestic wastewater by various mesocosm-scale constructed wetlands (CWs) with different flow configurations or plant species including the constructed wetland with or without plant. Six mesocosm-scale CWs with three flow types (surface flow, horizontal subsurface flow and vertical subsurface flow) and two plant species (Thaliadealbata Fraser and Iris tectorum Maxim) were set up in the outdoor. 8 antibiotics including erythromycin-H2O (ETM-H2O), monensin (MON), clarithromycin (CTM), leucomycin (LCM), sulfamethoxazole (SMX), trimethoprim (TMP), sulfamethazine (SMZ) and sulfapyridine (SPD) and 12 genes including three sulfonamide resistance genes (sul1, sul2 and sul3), four tetracycline resistance genes (tetG, tetM, tetO and tetX), two macrolide resistance genes (ermB and ermC), two chloramphenicol resistance genes (cmlA and floR) and 16S rRNA (bacteria) were determined in different matrices (water, particle, substrate and plant phases) from the mesocosm-scale systems. The aqueous removal efficiencies of total antibiotics ranged from 75.8 to 98.6%, while those of total ARGs varied between 63.9 and 84.0% by the mesocosm-scale CWs. The presence of plants was beneficial to the removal of pollutants, and the subsurface flow CWs had higher pollutant removal than the surface flow CWs, especially for antibiotics. According to the mass balance analysis, the masses of all detected antibiotics during the operation period were 247,000, 4920-10,600, 0.05-0.41 and 3500-60,000μg in influent, substrate, plant and effluent of the mesocosm-scale CWs. In the CWs, biodegradation, substrate adsorption and plant uptake all played certain roles in reducing the loadings of nutrients, antibiotics and ARGs, but biodegradation was the most important process in the removal of these pollutants.201627443461
355020.9852Conjugative transmission of antibiotic-resistance from stream water Escherichia coli as related to number of sulfamethoxazole but not class 1 and 2 integrase genes. A conjugation assay was used to determine the effects of phenotypic resistance to one to up to 5 antibiotics, sampling site of origin, presence or absence of class 1 and/or class 2 integrase (intI) genes (intI1 and intI2), and the number of sulfamethoxazole resistance (sul) and trimethoprim resistance (dfr) genes on the transfer frequencies of plasmids from environmental, antibiotic-resistant Escherichia coli. Of 51 sulfamethoxazole and trimethoprim-resistant E. coli isolates conferring at least one mob gene (mob(P51), mob(F11), mob(F12), mob(Q11), mob(Q12) , or mob(Qu) ), 38 produced transconjugants with an overall mean frequency of 1.60 × 10(-3) transconjugants/ donors (T/D) or 5.89 × 10(-3) transconjugants/recipients (T/R). The presence or absence of intI1 and intI2 and the presence or absence of different targeted dfr genes (dfrA1, dfrA8, dfrA12, dfrA14, dfrA17, and/or dfrB3) were not statistically related to plasmid transfer frequencies as determined by ANOVA (P ≥ 0.05). However, E. coli isolates recovered 2 km downstream of wastewater treatment plant effluent input, and those possessing resistance to 3 antibiotics had significantly greater plasmid transfer frequency than their counterparts when calculated as T/D (ANOVA followed by Fisher's least significant difference means comparison, P < 0.05). Greater plasmid transfer frequency calculated as T/D was also measured for E. coli possessing 3 compared to a single sul gene. The in-vitro frequency suggests that horizontal gene transfer of conjugative mediated-antibiotic (sul) resistance genes may be significant among resistant, stream bacteria.201628090382
774930.9851Interaction of ciprofloxacin chlorination products with bacteria in drinking water distribution systems. The interaction of ciprofloxacin chlorination products (CIP-CPs) with bacteria in drinking water distribution systems (DWDSs) was investigated. The piperazine ring of CIP was destroyed by chlorination. Among of CIP-CPs, by the bacterial role, 7.63% of the derivative with two carboxylic groups went through decarboxylation to form desethylene ciprofloxacin, and then loss of C(2)H(5)N group generated aniline compound. Furthermore, 12.3% of the aniline compound, 7.60% of chlorinated aniline compound and 1.35% of defluorinated product were bio-mineralized. Therefore, the chlorine and bacteria played synergistic effects on transformation of CIP-CPs in DWDSs, contributing to the obvious decrease of genotoxicity in effluents. Correspondingly, the TEQ(4-NQO) decreased from 667μg/L to 9.41μg/L. However, compared with DWDSs without CIP-CPs, the relative abundance of mexA and qnrS increased 1-fold in effluents and the relative abundance of qnrA and qnrB increased 3-fold in biofilms in DWDSs with CIP-CPs. mexA and qnrS positively correlated with Hyphomicrobium, Sphingomonas and Novosphingobium (p<0.05), while qnrA and qnrB positively correlated with Shewanella and Helicobacter (p<0.05), indicating the increase of antibiotic resistance genes (ARGs) came from the growth of these bacterial genera by transformation of CIP-CPs in DWDSs. These results suggested that biotransformation of antibiotics might increase ARGs risk in DWDSs.201728648729
