Comprehensive genomic landscape of antibiotic resistance in Staphylococcus epidermidis.

Staphylococcus epidermidis, a common commensal bacterium found on human skin, can cause infections in clinical settings, and the presence of antibiotic resistance genes (ARGs) impedes the treatment of S. epidermidis infections. However, studies characterizing the ARGs in S. epidermidis with regard to genomic and ecological diversities are limited. Thus, we performed a comprehensive and comparative analysis of 405 high-quality S. epidermidis genomes, including those of 35 environmental isolates from the Han River, to investigate the genomic diversity of antibiotic resistance in this pathogen. Comparative genomic analysis revealed the prevalence of ARGs in S. epidermidis genomes associated with multi-locus sequence types. The genes encoding dihydrofolate reductase (dfrC) and multidrug efflux pump (norA) were genome-wide core ARGs. ß-Lactam class ARGs were also highly prevalent in the S. epidermidis genomes, which was consistent with the resistance phenotype observed in river isolates. Furthermore, we identified chloramphenicol acetyltransferase genes (cat) in the plasmid-like sequences of the six river isolates, which have not been reported previously in S. epidermidis genomes. These genes were identical to those harbored by the Enterococcus faecium plasmids and associated with the insertion sequence 6 family transposases, homologous to those found in Staphylococcus aureus plasmids, suggesting the possibility of horizontal gene transfer between these Gram-positive pathogens. Comparison of the ARG and virulence factor profiles between S. epidermidis and S. aureus genomes revealed that these two species were clearly distinguished, suggesting genomic demarcation despite ecological overlap. Our findings provide a comprehensive understanding of the genomic diversity of antibiotic resistance in S. epidermidis. IMPORTANCE: A comprehensive understanding of the antibiotic resistance gene (ARG) profiles of the skin commensal bacterium and opportunistic pathogen Staphylococcus epidermidis needs to be documented from a genomic point of view. Our study encompasses a comparative analysis of entire S. epidermidis genomes from various habitats, including those of 35 environmental isolates from the Han River sequenced in this study. Our results shed light on the distribution and diversity of ARGs within different S. epidermidis multi-locus sequence types, providing valuable insights into the ecological and genetic factors associated with antibiotic resistance. A comparison between S. epidermidis and Staphylococcus aureus revealed marked differences in ARG and virulence factor profiles, despite their overlapping ecological niches.

Flavobacterium psychrotrophum sp. nov. and Flavobacterium panacagri sp. nov., Isolated from Freshwater and Soil.

Two novel bacterial strains CJ74T and CJ75T belonging to the genus Flavobacterium were isolated from freshwater of Han River and ginseng soil, South Korea, respectively. Strain CJ74T was Gram-stain-negative, aerobic, rod-shaped, non-motile, and non-flagellated, and did not produce flexirubin-type pigments. Strain CJ75T was Gram-stain-negative, aerobic, rod-shaped, motile by gliding, and non-flagellated, and produced flexirubin-type pigments. Both strains were shown to grow optimally at 30 °C in the absence of NaCl on R2A medium. Phylogenetic analysis based on 16S rRNA gene sequences showed that strains CJ74T and CJ75T belonged to the genus Flavobacterium and were most closely related to Flavobacterium niveum TAPW14T and Flavobacterium foetidum CJ42T with 96.17% and 97.29% 16S rRNA sequence similarities, respectively. Genomic analyses including the reconstruction of phylogenomic tree, average nucleotide identity, and digital DNA-DNA hybridization suggested that they were novel species of the genus Flavobacterium. Both strains contained menaquinone 6 (MK-6) as the primary respiratory quinone and phosphatidylethanolamine as a major polar lipid. The predominant fatty acids of both strains were iso-C15:0 and summed feature 3 (C16:1 ω7c and/or C16:1 ω6c). Based on the polyphasic taxonomic study, strains CJ74T and CJ75T represent novel species of the genus Flavobacterium, for which names Flavobacterium psychrotrophum sp. nov. and Flavobacterium panacagri sp. nov. are proposed, respectively. The type strains are CJ74T (=KACC 19819T =JCM 32889T) and CJ75T (=KACC 23149T =JCM 36132T).

