Ubiquitous and persistent Proteobacteria and other Gram-negative bacteria in drinking water. - Related Documents




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337101.0000Ubiquitous and persistent Proteobacteria and other Gram-negative bacteria in drinking water. Drinking water comprises a complex microbiota, in part shaped by the disinfection and distribution systems. Gram-negative bacteria, mainly members of the phylum Proteobacteria, represent the most frequent bacteria in drinking water, and their ubiquity and physiological versatility raises questions about possible implications in human health. The first step to address this concern is the identification and characterization of such bacteria that is the first objective of this study, aiming at identifying ubiquitous or persistent Gram-negative bacteria, Proteobacteria or members of other phyla, isolated from tap water or from its source. >1000 bacterial isolates were characterized and identified, and a selected group (n=68) was further analyzed for the minimum inhibitory concentrations (MIC) to antibiotics (amoxicillin and gentamicin) and metals (copper and arsenite). Total DNA extracts of tap water were examined for the presence of putatively acquired antibiotic resistance or related genes (intI1, bla(TEM), qnrS and sul1). The ubiquitous tap water genera comprised Proteobacteria of the class Alpha- (Blastomonas, Brevundimonas, Methylobacterium, Sphingobium, Sphingomonas), Beta- (Acidovorax, Ralstonia) and Gamma- (Acinetobacter and Pseudomonas). Persistent species were members of genera such as Aeromonas, Enterobacter or Dechloromonas. Ralstonia spp. showed the highest MIC values to gentamicin and Acinetobacter spp. to arsenite. The genes intI1, bla(TEM) or sul1 were detected, at densities lower than 2.3×10(5)copies/L, 2.4×10(4)copies/L and 4.6×10(2)copies/L, respectively, in most tap water samples. The presence of some bacterial groups, in particular of Beta- or Gammaproteobacteria (e.g. Ralstonia, Acinetobacter, Pseudomonas) in drinking water may deserve attention given their potential as reservoirs or carriers of resistance or as opportunistic pathogens.201728238372
337010.9999Microbiological contamination and resistance genes in biofilms occurring during the drinking water treatment process. Biofilms are the predominant mode of microbial growth in drinking water systems. A dynamic exchange of individuals occurs between the attached and planktonic populations, while lateral gene transfer mediates genetic exchange in these bacterial communities. Integrons are important vectors for the spread of antimicrobial resistance. The presence of class 1 integrons (intI1, qac and sul genes) was assessed in biofilms occurring throughout the drinking water treatment process. Isolates from general and specific culture media, covering a wide range of environmental bacteria, fecal indicators and opportunistic pathogens were tested. From 96 isolates tested, 9.37% were found to possess genetic determinants of putative antimicrobial resistance, and these occurred in both Gram-positive and Gram-negative bacteria. Class 1 integron integrase gene was present in 8.33% of bacteria, all positive for the qacEΔ1 gene. The sul1 gene was present in 3.12% of total isolates, representing 37.5% of the class 1 integron positive cells. The present study shows that biofilm communities in a drinking water treatment plant are a reservoir of class 1 integrons, mainly in bacteria that may be associated with microbiological contamination. Eight out of nine integron bearing strains (88.8%) were identified based on 16S rRNA gene sequencing as either enteric bacteria or species that may be connected to animal and anthropogenic disturbance.201323247295
286320.9999Detection of Aminoglycoside Resistant Bacteria in Sludge Samples From Norwegian Drinking Water Treatment Plants. Through a culture-based approach using sludge from drinking water treatment plants, this study reports on the presence of aminoglycoside resistant bacteria at 23 different geographical locations in Norway. Sludge samples are derived from a large environmental area including drinking water sources and their surrounding catchment areas. Aminoglycoside resistant bacteria were detected at 18 of the sample sites. Only five samples did not show any growth of isolates resistant to the selected aminoglycosides, kanamycin and gentamycin. There was a statistically significant correlation between the numbers of kanamycin and gentamycin resistant