526140.9851Prevalence of antibiotic resistance genes from effluent of coastal aquaculture, South Korea. The wide use of antibiotics in aquaculture for prophylactic and therapeutic purposes can potentially lead to the prevalence of antibiotic resistance genes (ARGs). This study reports for the first time the profile of ARGs from effluents of coastal aquaculture located in South Jeolla province and Jeju Island, South Korea. Using quantitative PCR (qPCR), twenty-two ARGs encoding tetracycline resistance (tetA, tetB, tetD, tetE, tetG, tetH, tetM, tetQ, tetX, tetZ, tetBP), sulfonamide resistance (sul1, sul2), quinolone resistance (qnrD, qnrS, aac(6')-Ib-cr), β-lactams resistance (bla(TEM), bla(CTX), bla(SHV)), macrolide resistance (ermC), florfenicol resistance (floR) and multidrug resistance (oqxA) and a class 1 integrons-integrase gene (intI1) were quantified. In addition, Illumina Miseq sequencing was applied to investigate microbial community differences across fish farm effluents. Results from qPCR showed that the total number of detected ARGs ranged from 4.24 × 10(-3) to 1.46 × 10(-2) copies/16S rRNA gene. Among them, tetB and tetD were predominant, accounting for 74.8%-98.0% of the total ARGs. Furthermore, intI1 gene showed positive correlation with tetB, tetD, tetE, tetH, tetX, tetZ tetQ and sul1. Microbial community analysis revealed potential host bacteria for ARGs and intI1. Two genera, Vibrio and Marinomonas belonging to Gammaproteobacteria, showed significant correlation with tetB and tetD, the most dominant ARGs in all samples. Also, operational taxonomic units (OTUs)-based network analysis revealed that ten OTUs, classified into the phyla Proteobacteria, Cyanobacteria/Chloroplast, Bacteroidetes, Verrucomicrobia and an unclassified phylum, were potential hosts of tetracycline resistance genes (i.e., tetA, tetG, tetH, tetM, tetQ and tetZ). Further systematic monitoring of ARGs is warranted for risk assessment and management of antibacterial resistance from fish farm effluents.201829031406
523450.9851A Multidrug-Resistant Escherichia coli Caused the Death of the Chinese Soft-Shelled Turtle (Pelodiscus sinensis). The rapid increase in drug resistance in recent years has become a significant global public health concern. Escherichia coli are ubiquitous bacteria, widely distributed in various environments. This study isolated a bacterial strain (HD-593) from diseased Chinese soft-shelled turtles (Pelodiscus sinensis). The bacterium was identified based on morphology, biochemical tests, and 16S rRNA sequencing, confirming it as E. coli. Drug susceptibility tests revealed that the HD-593 strain was highly resistant to ceftriaxone, enrofloxacin, doxycycline, sulfadiazine, gentamicin, neomycin, florfenicol, carbenicillin, cefradine, erythromycin, penicillin, ampicillin, midecamycin, and streptomycin. Resistance gene analysis confirmed the presence of quinolone resistance genes (oqxA and oqxB), aminoglycoside resistance genes (aac(3)-II and aphA1), a β-lactam resistance gene (blaTEM), and an acylaminol resistance gene (floR) in HD-593. The median lethal dose (LD50) of HD-593 for P. sinensis was 6.53 × 10(5) CFU/g. Biochemical analysis of serum revealed that HD-593 infection caused a significant reduction in total protein, albumin, and globulin levels, while markedly increasing the levels of aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase. Histopathological analysis revealed severe intestinal damage characterized by villi detachment and muscle cell necrosis. Additionally, extensive splenocyte necrosis with nuclear marginalization, glomerular swelling, and pronounced hepatic steatosis accompanied by distended sinusoids were observed. This study identified a multidrug-resistant E. coli strain from deceased P. sinensis, suggesting that drug resistance genes may circulate in aquaculture ecosystems, posing potential risks to aquaculture.202540431566