The combined effect of pit and fissure sealant application and oral health education on oral health status of children aged 6-9 years: a 12-month follow-up study in Northeast China.

BACKGROUND: Children aged 6-9 years are vulnerable to dental caries due to age-related limitations and a lack of adequate knowledge regarding oral health and hygiene practices. This study aimed to establish a cohort of children aged between 6 and 9 years and conducted a 12-month follow-up to examine the combined effect of pit and fissure sealant (PFS) application and oral health education on their oral health status. METHODS: A cohort study with 12-month follow-up was conducted in Liaoning province, China. A multi-stage stratified cluster sampling approach was employed in the study. The enrolled 6- to 9-year-old children were all from the selected primary schools, who had resided in the designated area for at least 6 months. Children who were unable to cooperate with the examiner or without informed consent from their guardians were excluded. Experienced dental professionals examined the oral health status of primary school children aged 6-9 years. All children and their guardians were mandated to complete a questionnaire (qualitative data) at the beginning of the study. In the experiment group, children underwent PFS application and chairside oral health education. Clinical examinations and questionnaire surveys were repeated at the 12-month follow-up. The chi-square test and binary logistic regression were conducted to investigate the potential risk factors associated with dental caries prevalence (dependent variable). Independent variables were items from the questionnaire (such as living place, parents' education level and children' birth weight). The significant variables identified in the chi-square tests were subsequently included in the binary logistic regression analysis. RESULTS: A total of 4,085 children aged 6-9 years were included in the study, with 1805 participants assigned to the experiment group and 2280 to the control group. At baseline, the caries rates of the experimental and control group were 77.95% and 80.35%, respectively without any statistically significant differences. However, at the 12-month follow-up, the caries rate in the experimental group (83.65%) was significantly lower than that in the control group (86.62%) (P < 0.05). The results from the binary logistic regression analysis indicated that parents with a college degree and children in the experimental group exhibited lower caries rates. Conversely, higher caries rates were associated with the consumption of sweet beverages and foods more than once a day and a lack of knowledge regarding the causes of caries (P < 0.05). CONCLUSIONS: In Liaoning, China, children aged 6 to 9 years exhibited a high prevalence of dental caries. Several factors, including the parent's education level, the frequency of consuming sweet beverages and foods, and the children's understanding of the cause of caries, significantly affected the caries prevalence rates. The implementation of PFS application and oral health education effectively reduce the caries rate among the surveyed children.

Persistence of antibiotic resistance from animal agricultural effluents to surface water revealed by genome-centric metagenomics.

Concerns about antibiotic resistance genes (ARGs) released from wastewaters of livestock or fish farming into the natural environment are increasing, but studies on unculturable bacteria related to the dissemination of antibiotic resistance are limited. Here, we reconstructed 1100 metagenome-assembled genomes (MAGs) to assess the impact of microbial antibiotic resistome and mobilome in wastewaters discharged to Korean rivers. Our results indicate that ARGs harbored in the MAGs were disseminated from wastewater effluents into downstream rivers. Moreover, it was found that ARGs are more commonly co-localized with mobile genetic elements (MGEs) in agricultural wastewater than in river water. Among the effluent-derived phyla, uncultured members of the superphylum Patescibacteria possessed a high number of MGEs, along with co-localized ARGs. Our findings suggest that members of the Patesibacteria are a potential vector for propagating ARGs into the environmental community. Therefore, we propose that the dissemination of ARGs by uncultured bacteria should be further investigated in multiple environments.

Toward a Universal Unit for Quantification of Antibiotic Resistance Genes in Environmental Samples.

