Tracking Klebsiella pneumoniae carbapenemase gene as an indicator of antimicrobial resistance dissemination from a hospital to surface water via a municipal wastewater treatment plant

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.

Mobile genetic elements affect the dissemination of antibiotic resistance genes (ARGs) of clinical importance in the environment

The prevalence of antibiotic resistance genes (ARGs) in the environment is a quintessential One Health issue that threats both human and ecosystem health; however, the source and transmission of ARGs, especially clinically important ARGs (CLIARGs), in the environment have not yet been well studied. In the present study, shotgun metagenomic approaches were used to characterize the microbiome, resistome, and mobilome composition in human feces and six different environment sample types in South China. Overall, the resistome harbored 157 CLIARGs, with specific ARG hotspots (e.g., human feces, wastewater treatment plants, livestock manure and wastewater) excreting significantly higher abundance of CLIARGs compared with the natural environment. A redundancy analysis (RDA) was performed and revealed that the bacterial community compositions and mobile genetic elements (MGEs) explained 55.08% and 34.68% of the variations in ARG abundance, respectively, indicating that both bacterial community and MGEs are key contributors to the maintenance and dissemination of CLIARGs in the environment. The network analysis revealed non-random co-occurrence patterns between 200 bacterial genera and 147 CLIARGs, as well as between 135 MGEs and 123 CLIARGs. In addition to numerous co-shared CLIARGs among different sample types, the source tracking program based on the FEAST probabilistic model was used to estimate the relative contributions of the CLIARGs from potential sources to the natural environment. The source tracking analysis results delineated that mobilome, more than microbiome, contributed CLIARG transmission from those ARG hotspots into natural environment, and the MGEs in WWTPs seem to play the most significant role in the spread of CLIARGs to the natural environment (average contribution 32.9%-46.4%). Overall, this study demonstrated the distribution and dissemination of CLIARGs in the environment, and aimed to better inform strategies to control the spread of CLIARGs into the natural environment.

Antibiotic resistance determinants among carbapenemase producing bacteria isolated from wastewaters of Kathmandu, Nepal

The emergence of carbapenem resistant bacteria (CRB) possesses a remarkable threat to the health of humans. CRB and carbapenem resistance genes (CRGs) have frequently been reported in clinical isolates from hospitals, however, their occurrence and distribution in wastewaters from various sources and river water have not been emphasized in Nepal. So, this study aimed to detect carbapenem resistant bacterial isolates and their resistance determinants in river water and different types of wastewaters. River water and both untreated and treated wastewater samples from hospitals, pharmaceutical industries, and municipal sewage were collected in summer and winter seasons. From 68 grab wastewater samples, CRB were detected only in 16 samples, which included eight hospital wastewater, and four each from untreated municipal sewage and river water. A total of 25 CRB isolates were detected with dominance of E. coli (44.0%) and K. pneumoniae (24.0%). The majority of the isolates harbored blaNDM-1 (76.0%), followed by blaOXA (36.0%) and blaKPC (20.0%) genes. Hospital wastewater majorly contributed to the presence of blaNDM-1, blaKPC, and blaOXA along with intI1 genes compared to river water and untreated municipal sewage, especially during the winter season. However, CRB were not detected in treated effluents of hospitals and municipal sewage, and both influents and effluents from pharmaceutical industries. The combined presence of each blaNDM-1 & blaOXA and blaKPC & blaOXA occurred in 16.0% of the bacterial isolates. The increased minimum inhibitory concentration (MIC) of meropenem was significantly associated with the presence of CRGs. The results of this study highlight the significance of carbapenem resistance in bacteria isolated from wastewater and river water, and underscore the necessity for efficient monitoring and control strategies to prevent the dispersion of carbapenem resistance in the environment and its potential consequences on human health.

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.

