Abstract
Plasmids can mediate horizontal gene transfer of antibiotic resistance, virulence genes, and other adaptive factors across bacterial populations. Here, we analyze genomic composition and ...pairwise sequence identity for over 10,000 reference plasmids to obtain a global map of the prokaryotic plasmidome. Plasmids in this map organize into discrete clusters, which we call plasmid taxonomic units (PTUs), with high average nucleotide identity between its members. We identify 83 PTUs in the order
Enterobacterales
, 28 of them corresponding to previously described archetypes. Furthermore, we develop an automated algorithm for PTU identification, and validate its performance using stochastic blockmodeling. The algorithm reveals a total of 276 PTUs in the bacterial domain. Each PTU exhibits a characteristic host distribution, organized into a six-grade scale (I–VI), ranging from plasmids restricted to a single host species (grade I) to plasmids able to colonize species from different phyla (grade VI). More than 60% of the plasmids in the global map are in groups with host ranges beyond the species barrier.
Display omitted
•Both bacteria and bacteriophages are important source of ARGs in soil.•Existence of microplastic inhibited the dissipation of soil antibiotics and ARGs.•Sophorolipid clearly prompted ...the dissipation of soil antibiotics and ARGs.•Sophorolipid outweighed microplastic in impacting soil antibiotic/ARGs attenuation.•Water soluble TC best positively correlated to ARGs level in bacteria and phages.
The emerging mixed contamination of antibiotics and microplastics in greenhouse soil has made the control of antibiotic resistant gene (ARG) transmission a novel challenge. In this work, surfactant sophorolipid was applied to enhance the dissipation of tetracycline (TC) and tet genes in the presence of microplastics in greenhouse soil. During 49days of incubation, soil bacteria and phages were both found to be the crucial reservoirs of ARGs. Meanwhile, microplastic’s presence significantly inhibited the dissipation of TC and ARGs in the soil. However, sophorolipid application was proved to outweigh the negative impact caused by microplastic existence, and lead to the highest dissipation of soil TC and ARGs. Significant positive correlation was detected between the dissipation rate of water-soluble and exchangeable TC content and bacteria/phage co-mediated ARG levels. This also held true between the two fractions of soil TC and the ratio of ARG level in the bacteria to that in the phages (BARGs/PARGs). The opposite impacts of microplastic presence and sophorolipid amendment on the TC/ARG dissipation found in this work provides new information for understanding ARG transmission between bacteria and phages in the mixed contaminated greenhouse soil.
Antibiotics have always been considered as one of the most relevant discoveries of the twentieth century. Unfortunately, the dawn of the antibiotic era has sadly corresponded to the rise of the ...phenomenon of antimicrobial resistance (AMR), which is a natural process whereby microbes evolve in such a way to withstand the action of drugs. In this context, the identification of new potential antimicrobial targets and/or the identification of new chemical entities as antimicrobial drugs are in great demand. To date, among the many possible approaches used to deal with antibiotic resistance is the use of antibiotic adjuvants that hit bacterial non-essential targets. In this review, the author focuses on the discovery of antibiotic adjuvants and on new tools to study and reduce the prevalence of resistant bacterial infections.
Display omitted
•UV disinfection decreased antibiotic resistant bacteria/genes significantly.•UV treatment has selectivity on antibiotic resistance bacteria.•Tetracycline-resistant bacteria showed ...more tolerance to low UV fluence.•Proportion of tetracycline-resistant bacteria increased during UV treatment.•Removals of ARB and ARGs are not statistically correlated.
Antibiotic resistance in wastewater is becoming a major public health concern, but poorly understood about impact of disinfection on antibiotic resistant bacteria and antibiotic resistance genes. The UV disinfection of antibiotic resistant heterotrophic bacteria and their relevant genes in the wastewater of a municipal wastewater treatment plant has been evaluated. Two commonly used antibiotics, erythromycin and tetracycline were selected because of their wide occurrences in regard to the antibiotic resistance problem.