Surveillance of antibiotic resistance genes (ARGs) has been increasingly conducted in environmental sectors to complement the surveys in human and animal sectors under the "One-Health" framework. However, there are substantial challenges in comparing and synthesizing the results of multiple studies that employ different test methods and approaches in bioinformatic analysis. In this article, we consider the commonly used quantification units (ARG copy per cell, ARG copy per genome, ARG density, ARG copy per 16S rRNA gene, RPKM, coverage, PPM, etc.) for profiling ARGs and suggest a universal unit (ARG copy per cell) for reporting such biological measurements of samples and improving the comparability of different surveillance efforts.

Oral health status of students with visual or hearing impairments in Northeast China.

BACKGROUND: Visual or hearing impairments in students seriously affect their quality of life. The aim of this study was to identify oral hygiene status and its influencing factors on visual or hearing impairments in students in Northeast China. METHODS: This study was conducted in May 2022. A total of 118 visually impaired students and 56 hearing impaired students from Northeast China were included in this study via census. Oral examinations and questionnaire-based surveys of students and their teachers were conducted. The oral examinations included caries experience, prevalence of gingival bleeding and dental calculus. The questionnaires included three parts: Social demographics (residence, sex and race) and parents' educational level; Oral hygiene habits and medical treatment behaviors; Knowledge and attitudes towards oral health care. This questionnaire was selected from the Fourth China National Oral Health Survey and the reliability and validity of the questionnaire were previously tested. T tests, one-way ANOVA, χ2 tests and multivariate logistic analyses were conducted to evaluate the differences and dependent variables of dental caries. RESULTS: The prevalence of dental caries in visually impaired and hearing impaired students were 66.10% and 66.07%. The mean number of DMFT, prevalence of gingival bleeding and dental calculus in visually impaired students were 2.71 ± 3.06, 52.08% and 59.38%, respectively. The mean number of DMFT, prevalence of gingival bleeding and dental calculus in hearing impaired students were 2.57 ± 2.83, 17.86% and 42.86%, respectively. The results of the multivariate logistic analysis showed that fluoride use and parents' educational background had an impact on the caries experience of visually impaired students. The daily toothbrushing frequency and parents' educational background had an impact on the caries experience of hearing impaired students. CONCLUSIONS: The oral health situation of students with visual or hearing impairments remains severe. It is still necessary to promote oral and general health in this population.

Population-level impacts of antibiotic usage on the human gut microbiome.

The widespread usage of antimicrobials has driven the evolution of resistance in pathogenic microbes, both increased prevalence of antimicrobial resistance genes (ARGs) and their spread across species by horizontal gene transfer (HGT). However, the impact on the wider community of commensal microbes associated with the human body, the microbiome, is less well understood. Small-scale studies have determined the transient impacts of antibiotic consumption but we conduct an extensive survey of ARGs in 8972 metagenomes to determine the population-level impacts. Focusing on 3096 gut microbiomes from healthy individuals not taking antibiotics we demonstrate highly significant correlations between both the total ARG abundance and diversity and per capita antibiotic usage rates across ten countries spanning three continents. Samples from China were notable outliers. We use a collection of 154,723 human-associated metagenome assembled genomes (MAGs) to link these ARGs to taxa and detect HGT. This reveals that the correlations in ARG abundance are driven by multi-species mobile ARGs shared between pathogens and commensals, within a highly connected central component of the network of MAGs and ARGs. We also observe that individual human gut ARG profiles cluster into two types or resistotypes. The less frequent resistotype has higher overall ARG abundance, is associated with certain classes of resistance, and is linked to species-specific genes in the Proteobacteria on the periphery of the ARG network.

Chryseobacterium paludis sp. nov. and Chryseobacterium foetidum sp. nov. Isolated from the Aquatic Environment, South Korea.