Portable biosensor combining CRISPR/Cas12a and loop-mediated isothermal amplification for antibiotic resistance gene ermB in wastewater

Wastewater is among the main sources of antibiotic resistance genes (ARGs) in the environment, but effective methods to quickly assess ARGs on-site in wastewater are lacking. Here, using the typical ARG ermB as the target, we report a portable biosensor combining CRISPR/Cas12a and loop-mediated isothermal amplification (LAMP) for the detection of ARGs. Six primers of LAMP and the crRNA of CRISPR/Cas12a were first designed to be preamplification with LAMP and lead Cas12a to recognize the ermB via base pairing. Due to the trans-cleavage activity of CRISPR/Cas12a after amplicon recognition, ssDNA probes modified with reporter molecules were used to implement a visual assay with lateral flow test strips and fluorescence. After a simple nucleic acid extraction with magnetic beads, the constructed biosensor possesses excellent sensitivity and selectivity as low as 2.75 × 103 copies/μL using fluorescence and later flow strips in wastewater. We further evaluated the community-wide prevalence of ermB in wastewater influent and found high mass loads of ermB during different months. This user-friendly and low-cost biosensor is applicable for rapid on-site ARG detection, providing a potential point-of-use method for rapid assessments of ARG abundance in wastewater from large city areas with many wastewater treatment plants and in resource-limited rural areas.

Multidrug antibiotic resistance in hospital wastewater as a reflection of antibiotic prescription and infection cases

Antimicrobial resistance (AMR) is an escalating issue that can render illnesses more difficult to treat if effective antibiotics become resistant. Many studies have explored antibiotic resistance in bacteria (ARB) in wastewater, comparing results with clinical data to ascertain the public health risk. However, few investigations have linked the prevalence of ARB in hospital wastewater (HWW) with these outcomes. This study aimed to bridge this gap by assessing the prevalence of ARB in HWW and its receiving waters. Among the 144 isolates examined, 24 were obtained from each of the six sites (untreated wastewater, aeration tank, sedimentation tank, effluent after disinfection, upstream canal, and downstream canal). A significant portion (87.5 %) belonged to the Enterobacteriaceae family, with Klebsiella pneumoniae as the predominant species (47.9 %). The antimicrobial sensitivity testing (AST) showed that 57.6 % of the isolates were resistant to amoxicillin/clavulanic acid (AMX), the most prevalent antibiotic used within the studied hospital. The total resistance rate before and after treatment was 27.7 % and 28.0 %, respectively, with an overall multi-drug resistance (MDR) rate of 33.3 %. The multiple antibiotic resistance index (MARI) range varied between 0.0 and 0.9. The outpatient ward's three-day mean bacterial infection cases showed a significant association (Spearman's rho = 0.98) with the MARI in the sedimentation tank. Moreover, a strong correlation (Spearman's rho = 0.88) was found between hospital effluent's MARI and the seven-day mean inpatient ward case. These findings indicate that applying wastewater-based epidemiology (WBE) to hospital wastewater could provide valuable insights into understanding ARB contamination across human domains and water cycles. Future studies, including more comprehensive collection data on symptomatic patients and asymptomatic carriers, will be crucial in fully unravelling the complexities between human health and environmental impacts related to AMR.

Transmission of clones of carbapenem-resistant Escherichia coli between a hospital and an urban wastewater treatment plant

Carbapenem-resistant Enterobacterales (CRE) constitute an urgent threat to worldwide public health. The spread of CRE is facilitated by transmission via the environment. Wastewater treatment plants (WWTPs) are considered to be important sources of antibiotic resistance and hot spots of antibiotic-resistant bacteria (ARB) which can facilitate dissemination of antibiotic resistance genes. In this study, water samples were collected over one year from a WWTP in Jinan, Shandong province, China, from different functional sites in the wastewater treatment process. Carbapenem-resistant Escherichia coli (CREC) were isolated by selective cultivation and whole-genome sequenced to investigate the occurrence and characteristics of CREC in the WWTP. A total of 77 CREC isolates were included in the study and the detection rate of CREC in the WWTP water inlet was found to be 85%. An additional 10 CREC were isolated from a nearby teaching hospital during the sampling period and included for comparison to the environmental isolates. Susceptibility testing showed that all CREC were multidrug-resistant. 6 different carbapenem resistance genes (CRGs) were detected, including blaNDM-5 (n = 75), blaNDM-1 (n = 6), blaNDM-4 (n = 3), blaNDM-6 (n = 1), blaNDM-9 (n = 1), and blaKPC-2 (n = 4). 42 CREC isolates were whole-genome sequenced with Illumina short-read sequencing. 11 of these were also sequenced with Nanopore long-read sequencing. Plasmids carrying CRGs were found to belong to IncX3 (n = 35), IncFII (n = 12), IncFIA (n = 5), IncFIB (n = 2), IncC (n = 1), and IncP6 (n = 1). Clonal dissemination of CREC belonging to ST167, ST448, and ST746 was observed between different parts of the WWTP. Furthermore, isolates from the WWTP, including an isolate belonging to the high-risk ST167 strain, were found to be clonally related to CREC isolated at the hospital. The spread of CRGs is of considerable concern and strategies to prevent environmental dissemination of this contaminant urgently needs to be implemented.

