Hospital effluent: A reservoir for carbapenemase-producing Enterobacterales?

Analysing carbapenemases in hospital wastewater: Insights from intracellular and extracellular DNA using qPCR and digital PCR

The widespread dissemination of carbapenem-resistant bacteria in wastewater systems, particularly from clinical sources, poses a significant public health risk. This study assessed the concentrations and distributions of extracellular DNA (exDNA) and intracellular DNA (iDNA) harboring carbapenemase genes in wastewater from six tertiary care hospitals in Germany. We collected a total of 36 samples, comprising six biological replicates from each hospital, and analysed them using quantitative real-time PCR (qPCR) and digital PCR (dPCR). The analysis targeted seven carbapenemase genes: blaNDM, blaKPC, blaIMP, blaVIM, blaOXA-23-like, blaOXA-48-like, and blaOXA-58-like across both DNA fractions. Our results revealed significant variability in the concentrations of exDNA and iDNA across the sampling sites, with iDNA typically present at higher concentrations. Using NanoDrop One spectrophotometry and the Qubit dsDNA kit, exDNA concentrations ranged from 2.7 to 7.7 ng/mL, while Qubit recorded lower values between 1.1 and 4.0 ng/mL. Conversely, iDNA concentrations were markedly higher, spanning from 42.3 to 191.7 ng/mL with NanoDrop and 12.0 to 46.5 ng/mL with Qubit, highlighting the variability between DNA types and quantification methods. Despite its lower concentrations, exDNA comprised up to 18.2 % of total DNA, highlighting its potential role in the horizontal transfer of antimicrobial resistance genes (ARGs). The study detected target ARGs in both DNA fractions at all sites, with notable differences in their concentrations; iDNA consistently exhibited higher levels of ARGs, with the highest concentrations reaching 10.57 ± 0.20 log gene copies per liter (GC/L) for blaVIM in iDNA and 6.96 ± 0.72 log GC/L for blaIMP in exDNA. dPCR demonstrated greater sensitivity than qPCR, especially effective for detecting low-abundance targets like blaOXA-23-like in the exDNA fraction. Additionally, qPCR's susceptibility to inhibition and contamination emphasizes the superior robustness of dPCR. This research highlights the need for improved monitoring and the implementation of advanced treatment technologies to mitigate ARG dissemination in wastewater.

Whole genome sequencing reveals antibiotic resistance pattern and virulence factors in Klebsiella quasipneumoniae subsp. Similipneumoniae from Hospital wastewater in South-West, Nigeria

Klebsiella quasipneumoniae is a distinct species from K. pneumoniae, even though it is sometimes mistaken phenotypically for the latter in clinical situations. K. quasipneumoniae is a pathogen and this study aims at understanding the genomic antibiotic resistance and virulence characteristics of Klebsiella quasipneumoniae subsp. similipneumoniae (B105 strain) isolated from tertiary hospital wastewater and the potential risks associated with its environmental spread. The Illumina platform was used for whole-genome sequencing (WGS), the generated raw reads (de novo) was assembled using RAPT NCBI, while other standardized bioinformatics tools were utilized to validate and examine the landscape of the genome's antibiotic resistance and virulence factors. The K. quasipneumoniae subsp. similipneumoniae (B105 strain), belonged to sequence type 1422 and was resistant to ampicillin, amoxicillin-clavulanic acid, ceftazidime, cefepime, meropenem, tetracycline, but susceptible to gentamicin. The annotated genome acknowledged the presence of blaOKP-B-2, ompK 36, fosA5, oqxAB, virulence genes responsible for capsule formation, lipopolysaccharide, iron uptake aerobactin (iutA), salmochelins (iroE, iroN), enterobactin siderophore, efllux pump (acrA, acrB) adherence, (mrkC, mrkD, and fimD) and two plasmids replicon IncFIB(K) and IncR. The study resonates the inadequacy of conventional microbiological identification methods to distinguish K. pneumoniae and K. quasipneumoniae and at the same time heightens the importance of using a genomic platform to extol the identity of K. quasipneumoniae subsp. similipneumoniae strain. Furthermore, the peculiarities of the acquired antimicrobial resistance and virulence genes, in this strain, are a potential risk to the environment.