Two novel bacterial species CJ51T and CJ63T belonging to the genus Chryseobacterium were isolated from the Upo wetland and the Han River, South Korea, respectively. Cells of these strains were Gram-stain-negative, aerobic, non-motile, rod-shaped, and catalase- and oxidase-positive. Both strains were shown to grow optimally at 30 °C and pH 7 in the absence of NaCl on tryptic soy agar. Phylogenetic analysis based on 16S rRNA gene sequences showed that strains CJ51T and CJ63T belonged to the genus Chryseobacterium and were most closely related to Chryseobacterium piperi CTMT and Chryseobacterium piscicola VQ-6316sT with 98.47% and 98.46% 16S rRNA sequence similarities, respectively. The average nucleotide identity values of strains CJ51T and CJ63T with its closely related type strains Chryseobacterium piperi CTMT and Chryseobacterium piscicola VQ-6316sT were 81.9% and 82.1%, respectively. The major fatty acids of strains CJ51T and CJ63T were iso-C15:0, iso-C17:0 3-OH and summed feature 9 (C16:0 10-methyl and/or iso-C17:1ω9c). Menaquinone 6 (MK-6) was identified as the primary respiratory quinone in both strains. The major polar lipids of strains CJ51T and CJ63T were phosphatidylethanolamine and several unidentified amino lipids and lipids. Based on polyphasic taxonomy data, strains CJ51T and CJ63T represent novel species of the genus Chryseobacterium, for which names Chryseobacterium paludis sp. nov. and Chryseobacterium foetidum sp. nov. are proposed respectively. The type strains are CJ51T (= KACC 22749T = JCM 35632T) and CJ63T (= KACC 22750T = JCM 35633T).

Biodegradation of plastics: mining of plastic-degrading microorganisms and enzymes using metagenomics approaches.

Plastic pollution exacerbated by the excessive use of synthetic plastics and its recalcitrance has been recognized among the most pressing global threats. Microbial degradation of plastics has gained attention as a possible eco-friendly countermeasure, as several studies have shown microbial metabolic capabilities as potential degraders of various synthetic plastics. However, still defined biochemical mechanisms of biodegradation for the most plastics remain elusive, because the widely used culture-dependent approach can access only a very limited amount of the metabolic potential in each microbiome. A culture-independent approach, including metagenomics, is becoming increasingly important in the mining of novel plastic-degrading enzymes, considering its more expanded coverage on the microbial metabolism in microbiomes. Here, we described the advantages and drawbacks associated with four different metagenomics approaches (microbial community analysis, functional metagenomics, targeted gene sequencing, and whole metagenome sequencing) for the mining of plastic-degrading microorganisms and enzymes from the plastisphere. Among these approaches, whole metagenome sequencing has been recognized among the most powerful tools that allow researchers access to the entire metabolic potential of a microbiome. Accordingly, we suggest strategies that will help to identify plastisphere-enriched sequences as de novo plastic-degrading enzymes using the whole metagenome sequencing approach. We anticipate that new strategies for metagenomics approaches will continue to be developed and facilitate to identify novel plastic-degrading microorganisms and enzymes from microbiomes.

Colistin-degrading proteases confer collective resistance to microbial communities during polymicrobial infections.

BACKGROUND: The increasing prevalence of resistance against the last-resort antibiotic colistin is a significant threat to global public health. Here, we discovered a novel colistin resistance mechanism via enzymatic inactivation of the drug and proposed its clinical importance in microbial communities during polymicrobial infections. RESULTS: A bacterial strain of the Gram-negative opportunistic pathogen Stenotrophomonas maltophilia capable of degrading colistin and exhibiting a high-level colistin resistance was isolated from the soil environment. A colistin-degrading protease (Cdp) was identified in this strain, and its contribution to colistin resistance was demonstrated by growth inhibition experiments using knock-out (Δcdp) and complemented (Δcdp::cdp) mutants. Coculture and coinfection experiments revealed that S. maltophilia carrying the cdp gene could inactivate colistin and protect otherwise susceptible Pseudomonas aeruginosa, which may seriously affect the clinical efficacy of the drug for the treatment of cystic fibrosis patients with polymicrobial infection. CONCLUSIONS: Our results suggest that Cdp should be recognized as a colistin resistance determinant that confers collective resistance at the microbial community level. Our study will provide vital information for successful clinical outcomes during the treatment of complex polymicrobial infections, particularly including S. maltophilia and other colistin-susceptible Gram-negative pathogens such as P. aeruginosa. Video abstract.