540460.9849Characterization of tetracycline resistance lactobacilli isolated from swine intestines at western area of Taiwan. To investigate the frequency of tetracycline resistance (Tet-R) lactobacilli in pig intestines, a total of 256 pig colons were analyzed and found to contain typical colonies of Tet-R lactic acid bacteria in every sample, ranging from 3.2 × 10(3) to 6.6 × 10(5) CFU/cm(2). From these samples, a total of 159 isolates of Tet-R lactobacilli were obtained and identified as belonging to 11 species, including Lactobacillus reuteri, Lactobacillus amylovorus, Lactobacillus salivarius, Lactobacillus plantarum, Lactobacillus ruminis, Lactobacillus kefiri, Lactobacillus fermentum, Lactobacillus sakei, Lactobacillus coryniformis, Lactobacillus parabuchneri and Lactobacillus letivazi. Based on the EFSA (2008) breakpoints, all isolates, after MIC analysis, were qualified as Tet-R, from which the significant high Tet-R MIC(50) and MIC(90) values indicated an ecological distribution of Tet-R lactobacilli mostly with high resistance potency in pig colons. PCR-detection identified 5 tet genes in these isolates, the most predominant one being tet (W), followed by tet (M), (L), (K), and (Q). Their detection rates were 82.0%, 22.5%, 14.4%, 8.1% and 0.9%, respectively. Noteworthily, isolates of the same species carrying identical tet gene(s) usually had a wide different MIC values. Furthermore, strain-subtyping of these isolates by REP-PCR demonstrated a notable genotypic biodiversity % (average = 62%).201121906691
362670.9848Multiple antibiotic resistance and herbicide catabolic profiles of bacteria isolated from Lake Villarrica surface sediments (Chile). Antibiotics and herbicides are contaminants of emerging concern in aquatic environments. Lake Villarrica is a relevant freshwater body in Chile and was recently designated a 'saturated nutrient zone'. Here, we investigated the occurrence of multiple antibiotic resistance (MAR) and herbicide catabolic profiles among bacteria present in the surface sediments of Lake Villarrica. The occurrence of antibiotic-resistant genes (ARGs; blaTEM, catA and tetM) and herbicide-catabolic genes (HCGs; phnJ and atzA) was investigated by qPCR. Subsequently, the presence of culturable bacteria with multiple resistance to amoxicillin (AMX), chloramphenicol (CHL) and oxytetracycline (OXT) was studied. Forty-six culturable MAR (AMX + CHL + OXT) strains were isolated and characterized with respect to their resistance to 11 antibiotics by using a disc diffusion assay and testing their ability to use herbicides as a nutrient source. qPCR analyses revealed that ARGs and HCGs were present in all sediment samples (10(1) to 10(3) gene copies g(-1)), with significant (P ≤ 0.05) higher values in sites near Villarrica city and cattle pastures. The plate method was used to recover MAR isolates from sediment (10(3)-10(6) CFU g(-1)), and most of the 46 isolates also showed resistance to oxacillin (100%), cefotaxime (83%), erythromycin (96%) and vancomycin (93%). Additionally, 54 and 57% of the MAR isolates were able to grow on agar supplemented (50 mg L(-1)) with atrazine and glyphosate as nutrient sources, respectively. Most of the MAR isolates were taxonomically close to Pseudomonas (76.1%) and Pantoea (17.4%), particularly those isolated from urbanized sites (Pucón city). This study shows the presence of MAR bacteria with herbicide catabolic activity in sediments, which is valuable for conservation strategies and risk assessments of Lake Villarrica. However, major integrative studies on sediments as reservoirs or on the fate of MAR strains and traces of antibiotics and herbicides as a result of anthropic pressure are still needed.202439002747
527780.9848Antibiotic resistance of bacteria isolated from shrimp hatcheries and cultural ponds on Donghai Island, China. The resistance of bacteria to 12 different antibiotics was investigated in shrimp farms on Donghai Island, China. Antibiotic-resistant bacteria were found to be widespread in shrimp farms, indicating a high environmental risk. Further, significant differences were found in bacterial strains among farms (ANOVA, p<0.05), showing resistance to antibiotics such as ampicillin, trimethoprim, compound sinomi, tetracycline, chloramphenicol and cefazolin. No significant differences in antibiotic resistance were found among 6 hatcheries evaluated in this study (ANOVA, p>0.05), between exalted and traditional shrimp ponds (ANOVA, p>0.05), and between cultural ponds and corresponding control water source sites (T-test, p>0.05). In cultural ponds, no significant difference in bacterial resistance to antibiotics was found between water and sediment (T-test, p>0.05), and antibiotic resistance of bacteria from water showed a significant positive correlation with that from sediment (p<0.05). Therefore, our study indicates that bacterial multiple antibiotic resistance (MAR) is more widespread in shrimp hatcheries than ponds.201121945557