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.

Use of Antibiotics in Animal Agriculture: Implications for Pediatrics: Technical Report

Antimicrobial resistance is a global public health threat. Antimicrobial-resistant infections are on the rise and are associated with increased morbidity, mortality, and health care costs. Infants and children are affected by transmission of antimicrobial-resistant zoonotic pathogens through the food supply, direct contact with animals, environmental pathways, and contact with infected or colonized humans. Although the judicious use of antimicrobial agents is necessary for maintaining the health and welfare of humans and animals, it must be recognized that all use of antimicrobial agents exerts selective pressure that increases the risk of development of resistance. This report describes historical and recent use of antibiotics in animal agriculture, reviews the mechanisms of how such use contributes to development of resistance and can adversely affect child health, and discusses US initiatives to curb unnecessary use of antimicrobial agents in agriculture.

Genomic epidemiology and longitudinal sampling of ward wastewater environments and patients reveals complexity of the transmission dynamics of bla KPC-carbapenemase-producing Enterobacterales in a hospital setting

Background

Healthcare-associated wastewater and asymptomatic patient reservoirs colonized by carbapenemase-producing Enterobacterales (CPE) contribute to nosocomial CPE dissemination, but the characteristics and dynamics of this remain unclear.

Methods

We systematically sampled wastewater sites (n = 4488 samples; 349 sites) and patients (n = 1247) across six wards over 6-12 months to understand blaKPC-associated CPE (KPC-E) diversity within these reservoirs and transmission in a healthcare setting. Up to five KPC-E-positive isolates per sample were sequenced (Illumina). Recombination-adjusted phylogenies were used to define genetically related strains; assembly and mapping-based approaches were used to characterize antimicrobial resistance genes, insertion sequences (ISs) and Tn4401 types/target site sequences. The accessory genome was evaluated in some of the largest clusters, and those crossing reservoirs.

Results

Wastewater site KPC-E-positivity was substantial [101/349 sites (28.9%); 228/5601 (4.1%) patients cultured]. Thirteen KPC-E species and 109 strains were identified using genomics, and 24% of wastewater and 26% of patient KPC-E-positive samples harboured one or more strains. Most diversity was explained by the individual niche, suggesting localized factors are important in selection and spread. Tn4401 + flanking target site sequence diversity was greater in wastewater sites (P < 0.001), which might favour Tn4401-associated transposition/evolution. Shower/bath- and sluice/mop-associated sites were more likely to be KPC-E-positive (adjusted OR = 2.69; 95% CI: 1.44-5.01; P = 0.0019; and adjusted OR = 2.60; 95% CI: 1.04-6.52; P = 0.0410, respectively). Different strains had different blaKPC dissemination dynamics.

Conclusions

We identified substantial and diverse KPC-E colonization of wastewater sites and patients in this hospital setting. Reservoir and niche-specific factors (e.g. microbial interactions, selection pressures), and different strains and mobile genetic elements likely affect transmission dynamics. This should be considered in surveillance and control strategies.

Risk factors and molecular characterization of carbapenem resistant Escherichia coli recovered from a tertiary hospital in Fujian, China from 2021 to 2023

BACKGROUND

There is a serious public health concern regarding the emergence of carbapenem-resistant Escherichia coli (CREC). The purpose of this study is to identify the molecular characterization and risk factors of CREC in Fujian province, China.

METHODS

A total of 48 CREC isolates were collected from various clinical samples. The strains were identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/MS). Susceptibility to antibiotics was determined by the standard broth microdilution method. Polymerase chain reaction (PCR) was used to screen common drug resistance genes. Multilocus sequence typing (MLST) was used to type isolates. RT-qPCR was used to detect gene expression of acrA, acrB, and tolC. Conjugation assays were used to analyze the transferability of plasmids carrying mcr-1 or blaNDM. Risk factors for CREC infection were identified by logistic regression analysis.