Effects of biochar addition on the fate of ciprofloxacin and its associated antibiotic tolerance in an activated sludge microbiome.

This study investigated the effects of adding biochar (BC) on the fate of ciprofloxacin (CIP) and its related antibiotic tolerance (AT) in activated sludge. Three activated sludge reactors were established with different types of BC, derived from apple, pear, and mulberry tree, respectively, and one reactor with no BC. All reactors were exposed to an environmentally relevant level of CIP that acted as a definitive selective pressure significantly promoting AT to four representative antibiotics (CIP, ampicillin, tetracycline, and polymyxin B) by up to two orders of magnitude. While CIP removal was negligible in the reactor without BC, the BC-dosed reactors effectively removed CIP (70-95% removals) through primarily adsorption by BC and biodegradation/biosorption by biomass. The AT in the BC-added reactors was suppressed by 10-99%, compared to that without BC. The BC addition played a key role in sequestering CIP, thereby decreasing the selective pressure that enabled the proactive prevention of AT increase. 16S rRNA gene sequencing analysis showed that the BC addition alleviated the CIP-mediated toxicity to community diversity and organisms related to phosphorous removal. Machine learning modeling with random forest and support vector models using AS microbiome data collectively pinpointed Achromobacter selected by CIP and strongly associated with the AT increase in activated sludge. The identification of Achromobacter as an important AT bacteria revealed by the machine learning modeling with multiple models was also validated with a linear Pearson's correlation analysis. Overall, our study highlighted Achromobacter as a potential useful sentinel for monitoring AT occurring in the environment and suggested BC as a promising additive in wastewater treatment to improve micropollutant removal, mitigate potential AT propagation, and maintain community diversity against toxic antibiotic loadings.

Comamonas fluminis sp. nov., isolated from the Han River, Republic of Korea.

A Gram-stain-negative, aerobic and motile bacterial strain, designated CJ34T, was isolated from Han River water in the Republic of Korea. Strain CJ34T grew optimally on tryptic soy agar at 30 °C and pH 7.0 in the absence of NaCl. Results of phylogenetic analysis based on 16S rRNA gene sequence showed that strain CJ34T belonged to the genus Comamonas within the family Comamonadaceae and was most closely related to Comamonas testosteroni ATCC 11996T and Comamonas thiooxydans DSM 17888T (both 98.63 % similarity). The average nucleotide identity values between strain CJ34T and two closely related type strains C. testosteroni ATCC 11996T and C. thiooxydans DSM 17888T were 82.77 and 82.73 %, respectively. The major isoprenoid quinone of strain CJ34T was ubiquinone Q-8. The major cellular fatty acids of strain CJ34T were C16 : 0, C16 : 1 ω6c and/or C16 : 1 ω7c and C18 : 1 ω6c and/or C18 : 1 ω7c. The predominant polar lipids of strain CJ34T were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol and an unidentified aminophospholipid. Whole genome sequencing revealed that strain CJ34T had a genome of 4.9 Mbp and the G+C content of the genomic DNA was 59.73 mol%. On the basis of the results of this polyphasic taxonomy study, strain CJ34T represents a novel species in the genus Comamonas, for which the name Comamonas fluminis sp. nov. is proposed. The type strain is CJ34T (=KACC 22237T=JCM 34454T).

Pedobacter aquae sp. nov., a multi-drug resistant bacterium isolated from fresh water.

