Landscape of genes in hospital wastewater breaking through the defense line of last-resort antibiotics

Transfer dynamics of intracellular and extracellular last-resort antibiotic resistome in hospital wastewater

The increasing prevalence of last-resort antibiotic resistance genes (LARGs) has posed severe public health hazards. Previous studies focused primarily on the profiles of intracellular LARGs (iLARGs) in hospital wastewater (HWW), while largely neglecting the expression patterns of iLARGs and the presence of extracellular LARGs (eLARGs). Currently, wastewater resistomes and transfer dynamics of LARGs are still poorly characterized. This study integrates Nanopore-metagenomic and metatranscriptomic sequencing to conduct the comprehensive longitudinal analysis of both iLARGs and eLARGs in HWW. Our study firstly revealed the distinct seasonal patterns of iLARGs and eLARGs. Specifically, iLARGs showed higher abundance during colder seasons, whereas eLARGs showed higher abundance in warm seasons. Both clinical pathogens and functional bacteria of wastewater treatments were identified as important hosts of LARGs, while clinical pathogens played predominant roles in the high expression levels of LARGs. Acinetobacter spp. was identified as major host of blaNDM-1 in HWW, which is unrestricted by plasmid host range compatibility. However, HWW treatments could not remove LARGs effectively and instead facilitated their transmission by enhancing the expression and horizontal transfer of mobile genetic element (MGE)-derived LARGs. Our study provides comprehensive insights for the atlas and transfer dynamics of LARGs in HWW for the development of control strategies under worldwide spread of antibiotic resistance.

Epidemiological and genomic insights of mcr-1-positive colistin-resistant Klebsiella pneumoniae species complex strains from wastewater treatment plants in Shanghai

The emergence of mcr-1-positive Klebsiella pneumoniae species complex (MP-KpSC) poses a significant threat to public health due to its resistance to last-resort antibiotics like colistin. This study aimed to investigate the prevalence, genomic characteristics, and transmission features of MP-KpSC in wastewater treatment plants (WWTPs) in Shanghai, China. A total of 13 (0.36 %) MP-KpSC isolates were identified, including 12 K. pneumoniae and 1 K. quasipneumoniae subsp. similipneumoniae (Kqps). Nine multidrug-resistant (MDR) MP-KpSC and 3 extensively drug-resistant (XDR) MP-KpSC strains were identified. Twenty-two resistance determinants were present in over 30 % of the strains, with the most prevalent being mcr-1 (100 %), floR (84.62 %), mphA (69.23 %), and tet(A) (69.23 %). MP-KpSC exhibited 11 sequence types, 4 plasmid types, 6 mcr-1-flanked regions, 4 clonal groups, and diverse serotypes. In 53.85 % of strains, transposons were identified within the mcr-1-flanked regions. One strain contained both mcr-8.2 and mcr-1 gene. Notably, the mcr-1 gene was identified for the first time in Kqps and was located on the conjugative IncP1 plasmid, with ISApl1 elements upstream of it. Worryingly, two carbapenem- and colistin-resistant XDR MP-KpSC stains, and three possible hypervirulence (hv) were found in MDR MP-KpSC strains. Moreover, multiple virulence genes and mcr-1, on the same contig with IS679 insert element. The evolutionary trajectories of these strains among WWTPs-human-animals were unveiled in Shanghai. The study reveals that WWTPs serve as critical environmental reservoirs for MP-KpSC, highlighting the potential transmission risks posed by XDR and hv strains to both humans and aquatic ecosystems. These findings advocate for the implementation of active surveillance targeting WWTPs to curb the spread of MP-KpSC.

Characterization and risk-quantification of antibiotic resistome in grain-based and non-grain cropping soils

Microbial contamination in soils, encompassing human bacterial pathogens (HBPs), antibiotic resistance genes (ARGs), and virulence factor genes (VFGs), poses a significant threat to human health via the food chain. Currently, there is a lack of comprehensive assessments of microbial contamination and associated health risks of ARGs in agricultural soils. In this study, metagenomic sequencing was used to evaluate microbial contamination in grain-based cropping soils (rice cultivation) and non-grain cropping soils (vegetable cultivation and aquaculture). The results showed that the diversity and abundance of HBPs and VFGs were significantly higher in non-grain soils. Further resistome analysis revealed higher abundances of high-risk (from 0.014 to 0.018-0.023) and "last-resort" ARGs (from 0.007 to 0.034-0.046) in non-grain soils. Besides ARGs abundance, health risk quantification revealed that non-grain soils exhibited 1.49-2.14-fold greater ARG-related risks than grain-based soils. Additionally, stronger network associations were found between HBPs, ARGs, and mobile genetic elements (MGEs) in non-grain soils. This study indicated that the non-grain cropping pattern of soils elevated the risk of microbial contamination and ARGs health risk, which provided an important basis for accurately quantifying the risk of microbial contamination in different agricultural soils.