RESULTS

48 CREC strains were collected, with 81.25% producing carbapenemase (CP-CREC), and 18.75% were not producing carbapenemase (no-CP-CREC). They belonged to 21 sequence type (STs) and five unknown STs. Perianal swabs were the main sample type, with 25 patients found to have hematological malignancies. All isolates of CP-CREC were found to contain blaNDM (blaNDM-5 (n = 32), blaNDM-1 (n = 5), blaNDM-4 (n = 1), and blaNDM-13 (n = 1)), among which one isolate co-existence blaNDM-5 and blaOXA-48. Two blaNDM-positive strains, specifically blaNDM-5 and blaNDM-4, were found to co-habor mcr-1 with ST617. Conjugation assays confirmed that blaNDM-1, blaNDM-13, and most blaNDM-5(68.75%, 22/32) could be transferred between E. coli strains. Four of the 9 non-CP-CREC isolates had deletions in ompC and ompF with blaCTX-M production, while the other five showed high expression of acrA, acrB, and tolC. Antibiotics usage, antifungal treatment, detection of other pathogens (prior to CREC infection), and respiratory disease were identified as independent risk factors for CREC infection. The area under the receiver operating characteristic curve for the scoring system was 0.937. Youden's index, with sensitivity and specificity of 0.96 and 0.78, was maximal when 2 points were scored.

CONCLUSIONS

In CP-CREC, carbapenem resistance is caused primarily by multiple types of blaNDM, while non-CP-CREC is caused by loss of porin protein or high expression of efflux pumps coupled with carrying blaCTX-M. CREC isolates were highly diverse in terms of ST, with a total of 21 STs identified. Here, we first describe a clinical strain of CREC from China both mcr-1 and blaNDM -4 with ST617. An easy-to-use scoring system was developed to diagnose CREC infections.

Extended-spectrum β-lactamase-producing bacteria and their resistance determinants in different wastewaters and rivers in Nepal

Wastewaters serve as significant reservoirs of antibiotic resistant bacteria. Despite the evidence of antimicrobial resistance in wastewaters and river water in Kathmandu, direct linkage between them is not discussed yet. This study investigated the prevalence of extended-spectrum β-lactamase (ESBL)-producing bacteria and associated resistance genes in wastewaters and river water. Out of 246 bacteria from wastewaters, 57.72% were ESBL producers and 77.64% of them were multidrug resistant (MDR). ESBL producing E. coli was dominant in municipal and hospital wastewaters (HWW) as well as in river water while K. pneumoniae was common in pharmaceutical wastewater. The blaSHV and blaTEM genes were prevalent and commonly co-occurred with aac(6')-Ib-cr in K. pneumoniae isolated pharmaceutical wastewater. blaCTX-M carrying E. coli from hospital co-harbored aac(6')-Ib-cr while that from municipal influent and river water co-harbored qnrS. Whole genome sequencing data revealed the presence of diverse ARGs in bacterial isolates against multiple antibiotics. In average, an E. coli and a K. pneumoniae isolate contained 55.75 ± 0.96 and 40.2 ± 5.36 ARGs, respectively. Multi-locus sequence typing showed the presence of globally high-risk clones with wider host range such as E. coli ST10, and K. pneumoniae ST15 and ST307 in HWW and river indicating frequent dissemination of antimicrobial resistance in wastewater of Kathmandu. Whole genome sequence data aligned with phenotypic antibiograms and resistance genes detected by PCR in selected isolates. The presence of significant plasmid replicons (IncF, IncY) and mobile genetic elements (IS903, IS26) indicate high frequency of spreading antibiotic resistance. These findings indicate burden and dissemination of antimicrobial resistance in the environment and highlight the need for effective strategies to mitigate the antibiotic resistance.