779290.9848Comparative removal of two antibiotic resistant bacteria and genes by the simultaneous use of chlorine and UV irradiation (UV/chlorine): Influence of free radicals on gene degradation. The research aimed to remove antibiotic resistance by the simultaneous use of UV irradiation and chlorine (UV/chlorine). The inactivations of tetracycline resistant bacteria (TRB) during chlorination, UV irradiation, and UV/chlorine was investigated and compared with those of amoxicillin resistant bacteria (AmRB). Similar examination was also conducted for comparing the removals of their resistant genes (i.e., tetM and blaTem). The removals of antibiotic resistance highly depended on chlorine doses and UV intensities. The sufficient chlorine dose (20 mg.L(-1)) in the chlorination and the UV/chlorine completely inactivated TRB and AmRB (>7.3 log), while the UV irradiation could not achieve the complete disinfection. Microorganisms resistant to different antibiotics exhibit different susceptibility to the disinfection processes. The removals of antibiotic resistant genes (i.e., tetM and blaTem) were more difficult than those of TRB and AmRB. The UV/chlorine was the greatest process for tetM and blaTem removals, followed by chlorination and UV irradiation, respectively. Chlorination decreased the tetM and blaTem by 0.40-1.45 log and 1.04-2.45 log, respectively. The blaTem gene was highly reactive to chlorine, compared with tetM. The UV irradiation caused the tetM and blaTem reductions by 0.32-0.91 log and 0.59-0.96 log, respectively. The UV/chlorine improved the tetM and blaTem removals by 0.98-3.20 log and 1.28-3.36 log, respectively. The •OH contributed to the fraction of tetM and blaTem removals by 48% and 19%, respectively. The effect of reactive chlorine species on the tetM and blaTem removals was minor. The pseudo 1st-order kinetic constants (k') for tetM and blaTem removals by the UV/chlorine were highest. The •OH enhanced the k' values by 120% and 20% for the tetM and blaTem removals, respectively. The study showed the potential use of UV/chlorine for controlling antibiotic resistance.202133059146
7745100.9847Iron-modified biochar boosts anaerobic digestion of sulfamethoxazole pharmaceutical wastewater: Performance and microbial mechanism. The accumulation of volatile fatty acids (VFAs) caused by antibiotic inhibition significantly reduces the treatment efficiency of sulfamethoxazole (SMX) wastewater. Few studies have been conducted to study the VFAs gradient metabolism of extracellular respiratory bacteria (ERB) and hydrogenotrophic methanogen (HM) under high-concentration sulfonamide antibiotics (SAs). And the effects of iron-modified biochar on antibiotics are unknown. Here, the iron-modified biochar was added to an anaerobic baffled reactor (ABR) to intensify the anaerobic digestion of SMX pharmaceutical wastewater. The results demonstrated that ERB and HM were developed after adding iron-modified biochar, promoting the degradation of butyric, propionic and acetic acids. The content of VFAs reduced from 1166.0 mg L(-1) to 291.5 mg L(-1). Therefore, chemical oxygen demand (COD) and SMX removal efficiency were improved by 22.76% and 36.51%, and methane production was enhanced by 6.19 times. Furthermore, the antibiotic resistance genes (ARGs) such as sul1, sul2, intl1 in effluent were decreased by 39.31%, 43.33%, 44.11%. AUTHM297 (18.07%), Methanobacterium (16.05%), Geobacter (6.05%) were enriched after enhancement. The net energy after enhancement was 0.7122 kWh m(-3). These results confirmed that ERB and HM were enriched via iron-modified biochar to achieve high efficiency of SMX wastewater treatment.202337030222
