# | Rank | Similarity | Title + Abs. | Year | PMID |
|---|---|---|---|---|---|
| 0 | 1 | 2 | 3 | 4 | 5 |
| 2867 | 0 | 0.9990 | Enzymatic 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. | 2022 | 36523753 |
| 3529 | 1 | 0.9990 | High dietary zinc supplementation increases the occurrence of tetracycline and sulfonamide resistance genes in the intestine of weaned pigs. BACKGROUND: Dietary zinc oxide is used in pig nutrition to combat post weaning diarrhoea. Recent data suggests that high doses (2.5 g/kg feed) increase the bacterial antibiotic resistance development in weaned pigs. Therefore, the aim of this study was to investigate the development of enterobacterial antibiotic resistance genes in the intestinal tract of weaned pigs. FINDINGS: Weaned pigs were fed diets for 4 weeks containing 57 (low), 164 (intermediate) or 2425 (high) mg kg(-1) analytical grade ZnO. DNA extracts from stomach, mid-jejunum, terminal ileum and colon ascendens were amplified by qPCR assays to quantify copy numbers for the tetracycline (tetA) and sulfonamide (sul1) resistance genes in Gram-negative bacteria. Overall, the combined data (n = 336) showed that copy numbers for tetracycline and sulfonamide resistance genes were significantly increased in the high zinc treatment compared to the low (tetA: p value < 10(-6); sul1: p value = 1 × 10(-5)) or intermediate (tetA: P < 1.6 × 10(-4); sul1: P = 3.2 × 10(-4)) zinc treatment. Regarding the time dependent development, no treatment effects were seen 1 week after weaning, but significant differences between high and low/intermediate zinc treatments evolved 2 weeks after weaning. The increased number of tetA and sul1 copies was not confined to the hind gut, but was already present in stomach contents. CONCLUSIONS: The results of this study suggest that the use of high doses of dietary zinc beyond 2 weeks after weaning should be avoided in pigs due to the possible increase of antibiotic resistance in Gram-negative bacteria. | 2015 | 26322131 |
| 5284 | 2 | 0.9989 | Long-term impact of oral surgery with or without amoxicillin on the oral microbiome-A prospective cohort study. Routine postoperative antibiotic prophylaxis is not recommended for third molar extractions. However, amoxicillin still continues to be used customarily in several clinical practices worldwide to prevent infections. A prospective cohort study was conducted in cohorts who underwent third molar extractions with (group EA, n = 20) or without (group E, n = 20) amoxicillin (250 mg three times daily for 5 days). Further, a control group without amoxicillin and extractions (group C, n = 17) was included. Salivary samples were collected at baseline, 1-, 2-, 3-, 4-weeks and 3 months to assess the bacterial shift and antibiotic resistance gene changes employing 16S rRNA gene sequencing (Illumina-Miseq) and quantitative polymerase chain reaction. A further 6-month follow-up was performed for groups E and EA. Seven operational taxonomic units reported a significant change from baseline to 3 months for group EA (adjusted p < 0.05). No significant change in relative abundance of bacteria and β-lactamase resistance genes (TEM-1) was observed over 6 months for any group (adjusted p > 0.05). In conclusion, the salivary microbiome is resilient to an antibiotic challenge by a low-dose regimen of amoxicillin. Further studies evaluating the effect of routinely used higher dose regimens of amoxicillin on gram-negative bacteria and antibiotic resistance genes are warranted. | 2019 | 31822712 |
| 3536 | 3 | 0.9989 | Initial diet shapes resistance-gene composition and fecal microbiome dynamics in young ruminants during nursing. This study was conducted to examine how colostrum pasteurization affects resistance genes and microbial communities in calf feces. Forty female Holstein calves were randomly assigned to either the control (CON) group, which received unheated colostrum, or the pasteurized colostrum (PAT) group. The calves body weight was measured weekly before morning feeding. Calf starter intake were measured and recorded daily before morning feeding. Samples of colostrum were collected before feeding. Blood was collected on d 1 and 70 before morning feeding. Ten calves were