Intensive care unit sinks are persistently colonized with multidrug resistant bacteria and mobilizable, resistance-conferring plasmids

Contamination of hospital sinks with microbial pathogens presents a serious potential threat to patients, but our understanding of sink colonization dynamics is largely based on infection outbreaks. Here, we investigate the colonization patterns of multidrug-resistant organisms (MDROs) in intensive care unit sinks and water from two hospitals in the USA and Pakistan collected over 27 months of prospective sampling. Using culture-based methods, we recovered 822 bacterial isolates representing 104 unique species and genomospecies. Genomic analyses revealed long-term colonization by Pseudomonas spp. and Serratia marcescens strains across multiple rooms. Nanopore sequencing uncovered examples of long-term persistence of resistance-conferring plasmids in unrelated hosts. These data indicate that antibiotic resistance (AR) in Pseudomonas spp. is maintained both by strain colonization and horizontal gene transfer (HGT), while HGT maintains AR within Acinetobacter spp. and Enterobacterales, independent of colonization. These results emphasize the importance of proactive, genomic-focused surveillance of built environments to mitigate MDRO spread. IMPORTANCE Hospital sinks are frequently linked to outbreaks of antibiotic-resistant bacteria. Here, we used whole-genome sequencing to track the long-term colonization patterns in intensive care unit (ICU) sinks and water from two hospitals in the USA and Pakistan collected over 27 months of prospective sampling. We analyzed 822 bacterial genomes, representing over 100 different species. We identified long-term contamination by opportunistic pathogens, as well as transient appearance of other common pathogens. We found that bacteria recovered from the ICU had more antibiotic resistance genes (ARGs) in their genomes compared to matched community spaces. We also found that many of these ARGs are harbored on mobilizable plasmids, which were found shared in the genomes of unrelated bacteria. Overall, this study provides an in-depth view of contamination patterns for common nosocomial pathogens and identifies specific targets for surveillance.

Wastewater treatment plants, an "escape gate" for ESCAPE pathogens

Antibiotics are an essential tool of modern medicine, contributing to significantly decreasing mortality and morbidity rates from infectious diseases. However, persistent misuse of these drugs has accelerated the evolution of antibiotic resistance, negatively impacting clinical practice. The environment contributes to both the evolution and transmission of resistance. From all anthropically polluted aquatic environments, wastewater treatment plants (WWTPs) are probably the main reservoirs of resistant pathogens. They should be regarded as critical control points for preventing or reducing the release of antibiotics, antibiotic-resistant bacteria (ARB), and antibiotic-resistance genes (ARGs) into the natural environment. This review focuses on the fate of the pathogens Enterococcus faecium, Staphylococcus aureus, Clostridium difficile, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacteriaceae spp. (ESCAPE) in WWTPs. All ESCAPE pathogen species, including high-risk clones and resistance determinants to last-resort antibiotics such as carbapenems, colistin, and multi-drug resistance platforms, were detected in wastewater. The whole genome sequencing studies demonstrate the clonal relationships and dissemination of Gram-negative ESCAPE species into the wastewater via hospital effluents and the enrichment of virulence and resistance determinants of S. aureus and enterococci in WWTPs. Therefore, the efficiency of different wastewater treatment processes regarding the removal of clinically relevant ARB species and ARGs, as well as the influence of water quality factors on their performance, should be explored and monitored, along with the development of more effective treatments and appropriate indicators (ESCAPE bacteria and/or ARGs). This knowledge will allow the development of quality standards for point sources and effluents to consolidate the WWTP barrier role against the environmental and public health AR threats.