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2021-2022

The use of matrix-assisted laser desorption/ionization (MALDI) mass spectrometry for the analysis of carbohydrates and glycoconjugates is a well-established technique and this review is the 12th update of the original article published in 1999 and brings coverage of the literature to the end of 2022. As with previous review, this review also includes a few papers that describe methods appropriate to analysis by MALDI, such as sample preparation, even though the ionization method is not MALDI. The review follows the same format as previous reviews. It is divided into three sections: (1) general aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, fragmentation, quantification and the use of computer software for structural identification. (2) Applications to various structural types such as oligo- and polysaccharides, glycoproteins, glycolipids, glycosides and biopharmaceuticals, and (3) other general areas such as medicine, industrial processes, natural products and glycan synthesis where MALDI is extensively used. Much of the material relating to applications is presented in tabular form. MALDI is still an ideal technique for carbohydrate analysis, particularly in its ability to produce single ions from each analyte and advancements in the technique and range of applications show little sign of diminishing.

Deciphering antibiotic resistance genes and plasmids in pathogenic bacteria from 166 hospital effluents in Shanghai, China

Although previous studies using phenotypic or metagenomic approaches have revealed the patterns of antibiotic resistance genes (ARGs) in hospital effluents in local regions, limited information is available regarding the antibiotic resistome and plasmidome in human pathogenic bacteria in hospital effluents of megacity in China. To address this knowledge gap, we analyzed effluent samples from 166 hospitals across 13 geographical districts in Shanghai, China, using both cultivation-based approaches and metagenomics. A total of 357 strains were isolated from these samples, with the predominant species being Escherichia coli (n = 61), Aeromonas hydrophila (n = 57), Klebsiella pneumoniae (n = 48), and Aeromonas caviae (n = 42). Those identified indicator bacteria were classified into biosafety level 1 (BSL-1, 60 %) and BSL-2 (40 %). We identified 1237 ARG subtypes across 22 types, predominantly including beta-lactam, tetracycline, multidrug, polymyxin, and aminoglycoside resistance genes, using culture-enriched phenotypic metagenomics. Mobile genetic elements such as plasmids, transposons (tnpA), integrons (intI1), and insertion sequences (IS91) were abundant. We recovered 135 plasmids classified into mobilizable (n = 94) and non-mobilizable (n = 41) types. Additionally, 80 metagenome-assembled genomes (MAGs) were reconstructed from the hospital effluents for the assessment of ARG transmission risks, including genes for last-line antibiotics such as blaNDM, blaKPC, blaimiH, and mcr. This study is the first to comprehensively characterize and assess the risk of antimicrobial resistance levels and plasmidome in the hospital effluents of China's megacity, providing city-wide surveillance data and evidence to inform public health interventions.

Antimicrobial Resistance Genes in Clinical Escherichia coli Strains from Livestock and Poultry in Shandong Province, China During 2015-2020

Antimicrobial resistant (AMR) Escherichia coli (E. coli) isolated from animals may lead to antibiotic treatment failure and economic losses to farmers. The co-existence of antimicrobial resistant genes (ARGs) in the same isolate presents a major challenge for the prevention and control of infection in multidrug-resistant (MDR) Gram-negative organisms. There have been a lot of studies on the antibiotic resistance of E. coli in livestock and poultry, but few of them have focused on clinical pathogens. Objective: The aim of this study was to explore the genetic characteristics, co-occurrence, and correlations between ARGs of E. coli isolated from the pathological tissues of livestock and poultry in Shandong Province, East China during 2015-2020. Methods: A total of 158 E. coli strains were collected and subjected to antimicrobial susceptibility testing and sequencing by whole-genome Next Generation Sequencing (NGS). Results: MDR strains accounted for 46.20% of the 158 E. coli strains with the highest resistant rate of ciprofloxacin (71.52%). In addition, strains with blaNDM-5/mcr-1.1 and mcr-1.1/mcr-3.24 were found in chickens, while three strains with Tet(X4) were found in pigs. In addition, the most common serotypes detected were the O serotype (76/158) and H serotype (36/158). Moreover, seventy-one STs were found and the most common STs were ST10 (6.33%), ST155 (6.33%), and ST101 (5.69%). The genetic environment analysis of the phylogroups revealed that E. coli belonging to phylogroup B1, phylogroup A, and phylogroup C constituted 39.87%, 27.85%, and 15.19%, respectively. Through the correlation analysis, mcr genes were observed to have certain relationships with ARGS such as blaTEM, floR, catA/B, and oqx. Conclusions: This study demonstrates the high prevalence and gene diversity of MDR E. coli isolated from a clinic in Shandong Province, East China. We predicted the transmission risk of animal-borne Tet(X4)-bearing and mcr-harboring E. coli to public health and provided insight into the relationship of co-existence or co-transfer between mcr with ARGS. These relationships present a great challenge for the infection control of MDR Gram-negative organisms.