7775110.9847Accumulation of pharmaceuticals, Enterococcus, and resistance genes in soils irrigated with wastewater for zero to 100 years in central Mexico. Irrigation with wastewater releases pharmaceuticals, pathogenic bacteria, and resistance genes, but little is known about the accumulation of these contaminants in the environment when wastewater is applied for decades. We sampled a chronosequence of soils that were variously irrigated with wastewater from zero up to 100 years in the Mezquital Valley, Mexico, and investigated the accumulation of ciprofloxacin, enrofloxacin, sulfamethoxazole, trimethoprim, clarithromycin, carbamazepine, bezafibrate, naproxen, diclofenac, as well as the occurrence of Enterococcus spp., and sul and qnr resistance genes. Total concentrations of ciprofloxacin, sulfamethoxazole, and carbamazepine increased with irrigation duration reaching 95% of their upper limit of 1.4 µg/kg (ciprofloxacin), 4.3 µg/kg (sulfamethoxazole), and 5.4 µg/kg (carbamazepine) in soils irrigated for 19-28 years. Accumulation was soil-type-specific, with largest accumulation rates in Leptosols and no time-trend in Vertisols. Acidic pharmaceuticals (diclofenac, naproxen, bezafibrate) were not retained and thus did not accumulate in soils. We did not detect qnrA genes, but qnrS and qnrB genes were found in two of the irrigated soils. Relative concentrations of sul1 genes in irrigated soils were two orders of magnitude larger (3.15 × 10(-3) ± 0.22 × 10(-3) copies/16S rDNA) than in non-irrigated soils (4.35 × 10(-5)± 1.00 × 10(-5) copies/16S rDNA), while those of sul2 exceeded the ones in non-irrigated soils still by a factor of 22 (6.61 × 10(-4) ± 0.59 × 10(-4) versus 2.99 × 10(-5) ± 0.26 × 10(-5) copies/16S rDNA). Absolute numbers of sul genes continued to increase with prolonging irrigation together with Enterococcus spp. 23S rDNA and total 16S rDNA contents. Increasing total concentrations of antibiotics in soil are not accompanied by increasing relative abundances of resistance genes. Nevertheless, wastewater irrigation enlarges the absolute concentration of resistance genes in soils due to a long-term increase in total microbial biomass.201223049795
5401120.9847Safety and Growth Optimization of Lactic Acid Bacteria Isolated From Feedlot Cattle for Probiotic Formula Design. In order to eliminate the widespread use of antibiotics in livestock production, the research for alternatives has increased lately. This study examined the safety of 40 lactic acid bacteria (LAB) isolated from bovine feedlot environment and previously selected as potential probiotics. A high sensitivity prevalence to ampicillin (AMP, 100%), gentamicin (GEN, 96.3%), kanamycin (KAN, 96.3%), clindamycin (CLI, 85.2%), chloramphenicol (CHL, 92.6%) and streptomycin (STR, 88.9%) while moderate and high resistance against erythromycin (ERY, 48%) and tetracycline (TET, 79%) respectively, were determined. Feedlot enterococci and pediococci displayed high resistance to CLI, ERY, GEN and TET (73, 100, 54.5, and 73%, respectively). Among fifteen resistance genes investigated, seven were identified in lactobacilli; their presence not always was correlated with phenotypic resistance. STR resistance genes, aadA and ant(6) were observed in 7.4 and 3.7% of isolates, respectively; genes responsible for aminoglycosides resistance, such as bla (7.4%), and aph(3")-III (3.7%) were also recognized. In addition, resistance cat and tetS genes (3.7 and 7.4%, respectively) were harbored by feedlot lactobacilli strains. The presence of ermB gene in 22.3% of isolates, including two of the six strains phenotypically resistant to ERY, exhibited the highest prevalence among the assessed antibiotics. None of the feedlot lactobacilli harbored virulence factors genes, while positive PCR amplification for ace, agg, fsrA, and atpA genes was found for enterococci. With the objective of producing large cell biomass for probiotic delivery, growth media without peptone but containing glucose and skim milk powder (Mgl and Mlac) were selected as optimal. Lactobacillus acidophilus CRL2074, L. amylovorus CRL2115, L. mucosae CRL2069, and L. rhamnosus CRL2084 were strains selected as free of antibiotic resistance and virulence determinants, able to reach high cell numbers in non-expensive culture media and being compatible among them.201830323790