Genomic and functional characterization of carbapenem-resistant Klebsiella pneumoniae from hospital wastewater

BACKGROUND

The emergence of carbapenem-resistant Klebsiella pneumoniae (CRKP) attracted extensive attention. Information on CRKP from hospital wastewater (HWW) is limited. The aims of this study were to investigate the genomic characteristics and to evaluate the survivability characteristics of 11 CRKP from HWW in a Chinese teaching hospital in Fujian province.

RESULTS

A total of 11 CRKP from HWW were recovered in this study. All CRKP from HWW were resistant to most antibiotics. Comparative genetic analysis demonstrated that all CRKP isolates were clustered into the three distinct phylogenetic clades and clade 2 and clade 3 were mixtures of samples collected from both HWW and clinical settings. Varieties of resistance genes, virulence genes and plasmid replicon types were detected in CRKP from HWW. In vitro transfer of bla_KPC-2 was successful for 3 bla_KPC-2-positive CRKP from HWW with high conjugation frequency. Our study demonstrated that the genetic environments of bla_KPC-2 shared core structure with ISKpn27-bla_KPC-2-ISKpn6. Group analysis showed that CRKP from HWW had a lower survivability in serum compared to clinical CRKP (p < 005); and CRKP from HWW had no significant difference in survivability in HWW compared to clinical CRKP (p > 005).

CONCLUSIONS

We analyzed the genomic and survivability characteristics of CRKP from HWW in a Chinese teaching hospital. These genomes represent a significant addition of genomic data from the genus and could serve as a valuable resource for future genomic studies about CRKP from HWW.

Post-treatment disinfection technologies for sustainable removal of antibiotic residues and antimicrobial resistance bacteria from hospital wastewater

The World Health Organization (WHO) has identified antimicrobial resistance bacteria and its spread as one of the most serious threats to public health and the environment in the twenty-first century. Different treatment scenarios are found in several countries, each with their own regulations and selection criteria for the effluent quality and management practices of hospital wastewater. To prevent the spread of disease outbreaks and other environmental threats, the development of sustainable treatment techniques that remove all antibiotics and antimicrobial resistant bacteria and genes should be required. Although few research based articles published focusing this issues, explaining the drawbacks and effectiveness of post-treatment disinfection strategies for eliminating antibiotic residues and antimicrobial resistance from hospital wastewater is the reason of this review. The application of conventional activated sludge (CAS) in large scale hospital wastewater treatments poses high energy supply needs for aeration, capital and operational costs. Membrane bioreactors (MBR) have also progressively replaced the CAS treatment systems and achieved better treatment potential, but membrane fouling, energy cost for aeration, and membrane permeability loss restrict their performance at large scale operations. In addition, the membrane process alone doesn't completely remove/degrade these micropollutants; as a substitute, the pollutants are being concentrated in a smaller volume, which requires further post-treatment. Therefore, these drawbacks should be solved by developing advanced techniques to be integrated into any of these or other secondary wastewater treatment systems, aiming for the effective removal of these micropollutants. The purpose of this paper is to review the performances of post-treatment disinfection technologies in the removal of antibiotics, antimicrobial resistant bacteria and their gens from hospital wastewater. The performance of advanced disinfection technologies (such as granular and powered activated carbon adsorption, ozonation, UV, disinfections, phytoremediation), and other integrated post-treatment techniques are primarily reviewed. Besides, the ecotoxicology and public health risks of hospital wastewater, and the development, spreading and mechanisms of antimicrobial resistant and the protection of one health are also highlighted.

Deciphering basic and key traits of antibiotic resistome in influent and effluent of hospital wastewater treatment systems

