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

Emerging multi-drug resistant and extended-spectrum β-lactamase (ESBL)-positive enterotoxigenic E. coli (ETEC) clones circulating in aquatic environments and in patients

Diarrheal disease pathogens often spread through water-borne routes. Enterotoxigenic Escherichia coli (ETEC) is a major bacterial agent causing diarrheal disease in children, adults, and travelers in endemic areas. In addition, ETEC is responsible for outbreaks of water and food-borne gasteroenteritis globally, ETEC isolates also show robust survival capacity in various environmental settings, including aquatic environments. During the last decade, studies of ETEC isolates have indicated a rapid increase in multi-drug resistant and extended-spectrum β-lactamase (ESBL)-positive human-specific ETEC strains. These have been found in both environmental water sources and human patients, warranting the urgent need for focused monitoring of antibiotic resistance development in ETEC. Whole genome sequencing (WGS) of isolates from environmental, animal, and human sources enables in silico surveillance of emerging pathogenic and multi-drug resistant strains. This method allows for re-analysis of genomic data, aiding in identification of new variants of pathogenic clones. By integrating data from diverse sources inclusing sequenced isolates, we found that certain ETEC clonal lineages e.g., those expressing certain toxin-colonization factor profiles including STp/CS6, LT STh/CS2 + CS3, and LT STh/CFA/I are more at risk to develop multi-drug resistance than other ETEC lineages. Comparizon of multi-locus sequence types from papers with WGS data indicated ST182, ST4, ST2332 and new ST types to be emerging multi-drug resistant ETEC. We conclude that further studies on sequenced ETEC/E. coli genomes are needed to enhance our understanding of the dynamics of ETEC evolution, and the relation of virulence and resistance profiles in both environmental and clinical isolates.

Particulate matter pollution alters the bacterial community structure on the human skin with enriching the Acinetobacter and Pseudomonas

Particulate matter (PM) has been recognized as a significant environmental contaminant with substantial effects on human health, although the impact of PM pollution on the skin microbiota is less understood. In this study, 78 skin microbiota samples from volunteers were obtained during periods of haze and non-haze in the spring and winter. The diversity, composition, and co-occurrence networks of the skin bacterial community were revealed using high-throughput sequencing. Acinetobacter sp. XSB125 and Pseudomonas sp. XSB6 were isolated and cocultured with PM collected during haze days. Significant seasonal variations were observed in the skin bacterial community, with winter samples showing greater diversities than spring samples. Supervised partial least squares discriminant analysis indicated that PM pollution influenced the skin bacterial community composition. Stronger interactions were detected in the network structure of the skin bacterial community during haze days. Differential and random forest analyses revealed that Acinetobacter and Pseudomonas, which are important resistant opportunistic pathogens, were significantly enriched during haze days in winter. To confirm the increases in Acinetobacter and Pseudomonas during haze days, an Acinetobacter strain and a Pseudomonas strain were isolated and cultured with the PM we collected during haze days. In vitro experiments confirmed that PM promoted the growth of the Acinetobacter and Pseudomonas strains. Function analysis revealed increased metabolic function and enrichment of antibiotic resistance- and pathogenicity-related functions during haze days, including the beta-lactamase gene and attachment invasion locus protein. These findings reveal the complex interplay between PM pollution and the skin microbiota, highlighting the need for further research into mitigation strategies to protect the public health from PM exposure.

Unveiling the Genetic Landscape of Staphylococcus aureus Isolated From Hospital Wastewaters: Emergence of Hypervirulent CC8 Strains in Tehran, Iran

Objective(s): Multidrug-resistant bacteria and priority pathogens, including MRSA, are frequently found in hospital wastewaters. It is crucial to investigate the genetic diversity, biofilm formation, and virulence analysis of Staphylococcus aureus isolated from hospital wastewaters. Materials and Methods: In this cross-sectional study, 70 S. aureus isolated from hospital wastewaters were subjected to characterization through antimicrobial susceptibility tests, biofilm formation, multilocus sequence typing (MLST), and PCR analysis for detecting resistance (mecA, mecC, vanA, vanB, mupB, mupA, msr(A), msr(B), erm(A), erm(B), erm(C), tet(M), ant (4⁣')-Ia, aac (6⁣')-Ie/aph (2⁣″), and aph (3⁣')-IIIa) and virulence genes (eta, etb, pvl, and tst). Results: Our results showed that 55.7%, 31.4%, and 12.9% of isolates were classified as strong, intermediate, and weak biofilm-forming strains, respectively. Our result revealed that about three-quarters of isolates harbored mecA (100%), ant (4⁣')-Ia (100%), tet(M) (92.9%), erm(B) (80%), and msr(A) (74.3%) resistance genes. MLST revealed that the 70 isolates belonged to five clonal complexes, including CC8 (52.9%), followed by CC30 (15.7%), CC5 (14.3%), CC1 (11.4%), and CC22 (5.7%). The vast majority of S. aureus isolates belonged to CC8/ST239-MRSA (21.5%). Among the 39 strong biofilm producers, the majority (25.6%) belonged to CC8/ST239-MRSA clone. Our result revealed that about one-third of Panton-Valentine leukocidin (PVL)-positive strains belonged to CC30/ST30. The high-level mupirocin-resistant (HLMUPR) isolates belonged to CC8/ST239-MRSA (36%), CC30/ST30-MRSA (16%), CC8/ST8-MRSA (12%), CC5/ST5-MRSA (12%), CC8/ST585-MRSA (8%), CC5/ST225-MRSA (8%), CC5/ST1637-MRSA (4%), and CC8/ST1465-MRSA (4%) lineages carrying mupA. The VRSA strain belonged to the CC8/ST239-MRSA, CC8/ST8-MRSA, and CC22/ST22-MRSA clonal lineages, carrying the vanA determinant. Conclusion: These findings highlight significant genotypic diversity and high biofilm formation among our isolates. From this study, we identified highly virulent strains of S. aureus associated with biofilm production and drug resistance; some of these strains were highly similar, highlighting the possibility of rapid spread. The high prevalence of CC8 and CC30 clones among S. aureus strains reflects the emergence of these lineages as successful clones in hospital wastewaters in Iran, which is a serious concern. The study highlights the importance of wastewater surveillance to understand genetic pattern and antimicrobial resistance profiles in surrounding communities, which can in turn support public health efforts.