After UV treatment at a fluence of 5mJcm−2, the log reductions of heterotrophic bacteria resistant to erythromycin and tetracycline in the wastewater were found to be 1.4±0.1 and 1.1±0.1, respectively. The proportion of tetracycline-resistant bacteria (5%) was nearly double of that before UV disinfection (3%). Tetracycline-resistant bacteria exhibited more tolerance to UV irradiation compared to the erythromycin-resistant bacteria (p<0.05).
Gene copy numbers were quantified via qPCR and normalized to the volume of original sample. The total concentrations of erythromycin- and tetracycline-resistance genes were (3.6±0.2)×105 and (2.5±0.1)×105 copies L−1, respectively. UV treatment at a fluence of 5mJcm−2 removed the total erythromycin- and tetracycline-resistance genes by 3.0±0.1 log and 1.9±0.1 log, respectively. UV treatment was effective in reducing antibiotic resistance in the wastewater.
The major concern regarding the biocide triclosan (TCS) stems from its potential coselection for antibiotic resistance. However, environmental impacts are often investigated using high concentrations ...and acute exposure, while predicted releases are typified by chronic low concentrations. Moreover, little information is available regarding the reversibility of TCS and derived antibiotic resistance with diminishing TCS usage. Here, the model Gram-negative bacterium Escherichia coli was exposed to 0.01 mg/L TCS continuously for more than 100 generations. The adapted cells gained considerable resistance to TCS as indicated by a significant increase in the minimal inhibitory concentration (MIC50) from 0.034 to 0.581 mg/L. This adaptive evolution was attributed to overexpression and mutation of target genes (i.e., fabI) as evidenced by transcriptomic and genomic analyses. However, only mild tolerance to various antibiotics was observed, possibly due to reduced membrane permeability and biofilm formation. After TCS exposure ceased, the adapted cells showed persistent resistance to TCS due to inheritable genetic mutations, whereas their antibiotic tolerance declined over time. Our results suggest that extensive use of TCS may promote the evolution and persistence of TCS-resistant bacterial pathogens. A quantitative definition of the conditions under which TCS selects for multidrug resistance in the environment is crucially needed.
While there is increasing knowledge about the gut microbiome, the factors influencing and the significance of the gut resistome are still not well understood. Infant gut commensals risk transferring ...multidrug-resistant antibiotic resistance genes (ARGs) to pathogenic bacteria. The rapid spread of multidrug-resistant pathogenic bacteria is a worldwide public health concern. Better understanding of the naïve infant gut resistome may build the evidence base for antimicrobial stewardship in both humans and in the food industry. Given the high carriage rate of extended spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae in Asia, we aimed to evaluate community prevalence, dynamics, and longitudinal changes in antibiotic resistance gene (ARG) profiles and prevalence of ESBL-producing E. coli and K. pneumoniae in the intestinal microbiome of infants participating in the Growing Up in Singapore Towards Healthy Outcomes (GUSTO) study, a longitudinal cohort study of pregnant women and their infants.
We analysed ARGs in the first year of life among 75 infants at risk of eczema who had stool samples collected at multiple timepoints using metagenomics.
The mean number of ARGs per infant increased with age. The most common ARGs identified confer resistance to aminoglycoside, beta-lactam, macrolide and tetracycline antibiotics; all infants harboured these antibiotic resistance genes at some point in the first year of life. Few ARGs persisted throughout the first year of life. Beta-lactam resistant Escherichia coli and Klebsiella pneumoniae were detected in 4 (5.3%) and 32 (42.7%) of subjects respectively.
In this longitudinal cohort study of infants living in a region with high endemic antibacterial resistance, we demonstrate that majority of the infants harboured several antibiotic resistance genes in their gut and showed that the infant gut resistome is diverse and dynamic over the first year of life.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Display omitted
•UV/Cl2 is an effective disinfection method for ARG and MGE elimination.•RCS radicals play an effective role on target gene removal in UV/Cl2 process.•Sul1-qPCR is easier to remove ...than intI1-qPCR by UV/Cl2 with low-dose chlorine.•Log reduction of target genes decreased with pH increasing in UV/Cl2 process.•UV/Cl2 shows more advantages in simultaneous removal of antibiotics, ARBs and ARGs.