7748130.9847Bacillus subtilis reduces antibiotic resistance genes of animal sludge in vermicomposting by improving heat stress tolerance of Eisenia foetida and bacterial community adjustment. Antibiotic resistance genes (ARGs) in livestock industry have been recognized as a kind of pollutant. The effect of Bacillus subtilis (B. subtilis) as an additive for the reduction of ARGs in animal sludge from livestock and poultry wastewater treatment plant during vermicomposting was investigated. We also evaluated the oxidative stress level and growth of earthworms, Eisenia foetida, bacterial community succession, and the quality of the end products. Two treatments were conducted using B. subtilis, one at 18 °C and another at 28 °C. Controls were setup without the bacteria. The results showed that inoculation of B. subtilis promoted the degradation of organics at 28 °C and increased the germination index to 236%. The increased activities of the superoxide dismutase (1.69 U/mg pr) and catalase (8.05 U/mg pr) and the decreased activity of malondialdehyde (0.02 nmol/mg pr) by B. subtilis at 28 °C showed that the earthworms were relieved of heat stress. The addition of B. subtilis reduced the abundance of 32 target ARGs, including integron (intI-1), transposase (IS613) and resistant genes, such as sulfonamide (sul2), quinolone (oprJ), macrolide-lincosamide-streptogramin group B (ermF, ermB), tetracycline (tetL-02, tetX), β-lactama (blaOXA10-01) and aminoglycoside [strB, aac(6')-Ib(aka aacA4)-01, aac(6')-Ib(aka aacA4)-02]. Organic matter degrading Membranicola, Paludisphaera, Sphingorhabdus and uncultured bacterium belonging to the order Chitinophagales, nitrifying and nitrogen-fixing Singulisphaera and Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium, soil remediating Achromobacter, and plant growth promoting Kaistia, Galbibacter and Ilumatobacter were increased significantly (P < 0.05). However, the growth of harmful bacteria such as Burkholderiaceae was inhibited in the vermicompost. In earthworm guts, the probiotic Mesorhizobium was promoted, while the pathogenic uncultured bacterium belonging to the family Enterobacteriaceae was reduced. Besides, B. subtilis enhanced the host relationships between bacteria and ARGs. These findings might be helpful in the removal of ARGs in animal wastes and in understanding the synergy between earthworms and microorganisms.202336529325
7773140.9847Correlation of tetracycline and sulfonamide antibiotics with corresponding resistance genes and resistant bacteria in a conventional municipal wastewater treatment plant. Antibiotics and corresponding resistance genes and resistant bacteria have been considered as emerging pollutants worldwide. Wastewater treatment plants (WWTPs) are potential reservoirs contributing to the evolution and spread of antibiotic resistance. In this study, total concentrations of tetracycline and sulfonamide antibiotics in final effluent were detected at 652.6 and 261.1ng/L, respectively, and in treated sludge, concentrations were at 1150.0 and 76.0μg/kg dry weight (dw), respectively. The quantities of antibiotic resistance genes and antibiotic resistant bacteria in final effluent were quantified in the range of 9.12×10(5)-1.05×10(6) gene abundances /100mL (genomic copies/100mL) and 1.05×10(1)-3.09×10(3)CFU/mL, respectively. In treated sludge, they were quantified at concentrations of 1.00×10(8)-1.78×10(9) gene abandances/100mL and 7.08×10(6)-1.91×10(8)CFU/100mL, respectively. Significant reductions (2-3 logs, p<0.05) of antibiotic resistance genes and antibiotic resistant bacteria were observed between raw influent and final effluent. The gene abundances of tetO and tetW normalized to that of 16S rRNA genes indicated an apparent decrease as compared to sulI genes, which remained stable along each treatment stage. Significant correlations (R(2)=0.75-0.83, p<0.05) between numbers of resistant bacteria and antibiotic concentrations were observed in raw influent and final effluent. No significance (R(2)=0.15, p>0.05) was found between tet genes (tetO and tetW) with concentration of tetracyclines identified in wastewater, while a significant correlation (R(2)=0.97, p<0.05) was observed for sulI gene and total concentration of sulfonamides. Correlations of the quantities of antibiotic resistance genes and antibiotic resistant bacteria with corresponding concentrations of antibiotics in sludge samples were found to be considerably weak (R(2)=0.003-0.07).201222369865