bacteria isolated from the 23 samples, perhaps suggesting common determinants of resistance. Based on 16S rRNA sequencing of 223 aminoglycoside resistant isolates, three different genera of Bacteroidetes were found to dominate across samples. These were Flavobacterium, Mucilaginibacter and Pedobacter. Further phenotypic and genotypic analyses showed that efflux pumps, reduced membrane permeability and four assayed genes coding for aminoglycoside modifying enzymes AAC(6')-Ib, AAC(3')-II, APH(3')-II, APH(3')-III, could only explain the resistance of a few of the isolates selected for testing. aph(3')-II was detected in 1.6% of total isolates, aac(6')-Ib and aph(3')-III in 0.8%, while aac(3')-II was not detected in any of the isolates. The isolates, for which potential resistance mechanisms were found, represented 13 different genera suggesting that aminoglycoside resistance is widespread in bacterial genera indigenous to sludge. The present study suggests that aminoglycoside resistant bacteria are present in Norwegian environments with limited anthropogenic exposures. However, the resistance mechanisms remain largely unknown, and further analyses, including culture-independent methods, could be performed to investigate other potential resistance mechanisms. This is, to our knowledge, the first large scale nationwide investigation of aminoglycoside resistance in the Norwegian environment.201930918503
286630.9998Characterization of tetracycline-resistant bacteria in an urbanizing subtropical watershed. AIMS: The objective of this study was to determine whether varying levels of urbanization influence the dominant bacterial species of mildly resistant (0·03 mmol l(-1) tetracycline) and highly resistant (0·06 mmol l(-1) tetracycline) bacteria in sediment and water. Also, the level of urbanization was further evaluated to determine whether the diversity of tetracycline resistance genes present in the isolates and the capability of transferring their resistance were influenced. METHODS AND RESULTS: Sediment and water samples collected from five sampling sites were plated in triplicate on nutrient agar plates with a mild dose (0·03 mmol l(-1) ) and a high dose (0·06 mmol l(-1) ) of tetracycline. Five colonies from each plate plus an additional five from each triplicate group were randomly selected and isolated on nutrient agar containing 0·03 mmol l(-1) tetracycline (400 isolates). The isolates were identified by 16S rRNA gene sequencing and comparison to GenBank using blast. The isolates were also screened for 15 tetracycline resistance genes using a multiplex PCR assay and their ability to transfer resistance through conjugation experiments using a kanamycin-resistant Escherichia. coli K-12 strain labelled with a green fluorescent protein gene. Results from this study indicate that the dominant resistant organisms in this watershed are Acinetobacter spp., Chryseobacterium spp., Serratia spp., Pseudomonas spp., Aeromonas spp. and E. coli. All of these organisms are Gram negative and are closely related to pathogenic species. A majority of the isolates (66%) were capable of transferring their resistance, and there was a greater incidence of tet resistance transfer with increasing urbanization. Also, it was determined that the dominant resistance genes in the watershed are tet(W) and tet(A). CONCLUSION: Urbanization significantly affected dominant tetracycline-resistant bacteria species, but did not affect dominant resistance genes. There was correlation between increased urbanization with an increase in the ability to transfer tetracycline resistance. This indicates that urban areas may select for bacterial species that are capable of transferring resistance. SIGNIFICANCE AND IMPACT OF STUDY: These results indicate that urbanization influences the occurrence of tetracycline-resistant bacteria and the potential for transfer of resistance genes.201323773226