Bacterial Communities and Resistance and Virulence Genes in Hospital and Community Wastewater: Metagenomic Analysis

Metagenomic studies have made it possible to deepen the analysis of the abundance of bacterial populations that carry resistance and virulence determinants in the wastewater environment. In this study, a longitudinal collection of samples of community and hospital wastewater from August 2021 to September 2022 was obtained. Shotgun metagenomic sequencing and bioinformatic analysis were performed to characterize the bacterial abundance, antimicrobial resistance genes (ARGs), plasmids, and virulence factor genes (VFGs) contained in the wastewater. The microbial composition of the community and hospital wastewater showed that the most abundant bacterial phyla detected in all samples were: Proteobacteria, Bacteroides, Firmicutes, Campylobacterota, and Actinobacteria. Seasonal differences in the relative abundances of species, ARGs, plasmids, and VFGs were observed. In this study, a total of 270 ARGs were detected, and it was found that the absolute abundance of ARGs only showed a 39% reduction in the treated wastewater. Furthermore, the ARGs detected in this study were found to encode resistance to antibiotics of the last choice. Our results showed that plasmids carrying resistance genes were more abundant in raw wastewater, and 60% more abundant in hospital wastewater compared to community wastewater. Several of the VFGs detected in this study encode for adhesion, motility, and biofilm formation, which likely allows bacteria to remain and persist in the wastewater environment and survive WWTP treatment systems, thus managing to escape into the environment via treated wastewater.

Antibiotic resistance and pathogen spreading in a wastewater treatment plant designed for wastewater reuse

Climate change significantly contributes to water scarcity in various regions worldwide. While wastewater reuse is a crucial strategy for mitigating water scarcity, it also carries potential risks for human health due to the presence of pathogenic and antibiotic resistant bacteria (ARB). Antibiotic resistance represents a Public Health concern and, according to the global action plan on antimicrobial resistance, wastewater role in selecting and spreading ARB must be monitored. Our aim was to assess the occurrence of ARB, antibiotic resistance genes (ARGs), and potential pathogenic bacteria throughout a wastewater treatment plant (WWTP) designed for water reuse. Furthermore, we aimed to evaluate potential association between ARB and ARGs with antibiotics and heavy metals. The results obtained revealed the presence of ARB, ARGs and pathogenic bacteria at every stage of the WWTP. Notably, the most prevalent ARB and ARG were sulfamethoxazole-resistant bacteria (up to 7.20 log CFU mL-1) and sulII gene (up to 5.91 log gene copies mL-1), respectively. The dominant pathogenic bacteria included Arcobacter, Flavobacterium and Aeromonas. Although the abundance of these elements significantly decreased during treatment (influent vs. effluent, p < 0.05), they were still present in the effluent designated for reuse. Additionally, significant correlations were observed between heavy metal concentrations (copper, nickel and selenium) and antibiotic resistance elements (ampicillin-resistant bacteria, tetracycline-resistant bacteria, ARB total abundance and sulII) (p < 0.05). These results underscore the importance of monitoring the role of WWTP in spreading antibiotic resistance, in line with the One Health approach. Additionally, our findings suggest the need of interventions to reduce human health risks associated with the reuse of wastewater for agricultural purposes.

Metagenomics insights into bacterial diversity and antibiotic resistome of the sewage in the city of Belém, Pará, Brazil

Introduction

The advancement of antimicrobial resistance is a significant public health issue today. With the spread of resistant bacterial strains in water resources, especially in urban sewage, metagenomic studies enable the investigation of the microbial composition and resistance genes present in these locations. This study characterized the bacterial community and antibiotic resistance genes in a sewage system that receives effluents from various sources through metagenomics.

Methods

One liter of surface water was collected at four points of a sewage channel, and after filtration, the total DNA was extracted and then sequenced on an NGS platform (Illumina® NextSeq). The sequenced data were trimmed, and the microbiome was predicted using the Kraken software, while the resistome was analyzed on the CARD webserver. All ecological and statistical analyses were performed using the. RStudio tool.