randomly selected from each group (n = 20 calves total) for fecal sampling on d 3, 28, 56 and 70 for subsequent DNA extraction and metagenomic sequencing. Total bacterial counts in the colostrum were markedly higher in the CON group than in the PAT group. Pasteurized colostrum administration substantially reduced the ARO diversity and diminishes the abundance of Enterobacteriaceae, thereby decreasing their contribution to resistance genes. Pasteurization also reduced glucoside hydrolase-66 activity in 3-day-old calves which led to an increase in the activity of aminoglycoside antibiotics, resulting in 52.63 % of PAT-enriched bacteria acquiring aminoglycoside resistance genes. However, from the perspective of overall microbial community, the proportion of aminoglycoside, beta-lactam and tetracycline resistance genes carried by microbial community in PAT group was lower than CON group (P < 0.05). Fecal samples from the PAT group contained greater abundances of Subdoligranulum (P < 0.05) and Lachnospiraceae_NK4A136_group (P < 0.05) on days 28 and 70 compared to CON. Network analysis and abundance variations of the different bacteria obtained by linear discriminant analysis effect size analysis showed that pasteurized colostrum feeding reduced the interactions among related bacteria and maintained stability of the hind-gut microbiome. In conclusion, these findings underscore the intricate interactions between early diet, calf resistance-gene transmission and microbial dynamics, which should be carefully considered in calf-rearing practices. | 2024 | 38556024 |
| 2862 | 4 | 0.9989 | Regulation Transcriptional of Antibiotic Resistance Genes (ARGs) in Bacteria Isolated from WWTP. The incidence of antibiotics and transcriptional regulation of ARGs in isolated bacteria from wastewater needs to be explored. By HPLC, in samples of untreated wastewater, ampicillin (49.74 ± 5.70 µg/mL), chloramphenicol (0.60 ± 0.03 µg/mL), tylosin (72.95 ± 2.03 µg/mL), and oxytetracycline (0.22 ± 0.01 µg/mL) was determined. Through metagenomic analysis identified 58 bacterial species belonging to 9 phyla and at least 14 species have shown resistance to a variety of antibiotics. Twenty-two bacterial isolates were proved to be resistant to fifteen antibiotics of new generation and used in medical research to combat infectious diseases. Fourteen strains were shown to harbor plasmids in size ranges of 2-5 Kb, 6-10 Kb and plasmids with size greater than 10 Kb. By quantitative PCR it was possible to identify genes sul, qnr, cat1, aadA1, and sat-1 gene were shown to be present in gDNA samples from treated and untreated samples of wastewater and by relative expression analysis, differential expression of cat1, ermB, act, and tetA genes was demonstrated in strains that showed identity with Escherichia coli, Bacteroides fragilis, and Salmonella thyphi, and that were stressed with different concentrations of antibiotics. The presence of ARGs in untreated water samples, as well as in bacterial isolates, was indicative that in these habitats there are microorganisms that can resist β-lactams, aminoglycosides, tetracyclines, sulfonamides, and quinolones. | 2023 | 37672120 |
| 3525 | 5 | 0.9989 | Characterization of tetracycline effects on microbial community, antibiotic resistance genes and antibiotic resistance of Aeromonas spp. in gut of goldfish Carassius auratus Linnaeus. The gut of aquatic animals was a significant niche for dissemination of antibiotic resistance genes (ARGs) and direct response of living conditions. In this study, the gut microbiota of goldfish Carassius auratus Linnaeus was sampled at 7 days and 21 days after treatment with tetracycline at 0.285 and 2.85 μg L(-1) to investigate the influences on the microbial structure and antibiotic resistance. The proportion of tetracycline resistance bacteria was 1.02% in the control group, while increased to 23.00%, 38.43%, 62.05% in groups of high concentration for 7 days (H7), low concentration for 21 days (L21) and high concentration for 21 days (H21), respectively. Compared to the control group, the diversity of isolated Aeromonas spp. was decreased in the treatment groups and the minimal inhibitory concentration (MIC) of resistant