337340.9998Evidence of Increased Antibiotic Resistance in Phylogenetically-Diverse Aeromonas Isolates from Semi-Intensive Fish Ponds Treated with Antibiotics. The genus Aeromonas is ubiquitous in aquatic environments encompassing a broad range of fish and human pathogens. Aeromonas strains are known for their enhanced capacity to acquire and exchange antibiotic resistance genes and therefore, are frequently targeted as indicator bacteria for monitoring antimicrobial resistance in aquatic environments. This study evaluated temporal trends in Aeromonas diversity and antibiotic resistance in two adjacent semi-intensive aquaculture facilities to ascertain the effects of antibiotic treatment on antimicrobial resistance. In the first facility, sulfadiazine-trimethoprim was added prophylactically to fingerling stocks and water column-associated Aeromonas were monitored periodically over an 11-month fish fattening cycle to assess temporal dynamics in taxonomy and antibiotic resistance. In the second facility, Aeromonas were isolated from fish skin ulcers sampled over a 3-year period and from pond water samples to assess associations between pathogenic strains to those in the water column. A total of 1200 Aeromonas isolates were initially screened for sulfadiazine resistance and further screened against five additional antimicrobials. In both facilities, strong correlations were observed between sulfadiazine resistance and trimethoprim and tetracycline resistances, whereas correlations between sulfadiazine resistance and ceftriaxone, gentamicin, and chloramphenicol resistances were low. Multidrug resistant strains as well as sul1, tetA, and intI1 gene-harboring strains were significantly higher in profiles sampled during the fish cycle than those isolated prior to stocking and these genes were extremely abundant in the pathogenic strains. Five phylogenetically distinct Aeromonas clusters were identified using partial rpoD gene sequence analysis. Interestingly, prior to fingerling stocking the diversity of water column strains was high, and representatives from all five clusters were identified, including an A. salmonicida cluster that harbored all characterized fish skin ulcer samples. Subsequent to stocking, diversity was much lower and most water column isolates in both facilities segregated into an A. veronii-associated cluster. This study demonstrated a strong correlation between aquaculture, Aeromonas diversity and antibiotic resistance. It provides strong evidence for linkage between prophylactic and systemic use of antibiotics in aquaculture and the propagation of antibiotic resistance.201627965628
337250.9998Antibiotic and Disinfectant Resistance in Tap Water Strains - Insight into the Resistance of Environmental Bacteria. Although antibiotic-resistant bacteria (ARB) have been isolated from tap water worldwide, the knowledge of their resistance patterns is still scarce. Both horizontal and vertical gene transfer has been suggested to contribute to the resistance spread among tap water bacteria. In this study, ARB were isolated from finished water collected at two independent water treatment plants (WTPs) and tap water collected at several point-of-use taps during summer and winter sampling campaigns. A total of 24 strains were identified to genus or species level and subjected to antibiotic and disinfectant susceptibility testing. The investigated tap water ARB belonged to phyla Proteobacteria, Bacteroidetes, Actinobacteria, and Firmicutes. The majority of the isolates proved multidrug resistant and resistant to chemical disinfectant. Neither seasonal nor WTP-dependent variabilities in antibiotic or disinfectant resistance were found. Antibiotics most effective against the investigated isolates included imipenem, tetracyclines, erythromycin, and least effective - aztreonam, cefotaxime, amoxicillin, and ceftazidime. The most resistant strains originate from Afipia sp. and Methylobacterium sp. Comparing resistance patterns of isolated tap water ARB with literature reports concerning the same genera or species confirms intra-genus or even intra-specific variabilities of environmental bacteria. Neither species-specific nor acquired resistance can be excluded.202133815527
528960.9998Examination 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
286770.9998Enzymatic Activity and Horizontal Gene Transfer of Heavy Metals and Antibiotic Resistant Proteus vulgaris from Hospital Wastewater: An Insight. Globally, the issue of microbial resistance to medicines and heavy metals is getting worse. There are few reports or data available for Proteus vulgaris (P. vulgaris), particularly in India. This investigation intends to reveal the bacteria's ability to transmit genes and their level of resistance as well. The wastewater samples were taken from several hospitals in Lucknow City, India, and examined for the presence of Gram-negative bacteria that were resistant to antibiotics and heavy metals. The microbial population count in different hospital wastewaters decreases with increasing concentrations of metal and antibiotics. Among