A novel bacterial strain designated CJ43T was isolated from fresh water located in Gangwon-do, South Korea, displaying multi-drug resistance. The isolate was Gram-stain-negative, aerobic, orange-pigmented, and rod-shaped. Strain CJ43T grew optimally at 30 °C and pH 7 on R2A agar in the absence of NaCl. Phylogenetic analyses based on 16S rRNA gene sequences revealed that strain CJ43T belonged to the genus Pedobacter in the family Sphingobacteriaceae and was most closely related to Pedobacter puniceum HX-22-1 T and P. glucosidilyticus 1-2 T (98.3 and 98.1% sequence similarity). The genome size of strain CJ43T was 3.9 Mb in a single contig with DNA G + C content of 34.9%. The genome included 3144 predicted protein-coding genes, as well as 55 tRNA, 9 rRNA and 3 ncRNA genes. The genome also contained 128 putative antibiotic resistance genes, reflecting its phenotypes. The average nucleotide identity values between strain CJ43T and two closely related strains P. puniceum HX-22-1 T and P. glucosidilyticus 1-2 T were 91.0 and 88.7%, respectively. In silico digital DNA-DNA hybridization results between strain CJ43T and the related strains were 42.8 and 38.6%, respectively. The major fatty acids of strain CJ43T were iso-C15:0, iso-C17:0 3-OH, and summed feature 3 (C16:1 ω6c and/or C16:1 ω7c). Strain CJ43T contained phosphatidylethanolamine as the major polar lipid and menaquinone-7 as the sole respiratory quinone. Based on the polyphasic taxonomy data, strain CJ43T represents a novel species of the genus Pedobacter, for which the name Pedobacter aquae sp. nov. is proposed with the type strain CJ43T (= KACC 21350 T = JCM 33709 T).

Fungal ß-Glycosidase Belonging to Subfamily 4 of Glycoside Hydrolase Family 30 with Transglycosylation Activity.

Fomitopsis palustris, a prominent wood decayer, is known to produce a variety of glycoside hydrolases (GHs). In this study, we characterized a fungal ß-glycosidase belonging to subfamily 4 of GH family 30 (GH30). The recombinant protein (FpGH30) showed the highest hydrolytic activity toward p-nitrophenyl-ß-d-fucopyranoside (pNPßFuc), followed by p-nitrophenyl-α-l-arabinopyranoside (pNPαAra) and p-nitrophenyl-ß-d-galactopyranoside (pNPßGal). FpGH30 also exhibited transglycosylation activities, which catalyzed the transfer of glycosyl moieties to different glycosides and alkyl alcohols. When pNPßFuc, pNPßGal, and pNPαAra were used as substrates, self-condensation reactions occurred, leading to the production of the corresponding transglycosylated products with yields of 21, 26, and 25%, respectively. The enzyme was also able to catalyze the transfucosylation of pNP derivatives of ß-d-glucose, ß-d-mannose, and ß-d-xylose and alkyl alcohols (C1-C6), producing the corresponding transfucosylated products and alkyl fucosides. Our study indicates that FpGH30 is the first characterized fungal ß-glycosidase belonging to subfamily 4 of GH30 with transglycosylation activities.

The effects of dehiscence and fenestration before orthodontic treatment on external apical root resorption in maxillary incisors.

INTRODUCTION: The objective of this study was to investigate the effects of dehiscence and fenestration on external apical root resorption (EARR) in maxillary incisors. METHODS: Seventy-eight patients were selected for this study. We set dehiscence, fenestration, sex, extraction, or nonextraction, tooth position, initial age, and duration of treatment as independent variables and EARR as the dependent variable. General statistical descriptions for these variables were made by mean, standard deviation and occurrence rates, etc. To make the data visualization and find more information, 2 heat maps were made. Generalized estimation equation analysis was performed to determine associations between EARR and independent variables. RESULTS: The occurrence rates of dehiscence and fenestration in maxillary incisors were 14.77% and 10.74%, respectively. The average value of EARR was 1.09 ± 0.87 mm in this study. Dehiscence, tooth position, extraction, initial age, and duration had significant correlations with EARR. The ratio of exponent B was 1:1.643 for dehiscence and nondehiscence, whereas fenestration and sex had no significant association with EARR. CONCLUSIONS: The amount of EARR at maxillary incisors in patients with dehiscence before orthodontic treatment might be less than that in patients without it, and different incisors might have different contributions to it. However, the low value of exponent B for dehiscence meant that there might be other unknown factors that were involved in this study.