isolates was enhanced from 32 to 256 μg mL(-1) with the treatment of tetracycline in time- and dose-dependent manners. Furthermore, the abundance of most genes was increased in treatment groups and efflux genes mainly responded to the stress of tetracycline with an average level of 1.0 × 10(-2). After treatment with tetracycline, the predominant species were changed both at phylum and genus levels. The present study explored the impact of tetracycline on gut microbiota of goldfish at environmentally realistic concentrations for the first time and our findings will provide a reference for characterizing the microbiome of fish in the natural environment. | 2020 | 31958628 |
| 2863 | 6 | 0.9989 | Detection 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. | 2019 | 30918503 |
| 5297 | 7 | 0.9989 | Identification of antibiotic resistant bacteria community and a GeoChip based study of resistome in urban watersheds. Urban watersheds from point sources are potential reservoirs of antibiotic resistance genes (ARGs). However, few studies have investigated urban watersheds of non-point sources. To understand the type of ARGs and bacteria that might carry such genes, we investigated two non-point source urban watersheds with different land-use profiles. Antibiotic resistance levels of two watersheds (R1, R3) were examined using heterotrophic plate counts (HPC) as a culturing method to obtain counts of bacteria resistant to seven antibiotics belonging to different classes (erythromycin, kanamycin, lincomycin, norfloxacin, sulfanilamide, tetracycline and trimethoprim). From the HPC study, 239 antibiotic resistant bacteria were characterized for resistance to more antibiotics. Furthermore, ARGs and antimicrobial biosynthesis genes were identified using GeoChip version 5.0 to elucidate the resistomes of surface waters in watersheds R1 and R3. The HPC study showed that water samples from R1 had significantly higher counts of bacteria resistant to erythromycin, kanamycin, norfloxacin, sulfanilamide, tetracycline and trimethoprim than those from R3 (Analysis of Similarity (ANOSIM), R = 0.557, p < 0.01). Of the seven antibiotics tested, lincomycin and trimethoprim resistant bacteria are greater in abundances. The 239 antibiotic resistant isolates represent a subset of resistant bacterial populations, including bacteria not previously known for resistance. Majority of the isolates had resistance to ampicillin, vancomycin, lincomycin and trimethoprim. GeoChip revealed similar ARGs in both watersheds, but with significantly higher intensities for tetX and β-lactamase B genes in R1 than R3. The genes with the highest average normalized intensities in R1 and R3 were tetracycline (tet) and fosfomycin (fosA) resistance genes, respectively. The higher abundance of tetX genes in R1 is congruent with the higher abundance of tetracycline resistant HPC observed in R1 samples. Strong correlations (r ≥ 0.8) of efflux pumps with antimicrobial biosynthesis genes suggest that natural production of antimicrobials may act as a selective pressure of transporter proteins in the absence of antibiotics from anthropogenic sources. In conclusion, distinct antibiotic resistant bacteria phylotypes and a variety of ARGs were present in the non-point sources urban watersheds of different land-use profiles, suggesting that ARG risk assessments and monitoring studies need to include these types of watersheds. | 2016 | 27750121 |
| 3530 | 8 | 0.9989 | Occurrence of the transferable copper resistance gene tcrB among fecal enterococci of U.S. feedlot cattle fed copper-supplemented diets. Copper, an essential micronutrient, is supplemented in the diet at elevated levels to reduce morbidity and mortality and to promote growth in feedlot cattle. Gut bacteria exposed to copper can acquire resistance, which among enterococci is conferred by a transferable copper resistance gene (tcrB) borne on a plasmid. The present study was undertaken to investigate whether the feeding of copper at levels sufficient to promote growth increases the prevalence of the tcrB gene among the fecal enterococci of feedlot cattle. The study was performed with 261 crossbred yearling heifers housed in 24 pens, with pens assigned randomly