Molecular level decontamination of trace quinolones and Serratia marcescens in wastewater via in situ Cu(III) complexes mediated Fenton-like oxidation

Co-pollution caused by antibiotics and antibiotic-resistant bacteria (ARB) in wastewater has led to widespread concerns. Hence, their targeted and synergistic decontamination is urgently required. A homogeneous Fenton-like oxidation system comprising cupric complexes-activated peroxymonosulfate (PMS) was demonstrated to synergistically decontaminate trace quinolones (QNs) and QNs-resistant Serratia marcescens (QRSM) in wastewater. More than 99 % of QNs were degraded within 60 min under alkaline condition, and the degradation efficiency was only slightly influenced by humic acid (up to 1 %) and various anions (up to 20 %), furthermore, the degraded pathway was proposed and the environmental risk after QNs degradation were also reduced. The activation of PMS via cupric complexes coupling in situ Cu(III) complexes generation promoted intramolecular electron transfer (IET) featuring the targeted oxidation of QNs. The produced Cu(III) and •OH played primary and secondary roles in the synergistic inactivation of QRSM by destroying the cell membranes and walls, DNA bases (T, A, C, and G), antibiotic resistance genes (ARGs, including intracellular ARGs and extracellular ARGs), and total DNA (including intracellular DNA and extracellular DNA). This study demonstrates a successful strategy and provides an innovative perspective for the molecular level decontamination of trace antibiotics and ARB using a homogeneous cupric complexes-activated Fenton-like oxidation system from metal ions inherent in breeding wastewater under alkaline condition.

Antibiotic resistance genes and crAssphage in hospital wastewater and a canal receiving the treatment effluent

Hospital wastewater is a major hotspot for the spread of antimicrobial resistance (AMR) in aquatic ecosystems. This study aimed to investigate the prevalence of antibiotic resistance genes (ARGs) and their correlation with crAssphage in a hospital wastewater treatment plant (HWWTP) and a receiving canal. Water samples were analyzed for 94 ARGs and crAssphage relative to the 16S rRNA using high-throughput quantitative polymerase chain reaction (HT-qPCR). Subsequently, 7 ARGs and crAssphage were selected and quantified using qPCR. The results showed that the detected genes ranged from 79 to 93 out of 95 genes. The raw wastewater (WW) samples had the highest gene diversity compared to the upstream canal, which had less diversity than downstream samples, as determined by HT-qPCR. The blaGES was the most abundant in WW samples, while qacEΔ1, merA, IS6100, tnpA, and IS26 showed high prevalence throughout the treatment processes. The concentrations of intI1, sul1, blaTEM,blaNDM,blaVIM,tetQ, mcr-1, crAssphage, and 16S rRNA, measured using qPCR, were the highest in WW and significantly reduced in treated water samples. Although some water quality parameters, such as total suspended solids and dissolved oxygen, did not significantly differ before and after treatment, removal efficiency ranged from 0.60 to 3.23 log reduction values (LRV). The highest LRV was observed for the tetQ, whereas the mcr-1 had the lowest LRV. Strong positive correlations among the absolute concentrations of ARGs and crAssphage were observed (Spearman's rho = 0.6-1.0), and biochemical oxygen demand correlated with blaTEM and blaVIM (Spearman's rho = 0.6). These results indicate that crAssphage and water quality could reflect the distribution of other ARGs throughout the HWWTP. Further studies are needed to underscore the importance of monitoring ARGs and genetic markers such as crAssphage in HWWTPs and their receiving waters to enhance our understanding of ARG distribution.

Integrative metagenomic dissection of last-resort antibiotic resistance genes and mobile genetic elements in hospital wastewaters

Hospital wastewater is a critical source of antimicrobial resistance (AMR), which facilitates the proliferation and spread of clinically significant antimicrobial resistance genes (ARGs) and pathogenic bacteria. This study utilized metagenomic approaches, including advanced binning techniques, such as MetaBAT2, MaxBin2, and CONCOCT, which offer significant improvements in accuracy and completeness over traditional binning methods. These methods were used to comprehensively assess the dynamics and composition of resistomes and mobilomes in untreated wastewater samples taken from two general hospitals and one cancer hospital. This study revealed a diverse bacterial landscape, largely consisting of Proteobacteria, Firmicutes, Bacteroidetes, and Actinobacteria, with notable variations in microbial composition among hospitals. Analysis of the top 15 genera showed unique microbial pattern distribution in each hospital: Aeromonas was predominant in 1stHWTS (49.39 %), Acidovorax in the CAHWTS at 16.85 %, and Escherichia and Bacteroides in the 2ndHWTS at 11.44 % and 11.33 %, respectively. A total of 114 pathogenic bacteria were identified, with drug-resistant Aeromonas caviae and Escherichia coli being the most prevalent. The study identified 34 types and 1660 subtypes of ARGs, including important last-resort antibiotic resistance genes (LARGs), such as blaNDM, mcr, and tet(X). Using metagenomic binning, this study uncovered distinct patterns of host-resistance associations, particularly with Proteobacteria and Firmicutes. Network analysis highlighted the complex interactions among ARGs, mobile genetic elements (MGEs), and bacterial species, all contributing to the dissemination of AMR. These findings emphasize the intricate nature of AMR in hospital wastewater and the influence of hospital-specific factors on microbial resistance patterns. This study provides support for implementing integrated management strategies, including robust surveillance, advanced wastewater treatment, and strict antibiotic stewardship, to control the dissemination of AMR. Understanding the interplay among bacterial communities, ARGs, and MGEs is important for developing effective public health measures against AMR.