Impact of sulfamethoxazole on a riverine microbiome.

The continued emergence of bacterial pathogens presenting antimicrobial resistance is widely recognised as a global health threat and recent attention focused on potential environmental reservoirs of antibiotic resistance genes (ARGs). Freshwater environments such as rivers represent a potential hotspot for ARGs and antibiotic resistant bacteria as they are receiving systems for effluent discharges from wastewater treatment plants (WWTPs). Effluent also contains low levels of different antimicrobials including antibiotics and biocides. Sulfonamides are antibacterial chemicals widely used in clinical, veterinary and agricultural settings and are frequently detected in sewage sludge and manure in addition to riverine ecosystems. The impact of such exposure on ARG prevalence and diversity is unknown, so the aim of this study was to investigate the release of a sub-lethal concentration of the sulfonamide compound sulfamethoxazole (SMX) on the river bacterial microbiome using a flume system. This system was a semi-natural in vitro flume using river water (30 L) and sediment (6 kg) with circulation to mimic river flow. A combination of 'omics' approaches were conducted to study the impact of SMX exposure on the microbiomes within the flumes. Metagenomic analysis showed that the addition of low concentrations of SMX (<4 µg L-1) had a limited effect on the bacterial resistome in the water fraction only, with no impact observed in the sediment. Metaproteomics did not show differences in ARGs expression with SMX exposure in water. Overall, the river bacterial community was resilient to short term exposure to sub-lethal concentrations of SMX which mimics the exposure such communities experience downstream of WWTPs throughout the year.

Antibiotic resistome from the One-Health perspective: understanding and controlling antimicrobial resistance transmission.

The concept of the antibiotic resistome was introduced just over a decade ago, and since then, active resistome studies have been conducted. In the present study, we describe the previously established concept of the resistome, which encompasses all types of antibiotic resistance genes (ARGs), and the important findings from each One-Health sector considering this concept, thereby emphasizing the significance of the One-Health approach in understanding ARG transmission. Cutting-edge research methodologies are essential for deciphering the complex resistome structure in the microbiomes of humans, animals, and the environment. Based on the recent achievements of resistome studies in multiple One-Health sectors, future directions for resistome research have been suggested to improve the understanding and control of ARG transmission: (1) ranking the critical ARGs and their hosts; (2) understanding ARG transmission at the interfaces of One-Health sectors; (3) identifying selective pressures affecting the emergence, transmission, and evolution of ARGs; and (4) elucidating the mechanisms that allow an organism to overcome taxonomic barriers in ARG transmission.

Overview of bioinformatic methods for analysis of antibiotic resistome from genome and metagenome data.

Whole genome and metagenome sequencing are powerful approaches that enable comprehensive cataloging and profiling of antibiotic resistance genes at scales ranging from a single clinical isolate to ecosystems. Recent studies deal with genomic and metagenomic data sets at larger scales; therefore, designing computational workflows that provide high efficiency and accuracy is becoming more important. In this review, we summarize the computational workflows used in the research field of antibiotic resistome based on genome or metagenome sequencing. We introduce workflows, software tools, and data resources that have been successfully employed in this rapidly developing field. The workflow described in this review can be used to list the known antibiotic resistance genes from genomes and metagenomes, quantitatively profile them, and investigate the epidemiological and evolutionary contexts behind their emergence and transmission. We also discuss how novel antibiotic resistance genes can be discovered and how the association between the resistome and mobilome can be explored.