all the examined metals, Ni and Zn had the highest viable counts, whereas Hg, Cd, and Co had the lowest viable counts. Penicillin, ampicillin, and amoxicillin, among the antibiotics, demonstrated higher viable counts, whereas tetracycline and erythromycin exhibited lower viable counts. The MIC values for the P. vulgaris isolates tested ranged from 50 to 16,00 μg/ml for each metal tested. The multiple metal resistance (MMR) index, which ranged from 0.04 to 0.50, showed diverse heavy metal resistance patterns in all P. vulgaris isolates (in the case of 2-7 metals in various combinations). All of the tested isolates had methicillin resistance, whereas the least number of isolates had ofloxacin, gentamycin, or neomycin resistance. The P. vulgaris isolates displayed multidrug resistance patterns (2-12 drugs) in various antibiotic combinations. The MAR indexes were shown to be between (0.02-0.7). From the total isolates, 98%, 84%, and 80% had urease, gelatinase, and amylase activity, whereas 68% and 56% displayed protease and beta-lactamase activity. Plasmids were present in all the selected resistant isolates and varied in size from 42.5 to 57.0 kb and molecular weight from 27.2 to 37.0 MD. The transmission of the antibiotic/metal resistance genes was evaluated between a total of 7 pairs of isolates. A higher transfer frequency (4.4 × 10(-1)) was observed among antibiotics, although a lower transfer frequency (1.0 × 10(-2)) was observed against metals in both the media from the entire site tested. According to exponential decay, the population of hospital wastewater declined in the following order across all sites: Site II > Site IV > Site III > Site I for antibiotics and site IV > site II > site I >site III for metal. Different metal and antibiotic concentrations have varying effects on the population. The metal-tolerant P. vulgaris from hospital wastewater was studied in the current study had multiple distinct patterns of antibiotic resistance. It could provide cutting-edge methods for treating infectious diseases, which are essential for managing and assessing the risks associated with hospital wastewater, especially in the case of P. vulgaris.202236523753
336080.9998Gentamicin resistance genes in environmental bacteria: prevalence and transfer. A comprehensive multiphasic survey of the prevalence and transfer of gentamicin resistance (Gm(r)) genes in different non-clinical environments has been performed. We were interested to find out whether Gm(r) genes described from clinical isolates can be detected in different environmental habitats and whether hot spots can be identified. Furthermore, this study aimed to evaluate the impact of selective pressure on the abundance and mobility of resistance genes. The study included samples from soils, rhizospheres, piggery manure, faeces from cattle, laying and broiler chickens, municipal and hospital sewage water, and coastal water. Six clusters of genes coding for Gm-modifying enzymes (aac(3)-I, aac(3)-II/VI, aac(3)-III/IV, aac(6')-II/Ib, ant(2'')-I, aph(2'')-I) were identified based on a database comparison and primer systems for each gene cluster were developed. Gm-resistant bacteria isolated from the different environments had a different taxonomic composition. In only 34 of 207 isolates, mainly originating from sewage, faeces and coastal water polluted with wastewater, were known Gm(r) genes corresponding to five of the six clusters detected. The strains belonged to genera in which the genes had previously been detected (Enterobacteriaceae, Pseudomonas, Acinetobacter) but also to phylogenetically distant bacteria, such as members of the CFB group, alpha- and beta-Proteobacteria. Gm(r) genes located on mobile genetic elements (MGE) could be captured in exogenous isolations into recipients belonging to alpha-, beta- and gamma-Proteobacteria from all environments except for soil. A high proportion of the MGE, conferring Gm resistance isolated from sewage, were identified as IncPbeta plasmids. Molecular detection of Gm(r) genes, and broad host range plasmid-specific sequences (IncP-1, IncN, IncW and IncQ) in environmental DNA indicated a habitat-specific dissemination. A high abundance and diversity of Gm(r) genes could be shown for samples from faeces (broilers, layers, cattle), from sewage, from seawater, collected close to a wastewater outflow, and from piggery manure. In the latter samples all six clusters of Gm(r) genes could be detected. The different kinds of selective pressure studied here seemed to enhance the abundance of MGE, while an effect on Gm(r) genes was not obvious.200219709289