Molecular Epidemiological Characteristics of Carbapenem Resistant Aeromonas from Hospital Wastewater

Background

Hospital wastewater (HWW) promotes the spread of carbapenem resistance genes (CRGs). Aeromonas carry a large number of CRGs in HWW, they may play a role as a suitable reservoir for CRGs, while resistomes in HWW are still poorly characterized regarding carbapenem resistant Aeromonas. Thus, the aim of the study was to evaluate the molecular epidemiological characteristics of carbapenem resistant Aeromonas in HWW.

Methods

A total of 33 carbapenem resistant Aeromonas were isolated from HWW. Antimicrobial susceptibility testing and polymerase chain reaction (PCR) were used to assess the antimicrobial resistance profiles. Molecular typing was performed using enterobacterial repetitive intergenic consensus PCR (ERIC-PCR) and multilocus sequence typing (MLST). The horizontal transmission mode of bla KPC was explored through conjugation and transformation experiments. The stability of bla KPC-IncP-6 plasmids was assessed through plasmid stability and in vitro competition test. The PCR mapping method was used to investigate the structural diversity of bla KPC.

Results

The detection rates of bla KPC and cphA in Aeromonas were 97.0% and 39.4% respectively. Aeromonas caviae were grouped into 13 clusters by ERIC-PCR and 12 STs by MLST. Aeromonas veronii were grouped into 11 clusters by ERIC-PCR and 4 STs by MLST. 56.3% bla KPC were located on mobilizable IncP-6 plasmids. bla KPC-IncP-6 plasmid showed high stability and low cost fitness.

Conclusion

Carbapenem resistant Aeromonas from HWW mainly carried bla KPC, which exhibited great structural diversity. Aeromonas might serve as reservoirs for bla KPC and bla KPC might spread mainly through transformation in HWW.

Deciphering the removal of antibiotics and the antibiotic resistome from typical hospital wastewater treatment systems

Hospital wastewater treatment systems (HWTSs) are a significant source and reservoir of antibiotic resistance genes (ARGs) and a crucial hub for transmitting ARGs from clinical to natural environments. However, there is a lack of research on the antibiotic resistome of clinical wastewater in HWTSs. In this study, we used metagenomics to analyze the prevalence and abundance of ARGs in five typical HWTSs. A total of 17 antibiotics from six categories were detected in the five HWTSs; β-lactam antibiotics were found at the highest concentrations, with up to 4074.08 ng·L-1. We further found a total of 21 ARG types and 1106 subtypes of ARGs with the highest percentage of multi-drug resistance genes (evgS, msbA, arlS, and baeS). The most abundant last-resort ARGs were mcr, which were detected in 100 % of the samples. HWTSs effluent is a major pathway for the transmission of last-resort ARGs into urban wastewater networks. The removal of antibiotics, antibiotic-resistant bacteria, and ARGs from HWTSs was mainly achieved by tertiary treatment, i.e., chlorine disinfection, but antibiotics and ARGs were still present in the HWTSs effluent or even increased after treatment. Moreover, antibiotics and heavy metals (especially mercury) in hospital effluents can exert selective pressure for antibiotic resistance, even at low concentrations. Qualitative analyses based on metagenome-assembled genome analysis revealed that the putative hosts of the identified ARGs are widely distributed among Pseudomonas, Acidovorax, Flavobacterium, Polaromonas, and Arcobacter. Moreover, we further assessed the clinical availability of ARGs and found that multidrug ARGs had the highest clinical relevance values. This study provides new impulses for monitoring and removing antibiotics and ARGs in the hospital sewage treatment process.

Deciphering Multidrug-Resistant Plasmids in Disinfection Residual Bacteria from a Wastewater Treatment Plant

Current disinfection processes pose an emerging environmental risk due to the ineffective removal of antibiotic-resistant bacteria, especially disinfection residual bacteria (DRB) carrying multidrug-resistant plasmids (MRPs). However, the characteristics of DRB-carried MRPs are poorly understood. In this study, qPCR analysis reveals that the total absolute abundance of four plasmids in postdisinfection effluent decreases by 1.15 log units, while their relative abundance increases by 0.11 copies/cell compared to investigated wastewater treatment plant (WWTP) influent. We obtain three distinctive DRB-carried MRPs (pWWTP-01-03) from postdisinfection effluent, each carrying 9-11 antibiotic-resistant genes (ARGs). pWWTP-01 contains all 11 ARGs within an ∼25 Kbp chimeric genomic island showing strong patterns of recombination with MRPs from foodborne outbreaks and hospitals. Antibiotic-, disinfectant-, and heavy-metal-resistant genes on the same plasmid underscore the potential roles of disinfectants and heavy metals in the coselection of ARGs. Additionally, pWWTP-02 harbors an adhesin-type virulence operon, implying risks of both antibiotic resistance and pathogenicity upon entering environments. Furthermore, some MRPs from DRB are capable of transferring and could confer selective advantages to recipients under environmentally relevant antibiotic pressure. Overall, this study advances our understanding of DRB-carried MRPs and highlights the imminent need to monitor and control wastewater MRPs for environmental security.