7779150.9846Metagenomic and Resistome Analysis of a Full-Scale Municipal Wastewater Treatment Plant in Singapore Containing Membrane Bioreactors. Reclaimed water provides a water supply alternative to address problems of scarcity in urbanized cities with high living densities and limited natural water resources. In this study, wastewater metagenomes from 6 stages of a wastewater treatment plant (WWTP) integrating conventional and membrane bioreactor (MBR) treatment were evaluated for diversity of antibiotic resistance genes (ARGs) and bacteria, and relative abundance of class 1 integron integrases (intl1). ARGs confering resistance to 12 classes of antibiotics (ARG types) persisted through the treatment stages, which included genes that confer resistance to aminoglycoside [aadA, aph(6)-I, aph(3')-I, aac(6')-I, aac(6')-II, ant(2″)-I], beta-lactams [class A, class C, class D beta-lactamases (bla (OXA))], chloramphenicol (acetyltransferase, exporters, floR, cmIA), fosmidomycin (rosAB), macrolide-lincosamide-streptogramin (macAB, ereA, ermFB), multidrug resistance (subunits of transporters), polymyxin (arnA), quinolone (qnrS), rifamycin (arr), sulfonamide (sul1, sul2), and tetracycline (tetM, tetG, tetE, tet36, tet39, tetR, tet43, tetQ, tetX). Although the ARG subtypes in sludge and MBR effluents reduced in diversity relative to the influent, clinically relevant beta lactamases (i.e., bla (KPC), bla (OXA)) were detected, casting light on other potential point sources of ARG dissemination within the wastewater treatment process. To gain a deeper insight into the types of bacteria that may survive the MBR removal process, genome bins were recovered from metagenomic data of MBR effluents. A total of 101 close to complete draft genomes were assembled and annotated to reveal a variety of bacteria bearing metal resistance genes and ARGs in the MBR effluent. Three bins in particular were affiliated to Mycobacterium smegmatis, Acinetobacter Iwoffii, and Flavobacterium psychrophila, and carried aquired ARGs aac(2')-Ib, bla (OXA-278), and tet36 respectively. In terms of indicator organisms, cumulative log removal values (LRV) of Escherichia coli, Enterococci, and P. aeruginosa from influent to conventional treated effluent was lower (0-2.4), compared to MBR effluent (5.3-7.4). We conclude that MBR is an effective treatment method for reducing fecal indicators and ARGs; however, incomplete removal of P. aeruginosa in MBR treated effluents (<8 MPN/100 mL) and the presence of ARGs and intl1 underscores the need to establish if further treatment should be applied prior to reuse.201930833934
3549160.9846Examination of the horizontal gene transfer dynamics of an integrative and conjugative element encoding multidrug resistance in Histophilus somni. Integrative and conjugative elements (ICEs) are self-transferable mobile genetic elements that play a significant role in disseminating antimicrobial resistance between bacteria via horizontal gene transfer. A recently identified ICE in a clinical isolate of Histophilus somni (ICEHs02) is 72 914 base pairs in length and harbours seven predicted antimicrobial resistance genes conferring resistance to tetracycline (tetR-tet(H)), florfenicol (floR), sulfonamide (Sul2), aminoglycosides (APH(3″)-Ib, APH(6)-Id, APH(3')-Ia), and copper (mco). This study investigated ICEHs02 host range, assessed effects of antimicrobial stressors on transfer frequency, and examined effects of ICEHs02 acquisition on hosts. Conjugation assays examined transfer frequency of ICEHs02 to H. somni and Pasteurella multocida strains. Polymerase chain reaction assays confirmed the presence of a circular intermediate, ICE-associated core genes, and cargo genes in recipient strains. Susceptibility testing examined ICEHs02-associated resistance phenotypes in recipient strains. Tetracycline and ciprofloxacin induction significantly increased the transfer rates of ICEHs02 in vitro. The copy numbers of the circular intermediate of ICEHs02 per chromosome exhibited significant increases of ∼37-fold after tetracycline exposure and ∼4-fold after ciprofloxacin treatment. The acquisition of ICEHs02 reduced the relative fitness of H. somni transconjugants (TG) by 28% (w = 0.72 ± 0.04) and the relative fitness of P. multocida TG was decreased by 15% (w = 0.85 ± 0.01).202336495587