Results and discussion

The complete metagenome results showed a community with high diversity at the beginning and more restricted diversity at the end of the sampling, with a predominance of the phyla Bacteroidetes, Actinobacteria, Firmicutes, and Proteobacteria. Most species were considered pathogenic, with an emphasis on those belonging to the Enterobacteriaceae family. It was possible to identify bacterial groups of different threat levels to human health according to a report by the U.S. Centers for Disease Control and Prevention. The resistome analysis predominantly revealed genes that confer resistance to multiple drugs, followed by aminoglycosides and macrolides, with efflux pumps and drug inactivation being the most prevalent resistance mechanisms. This work was pioneering in characterizing resistance in a sanitary environment in the Amazon region and reinforces that sanitation measures for urban sewage are necessary to prevent the advancement of antibiotic resistance and the contamination of water resources, as evidenced by the process of eutrophication.

Wastewater-associated plastispheres: A hidden habitat for microbial pathogens?

Wastewater treatment plants (WWTPs) receive wastewater from various sources. Despite wastewater treatment aiming to remove contaminants, microplastics persist. Plastic surfaces are quickly colonized by microbial biofilm ("plastispheres"). Plastisphere communities are suggested to promote the spread and survival of potential human pathogens, suggesting that the transfer of plastispheres from wastewater to the environment could pose a risk to human and environmental health. The study aimed to identify pathogens in wastewater plastispheres, specifically food-borne pathogens, in addition to characterizing the taxonomic diversity and composition of the wastewater plastispheres. Plastispheres that accumulated on polypropylene (PP), polyvinyl chloride (PVC), and high-density polyethylene propylene (HDPE) surfaces exposed to raw and treated wastewater were analyzed via cultivation methods, quantitative reverse transcription PCR (RT‒qPCR) and 16S rRNA amplicon sequencing. RT‒qPCR revealed the presence of potential foodborne pathogenic bacteria and viruses, such as Listeria monocytogenes, Escherichia coli, norovirus, and adenovirus. Viable isolates of the emerging pathogenic species Klebsiella pneumoniae and Acinetobacter spp. were identified in the plastispheres from raw and treated wastewater, indicating that potential pathogenic bacteria might survive in the plastispheres during the wastewater treatment. These findings underscore the potential of plastispheres to harbor and disseminate pathogenic species, posing challenges to water reuse initiatives. The taxonomic diversity and composition of the plastispheres, as explored through 16S rRNA amplicon sequencing, were significantly influenced by the wastewater environment and the duration of time the plastic spent in the wastewater. In contrast, the specific plastic material did not influence the bacterial composition, while the bacterial diversity was affected. Without efficient wastewater treatment and proper plastic waste management, wastewater could act as a source of transferring plastic-associated pathogens into the food chain and possibly pose a threat to human health. Continued research and innovation are essential to improve the removal of microplastics and associated pathogenic microorganisms in wastewater.

Unnoticed antimicrobial resistance risk in Tibetan cities unveiled by sewage metagenomic surveillance: Compared to the eastern Chinese cities

Sewage surveillance is a cost-effective tool for assessing antimicrobial resistance (AMR) in urban populations. However, research on sewage AMR in remote areas is still limited. Here, we used shotgun metagenomic sequencing to profile antibiotic resistance genes (ARGs) and ARG-carrying pathogens (APs) across 15 cities in Tibetan Plateau (TP) and the major cities in eastern China. Notable regional disparities in sewage ARG composition were found, with a significantly higher ARG abundance in TP (2.97 copies/cell). A total of 542 and 545 APs were identified in sewage from TP and the East, respectively, while more than 40 % carried mobile genetic elements (MGEs). Moreover, 65 MGEs-carrying APs were identified as World Health Organization (WHO) priority-like bacterial and fungal pathogens. Notably, a fungal zoonotic pathogen, Enterocytozoon bieneusi, was found for the first time to carry a nitroimidazole resistance gene (nimJ). Although distinct in AP compositions, the relative abundances of APs were comparable in these two regions. Furthermore, sewage in TP was found to be comparable to the cities in eastern China in terms of ARG mobility and AMR risks. These findings provide insights into ARGs and APs distribution in Chinese sewage and stress the importance of AMR surveillance and management strategies in remote regions.

Treated wastewater: A hotspot for multidrug- and colistin-resistant Klebsiella pneumoniae

Wastewater treatment plants are hotspots for the release of antimicrobial resistant pathogenic bacteria into aquatic ecosystems, significantly contributing to the cycle of antimicrobial resistance. Special attention should be paid to antimicrobial resistant ESKAPE bacteria, which have been identified as high-priority targets for control measures. Among them, Klebsiella pneumoniae is particularly noteworthy. In this study, we collected wastewater samples from the inlet, sedimentation tank, and effluent water of a wastewater treatment plant in June, July, October, and November of 2018. We detected and characterized 42 K. pneumoniae strains using whole genome sequencing (15 from the inlet, 8 from the sedimentation tank, and 19 from the effluent). Additionally, the strains were tested for their antimicrobial resistance phenotype. Using whole genome sequencing no distinct patterns were observed in terms of their genetic profiles. All strains were resistant to tetracycline, meanwhile 60%, 47%, and 37.5% of strains isolated from the inlet, sedimentation tank, and effluent, respectively, were multidrug resistant. Some of the multidrug resistant isolates were also resistant to colistin, and nearly all tested positive for the eptB and arnT genes, which are associated with polymyxin resistance. Various antimicrobial resistance genes were linked to mobile genetic elements, and they did not correlate with detected virulence groups or defense systems. Overall, our results, although not quantitative, highlight that multidrug resistant K. pneumoniae strains, including those resistant to colistin and genetically unrelated, being discharged into aquatic ecosystems from wastewater treatment plants. This suggests the necessity of monitoring aimed at genetically characterizing these pathogenic bacteria.