This study investigated the reduction of one antibiotic resistance gene (ARG, sul1) and one integron (intI1) within a multiple-antibiotic-resistant bacterium (ARB), Pseudomonas. HLS-6, during UV, chlorination and UV/chlorination. This bacterial strain was easily inactivated by these three methods, but its gene inactivation was not so easy. Two short target gene sequences (sul1-qPCR and intI1-qPCR) were selected for quantitative analysis, and another two longer ones (sul1-PCR and intI1-PCR) were used for qualitative identification. During the initial reaction time (<20 min), the degradation rate order of sul1-qPCR and intI1-qPCR was as follows: UV/chlorination>chlorination>UV. The log reduction of sul1-qPCR and intI1-qPCR in UV/chlorination achieved >3.50 and 4.00 log, respectively. The removal efficiency of sul1-PCR and intI1-PCR was also identified by gel electrophoresis analysis, which further confirmed the advantage of UV/chlorination treatment on DNA damage. Among the radicals produced in UV/chlorination, only the reactive chlorine species (Cl⋅, Cl2⋅− and ClO⋅) can degrade the target genes. Under the condition of low chlorine dosage, sul1-qPCR was easier to be removed than intI1-qPCR by UV/chlorination. The log reduction of both sul1-qPCR and intI1-qPCR decreased with pH increasing during UV/chlorination. In the presence of sulfamethoxazole, UV/chlorination showed more advantages than direct UV and chlorination in the simultaneous removal of antibiotics, ARBs and ARGs.
Display omitted
•Four pilot-scale CWs differing in plant species and planting patterns were compared.•Nutrients, antibiotics and ARGs in aquaculture wastewater were efficiently removed.•Microbial ...structure and diversity spatially differed in four CWs.•Treatment performances of CWs attributed to the plant physiological features.
Four horizontal subsurface flow pilot-scale constructed wetlands (CWs) named as S1, S2, M1 and M2 were constructed to treat aquaculture wastewater. And two different plant species (Iris pseudacorus and Phragmites australis) were cultivated in single and mixed planting patterns in these four CWs. The removal rate of conventional pollutants (nutrient and organic compounds), antibiotics including enrofloxacin (ENR), sulfamethoxazole (SMZ), and antibiotic resistance genes (ARGs) were evaluated among those CWs. The total nitrogen and NH4+–N removal rates of all CWs were 73.24%–91.46% and 61.20%–92.27%, respectively. CWs with mixed planting patterns, such as M1 (planted with Iris pseudacorus at the forepart and Phragmites australis at the back) and M2 (alternate cultivation with Iris pseudacorus and Phragmites australis) showed better performances than CWs planted with single plant species, such as S1 (Iris pseudacorus) and S2 (Phragmites australis). However, S1 and S2 exhibited higher removal efficiencies for emerging contaminants: S1 had removal efficiencies of 77.64%, 68.70%, and 58.21% for ENR, SMZ, and total ARGs, respectively, and S2 had removal efficiencies of 81.11%, 64.94%, and 56.26% for ENR, SMZ, and total ARGs, respectively. Compared with single planting, the dominant genera in mixed planting exhibited lower relative abundance in anaerobes and higher percent of bacteria associated with nitrogen metabolism, indicating that different plant physiological characteristics affected the microbial community structures of the CWs.
Many bacteria can infect and persist inside their hosts for long periods of time. This can be due to immunosuppression of the host, immune evasion by the pathogen and/or ineffective killing by ...antibiotics. Bacteria can survive antibiotic treatment if they are resistant or tolerant to a drug. Persisters are a subpopulation of transiently antibiotic-tolerant bacterial cells that are often slow-growing or growth-arrested, and are able to resume growth after a lethal stress. The formation of persister cells establishes phenotypic heterogeneity within a bacterial population and has been hypothesized to be important for increasing the chances of successfully adapting to environmental change. The presence of persister cells can result in the recalcitrance and relapse of persistent bacterial infections, and it has been linked to an increase in the risk of the emergence of antibiotic resistance during treatment. If the mechanisms of the formation and regrowth of these antibiotic-tolerant cells were better understood, it could lead to the development of new approaches for the eradication of persistent bacterial infections. In this Review, we discuss recent developments in our understanding of bacterial persisters and their potential implications for the treatment of persistent infections.
PDF