342590.9998Horizontal 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
2865100.9998Antibiotic resistance in soil and water environments. Seven locations were screened for antibiotic-resistant bacteria using a modified agar dilution technique. Isolates resistant to high levels of antibiotics were screened for r plasmids. Low-level resistance (25 micro g x ml(-1)) was widespread for ampicillin, penicillin, tetracycline, vancomycin and streptomycin but not for kanamycin. Resistant populations dropped sharply at high antibiotic levels, suggesting that intrinsic non-emergent mechanisms were responsible for the multiple drug resistance exhibited at low doses. Dairy farm manure contained significantly (P < 0.01) more (%) resistant bacteria than the other sites. Bacteria isolated from a dairy water canal, a lake by a hospital and a residential garden (fertilized by farm manure) displayed resistance frequencies of 77, 75 and 70%, respectively. Incidence of tetracycline resistance was most prevalent at 47-89% of total bacteria. Out of 200 representative isolates analyzed, Pseudomonas, Enterococcus-like bacteria, Enterobacter and Burkholderia species constituted the dominant reservoirs of resistance at high drug levels (50-170 micro g x ml(-1)). Plasmids were detected in only 29% (58) of these bacteria with tetracycline resistance accounting for 65% of the plasmid pool. Overall, resistance trends correlated to the abundance and type of bacterial species present in the habitat. Environmental reservoirs of resistance include opportunistic pathogens and constitute some public health concern.200212396530
5290110.9998Antibiotic 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
2803120.9998Antimicrobial resistance, heavy metal resistance and integron content in bacteria isolated from a South African tilapia aquaculture system. Antibacterial compounds and metals co-select for antimicrobial resistance when bacteria harbour resistance genes towards both types of compounds, facilitating the proliferation and evolution of antimicrobial and heavy metal resistance. Antimicrobial and heavy metal resistance indices of 42 Gram-negative bacteria from a tilapia aquaculture system were determined to identify possible correlations between these phenotypes. Agar dilution assays were carried out to determine susceptibility to cadmium, copper, lead, mercury, chromate and zinc, while susceptibility to 21 antimicrobial agents was investigated by disk diffusion assays. Presence of merA, the mercury resistance gene, was determined by dot-blot hybridizations and PCR. Association of mercury resistance with integrons and transposon Tn21 was also investigated by PCR. Isolates displayed a high frequency of antimicrobial (erythromycin: 100%; ampicillin: 85%; trimethoprim: 78%) and heavy metal (Zn2+: 95%; Cd2+: 91%) resistance. No correlation was established between heavy metal and multiple antibiotic resistance indices. Significant positive correlations were observed between heavy metal resistance profiles, indices, Cu2+ and Cr3+ resistance with erythromycin resistance. Significant positive correlations were observed between merA (24%)/Tn21 (24%) presence and heavy metal resistance profiles and indices; however, significant negative correlations were obtained between integron-associated qacE∆1 (43%) and sulI (26%) gene presence and heavy metal resistance indices. Heavy metal and antimicrobial agents co-select for resistance, with fish-associated, resistant bacteria demonstrating simultaneous heavy metal resistance. Thus, care should be taken when using anti-fouling heavy metals as feed additives in aquaculture facilities.201729160218
2864130.9998Case study on the soil antibiotic resistome in an urban community garden. Urban agricultural soils can be an important reservoir of antibiotic resistance, and have great food safety and public health indications. This study investigated antibiotic-resistant bacteria and antibiotic resistance genes in urban agricultural soils using phenotypic and metagenomic tools. In total, 207 soil bacteria were recovered from 41 soil samples collected from an urban agricultural garden in Detroit, MI, USA. The most prevalent antibiotic resistance phenotype demonstrated by Gram-negative bacteria was resistance to ampicillin (94.2%), followed by chloramphenicol (80.0%), cefoxitin (79.5%), gentamicin (78.4%) and ceftriaxone (71.1%). All