to a 2×2 factorial arrangement of treatments consisting of dietary copper and a commercial linseed meal-based energy protein supplement. A total of 22 isolates, each identified as Enterococcus faecium, were positive for tcrB with an overall prevalence of 3.8% (22/576). The prevalence was higher among the cattle fed diets supplemented with copper (6.9%) compared to normal copper levels (0.7%). The tcrB-positive isolates always contained both erm(B) and tet(M) genes. Median copper MICs for tcrB-positive and tcrB-negative enterococci were 22 and 4 mM, respectively. The transferability of the tcrB gene was demonstrated via a filter-mating assay. Multilocus variable number tandem repeat analysis revealed a genetically diverse population of enterococci. The finding of a strong association between the copper resistance gene and other antibiotic (tetracycline and tylosin) resistance determinants is significant because enterococci remain potential pathogens and have the propensity to transfer resistance genes to other bacteria in the gut. | 2013 | 23666328 |
| 5915 | 9 | 0.9989 | Characterization of Two Macrolide Resistance-Related Genes in Multidrug-Resistant Pseudomonas aeruginosa Isolates. In analyzing the drug resistance phenotype and mechanism of resistance to macrolide antibiotics of clinical Pseudomonas aeruginosa isolates, the agar dilution method was used to determine the minimum inhibitory concentrations (MICs), and PCR (polymerase chain reaction) was applied to screen for macrolide antibiotics resistance genes. The macrolide antibiotics resistance genes were cloned, and their functions were identified. Of the 13 antibiotics tested, P. aeruginosa strains showed high resistance rates (ranging from 69.5-82.1%), and MIC levels (MIC90 > 256 μg/ml) to macrolide antibiotics. Of the 131 known macrolide resistance genes, only two genes, mphE and msrE, were identified in 262 clinical P. aeruginosa isolates. Four strains (1.53%, 4/262) carried both the msrE and mphE genes, and an additional three strains (1.15%, 3/262) harbored the mphE gene alone. The cloned msrE and mphE genes conferred higher resistance levels to three second-generation macrolides compared to two first-generation ones. Analysis of MsrE and MphE protein polymorphisms revealed that they are highly conserved, with only 1-3 amino acids differences between the proteins of the same type. It can be concluded that even though the strains showed high resistance levels to macrolides, known macrolide resistance genes are seldom present in clinical P. aeruginosa strains, demonstrating that a mechanism other than this warranted by the mphE and msrE genes may play a more critical role in the bacteria's resistance to macrolides. | 2020 | 33574864 |
| 2887 | 10 | 0.9989 | Diversity and characterization of oxytetracycline-resistant bacteria associated with non-native species, white-leg shrimp (Litopenaeus vannamei), and native species, black tiger shrimp (Penaeus monodon), intensively cultured in Thailand. AIMS: This study aimed at surveying prevalence of oxytetracycline (OTC)-resistant bacteria in the white-leg shrimp Litopenaeus vannamei, and the black tiger shrimp Penaeus monodon, intensively cultured in Thailand. We investigated the phylogenetic diversity of the bacterial isolates, as well as the minimum inhibitory concentration (MIC) of OTC, the occurrence of major OTC-resistant genes and multiple-antibiotic resistance in the isolates. METHODS AND RESULTS: Shrimps were collected from culture ponds, and the homogenates of whole bodies were plated on tryptic soy agar supplemented with or without OTC. Percentages of OTC-resistant bacteria were 0·3-52·1% in white-leg samples and 0·008-22·3% in black tiger samples. Analyses of 16S rDNA sequences indicated that most OTC-resistant isolates were closely related to Aeromonas spp. and Lactococcus garvieae. MICs of OTC were 4-128 μg ml(-1) in the OTC-resistant aeromonads and 128-256 μg ml(-1) in OTC-resistant L. garvieae. OTC resistance was found to be conferred by the genes tet(A), tet(C), tet(D), tet(E), tet(M) and tet(S), detected either singly or in pairs. No resistance to ceftazidime, imipenem or chloramphenicol was observed in any isolate. CONCLUSIONS: Both species of shrimp are associated with OTC-resistant bacteria, occasionally at high densities exceeding 10(6) cfu g(-1). The associated bacteria, predominantly Lactococcus and Aeromonas genera, are potential pathogens and are reservoirs of a variety of OTC-resistant genes. SIGNIFICANCE AND IMPACT OF THE STUDY: Cultured shrimps can be vehicle to carry OTC-resistant bacteria to domestic and foreign consumers via the food chain. Very low populations of OTC-resistant bacteria observed in the several ponds suggest that levels of the resistant bacteria are artificially high and should be reduced in farmed shrimps. | 2011 | 21219554 |