Ranking the risk of antibiotic resistance genes by metagenomic and multifactorial analysis in hospital wastewater systems

Antimicrobial resistance poses a serious threat to human health. Hospital wastewater system (HWS) is an important source of antibiotic resistance genes (ARGs). The risk of ARGs in HWS is still an under-researched area. In this study, we collected publicly metagenomic datasets of 71 hospital wastewater samples from 18 hospitals in 13 cities. A total of 9838 contigs were identified to carry 383 unique ARGs across all samples, of which 2946 contigs were plasmid-like sequences. Concurrently, the primary hosts of ARGs within HWS were found to be Escherichia coli and Klebsiella pneumoniae. To further evaluate the risk of each ARG subtype, we proposed a risk assessment framework based on the importance of corresponding antibiotics as defined by the WHO and three other indicators - ARG abundance (A), mobility (M), and host pathogenicity (P). Ninety ARGs were identified as R1 ARGs having high-risk scores, which meant having a high abundance, high mobility, and carried by pathogens in HWS. Furthermore, 25% to 49% of genomes from critically important pathogens accessed from NCBI carried R1 ARGs. A significantly higher number of R1 ARGs was carried by pathogens in the effluents of municipal wastewater treatment plants from NCBI, highlighting the role of R1 ARGS in accelerating health and environmental risks.

Sub-MIC Antibiotics Modulate Productions of Outer Membrane Vesicles in Tigecycline-Resistant Escherichia coli

Antimicrobial resistance (AMR) has been recognized as one of the most important crises affecting global human health in the 21st century. Tigecycline is one of the last resort antibiotics for treating severe infections caused by multi-drug resistant Enterobacteriaceae. However, the mobile resistance gene tet(X4), which could mediate high-level tigecycline resistance, was discovered in 2019. The outer membrane vesicle (OMV) has been recognized as a new route for horizontal gene transfer; antimicrobial resistant bacteria also have the ability to secret OMVs, while little is known about the impact of antibiotics on the secretion and characteristics of OMVs from tigecycline resistant bacteria till now. This study aimed to investigate the effects of antibiotics on the production and traits of a tigecycline resistant Escherichia coli strain of 47EC. The results showed that sub-inhibitory (1/2 MIC or 1/4 MIC) concentrations of gentamicin, meropenem, ceftazidime, chloramphenicol, tigecycline, ciprofloxacin, polymycin, rifaximin and mitomycin C could significantly increase the secretion of OMVs (0.713 ± 0.05~6.333 ± 0.15 mg/mL) from E. coli 47EC compared to the respective untreated control (0.709 ± 0.03 mg/mL). In addition, the particle sizes of OMVs were generally larger, and the zeta potential were lower in the antibiotics-treated groups than those of the antibiotic-free group. The copy numbers of the tigecycline resistance gene of tet(X4) in the OMVs of most antimicrobial-treated groups were higher than that of the control group. Moreover, transcriptome analysis on ciprofloxacin-treated E. coli 47EC indicated that the SOS response and prophage activation might participate in the ciprofloxacin-induced OMV formation. In conclusion, the clinical application of antibiotics in treating bacterial infections, especially multi-drug resistant bacteria, might lead to the increased secretion of bacterial OMVs and the enrichment of antimicrobial-resistant genes in the OMVs.

Meta-analysis addressing the characterization of antibiotic resistome in global hospital wastewater

Hospital wastewater (HWW) is a significant environmental reservoir of antibiotic resistance genes (ARGs). However, currently, no comprehensive understanding exists of the antibiotic resistome in global HWW. In this study, we attempted to address this knowledge gap through an in silico reanalysis of publicly accessible global HWW metagenomic data. We reanalyzed ARGs in 338 HWW samples from 13 countries in Africa, Asia, and Europe. In total, 2420 ARG subtypes belonging to 30 ARG types were detected, dominated by multidrug, beta-lactam, and aminoglycoside resistance genes. ARG composition in Europe differed from that in Asia and Africa. Notably, the ARGs presented co-occurrence with mobile genetic elements (MGEs), metal resistance genes (MRGs), and human bacterial pathogens (HBP), indicating a potential dissemination risk of ARGs in the HWW. Multidrug resistance genes presented co-occurrence with MGEs, MRGs, and HBP, is particularly pronounced. The abundance of contigs that contained ARG, contigs that contained ARG and HBP, contigs that contained ARG and MGE, contigs that contained ARG and MRG were used for health and transmission risk assessment of antibiotic resistome and screened out 40 high risk ARGs in the global HWW. This study first provides a comprehensive characterization and risk of the antibiotic resistome in global HWW.