A Surveillance Study of Culturable and Antimicrobial-Resistant Bacteria in Two Urban WWTPs in Northern Spain

BACKGROUND/OBJECTIVES

Wastewater treatment plants (WWTPs) are hotspots for the spread of antimicrobial resistance into the environment. This study aimed to estimate the proportion of clinically relevant antimicrobial-resistant bacteria in two Spanish urban WWTPs, located in the region of La Rioja (Spain); Methods: Ninety-four samples (48 water/46 sludge) were collected and streaked on ten different selective media, in order to recover the culturable bacterial diversity with relevant resistance phenotypes: Extended-Spectrum β-Lactamase-producing Escherichia coli/Klebsiella pneumoniae (ESBL-Ec/Kp), Carbapenem-resistant Enterobacteriaceae (CR-E), Methicillin-resistant Staphylococcus aureus (MRSA), and Vancomycin-resistant Enterococcus faecium/faecalis (VR-E. faecium/faecalis). Isolates were identified by MALDI-TOF and were tested for antimicrobial susceptibility using the disk diffusion method. The confirmation of ESBL production was performed by the double-disk test; Results: A total of 914 isolates were recovered (31 genera and 90 species). Isolates with clinically relevant resistance phenotypes such as ESBL-Ec/Kp and CR-E were recovered in the effluent (0.4 × 100-4.8 × 101 CFU/mL) and organic amendment samples (1.0-101-6.0 × 102 CFU/mL), which are discharged to surface waters/agricultural fields. We reported the presence of VR-E. faecium in non-treated sludge and in the digested sludge samples (1.3 × 101-1 × 103 CFU/mL). MRSA was also recovered, but only in low abundance in the effluent (0.2 × 101 CFU/mL); Conclusions: This study highlights the need for improved wastewater technologies and stricter regulations on the use of amendment sludge in agriculture. In addition, regular monitoring and surveillance of WWTPs are critical for early detection and the mitigation of risks associated with the spread of antimicrobial resistance.

Metagenomic Profiling of Internationally Sourced Sewage Influents and Effluents Yields Insight into Selecting Targets for Antibiotic Resistance Monitoring

It has been debated whether wastewater treatment plants (WWTPs) primarily act to attenuate or amplify antibiotic resistance genes (ARGs). However, ARGs are highly diverse with respect to their resistance mechanisms, mobilities, and taxonomic hosts and therefore their behavior in WWTPs should not be expected to be universally conserved. We applied metagenomic sequencing to wastewater influent and effluent samples from 12 international WWTPs to classify the behavior of specific ARGs entering and exiting WWTPs. In total, 1079 different ARGs originating from a variety of bacteria were detected. This included ARGs that could be mapped to assembled scaffolds corresponding to nine human pathogens. While the relative abundance (per 16S rRNA gene) of ARGs decreased during treatment at 11 of the 12 WWTPs sampled and absolute abundance (per mL) decreased at all 12 WWTPs, increases in relative abundance were observed for 40% of the ARGs detected at the 12th WWTP. Also, the relative abundance of mobile genetic elements (MGE) increased during treatment, but the fraction of ARGs known to be transmissible between species decreased, thus demonstrating that increased MGE prevalence may not be generally indicative of an increase in ARGs. A distinct conserved resistome was documented in both influent and effluent across samples, suggesting that well-functioning WWTPs generally attenuate influent antibiotic resistance loads. This work helps inform strategies for wastewater surveillance of antibiotic resistance, highlighting the utility of tracking ARGs as indicators of treatment performance and relative risk reduction.

Temporal changes in the morphological and microbial diversity of biofilms on the surface of a submerged stone in the Danube River

Epilithic biofilms are ubiquitous in large river environments and are crucial for biogeochemical processes, but their community structures and functions remain poorly understood. In this paper, the seasonal succession in the morphological structure and the taxonomic composition of an epilithic bacterial biofilm community at a polluted site of the Danube River were followed using electron microscopy, high-throughput 16S rRNA gene amplicon sequencing and multiplex/taxon-specific PCRs. The biofilm samples were collected from the same submerged stone and carried out bimonthly in the littoral zone of the Danube River, downstream of a large urban area. Scanning electron microscopy showed that the biofilm was composed of diatoms and a variety of bacteria with different morphologies. Based on amplicon sequencing, the bacterial communities were dominated by the phyla Pseudomonadota and Bacteroidota, while the most abundant archaea belonged to the phyla Nitrososphaerota and Nanoarchaeota. The changing environmental factors had an effect on the composition of the epilithic microbial community. Critical levels of faecal pollution in the water were associated with increased relative abundance of Sphaerotilus, a typical indicator of "sewage fungus", but the composition and diversity of the epilithic biofilms were also influenced by several other environmental factors such as temperature, water discharge and total suspended solids (TSS). The specific PCRs showed opportunistic pathogenic bacteria (e.g. Pseudomonas spp., Legionella spp., P. aeruginosa, L. pneumophila, Stenotrophomonas maltophilia) in some biofilm samples, but extended spectrum β-lactamase (ESBL) genes and macrolide resistance genes could not be detected.