| 2857 | 11 | 0.9989 | Changes in antibiotic resistance of Escherichia coli during the broiler feeding cycle. The purpose of this study was to investigate the drug-resistant phenotypes and genes of Escherichia coli in animal, environmental, and human samples before and after antibiotic use at a large-scale broiler farm to understand the respective effects on E. coli resistance during the broiler feeding cycle. The antibiotic use per broiler house was 143.04 to 183.50 mg/kg, and included tilmicosin, florfenicol, apramycin, and neomycin. All strains isolated on the first day the broilers arrived (T1; day 1) were antibiotic-resistant bacteria. E. coli strains isolated from animal samples were resistant to ampicillin, tetracycline, and sulfamethoxazole (100%), and those isolated from environmental samples were resistant to 5 different drugs (74.07%, 20 of 27). E. coli strains isolated on the last day before the broilers left (T2; day 47) had a higher resistance rate to florfenicol (100%, 36 of 36) than at T1 (P < 0.05). Multidrug resistance increased from T1 (84.21%, 32 of 38) to T2 (97.22%, 35 of 36). Most strains were resistant to 5 classes of antibiotics, and 2 strains were resistant to 6 classes of antibiotics. Among 13 identified drug resistance genes, 11 and 13 were detected at T1 and T2, respectively. NDM-1 was detected in 4 environmental samples and 1 animal sample. In conclusion, the use of antibiotics during breeding increases E. coli resistance to antibacterial drugs. Drug-resistant bacteria in animals and the environment proliferate during the feeding cycle, leading to the widespread distribution of drug resistance genes and an increase in the overall resistance of bacteria. | 2020 | 33248614 |
| 3527 | 12 | 0.9989 | Nutrient-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. | 2016 | 27685672 |
| 2865 | 13 | 0.9989 | Antibiotic 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. | 2002 | 12396530 |
| 5285 | 14 | 0.9989 | Antibiotic Use in Beekeeping: Implications for Health and Environment from a One-Health Perspective. BACKGROUND: The use of antibiotics in beekeeping has potential implications for honeybee health and environmental contamination. Recent research indicates that extensive antibiotic use in beekeeping, especially oxytetracycline, promotes antimicrobial resistance in bee-related bacteria. Honeybees can transport oxytetracycline-resistance genes during foraging, potentially establishing reservoirs of resistance in the colony and facilitating intergeneric gene transfer among various gut bacteria as well as in the microbiome of the flowers and the wider environment, where honeybees can spread antibiotic-resistance genes over a large distance. This study investigates the effects of oxytetracycline hydrochloride (OTC) treatment on honeybees from a One Health perspective, examining antibiotic residues in honey, environmental spread, and the presence of tetracycline-resistance genes (TET-RGs). METHODS: In the spring of 2022, two groups of four honeybee hives were placed near an almond grove in Central Italy. One group was treated with 1.68 g of OTC, while the other remained untreated. Samples were collected from bees, honey, hive entrances, and flowers before treatment and at 3 as well as 9 days post-treatment. OTC residues and TET-RGs were analyzed to assess contamination and resistance gene dissemination. RESULTS: OTC residues were detected in honey from both treated (day 3: 263,250.0 ± 100,854.3 µg/kg; day 9: 132,600 ± 146,753.9 µg/kg) and untreated hives (day 3: 20.5 ± 8.2 µg/kg; day 9: 135.8 ± 198.6 