Genetic epidemiology and plasmid-mediated transmission of mcr-1 by Escherichia coli ST155 from wastewater of long-term care facilities

Long-term care facilities (LTCFs) for older people play an important and unique role in multidrug-resistant organism transmission. Herein, we investigated the genetic characteristics of mobile colistin resistance gene (mcr-1)-carrying Escherichia coli strains isolated from wastewater of LTCFs in Shanghai. Antimicrobial susceptibility test was carried out by agar dilution methods. Whole-genome sequencing and plasmid sequencing were conducted, and resistance genes and sequence types of colistin in E. coli isolates were analyzed. Core genome multilocus sequence typing (cgMLST) analysis was performed by the Ridom SeqSphere+ software. Phylogenetic tree through the maximum likelihood method was constructed by MEGA X. Out of 306 isolates, only 1 E. coli named ECSJ33 was found, and the plasmid pECSJ33 from ECSJ33 harbored the mcr-1 gene that was located with 59,080 bp belonging to IncI2 type. The plasmid pECSJ33 was capable of conjugation with an efficiency of 2.9 × 10-2. Bioinformatic analysis indicated pECSJ33 shared backbone with the previously reported mcr-1-harboring pHNGDF93 isolated from fish source. Moreover, the cgMLST analysis revealed that ECSJ33 belongs to different lineages from those reported from previous E. coli strains but shared high similarity to NCTC11129 in cluster 11. The phylogenetic tree revealed MCR-1 of ECSJ33 in this study was mostly of animal food origin and that they were closely related. Our study firstly reports detection of genome sequence of a multidrug-resistant mcr-1-harboring E. coli ST155 from wastewater of LTCF source in China. The data may prove that the plasmid pECSJ33 belongs to food origin and help to understand the antimicrobial resistance mechanisms and genomic features of colistin resistance under One Health approach.IMPORTANCEOne Escherichia coli named ECSJ33 was found from wastewater of a long-term care facility (LTCF) and the plasmid pECSJ33 from ECSJ33 harbored the mobile colistin resistance gene (mcr-1) that was located with 59,080 bp belonging to IncI2 type, which was capable of conjugation with an efficiency of 2.9 × 10-2. This paper firstly reports an mcr-1-carrying E. coli strain ST155 isolated from LTCF in China. Comparative genomics analysis indicated pECSJ33 shared backbone with the previously reported mcr-1-harboring pHNGDF93 isolated from fish source. The phylogenetic tree revealed MCR-1 protein of ECSJ33 in this study was mostly of animal food origin and that they were closely related. Therefore, the pECSJ33 could be considered as food-origin transmission mcr-1-harboring plasmid.

Promising bioprocesses for the efficient removal of antibiotics and antibiotic-resistance genes from urban and hospital wastewaters: Potentialities of aerobic granular systems

The use, overuse, and improper use of antibiotics have resulted in higher levels of antibiotic-resistant bacteria (ARB) and antibiotic-resistance genes (ARGs), which have profoundly disturbed the equilibrium of the environment. Furthermore, once antibiotic agents are excreted in urine and feces, these substances often can reach wastewater treatment plants (WWTPs), in which improper treatments have been highlighted as the main reason for stronger dissemination of antibiotics, ARB, and ARGs to the receiving bodies. Hence, achieving better antibiotic removal capacities in WWTPs is proposed as an adequate approach to limit the spread of antibiotics, ARB, and ARGs into the environment. In this review, we highlight hospital wastewater (WW) as a critical hotspot for the dissemination of antibiotic resistance due to its high level of antibiotics and pathogens. Hence, monitoring the composition and structure of the bacterial communities related to hospital WW is a key factor in controlling the spread of ARGs. In addition, we discuss the advantages and drawbacks of the current biological WW treatments regarding the antibiotic-resistance phenomenon. Widely used conventional activated sludge technology has proved to be ineffective in mitigating the dissemination of ARB and ARGs to the environment. However, aerobic granular sludge (AGS) technology is a promising technology-with broad adaptability and excellent performance-that could successfully reduce antibiotics, ARB, and ARGs in the generated effluents. We also outline the main operational parameters involved in mitigating antibiotics, ARB, and ARGs in WWTPs. In this regard, WW operation under long hydraulic and solid retention times allows better removal of antibiotics, ARB, and ARGs independently of the WW technology employed. Finally, we address the current knowledge of the adsorption and degradation of antibiotics and their importance in removing ARB and ARGs. Notably, AGS can enhance the removal of antibiotics, ARB, and ARGs due to the complex microbial metabolism within the granular biomass.

Bacteriophages: Vectors of or weapons against the transmission of antibiotic resistance genes in hospital wastewater systems?

Antimicrobial resistance poses a serious threat to human health and is responsible for the death of millions of people annually. Hospital wastewater is an important hotspot for antibiotic-resistance genes (ARGs) and antibiotic-resistant bacteria (ARB). However, little is known about the relationship between phages and ARGs in hospital wastewater systems (HWS). In the present study, the viral diversity of 12 HWSs using data from public metagenomic databases was investigated. Viruses were widely found in both the influent and effluent of each HWS. A total of 45 unique ARGs were carried by 85 viral contigs, which accounted for only 0.14% of the total viral populations, implying that ARGs were not commonly present in phages. Three efflux pump genes were identified as shared between phages and bacterial genomes. However, the predominant types of ARGs in HWS such as aminoglycoside- and beta-lactam-resistance genes were rarely found in phages. Based on CRISPR spacer and tRNA matches, interactions between 171 viral contigs and 60 antibiotic-resistant genomes were predicted, including interactions involving phages and vancomycin-resistant Enterococcus_B faecium or beta-lactam-resistant Klebsiella pneumoniae. More than half (56.1%) of these viral contigs indicated lytic and none of them carried ARGs. As the vOTUs in this study had few ARGs and were primarily lytic, HWS may be a valuable source for phage discovery. Future studies will be able to experimentally validate these sequence-based results to confirm the suitability of HWS phages for pathogen control measures in wastewater.