Hospital wastewater treatment system (HWTS) is an important source and environmental reservoir of clinically relevant antibiotic resistance genes (ARGs). However, how antibiotic resistome of clinical wastewater changed in HWTS is poorly understood. Herein, the basic quantitative traits (i.e., diversity and abundance) of ARGs in three HWTSs were profiled by metagenomics. In total, 709 ARG subtypes belonging to 20 ARG types were detected with relative abundance ranging from 1.12 × 10^-5 to 7.33 × 10^-1 copies/cell. Notably, most ARGs could not be significantly removed by chlorination treatment in the HWTS. These ARGs were identified to confer resistance to almost all major classes of antibiotics and include ARGs of last-resort antibiotics, such as bla_NDM, mcr and tet(X) which were abundantly occurred in HWTS with 19, 5 and 7 variants, respectively. Moreover, qualitative analysis based on metagenome-assembled genome (MAG) analysis revealed that the putative hosts of the identified ARGs were broadly distributed into at least 8 dominant bacterial phyla. Of the 107 ARG-carrying MAGs recovered, 39 encoded multi-antibiotic resistance and 16 belonged to antibiotic resistant pathogens. Further analysis of co-occurrence patterns of ARGs with mobile genetic elements suggested their potential mobility. These key qualitative traits of ARGs provided further information about their phylogeny and genetic context. This study sheds light on the key traits of ARGs associated with resistance dissemination and pathogenicity and health risks of clinical wastewater.

Co-occurrence of phthalate esters and perfluoroalkyl substances affected bacterial community and pathogenic bacteria growth in rural drinking water distribution systems

The adverse health effects of phthalate esters (PAEs) and perfluoroalkyl substances (PFAS) in drinking water have attracted considerable attention. Our study investigated the effects of PAEs and PFAS on the bacterial community and the growth of potential human pathogenic bacteria in rural drinking water distribution systems. Our results showed that the total concentration of PAEs and PFAS ranged from 1.02 × 10² to 1.65 × 10⁴ ng/L, from 4.40 to 1.84 × 10² ng/L in rural drinking water of China, respectively. PAEs concentration gradually increased and PFAS slowly decreased along the pipeline distribution, compared to concentrations in the effluents of rural drinking water treatment plants. The co-occurrence of higher concentrations of PAEs and PFAS changed the structure and function of the bacterial communities found within these environments. The bacterial community enhanced their ability to respond to fluctuating environmental conditions through up-regulation of functional genes related to extracellular signaling and interaction, as well as genes related to replication and repair. Under these conditions, co-occurrence of PAEs and PFAS promoted the growth of potential human pathogenic bacteria (HPB), therefore increasing the risk of the development of associated diseases among exposed persons. The main HPB observed in this study included Burkholderia mallei, Mycobacterium tuberculosis, Klebsiella pneumoniae, Acinetobacter calcoaceticus, Escherichia coli, and Pseudomonas aeruginosa. Contaminants including particles, microorganisms, PAEs and PFAS were found to be released from corrosion scales and deposits of pipes and taps, resulting in the increase of the cytotoxicity and microbial risk of rural tap water. These results are important to efforts to improve the safety of rural drinking water.

Clonal complexes of carbapenem-resistant Klebsiella pneumoniae recovered from community sewage

Carbapenem-resistant Klebsiella pneumoniae (CR-Kp) are life-threatening multidrug-resistant bacteria. In this study, CR-Kp strains isolated from sewage treatment plants (STPs) (n = 12) were tested for carbapenemase genes (bla_KPC, bla_NDM, bla_IMP, bla_VIM and bla_OXA-48) and had their sequence types (ST) and clonal complexes (CCs) defined. A collection of clinical CR-Kp strains recovered in local hospitals was added to phylogenetic analyses along with sewage strains in order to infer clonality among CR-Kp strains. A total of 154 CR-Kp strains were isolated from raw sewage [55.8% (86/154)], treated sewage [25.3% (39/154)] and from water body downstream from STPs [18.8% (29/154)]. No CR-Kp strain was isolated from upstream water samples. bla_KPC or bla_NDM were detected in 143 (92.8%) strains. The occurrence of bla_KPC-or-NDM CR-Kp strains was positively associated with the number of hospitalized patients in the areas serviced by STPs. Eleven STs were detected in CR-Kp strains, most of them belonging to the clinically relevant CC11 [ST11 (n = 13-28.2%) and ST340 (n = 7-15.2%)]. CCs 11, 15, 17, 147 and 2703 are shared by clinical and sewage CR-Kp strains. In conclusion, sewage harbors clinically relevant clones of CR-Kp that resist sewage treatments, contaminating water bodies downstream from STPs.