µg/kg), suggesting cross-contamination. Residues were also found in almond tree flowers (0.7 ± 0.1 µg/kg), with TET-RGs (tet(K), tet(L), tet(M), tet(B), tet(O), tet(D)) detected pre- and post-treatment. In honeybee gut bacteria, resistance genes (tet(M), tet(A), tet(D), tet(B)) appeared post-treatment in both groups. No significant correlation was observed between hive distance and resistance gene presence in flowers, although the presence of other farms located within the bees' flight range, in which OTC might have been used in the past, could have influenced the results. CONCLUSIONS: These findings highlight the risk of OTC-induced antibiotic cross-contamination and the spread of TET-RG, raising concerns for bee health and environmental safety. Given honeybees' social nature and the negative effects of antibiotics on their health, an antibiotic-free management approach is recommended for sustainable apiculture. | 2025 | 40298498 |
| 5910 | 15 | 0.9988 | Antimicrobial Susceptibility Testing and Tentative Epidemiological Cutoff Values for Five Bacillus Species Relevant for Use as Animal Feed Additives or for Plant Protection. Bacillus megaterium (n = 29), Bacillus velezensis (n = 26), Bacillus amyloliquefaciens (n = 6), Bacillus paralicheniformis (n = 28), and Bacillus licheniformis (n = 35) strains from different sources, origins, and time periods were tested for the MICs for nine antimicrobial agents by the CLSI-recommended method (Mueller-Hinton broth, 35°C, for 18 to 20 h), as well as with a modified CLSI method (Iso-Sensitest [IST] broth, 37°C [35°C for B. megaterium], 24 h). This allows a proposal of species-specific epidemiological cutoff values (ECOFFs) for the interpretation of antimicrobial resistance in these species. MICs determined by the modified CLSI method were 2- to 16-fold higher than with the CLSI-recommended method for several antimicrobials. The MIC distributions differed between species for five of the nine antimicrobials. Consequently, use of the modified CLSI method and interpretation of resistance by use of species-specific ECOFFs is recommended. The genome sequences of all strains were determined and used for screening for resistance genes against the ResFinder database and for multilocus sequence typing. A putative chloramphenicol acetyltransferase (cat) gene was found in one B. megaterium strain with an elevated chloramphenicol MIC compared to the other B. megaterium strains. In B. velezensis and B. amyloliquefaciens, a putative tetracycline efflux gene, tet(L), was found in all strains (n = 27) with reduced tetracycline susceptibility but was absent in susceptible strains. All B. paralicheniformis and 23% of B. licheniformis strains had elevated MICs for erythromycin and harbored ermD The presence of these resistance genes follows taxonomy suggesting they may be intrinsic rather than horizontally acquired. Reduced susceptibility to chloramphenicol, streptomycin, and clindamycin could not be explained in all species.IMPORTANCE When commercializing bacterial strains, like Bacillus spp., for feed applications or plant bioprotection, it is required that the strains are free of acquired antimicrobial resistance genes that could potentially spread to pathogenic bacteria, thereby adding to the pool of resistance genes that may cause treatment failures in humans or animals. Conversely, if antimicrobial resistance is intrinsic to a bacterial species, the risk of spreading horizontally to other bacteria is considered very low. Reliable susceptibility test methods and interpretation criteria at the species level are needed to accurately assess antimicrobial resistance levels. In the present study, tentative ECOFFs for five Bacillus species were determined, and the results showed that the variation in MICs followed the respective species. Moreover, putative resistance genes, which were detected by whole-genome sequencing and suggested to be intrinsic rather that acquired, could explain the resistance phenotypes in most cases. | 2018 | 30030233 |
| 2866 | 16 | 0.9988 | Characterization 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. | 2013 | 23773226 |