Hospital sewage in Brazil: a reservoir of multidrug-resistant carbapenemase-producing Enterobacteriaceae

The One Health concept recognizes that human health is clearly linked to the health of animals and the environment. Infections caused by bacteria resistant to carbapenem antibiotics have become a major challenge in hospitals due to limited therapeutic options and consequent increase in mortality. In this study, we investigated the presence of carbapenem-resistant Enterobacteriaceae in 84 effluent samples (42 from hospital and 42 from non-hospital) from Campo Grande, midwest Brazil. First, sewage samples were inoculated in a selective culture medium. Bacteria with reduced susceptibility to meropenem and ertapenem were then identified and their antimicrobial susceptibility was determined using the Vitek-2 system. The blaKPC genes were detected using PCR and further confirmed by sequencing. Carbapenem-resistant Enterobacteriaceae (CRE) were identified in both hospital (n=32) and non-hospital effluent (n=16), with the most common being Klebsiella pneumoniae and of the Enterobacter cloacae complex species. This is the first study to indicate the presence of the blaKPC-2 gene in carbapenem-resistant Enterobacteriaceae, classified as a critical priority by the WHO, in hospital sewage in this region. The dissemination of carbapenem antibiotic-resistant genes may be associated with clinical pathogens. Under favorable conditions and microbial loads, resistant bacteria and antimicrobial-resistance genes found in hospital sewage can disseminate into the environment, causing health problems. Therefore, sewage treatment regulations should be implemented to minimize the transfer of antimicrobial resistance from hospitals.

Exploring the presence, genomic traits, and pathogenic potential of extended-spectrum β-lactamase Escherichia coli in freshwater, wastewater, and hospital effluents

AIMS

The purpose of this work was to study extended-spectrum β-lactamase (ESBL)-producing Escherichia coli (ESBL-EC) in freshwaters, hospital effluents, and wastewaters during two sampling campaigns in 2021.

METHODS AND RESULTS

Water sampling was performed at 24 stations in the Ourthe watershed in Belgium. A total of 644 ESBL (n = 642) and AmpC (n = 2) E. coli strains were isolated. Disk-diffusion assays were performed following the EUCAST's recommendations. All strains were tested for the presence of blaCTX-M-1, blaCTX-M-2, and blaCTX-M-9 gene groups by PCR. Genes belonging to blaCTX-M-1 and blaCTX-M-9 groups were detected, respectively, in 73.6% and 14.9% of the strains. No blaCTX-M-2 group's gene was found. A subset of strains (n = 40) was selected for whole genome sequencing. Escherichia coli serotype O18: H7 ST 1463 was predominant (n = 14) in the sequenced strains and showed pathogenicity in the Galleria mellonella larvae model. β-lactamase genes identified were blaCTX-M (n = 21), with blaCTX-M-15 mostly represented (n = 15), as well as blaTEM (n = 11), blaOXA (n = 7), blaSHV (n = 9), and carbapenemase (CP) genes were observed in several strains-blaKPC-3 (n = 19), blaNDM-1 (n = 1), blaVIM-1 (n = 2), and blaOXA-244 (n = 2)-even from freshwaters.

CONCLUSIONS

ESBL-EC are widely distributed in the aquatic environment in Belgium and contain a variety of ESBL and CP genes.

Carbapenem-resistant Enterobacterales in wastewater resources and healthy carriers: A survey in Iran

The carbapenem-resistant Enterobacterales (CRE) pose a pressing public health concern. Here, we investigated the frequency of CRE bacteria, carbapenemase-encoding genes, and the molecular epidemiology of carbapenemase-resistant Escherichia coli in wastewater resources and healthy carriers in Iran. Out of 617 Enterobacterales bacteria, 24% were carbapenem-resistant. The prevalence of CRE bacteria in livestock and poultry wastewater at 34% and hospital wastewater at 33% was significantly higher (P ≤ 0.05) than those in healthy carriers and municipal wastewater at 22 and 17%, respectively. The overall colonization rate of CRE in healthy individuals was 22%. Regarding individual Enterobacterales species, the following percentages of isolates were found to be CRE: E. coli (18%), Citrobacter spp. (24%), Klebsiella pneumoniae (28%), Proteus spp. (40%), Enterobacter spp. (25%), Yersinia spp. (17%), Hafnia spp. (31%), Providencia spp. (21%), and Serratia spp. (36%). The blaOXA-48 gene was detected in 97% of CRE isolates, while the blaNDM and blaVIM genes were detected in 24 and 3% of isolates, respectively. The B2 phylogroup was the most prominent group identified in carbapenem-resistant E. coli isolates, accounting for 80% of isolates. High prevalence of CRE with transmissible carbapenemase genes among healthy people and wastewater in Iran underscores the need for assertive measures to prevent further dissemination.