Occurrence and Removal of Antibiotic Resistance in Nationwide Hospital Wastewater Deciphered by Metagenomics Approach - China, 2018-2022

What is already known about this topic?

Hospital wastewater represents a significant conduit for the dissemination of antibiotic resistance genes (ARGs), including those that are of clinical importance. Yet, the variation in antibiotic resistance on a national level, which can be influenced by regional differences, has not been thoroughly elucidated.

What is added by this report?

Uniform methodologies were employed to analyze data from various provincial-level administrative divisions in China, aiming to investigate the patterns of antibiotic resistance across these regions. This analysis illuminated the location preferences of clinically ARGs on plasmids. Additionally, our study uncovered regional variations in the presumed bacterial hosts of ARGs at the genus level.

What are the implications for public health practice?

This investigation has shed light on the nationwide prevalence of ARGs in hospital wastewater in China, uncovering the significant ecological and public health risks associated with the disposal of such effluents.

Prevalence and Genomic Characteristics of mcr-Positive Escherichia coli Strains Isolated from Humans, Pigs, and Foods in China

Colistin is one of the last-resort antibiotics for treating infections caused by multidrug-resistant (MDR) Gram-negative bacteria. However, mcr genes conferring resistance to colistin have been widely identified, which is considered a global threat to public health. Here, we investigated the prevalence and characteristics of mcr-harboring Escherichia coli strains isolated from humans, animals, and foods in China by PCR, antimicrobial susceptibility testing, conjugation experiments, molecular typing, genome sequencing, and bioinformatics analysis. In total, 135 mcr-1-harboring E. coli isolates were acquired from 847 samples, and 6 isolates carried mcr-3. Among them, 131 isolates were MDR bacteria. Sixty-five resistance genes conferring resistance to multiple antimicrobials were identified in 135 isolates. The diverse pulsed-field gel electrophoresis (PFGE) patterns and sequence types (STs) of mcr-1-carrying isolates demonstrated that clonal dissemination was not the dominant mode of mcr-1 transmission. Seven types of plasmids were able to carry mcr-1 in this study, including IncI2, IncX4, IncHI2, p0111, IncY, and two hybrid plasmids. The genetic structures carrying mcr-1 of 60 isolates were successfully transferred into the recipient, including 25 IncI2 plasmids, 23 IncX4 plasmids, and an IncHI2 plasmid. mcr-1-pap2 was the dominant mcr-1-bearing structure, followed by ISApl1-mcr-1-pap2-ISApl1 (Tn6330) and ISApl1-mcr-1-pap2, among 7 mcr-1-bearing structures of 135 isolates. In conclusion, IncI2, IncX4, and IncHI2 plasmids were the major vectors spreading mcr-1 from different geographical locations and sources. The prevalence of Tn6330 may accelerate the transmission of mcr-1. Continuous surveillance of mcr-1 and variants in bacteria is vital for evaluating the public health risk posed by mcr genes. IMPORTANCE The spread of polymyxin-resistant Enterobacteriaceae poses a significant threat to public health and challenges the therapeutic options for treating infections on a global level. In this study, mcr-1-bearing ST10 E. coli was isolated from pigs, pork, and humans simultaneously, which demonstrated that ST10 E. coli was an important vehicle for the spread of mcr-1 among animals, foods, and humans. The high prevalence of mcr-1-positive E. coli strains in pigs and pork and the horizontal transmission of mcr-1-bearing plasmids in diverse E. coli strains suggest that pigs and pork are important sources of mcr-1-positive strains in humans and pose a potential threat to public health. Additional research on the prevalence and characteristics of mcr-1-positive E. coli is still required to facilitate early warning to improve polymyxin management in hospitals.

Microplastics and Antibiotic Resistance: The Magnitude of the Problem and the Emerging Role of Hospital Wastewater

The role of microplastics (MPs) in the spread of antibiotic resistance genes (ARGs) is increasingly attracting global research attention due to their unique ecological and environmental effects. The ubiquitous use of plastics and their release into the environment by anthropic/industrial activities are the main sources for MP contamination, especially of water bodies. Because of their physical and chemical characteristics, MPs represent an ideal substrate for microbial colonization and formation of biofilm, where horizontal gene transfer is facilitated. In addition, the widespread and often injudicious use of antibiotics in various human activities leads to their release into the environment, mainly through wastewater. For these reasons, wastewater treatment plants, in particular hospital plants, are considered hotspots for the selection of ARGs and their diffusion in the environment. As a result, the interaction of MPs with drug-resistant bacteria and ARGs make them vectors for the transport and spread of ARGs and harmful microorganisms. Microplastic-associated antimicrobial resistance is an emerging threat to the environment and consequently for human health. More studies are required to better understand the interaction of these pollutants with the environment as well as to identify effective management systems to reduce the related risk.