Antibiotic Residues and Resistance in Three Wastewater Treatment Plants in Romania

This study evaluates antibiotic residues and bacterial loads in influent and effluent samples from three wastewater treatment plants (WWTPs) in Romania, across four seasons from 2021 to 2022. Analytical methods included solid-phase extraction and high-performance liquid chromatography (HPLC) to quantify antibiotic concentrations, while microbiological assays estimated bacterial loads and assessed antibiotic resistance patterns. Statistical analyses explored the impact of environmental factors such as temperature and rainfall on antibiotic levels. The results showed significant seasonal variations, with higher antibiotic concentrations in warmer seasons. Antibiotic removal efficiency varied among WWTPs, with some antibiotics being effectively removed and others persisting in the effluent, posing high environmental risks and potential for antibiotic resistance development. Bacterial loads were higher in spring and summer, correlating with increased temperatures. Eight bacterial strains were isolated, with higher resistance during warmer seasons, particularly to amoxicillin and clarithromycin.

Comparative genomics of Tn6411 transposons carrying the blaIMP-1 gene in Pseudomonas aeruginosa

We aimed to determine the molecular characteristics of carbapenem-resistant Pseudomonas aeruginosa strains 18081308 and 18083286, which were isolated from the urine and the sputum of two Chinese patients, respectively. Additionally, we conducted a comparative analysis between Tn6411 carrying blaIMP-1 in strain 18083286 and transposons from the same family available in GenBank. Bacterial genome sequencing was carried out on strains 18081308 and 18083286 to obtain their whole genome sequence. Average nucleotide identity (ANI) was used for their precise species identification. Serotyping and multilocus sequence typing were performed. Furthermore, the acquired drug resistance genes of these strains were identified. The carbapenem-resistant P. aeruginosa strains isolated in the present study were of sequence type ST865 and serotype O6. They all carried the same resistance genes (aacC2, tmrB, and blaIMP-1). Tn6411, a Tn7-like transposon carrying blaIMP-1, was found in strain 18083286 by single molecule real time (SMRT) sequencing. We also identified the presence of this transposon sequence in other chromosomes of P. aeruginosa and plasmids carried by Acinetobacter spp. in GenBank, indicating the necessity for heightening attention to the potential transferability of this transposon.

Presence and Persistence of ESKAPEE Bacteria before and after Hospital Wastewater Treatment

The metagenomic surveillance of antimicrobial resistance in wastewater has been suggested as a methodological tool to characterize the distribution, status, and trends of antibiotic-resistant bacteria. In this study, a cross-sectional collection of samples of hospital-associated raw and treated wastewater were obtained from February to March 2020. Shotgun metagenomic sequencing and bioinformatic analysis were performed to characterize bacterial abundance and antimicrobial resistance gene analysis. The main bacterial phyla found in all the samples were as follows: Proteobacteria, Bacteroides, Firmicutes, and Actinobacteria. At the species level, ESKAPEE bacteria such as E. coli relative abundance decreased between raw and treated wastewater, but S. aureus, A. baumannii, and P. aeruginosa increased, as did the persistence of K. pneumoniae in both raw and treated wastewater. A total of 172 different ARGs were detected; blaOXA, blaVEB, blaKPC, blaGES, mphE, mef, erm, msrE, AAC(6'), ant(3″), aadS, lnu, PBP-2, dfrA, vanA-G, tet, and sul were found at the highest abundance and persistence. This study demonstrates the ability of ESKAPEE bacteria to survive tertiary treatment processes of hospital wastewater, as well as the persistence of clinically important antimicrobial resistance genes that are spreading in the environment.

Predictive statistical models for monitoring antimicrobial resistance spread in the environment using Apis mellifera (L. 1758) colonies

The rise of antimicrobial resistance (AMR) is one of the most relevant problems for human and animal health. According to One Health Approach, it is important to regulate the use of antimicrobials and monitor the spread of AMR in the environment as well. Apis mellifera (L. 1758) colonies were used as bioindicators thanks to their physical and behavioural characteristics. During their foraging flights, bees can intercept small particles, including atmospheric particulate matter, etc., and also microorganisms. To date, the antimicrobial surveillance network is limited to the sanitary level but lacks into environmental context. This study aimed to evaluate the use of A. mellifera colonies distributed throughout the Emilia-Romagna region (Italy) as indicators of environmental antimicrobial-resistant bacteria. This was performed by creating a statistical predictive model that establishes correlations between environmental characteristics and the likelihood of isolating specific bacterial genera and antimicrobial-resistant strains. A total of 608 strains were isolated and tested for susceptibility to 19 different antimicrobials. Aztreonam-resistant strains were significantly related to environments with sanitary structures, agricultural areas and wetlands, while urban areas present a higher probability of trimethoprim/sulfamethoxazole-resistant strains isolation. Concerning genera, environments with sanitary structures and wetlands are significantly related to the genera Proteus spp., while the Escherichia spp. strains can be probably isolated in industrial environments. The obtained models showed maximum values of Models Accuracy and robustness (R2) of 55 % and 24 %, respectively. The results indicate the efficacy of utilizing A. mellifera colonies as valuable bioindicators for estimating the prevalence of AMR in environmentally disseminated bacteria. This survey can be considered a good basis for the development of further studies focused on monitoring both sanitary and animal pathology, creating a specific network in the environments of interest.