A set of antibiotic-resistance mechanisms and virulence factors in GES-16-producing Klebsiella quasipneumoniae subsp. similipneumoniae from hospital wastewater revealed by whole-genome sequencing

Klebsiella quasipneumoniae subsp. similipneumoniae has emerged as a human pathogen and sporadic isolates from non-clinical sources were reported. Here, we described the phenotypic- and genomic-characteristics of a multidrug-resistant (MDR) and potentially hypervirulent (MDR-hv) Klebsiella quasipneumoniae subsp. similipneumoniae (KqA1) isolated from hospital wastewater. The antibiotic susceptibility profile of KqA1 was investigated using disk-diffusion method, broth microdilution method, and agar dilution method, and the genetic characteristics of antimicrobial resistance, mobile genetics elements, and virulence were evaluated by genomic DNA sequencing on the Illumina® NovaSeq6000 platform as well as by bioinformatic analysis. Resistome analyses revealed the presence of genes related to resistance to β-lactams, aminoglycosides, quinolones, tetracyclines, sulfonamides, trimethoprim, chloramphenicol, macrolides, and fosfomycin. New genetic contexts to bla_GES-16 (carbapenemase gene) and to fosA (fosfomycin resistance gene) were described. A set of mechanisms that can contribute to antibiotic resistance, commonly detected in Klebsiella spp., was also found including chromosomal mutations, efflux systems, proteins, and regulators. Moreover, KqA1 presented genes related to tolerance to metals (arsenic, copper, nickel, cobalt, magnesium, cadmium, zinc, tellurium, selenium) and to biocides (quaternary-ammonium compounds). The isolate was classified as potentially hypervirulent due to a wide range of virulence factors found associated to regulation, motility, biofilm, effector delivery systems, immune modulation, nutritional/metabolic factors, adherence, invasion, and competitive advantage. The occurrence of MDR-hv KqA1 in hospital wastewater points out how this environment matrix plays a crucial role in the maintenance and selection of critical bacterial pathogens. Regarding One Health perspective, it is evident the need for multidisciplinary implementation of control measures for antibiotic-resistant bacteria, not only in hospital settings but also in a general environmental context to mitigate the dissemination of MDR and hv bacteria.

Diversity of bacteria carrying antibiotic resistance genes in hospital raw sewage in Southeastern Brazil

In recent decades, antibiotic-resistant bacteria (ARB) emerged and spread among humans and animals worldwide. In this study, we evaluated the presence of ARB and antibiotic resistance genes (ARGs) in the raw sewage of two hospitals in Brazil. Sewage aliquots were inoculated in a selective medium with antibiotics. Bacterial identification was performed by MALDI-TOF and ARGs were assessed by polymerase chain reaction (PCR). A total of 208 strains from both hospitals were isolated (H1 = 117; H2 = 91). A wide variety of Enterobacterales and non-Enterobacterales species were isolated and most of them were Enterobacter spp. (13.0%), Proteus mirabilis (10.1%), and Klebsiella pneumoniae (9.6%). blaTEM and blaKPC were the most frequent β-lactamase-encoding genes and the predominant macrolide resistance genes were mph(A) and mel. Many species had the three tetracycline resistance genes (tetD, tetM, tetA) and strB was the prevalent aminoglycoside resistance gene. Two Staphylococcus haemolyticus strains had the mecA gene. Quinolone, colistin, and vancomycin resistance genes were not found. This study showed that hospital raw sewage is a great ARB and ARG disseminator. Strict monitoring of hospital sewage treatment is needed to avoid the spread of these genes among bacteria in the environment.

KPC-Producing Enterobacterales from Douro River, Portugal-Persistent Environmental Contamination by Putative Healthcare Settings

Carbapenemase-producing Enterobacterales (CPE) are a growing concern, representing a major public health threat to humans, especially in healthcare settings. In the present study, we evaluated the persistent contamination by carbapenem-resistant Enterobacterales in water from Douro River, Portugal. KPC-producing Enterobacterales were detected in five water samples separated chronologically by 15 days each. Susceptibility testing was performed by disk-diffusion-method according to Clinical and Laboratory Standards Institute (CLSI), phenotypic carbapenemase activity was evaluated by carbapenem inactivation method, presumptive identification of the isolates was performed by CHROMagar orientation and confirmed by API-20E. Carbapenemase genes were screened by PCR and the clonality of all isolates was assessed by XbaI-Pulsed Field Gel Electrophoresis (PFGE). Fifteen KPC-producing Enterobacterales isolates were selected, identified as multidrug-resistant and showed a resistance profile to non-beta-lactam antibiotics: sulfamethoxazole + trimethoprim (7/15), ciprofloxacin (3/15), fosfomycin (3/15) and chloramphenicol (2/15). Isolates were identified as (6) Escherichia coli and (9) Klebsiella pneumoniae. Our results suggest a punctual contamination with KPC-producing Enterobacterales continued through the time. The absence of clonality between the isolates suggests a circulation of mobile genetic element harbouring KPC gene in the origin of contamination. This work provides a better understanding on the impacts of water pollution resulting from human activities on aquatic environments.