| 2813 | 17 | 0.9988 | Quantity of the tetracycline resistance gene tet(M) differs substantially between meat at slaughterhouses and at retail. Concentrations of the tetracycline resistance gene tet(M) per square centimeter were assessed in meat from the slaughterhouse (n = 100) and from retail (n = 100) by real-time quantitative PCR. The study revealed a substantial contamination of retail meat with the tetracycline resistance gene tet(M), with a mean of 4.34 log copies per cm² fasces in chicken and 5.58 log copies per cm² fasces in pork. Quantitative resistance gene analysis provides an interesting tool for risk assessment and is becoming increasingly important. For both chicken and pork, tet(M) concentrations were significantly higher in meat at retail, compared to meat at slaughter. Cultural investigations revealed substantial differences in the prevalence of listeria and enterococci, and of E. coli and coliforms, between meat at slaughter (n = 500) and at retail (n = 500). However, the differences in the prevalence of 2 investigated groups of potential tet(M)-carriers (enterococci, listeria) could not sufficiently explain the differences in tet(M) concentrations, since increasing concentrations of tet(M) were accompanied by decreasing prevalences of these potential tet(M)-carriers. The percentage of tetracycline susceptible indicator bacteria (E. faecalis, E. coli) did not differ between meat at slaughter and meat at retail. Higher concentrations of tet(M) at retail might correlate with the proliferation of other genera than enterococci and listeria, but there is also a reason to discuss whether secondary contaminants might carry tet(M) more often than the primary flora of meat. PRACTICAL APPLICATION: We successfully applied the direct quantitative monitoring of resistance genes in meat, which generally might aid as a useful and rapid additional tool for risk assessment. We know that bacteria provide a large pool of resistance genes, which are widely shared between each other-the larger the pool is, the more genes might be exchanged. Thus, in terms of resistance gene monitoring, we should sometimes overcome the restricted view on single bacteria and look at the gene pool, instead. | 2011 | 21729069 |
| 5298 | 18 | 0.9988 | Investigation 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. | 2024 | 37972772 |
| 2859 | 19 | 0.9988 | Transmission of human-pet antibiotic resistance via aerosols in pet hospitals of Changchun. In recent years, aerosols have been recognized as a prominent medium for the transmission of antibiotic-resistant bacteria and genes. Among these, particles with a particle size of 2 μm (PM(2.5)) can directly penetrate the alveoli. However, the presence of antibiotic-resistant genes in aerosols from pet hospitals and the potential risks posed by antibiotic-resistant bacteria in these aerosols to humans and animals need to be investigated. In this study, cefotaxime-resistant bacteria were collected from 5 representative pet hospitals in Changchun using a Six-Stage Andersen Cascade Impactor. The distribution of bacteria in each stage was analyzed, and bacteria from stage 5 and 6 were isolated and identified. Minimal inhibitory concentrations of isolates against 12 antimicrobials were determined using broth microdilution method. Quantitative Polymerase Chain Reaction was employed to detect resistance genes and mobile genetic elements that could facilitate resistance spread. The results indicated that ARBs were enriched in stage 5 (1.1-2.1 μm) and stage 3 (3.3-4.7 μm) of the sampler. A total of 159 isolates were collected from stage 5 and 6. Among these isolates, the genera Enterococcus spp. (51%), Staphylococcus spp. (19%), and Bacillus spp. (14%) were the most prevalent. The isolates exhibited the highest resistance to tetracycline and the lowest resistance to cefquinome. Furthermore, 56 (73%) isolates were multidrug-resistant. Quantitative PCR revealed the expression of 165 genes in these isolates, with mobile genetic elements showing the highest expression levels. In conclusion, PM(2.5) from pet hospitals harbor a significant number of antibiotic-resistant bacteria and carry mobile genetic elements, posing a potential risk for alveolar infections and the dissemination of antibiotic resistance genes. | 2024 | 38855194 |