3526170.9845The impact of antibiotic residues on resistance patterns in leek at harvest. When crops are cultivated on fields fertilized with animal manure, the risk exists that plants may take up antibiotic residues and may be exposed to antibiotic resistance genes and antibiotic resistant bacteria. During cultivation in a greenhouse pot experiment, leek (Allium porrum) was fertilized with either pig slurry or mineral fertilizer and exposed to either no antibiotics, doxycycline (10,000 μg/kg manure), sulfadiazine (1000 μg/kg manure), or lincomycin (1000 μg/kg manure). At harvest, 4.5 months later, lincomycin, sulfadiazine or doxycycline were not detected in any of the leek samples nor in their corresponding soil samples. Further, antimicrobial susceptibility testing was performed on 181 Bacillus cereus group isolates and 52 Pseudomonas aeruginosa isolates from the grown leek. For the B. cereus group isolates, only a small shift in MIC50 for lincomycin was observed among isolates from the lincomycin and control treatment. For P. aeruginosa, only in the setup with doxycycline treatment a higher MIC50 for doxycycline was observed compared to the control, specifically the isolates selected from growth media supplemented with 8 mg/L doxycycline. Nine antibiotic resistance genes (tet(B), tet(L), tet(M), tet(O), tet(Q), tet(W), erm(B), erm(F) and sul2) were investigated at harvest in the leek and soil samples. In the leek samples, none of the antibiotic resistance genes were detected. In the soil samples fertilized with pig slurry, the genes erm(B), erm(F), tet(M), sul2, tet(W) and tet(O) were detected in significantly higher copy numbers in the lincomycin treatment as compared to the other antibiotic treatments. This could be due to a shift in soil microbiota induced by the addition of lincomycin. The results of this study indicate that consumption of leek carries a low risk of exposure to antibiotic residues or antibiotic resistance to doxycycline, sulfadiazine or lincomycin.202337215782
3527180.9845Nutrient-induced antibiotic resistance in Enterococcus faecalis in the eutrophic environment. Nutrient deposition and extensive use of antibiotics are increasing worldwide, especially in freshwater ecosystems. Bacteria display resistance to certain antibiotics and thus survive for extended periods in eutrophic environments. In this study, model ecosystems were established to investigate the effect of nitrate and phosphate nutrient salts on antibiotic resistance in strains of Enterococcus faecalis. Mesocosms were replicated to evaluate the ecological effects of nutrient influx. The mesocosms were divided into four different nitrogen (N) and phosphorus (P) regimens. Enterococcus faecalis strains were isolated on Days 0, 1, 7, 14, 21, 28, 40, 60 and 95 to evaluate their sensitivity to ampicillin, oxytetracycline (OXY), ciprofloxacin (CIP), chloramphenicol (CHL), vancomycin and erythromycin (ERY). Resistance genes for ERY (ermB, msrC and mefA), OXY [tet(M), tet(L) and tet(S)] and CHL (cat) as well as the enterococcal surface protein gene (esp) were investigated by PCR. The total nitrogen, total phosphorus, chemical oxygen demand permanganate index (COD(Mn)), chlorophyll-a, Secchi depth and trophic level index were observed. In conclusion, addition of N and P had a significant influence on the resistance phenotypes of E. faecalis to OXY, CHL and ERY. Only high dosage led to CIP resistance. Higher total N concentrations resulted in the development of relatively higher resistance to OXY and CIP. The resistance genes tet(L) and tet(S) for OXY, msrC for ERY and cat for CHL were found to be associated with resistance in E. faecalis.201627685672
7771190.9845Can chlorination co-select antibiotic-resistance genes? Selective pressures, such as chemical or heavy metal pollution, may co-select for bacterial antibiotic resistance in the environment. However, whether chlorination in water treatment can co-select antibiotic-resistant bacteria is controversial. In this study, high capacity quantitative polymerase chain reaction (qPCR) analysis was applied to target almost all known antibiotic-resistance genes (ARGs) (282 types) and 13 mobile genetic elements (MGEs) in bacteria detected in secondary effluents from a municipal wastewater treatment plant after chlorination. The results revealed that 125 unique ARGs were detected in non-chlorinated samples, and the number decreased (79-91 types) as the chlorine concentration was increased. Moreover, 7.49 × 10(4)-3.92 × 10(7) copies/100 ml water reduction of ARGs occurred with 4 mg Cl2/l. Considering the relative abundance of ARGs (i.e., ARG copies normalized to 16S rRNA gene copies), 119 ARGs decreased in response to chlorination, whereas only six ARGs, such as dfrA1, tetPB-03, tetPA, ampC-04, tetA-02, and erm(36), were potentially enriched by 10.90-, 10.06-, 8.63-, 6.86-, 3.77-, and 1.09-fold, respectively. Furthermore, the relative abundance of 12 detected MGEs was lower after chlorination. Therefore, chlorination was effective in reducing ARGs and MGEs rather than co-selecting them.201627192478