Gram-positive bacteria were resistant to gentamicin, kanamycin and penicillin. Genes encoding resistance to quinolones, β-lactams and tetracyclines were the most prevalent and abundant in the soil. qepA and tetA, both encoding efflux pumps, predominated in the quinolone and tetracycline resistance genes tested, respectively. Positive correlation (P<0.05) was identified among groups of antibiotic resistance genes, and between antibiotic resistance genes and metal resistance genes. The data demonstrated a diverse population of antibiotic resistance in urban agricultural soils. Phenotypic determination together with soil metagenomics proved to be a valuable tool to study the nature and extent of antibiotic resistance in the environment.201829857032
5298140.9998Investigation of the antimicrobial susceptibility patterns of marine cyanobacteria in Bohai Bay: Cyanobacteria may be important hosts of antibiotic resistance genes in marine environment. Marine cyanobacteria, as widely distributed and photosynthetically autotrophic bacteria in the ocean, may contribute to the global dissemination of antibiotic resistance genes (ARGs) and develop a different antimicrobial susceptibility pattern from heterotrophic bacteria and cyanobacteria from freshwater environments. However, studies on antimicrobial susceptibility and the carriage of ARGs in marine cyanobacteria are still very limited. In this study, the antibiotic resistance characteristics of cyanobacteria in nearshore waters were examined through field monitoring and laboratory investigations, which included PCR detection and ARG transformation. The results showed a positive correlation between marine cyanobacteria and some ARGs in the nearshore waters of Bohai Bay. Moreover, most screened cyanobacteria showed high minimum inhibitory concentration (MIC) values for polymyxins, tetracyclines, kanamycin, and sulfonamides, moderate MIC values for streptomycin, chloramphenicol, rifampicin, and norfloxacin, and low MIC values for roxithromycin and cephalosporins. The bla(TEM), bla(KPC), sul1, sul2, strA, tetA, tetB, tetC, tetM, mdfA, and intI1 genes were detected in the screened marine cyanobacteria. The highest detection rates were observed for bla(TEM) (93.3 %), sul1 (56.6 %), sul2 (90 %), and strA (73.3 %). The detection rate of tetA (33.3 %) was the highest among the tetracycline resistance genes, and mdfA, a multidrug-resistant pump gene with resistance to tetracycline, also showed a high detection level (23.3 %). Overall, most of the screened marine cyanobacteria were found to tolerate multiple antibiotics in seawater, and the condition of the ARGs carriage was serious. Furthermore, the screened marine Synechocystis sp. C12-2 demonstrated the ability to accept ARGs on the RP4 plasmid through natural transformation and showed reduced sensitivity to ampicillin, suggesting the possibility that some marine cyanobacteria could acquire ARGs from the environment through horizontal gene transfer. Thus, marine cyanobacteria may play an important role in the propagation of marine ARGs.202437972772
3423150.9998bla(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
5304160.9998Water metagenomic analysis reveals low bacterial diversity and the presence of antimicrobial residues and resistance genes in a river containing wastewater from backyard aquacultures in the Mekong Delta, Vietnam. The environmental pathways for the dissemination of antibiotic resistance have recently received increased attention. Aquatic environments act as reservoirs or sources of antimicrobial-resistant bacteria, antimicrobial residues, and antimicrobial resistance genes (ARGs). Therefore, it is imperative to identify the role of polluted water in the dissemination of antimicrobial resistance. The aim of this study was to evaluate the antimicrobial residues, ARGs, and microbiota in the freshwater systems of the Mekong Delta. We selected 12 freshwater sites from aquacultures and rivers in Can Tho, Vietnam and analyzed them for 45 antimicrobial residues and 8 ARGs by LC/MS/MS and real-time PCR, respectively. A 16S rDNA-based metagenomic analysis was conducted to characterize the water microbiota. Residues of sulfamethoxazole (10/12) and sulfadimidine (7/12) were widely detected, together with the sulfa-resistance genes sul1 (11/12) and sul2 (9/12). Additionally, sulfamethoxazole residues and the β-lactamase-resistance gene bla(CTX-M-1) were detected in eight freshwater systems (8/12), suggesting that these freshwater systems