Myroides fluvii sp. nov., isolated from the Han River, Republic of Korea.

A Gram-stain-negative, aerobic, short rod-shaped, pale yellow-pigmented, non-motile and gentamycin-resistant bacterial strain designated CJ210T was isolated from the Han River, Republic of Korea. Strain CJ210T grew optimally at 30 °C and pH 7.0 in the absence of NaCl on tryptic soy agar. Flexirubin-type pigments were not produced. Phylogenetic analysis based on 16S rRNA gene sequence similarity showed that strain CJ210T belonged to the genus Myroides within the family Flavobacteriaceae and was most closely related to Myroides odoratus KACC 14347T (98.1 % similarity), followed by M. injenensis KCTC 23367T (95.3 % similarity). The average nucleotide identity values between strain CJ210T and two closely related type strains M. odoratus KACC 14347T and M. injenensis KCTC 23367T were 83.7 and 73.8 %, respectively. The digital DNA-DNA hybridization results between strain CJ210T and the related type strains were 27.5 and 20.2 %, respectively. Strain CJ210T contained menaquinone 6 (MK-6) as the predominant menaquinone. The predominant polar lipids were phosphatidylethanolamine, two unidentified aminolipids and two unidentified lipids. The major fatty acids of strain CJ210T were iso-C15 : 0, iso-C17 : 0 3-OH and summed feature 9 (comprising iso-C17 : 1 ω9c and/or C16 : 0 10-methyl). Whole genome sequencing revealed that strain CJ210T had a genome of 3.8 Mbp with 36.5 % DNA G+C content. The genome contained several antimicrobial resistance genes including an aminoglycoside-resistant gene. On the basis of the polyphasic taxonomic study, strain CJ210T represents a novel species in the genus Myroides, for which name Myrodies fluvii sp. nov. is proposed. The type strain is CJ210T (=KACC 19954T=JCM 33306T).

Fate of antibiotic resistant E. coli and antibiotic resistance genes during full scale conventional and advanced anaerobic digestion of sewage sludge.

Antibiotic resistant bacteria (ARB) and their genes (ARGs) have become recognised as significant emerging environmental pollutants. ARB and ARGs in sewage sludge can be transmitted back to humans via the food chain when sludge is recycled to agricultural land, making sludge treatment key to control the release of ARB and ARGs to the environment. This study investigated the fate of antibiotic resistant Escherichia coli and a large set of antibiotic resistance genes (ARGs) during full scale anaerobic digestion (AD) of sewage sludge at two U.K. wastewater treatment plants and evaluated the impact of thermal hydrolysis (TH) pre-treatment on their abundance and diversity. Absolute abundance of 13 ARGs and the Class I integron gene intI1 was calculated using single gene quantitative (q) PCR. High through-put qPCR analysis was also used to determine the relative abundance of 370 ARGs and mobile genetic elements (MGEs). Results revealed that TH reduced the absolute abundance of all ARGs tested and intI1 by 10-12,000 fold. After subsequent AD, a rebound effect was seen in many ARGs. The fate of ARGs during AD without pre-treatment was variable. Relative abundance of most ARGs and MGEs decreased or fluctuated, with the exception of macrolide resistance genes, which were enriched at both plants, and tetracyline and glycopeptide resistance genes which were enriched in the plant employing TH. Diversity of ARGs and MGEs decreased in both plants during sludge treatment. Principal coordinates analysis revealed that ARGs are clearly distinguished according to treatment step, whereas MGEs in digested sludge cluster according to site. This study provides a comprehensive within-digestor analysis of the fate of ARGs, MGEs and antibiotic resistant E. coli and highlights the effectiveness of AD, particularly when TH is used as a pre-treatment, at reducing the abundance of most ARGs and MGEs in sludgeand preventing their release into the environment.