Analysis of the transmission chain of carbapenem-resistant Enterobacter cloacae complex infections in clinical, intestinal and healthcare settings in Zhejiang province, China (2022-2023)

Considerable attention is given to intensive care unit-acquired infections; however, research on the transmission dynamics of multichain carbapenemase-resistant Enterobacter cloacae complex (CRECC) outbreaks remains elusive. A total of 118 non-duplicated CRECC strains were isolated from the clinical, intestinal, and hospital sewage samples collected from Zhejiang province of China during 2022-2023. A total of 64 CRECC strains were isolated from the hospital sewage samples, and their prevalence increased from 10.0 % (95 % confidence interval, CI = 0.52-45.8 %) in 2022 to 63.6 % (95 % CI = 31.6-87.6 %) in 2023. Species-specific identification revealed that Enterobacter hormaechei was the predominant CRECC species isolated in this study (53.4 %, 95 % CI = 44.0-62.6 %). The antimicrobial susceptibility profiles indicated that all 118 CRECC strains conferred high-level resistance to β-lactam antibiotics, ceftacillin/avibactam, and polymyxin. Furthermore, all CRECC strains exhibited resistance to β-lactams, quinolones, and fosfomycin, with a higher colistin resistance rate observed in the hospital sewage samples (67.2 %, 95 % CI = 54.2-78.1 %). Several antibiotic resistance genes were identified in CRECC strains, including Class A carbapenemases (blaKPC-2) and Class B carbapenemases (blaNDM-1/blaIMP), but not Class D carbapenemases. The WGS analysis showed that the majority of the CRECC strains carried carbapenemase-encoding genes, with blaNDM-1 being the most prevalent (86.9 %, 95 % CI = 77.4-92.9 %). Furthermore, sequence typing revealed that the isolated CRECC strains belonged to diverse sequence types (STs), among which ST418 was the most prevalent blaNDM-positive strain. The high risk of carbapenemase-producing ST418 E. hormaechei and the blaNDM-harboring IncFIB-type plasmid (81.4 %, 95 % CI = 72.9-87.7 %) were detected and emphasized in this study. This study provides valuable insights into the prevalence, antimicrobial resistance, genomic characteristics, and plasmid analysis of CRECC strains in diverse populations and environments. The clonal relatedness analysis showed sporadic clonal transmission of ST418 E. hormaechei strains, supporting inter-hospital transmission.

Preliminary insights on the development of a continuous-flow solar system for the photocatalytic degradation of contaminants of emerging concern in water

The ubiquity and impact of pharmaceuticals and pesticides, as well as their residues in environmental compartments, particularly in water, have raised human and environmental health concerns. This emphasizes the need of developing sustainable methods for their removal. Solar-driven photocatalytic degradation has emerged as a promising approach for the chemical decontamination of water, sparking intensive scientific research in this field. Advancements in photocatalytic materials have driven the need for solar reactors that efficiently integrate photocatalysts for real-world water treatment. This study reports preliminary results from the development and evaluation of a solar system for TiO2-based photocatalytic degradation of intermittently flowing water contaminated with doxycycline (DXC), sulfamethoxazole (SMX), dexamethasone (DXM), and carbendazim (CBZ). The system consisted of a Fresnel-type UV solar concentrator that focused on the opening and focal point of a parabolic trough concentrator, within which tubular quartz glass reactors were fixed. Concentric springs coated with TiO2, arranged one inside the other, were fixed inside the quartz reactors. The reactors are connected to a raw water tank at the inlet and a check valve at the outlet. Rotating wheels at the collector base enable solar tracking in two axes. The substances (SMX, DXC, and CBZ) were dissolved in dechlorinated tap water at a concentration of 1.0 mg/L, except DXM (0.8 mg/L). The water underwent sequential batch (~ 3 L each, without recirculation) processing with retention times of 15, 30, 60, 90, and 120 min. After 15 min, the degradation rates were as follows: DXC 87%, SMX 35.5%, DXM 32%, and CBZ 31.8%. The system processed 101 L of water daily, simultaneously removing 870, 355, 256, and 318 µg/L of DXC, SMX, DXM, and CBZ, respectively, showcasing its potential for real-world chemical water decontamination application. Further enhancements that enable continuous-flow operation and integrate highly effective adsorbents and photocatalytic materials can significantly enhance system performance.

Molecular epidemiology and mechanisms of carbapenem and colistin resistance in Klebsiella and other Enterobacterales from treated wastewater in Croatia