may have been polluted by human activity. The metagenomic analysis showed that all the tested freshwater systems contained the phyla Proteobacteria, Actinobacteria, and Bacteroidetes, representing 64% of the total microbiota. Moreover, the Cai Rang River site (Ri-E), which is located at the merge point of wastewaters from backyard-based aquacultures, contained the genera Polynucleobacter, Variovorax, and Limnohabitans, representing more than 78.4% of the total microbiota. Bacterial diversity analysis showed that the Ri-E exhibited the lowest diversity compared with other regions. Principal coordinate analysis showed that the differences among water microbiotas in backyard-based aquacultures could be explained by the farmers' aquaculture techniques. In conclusion, this study demonstrated a collapse of bacterial diversity at the merge point of wastewaters from backyard-based aquacultures in the Mekong Delta.201728062224
5373170.9998Impact of soil supplemented with pig manure on the abundance of antibiotic resistant bacteria and their associated genes. This study was conducted to evaluate the abundance of antibiotic resistant bacteria and their resistance genes from agriculture soil supplemented with pig manure. Uncultivable soil sample was supplemented with pig manure samples under microcosm experimental conditions and plated on Luria-Bertani (LB) agar incorporated with commercial antibiotics. The supplementation of soil with 15% pig manure resulted in the highest increase in the population of antibiotic resistant bacteria (ARB)/multiple antibiotic resistant bacteria (MARB). Seven genera that included Pseudomonas, Escherichia, Providencia, Salmonella, Bacillus, Alcaligenes and Paenalcaligenes were the cultivable ARB identified. A total of ten antibiotic resistant bacteria genes (ARGs) frequently used in clinical or veterinary settings and two mobile genetic elements (MGEs) (Class 1 and Class 2 integrons) were detected. Eight heavy metal, copper, cadmium, chromium, manganese, lead, zinc, iron, and cobalt were found in all of the manure samples at different concentrations. Tetracycline resistance genes were widely distributed with prevalence of 50%, while aminoglycoside and quinolone-resistance gene had 16% and 13%, respectively. Eighteen ARB isolates carried more than two ARGs in their genome. Class 1 integron was detected among all the 18 ARB with prevalence of 90-100%, while Class 2 integron was detected among 11 ARB. The two classes of integron were found among 10 ARB. Undoubtedly, pig manure collected from farms in Akure metropolis are rich in ARB and their abundance might play a vital role in the dissemination of resistance genes among clinically-relevant pathogens.202337308603
3703180.9998Antibiotic resistance patterns of metal-tolerant bacteria isolated from an estuary. Estuarine bacteria isolated on metal-containing media were also found to be antibiotic resistant; ampicillin and chloramphenicol were the antibiotics to which resistance was most common. Patterns of antibiotic resistance were found associated with a variety of taxa.1977921251
3361190.9998The tetracycline resistance gene tet39 is present in both Gram-negative and Gram-positive bacteria from a polluted river, Southwestern Nigeria. AIM: Previous analysis of tet39 suggests it may be present in other bacterial species. Hence, we investigated the host range of tet39 among bacterial from a poultry waste polluted river in Southwestern Nigeria. METHODS AND RESULTS: Thirteen resistant bacterial isolated from the water and sediment of the polluted river was investigated for the presence of tetracycline resistance genes tetA, tetB, tetC, tet39 and the transposon integrase gene of the Tn916/1545 family by PCR. While tetA, tetB, tetC and integrase genes cannot be detected in any of the organisms, tet39 was detected in eight of the tested organisms including three Gram-positive species. Sequence analysis showed the genes have high sequence identities (> or =99%) with tet39 of Acinetobacter sp. LUH5605, the first and only bacterial genus from which the gene has been reported to date. This is a novel observation. CONCLUSIONS: This study shows that apart from Acinetobacter, tet39 is present in other bacterial species tested in this study. SIGNIFICANCE AND IMPACT OF THE STUDY: This study adds to available information on the occurrence and distribution of tet39 among environmental bacteria and suggests that the gene has a broader host range than previously reported.200919196439