Occurrence and Quantitative Microbial Risk Assessment of Methicillin-Resistant Staphylococcus aureus (MRSA) in a Sub-Catchment of the Yodo River Basin, Japan

The occurrence of Staphylococcus aureus (S. aureus) and methicillin-resistant S. aureus (MRSA) in a sub-catchment of the Yodo River Basin, a representative water system of a drinking water source in Japan, was investigated. The chromogenic enzyme-substrate medium method was used for the detection of S. aureus and MRSA by the presence or absence of antimicrobials in the medium for viable bacteria in a culture-based setting. The contributions of S. aureus and MRSA from wastewater to the rivers were estimated based on mass flux-based analysis, and quantitative microbial risk assessment (QMRA) was further conducted for S. aureus and MRSA in river environments. The mean abundance of S. aureus and MRSA was 31 and 29 CFU/mL in hospital effluent, 124 and 117 CFU/mL in sewage treatment plant (STP) influent, 16 and 13 CFU/mL in STP effluent, and 8 and 9 CFU/mL in river water, respectively. Contribution of the pollution load derived from the target STP effluent to river water ranged from 2% to 25%. The QMRA showed that to achieve the established health benchmarks, the drinking water treatment process would need to yield 1.7 log₁₀ and 2.9 log₁₀ inactivation in terms of infection risk and disability-adjusted life year (DALY) indexes, respectively. These findings highlight the link between medical environment and the importance of environmental risk management for antimicrobial-resistant bacteria in aquatic environments.

Distribution and characteristics of carbapenem-resistant and extended-spectrum β-lactamase (ESBL) producing Escherichia coli in hospital effluents, sewage treatment plants, and river water in an urban area of Japan

Occurrence of profiles of the carbapenem-resistant Escherichia coli (CRE-E) and extended-spectrum β-lactamase (ESBL)-producing Escherichia coli (ESBL-E) in an urban river in a sub-catchment of the Yodo River Basin, one of the representative water systems of Japan was investigated. We conducted seasonal and year-round surveys for the antimicrobial-resistant bacteria (AMRB) and antimicrobial-resistance genes (AMRGs) in hospital effluents, sewage treatment plant (STP) wastewater, and river water; subsequently, contributions to wastewater discharge into the rivers were estimated by analyses based on the mass flux. Furthermore, the characteristics of AMRB in the water samples were evaluated on the basis of antimicrobial susceptibility tests. CRE-E and ESBL-E were detected in all water samples with mean values 11 and 1900 CFU/mL in the hospital effluent, 58 and 4550 CFU/mL in the STP influent, not detected to 1 CFU/mL in the STP effluent, and 1 and 1 CFU/mL in the STP discharge into the river, respectively. Contributions of the pollution load derived from the STP effluent discharged into the river water were 1 to 21%. The resistome profiles for bla_IMP, bla_TEM, and bla_CTX-M genes in each water sample showed that AMRGs were not completely removed in the wastewater treatment process in the STP, and the relative abundances of bla_IMP, bla_TEM, and bla_CTX-M genes were almost similar (P<0.05). Susceptibility testing of antimicrobial-resistant E. coli isolates showed that CRE-E and ESBL-E detected in wastewaters and river water were linked to the prevalence of AMRB in clinical settings. These results suggest the importance of conducting environmental risk management of AMRB and AMRGs in the river environment. To our knowledge, this is the first detailed study that links the medical environment to CRE-E and ESBL-E for evaluating the AMRB and AMRGs in hospital effluents, STP wastewater, and river water at the basin scale on the basis of mass flux as well as the contributions of CRE-E and ESBL-E to wastewater discharge into the river.