Among the most problematic bacteria with clinical relevance are the carbapenem-resistant Enterobacterales (CRE), as there are very limited options for their treatment. Treated wastewater can be a route for the release of these bacteria into the environment and the population. The aim of this study was to isolate CRE from treated wastewater from the Zagreb wastewater treatment plant and to determine their phenotypic and genomic characteristics. A total of 200 suspected CRE were isolated, 148 of which were confirmed as Enterobacterales by MALDI-TOF MS. The predominant species was Klebsiella spp. (n = 47), followed by Citrobacter spp. (n = 40) and Enterobacter cloacae complex (cplx.) (n = 35). All 148 isolates were carbapenemase producers with a multidrug-resistant phenotype. Using multi-locus sequence typing and whole-genome sequencing (WGS), 18 different sequence types were identified among these isolates, 14 of which were associated with human-associated clones. The virulence gene analysis of the sequenced Klebsiella isolates (n = 7) revealed their potential pathogenicity. PCR and WGS showed that the most frequent carbapenemase genes in K. pneumoniae were blaOXA-48 and blaNDM-1, which frequently occurred together, while blaKPC-2 together with blaNDM-1 was mainly detected in K. oxytoca, E. cloacae cplx. and Citrobacter spp. Colistin resistance was observed in 40% of Klebsiella and 57% of Enterobacter isolates. Underlying mechanisms identified by WGS include known and potentially novel intrinsic mechanisms (point mutations in the pmrA/B, phoP/Q, mgrB and crrB genes) and acquired mechanisms (mcr-4.3 gene). The mcr-4.3 gene was identified for the first time in K. pneumoniae and is probably located on the conjugative IncHI1B plasmid. In addition, WGS analysis of 13 isolates revealed various virulence genes and resistance genes to other clinically relevant antibiotics as well as different plasmids possibly associated with carbapenemase genes. Our study demonstrates the important role that treated municipal wastewater plays in harboring and spreading enterobacterial pathogens that are resistant to last-resort antibiotics.

Inactivation of antibiotic-resistant bacteria Escherichia coli by electroporation

Introduction

In modern times, bacterial infections have become a growing problem in the medical community due to the emergence of antibiotic-resistant bacteria. In fact, the overuse and improper disposal of antibiotics have led to bacterial resistance and the presence of such bacteria in wastewater. Therefore, it is critical to develop effective strategies for dealing with antibiotic-resistant bacteria in wastewater. Electroporation has been found to be one of the most promising complementary techniques for bacterial inactivation because it is effective against a wide range of bacteria, is non-chemical and is highly optimizable. Many studies have demonstrated electroporation-assisted inactivation of bacteria, but rarely have clinical antibiotics or bacteria resistant to these antibiotics been used in the study. Therefore, the motivation for our study was to use a treatment regimen that combines antibiotics and electroporation to inactivate antibiotic-resistant bacteria.

Methods

We separately combined two antibiotics (tetracycline and chloramphenicol) to which the bacteria are resistant (with a different resistance mode) and electric pulses. We used three different concentrations of antibiotics (40, 80 and 150 µg/ml for tetracycline and 100, 500 and 2000 µg/ml for chloramphenicol, respectively) and four different electric field strengths (5, 10, 15 and 20 kV/cm) for electroporation.

Results and discussion

Our results show that electroporation effectively enhances the effect of antibiotics and inactivates antibiotic-resistant bacteria. The inactivation rate for tetracycline or chloramphenicol was found to be different and to increase with the strength of the pulsed electric field and/or the concentration of the antibiotic. In addition, we show that electroporation has a longer lasting effect (up to 24 hours), making bacteria vulnerable for a considerable time. The present work provides new insights into the use of electroporation to inactivate antibiotic-resistant bacteria in the aquatic environment.

Antibiotic Resistance Genes, Virulence Factors, and Biofilm Formation in Coagulase-Negative Staphylococcus spp. Isolates from European Hakes (Merluccius merluccius, L.) Caught in the Northeast Atlantic Ocean

The indiscriminate use of antibiotics has contributed to the dissemination of multiresistant bacteria, which represents a public health concern. The aim of this work was to characterize 27 coagulase-negative staphylococci (CoNS) isolated from eight wild Northeast Atlantic hakes (Merluccius merluccius, L.) and taxonomically identified as Staphylococcus epidermidis (n = 16), Staphylococcus saprophyticus (n = 4), Staphylococcus hominis (n = 3), Staphylococcus pasteuri (n = 2), Staphylococcus edaphicus (n = 1), and Staphylococcus capitis (n = 1). Biofilm formation was evaluated with a microtiter assay, antibiotic susceptibility testing was performed using the disk diffusion method, and antibiotic resistance and virulence determinants were detected by PCR. Our results showed that all staphylococci produced biofilms and that 92.6% of the isolates were resistant to at least one antibiotic, mainly penicillin (88.8%), fusidic acid (40.7%), and erythromycin (37%). The penicillin resistance gene (blaZ) was detected in 66.6% (18) of the isolates, of which 10 also carried resistance genes to macrolides and lincosamides (mphC, msr(A/B), lnuA, or vgaA), 4 to fusidic acid (fusB), and 3 to trimethoprim-sulfamethoxazole (dfrA). At least one virulence gene (scn, hla, SCCmecIII, and/or SCCmecV) was detected in 48% of the isolates. This study suggests that wild European hake destined for human consumption could act as a vector of CoNS carrying antibiotic resistance genes and/or virulence factors.

Epidemiology of vancomycin-resistant enterococci in the United Arab Emirates: a retrospective analysis of 12 years of national AMR surveillance data

INTRODUCTION

Enterococci are usually low pathogenic, but can cause invasive disease under certain circumstances, including urinary tract infections, bacteremia, endocarditis, and meningitis, and are associated with peritonitis and intra-abdominal abscesses. Increasing resistance of enterococci to glycopeptides and fluoroquinolones, and high-level resistance to aminoglycosides is a concern. National antimicrobial resistance (AMR) surveillance data for enterococci from the Middle East and North Africa (MENA) and the Gulf region is scarce.