The profile and persistence of clinically critical antibiotic resistance genes and human pathogenic bacteria in manure-amended farmland soils

Introduction

Microbial contamination in farmlands is usually underestimated and understudied. Different fertilization times and manure origins might introduce and change the microorganism diversity in farmland soils and thus might influence the abundance and persistence of microbial contamination including antibiotic resistance genes (ARGs), human bacterial pathogens (HBPs), and virulence factor genes (VFGs).

Methods

A 0.5-/1.5-year fertilization experiment was performed, and metagenomic sequencing was conducted to quantify microbial contamination. The resistomes of soil samples revealed that ARGs against antibiotics which were extensively used in veterinary medicine as well as clinically critical ARGs (CCARGs) persisted in manure-amended soils. Here the extended-spectrum beta-lactamase and carbapenemase bla genes, the high-level mobilized colistin resistance gene mcr, the tigecycline resistance gene tet(X), and the vancomycin resistance gene van, all of which can circumvent the defense line of these "last-resort" antibiotics were selected to investigate CCARG pollution in farm environments.

Results

A total of 254 potential HBPs and 2106 VFGs were detected in soil samples. Overall, our results revealed that (1) farmland soils could serve as a reservoir of some important bla, mcr, tet(X), and van gene variants, (2) the diversity and relative abundance of HBPs and VFGs increased significantly with incremental fertilization times and were discrepant among different manureamended soils, and (3) most CCARGs and VFGs coexisted in HBPs.

Disscusion

The results of this study suggested a biological risk of manure in spreading antimicrobial resistance and pathogenicity.

Comprehensive insights into profiles and bacterial sources of intracellular and extracellular antibiotic resistance genes in groundwater

Antibiotic resistance genes (ARGs), especially last-resort ARGs (LARGs), are receiving extensive attention as emerging environmental contaminants in groundwater. However, their prevalent intracellular and extracellular patterns and bacterial sources in groundwater remain unclear. Herein, groundwater samples were collected in Tianjin, and characterized based on the profiles of intracellular ARGs (iARGs) and extracellular ARGs (eARGs), as well as the resident bacterial communities and extracellular DNA (eDNA)-releasing bacterial communities. The quantitative real-time PCR assays showed that eARGs presented fewer subtypes than iARGs and generally displayed lower detection frequencies than the corresponding iARGs. Similarly, LARGs exhibited lower detection frequencies than common ARGs, but the total abundance showed no significant differences between them. Genes vanA and bla_VIM were the observed dominant LARGs, and aadA was the observed common ARG independent of location inside or outside the bacteria. Furthermore, the top 10 phyla showed much difference between the main eDNA-releasing bacteria and the dominant resident bacteria. Proteobacteria was the predominant resident bacterial phyla while dominating the source of eDNA in groundwater. Despite representing a minor portion of the abundance in the resident bacteria, Actinobacteriota, Acidobacteriota, and Chloroflex surprisingly accounted for a large majority of eDNA release. Co-occurrence patterns among persistent ARGs, the resident bacteria, and eDNA-releasing bacteria revealed that the dominant common iARG aadA and intracellular LARGs bla_VIM and vanA had significant positive correlations with Methylobacterium_Methylorubrum and Shewanella. Meanwhile, the dominant extracellular LARG bla_VIM may be released by bacteria belonging to at least five genera, including Ellin6067, Bifidobacterium, Blautia, Veillonella, and Dechloromonas. Collectively, the findings of this study extend our understanding regarding the distribution of ARGs and their bacterial sources in groundwater, and indicate the serious pollution of LARGs in groundwater, which poses potential risks to public health.

Antimicrobial Resistance in the COVID-19 Landscape: Is There an Opportunity for Anti-Infective Antibodies and Antimicrobial Peptides?

Although COVID-19 has captured most of the public health attention, antimicrobial resistance (AMR) has not disappeared. To prevent the escape of resistant microorganisms in animals or environmental reservoirs a "one health approach" is desirable. In this context of COVID-19, AMR has probably been affected by the inappropriate or over-use of antibiotics. The increased use of antimicrobials and biocides for disinfection may have enhanced the prevalence of AMR. Antibiotics have been used empirically in patients with COVID-19 to avoid or prevent bacterial coinfection or superinfections. On the other hand, the measures to prevent the transmission of COVID-19 could have reduced the risk of the emergence of multidrug-resistant microorganisms. Since we do not currently have a sterilizing vaccine against SARS-CoV-2, the virus may still multiply in the organism and new mutations may occur. As a consequence, there is a risk of the appearance of new variants. Nature-derived anti-infective agents, such as antibodies and antimicrobial peptides (AMPs), are very promising in the fight against infectious diseases, because they are less likely to develop resistance, even though further investigation is still required.