METHODS

A retrospective 12-year analysis of N = 37,909 non-duplicate diagnostic Enterococcus spp. isolates from the United Arab Emirates (UAE) was conducted. Data was generated by routine patient care during 2010-2021, collected by trained personnel and reported by participating surveillance sites to the UAE National AMR Surveillance program. Data analysis was conducted with WHONET.

RESULTS

Enterococcus faecalis was the most commonly reported species (81.5%), followed by Enterococcus faecium (8.5%), and other enterococci species (4.8%). Phenotypically vancomycin-resistant enterococci (VRE) were found in 1.8% of Enterococcus spp. isolates. Prevalence of VRE (%VRE) was highest for E. faecium (8.1%), followed by E. faecalis (0.9%). A significant level of resistance to glycopeptides (%VRE) for these two species has been observed in the majority of observed years [E. faecalis (0-2.2%), 2010: 0%, 2021: 0.6%] and E. faecium (0-14.2%, 2010: 0%, 2021: 5.8%). Resistance to fluoroquinolones was between 17 and 29% (E. faecalis) and was higher for E. faecium (between 42 and 83%). VRE were associated with higher patient mortality (RR: 2.97), admission to intensive care units (RR: 2.25), and increased length of stay (six excess inpatient days per VRE case), as compared to vancomycin-susceptible Enterococcus spp.

DISCUSSION

Published data on Enterococcus infections, in particular VRE-infections, in the UAE and MENA region is scarce. Our data demonstrates that VRE-enterococci are relatively rare in the UAE, however showing an increasing resistance trend for several clinically important antibiotic classes, causing a concern for the treatment of serious infections caused by enterococci. This study also demonstrates that VRE were associated with higher mortality, increased intensive care unit admission rates, and longer hospitalization, thus poorer clinical outcome and higher associated costs in the UAE. We recommend the expansion of current surveillance techniques (e.g., local VRE screening), stricter infection prevention and control strategies, and better stewardship interventions. Further studies on the molecular epidemiology of enterococci are needed.

Contribution to the Synthesis, Characterization, Separation and Quantification of New N-Acyl Thiourea Derivatives with Antimicrobial and Antioxidant Potential

The present study aimed to synthesize, characterize, and validate a separation and quantification method of new N-acyl thiourea derivatives (1a-1o), incorporating thiazole or pyridine nucleus in the same molecule and showing antimicrobial potential previously predicted in silico. The compounds have been physiochemically characterized by their melting points, IR, NMR and MS spectra. Among the tested compounds, 1a, 1g, 1h, and 1o were the most active against planktonic Staphylococcus aureus and Pseudomonas aeruginosa, as revealed by the minimal inhibitory concentration values, while 1e exhibited the best anti-biofilm activity against Escherichia coli (showing the lowest value of minimal inhibitory concentration of biofilm development). The total antioxidant activity (TAC) assessed by the DPPH method, evidenced the highest values for the compound 1i, followed by 1a. A routine quality control method for the separation of highly related compounds bearing a chlorine atom on the molecular backbone (1g, 1h, 1i, 1j, 1m, 1n) has been developed and validated by reversed-phase high-performance liquid chromatography (RP-HPLC), the results being satisfactory for all validation parameters recommended by the ICH guidelines (i.e., system suitability, specificity, the limits of detection and quantification, linearity, precision, accuracy and robustness) and recommending it for routine separation of these highly similar compounds.

T, Tomioka N, Ebie Y, Syutsubo K. Quantitative detection and reduction of potentially pathogenic bacterial groups of Aeromonas, Arcobacter, Klebsiella pneumoniae species complex, and Mycobacterium in wastewater treatment facilities

Water quality parameters influence the abundance of pathogenic bacteria. The genera Aeromonas, Arcobacter, Klebsiella, and Mycobacterium are among the representative pathogenic bacteria identified in wastewater. However, information on the correlations between water quality and the abundance of these bacteria, as well as their reduction rate in existing wastewater treatment facilities (WTFs), is lacking. Hence, this study aimed to determine the abundance and reduction rates of these bacterial groups in WTFs. Sixty-eight samples (34 influent and 34 non-disinfected, treated, effluent samples) were collected from nine WTFs in Japan and Thailand. 16S rRNA gene amplicon sequencing analysis revealed the presence of Aeromonas, Arcobacter, and Mycobacterium in all influent wastewater and treated effluent samples. Quantitative real-time polymerase chain reaction (qPCR) was used to quantify the abundance of Aeromonas, Arcobacter, Klebsiella pneumoniae species complex (KpSC), and Mycobacterium. The geometric mean abundances of Aeromonas, Arcobacter, KpSC, and Mycobacterium in the influent wastewater were 1.2 × 104-2.4 × 105, 1.0 × 105-4.5 × 106, 3.6 × 102-4.3 × 104, and 6.9 × 103-5.5 × 104 cells mL-1, respectively, and their average log reduction values were 0.77-2.57, 1.00-3.06, 1.35-3.11, and -0.67-1.57, respectively. Spearman's rank correlation coefficients indicated significant positive or negative correlations between the abundances of the potentially pathogenic bacterial groups and Escherichia coli as well as water quality parameters, namely, chemical/biochemical oxygen demand, total nitrogen, nitrate-nitrogen, nitrite-nitrogen, ammonium-nitrogen, suspended solids, volatile suspended solids, and oxidation-reduction potential. This study provides valuable information on the development and appropriate management of WTFs to produce safe, hygienic water.