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.

Simulating a reference medium for determining bacterial growth in hospital wastewater for Raman spectroscopic investigation

Wastewater is a very complex and diverse medium, which despite low nutrient density still harbors bacteria. Especially the wastewater from hospitals contains a high germ load. However, wastewater is also very variable and differs not only from day to day, but also from house to house. Since wastewater is always changing and medium has an impact on Raman spectra of bacteria, it is necessary to find a surrogate material in which bacteria can be cultured to mimic a real hospital wastewater sample. In this study, we investigate two different artificial wastewaters for their abilities as a good alternative to real wastewater from the Jena University Hospital and to serve as a reference material for bacterial cultivation with subsequent Raman measurement. Each of the artificial wastewater on its own was not suitable to be used as a reference medium. Only the combination of the two simulated wastewaters achieved satisfactory results in the Raman spectroscopic identification of bacteria from real wastewater. These results could be used later in new experiments as a reference dataset to identify bacteria from real hospital wastewater samples.

Characterization of bacterial resistance in treated hospital wastewater

This article seeks to characterize the bacterial profile of pediatric hospital wastewater samples collected at the outlet of a wastewater treatment plant, and to estimate their relative susceptibility to antimicrobial agents. A total of 64 strains were isolated in the wastewater samples, of which 49 were identified as belonging to different families: Enterobacteriaceae (e.g. Escherichia coli, Klebsiella sp., Citrobacter sp.) comprised 57.2% of the identified bacteria, non-Enterobacteriaceae (e.g. Aeromonas sp., Pseudomonas sp.) comprised 30.6%, and Streptococcaceae (e.g. Enterococcus sp.) comprised 12.2%. The tests of the susceptibility of the bacteria to the antimicrobial agents used in the hospital showed that 100% of the bacterial species found discharged in the hospital wastewater treatment system were resistant to one or more of the antimicrobial agents according to the criteria of the U.S. Clinical Laboratory Standards Institute/National Committee for Clinical Laboratory Standards. The antimicrobial agent tests showed that meropenem, norfloxacin, ciprofloxacin, levofloxacin, and cefepime were the most effective antimicrobials against bacteria of the Enterobacteriaceae family. For bacteria of the non-Enterobacteriaceae family, norfloxacin, ciprofloxacin, levofloxacin, and cefepime presented the most effective antimicrobial action, whereas for bacteria of the Streptococcaceae family, ampicillin, vancomycin, and gentamicin were the most effective antimicrobials. Hospital wastewater treatment plants could be considered as places of selection pressure for bacterial resistance because of the presence of antibiotic-resistant bacteria coming from sewers or created at the treatment plant.

Deciphering the Role of WWTPs in Cold Environments as Hotspots for the Dissemination of Antibiotic Resistance Genes

Cold environments are the most widespread extreme habitats in the world. However, the role of wastewater treatment plants (WWTPs) in the cryosphere as hotspots in antibiotic resistance dissemination has not been well established. Hence, a snapshot of the resistomes of WWTPs in cold environments, below 5 °C, was provided to elucidate their role in disseminating antibiotic resistance genes (ARGs) to the receiving waterbodies. The resistomes of two natural environments from the cold biosphere were also determined. Quantitative PCR analysis of the aadA, aadB, ampC, blaSHV, blaTEM, dfrA1, ermB, fosA, mecA, qnrS, and tetA(A) genes indicated strong prevalences of these genetic determinants in the selected environments, except for the mecA gene, which was not found in any of the samples. Notably, high abundances of the aadA, ermB, and tetA(A) genes were found in the influents and activated sludge, highlighting that WWTPs of the cryosphere are critical hotspots for disseminating ARGs, potentially worsening the resistance of bacteria to some of the most commonly prescribed antibiotics. Besides, the samples from non-disturbed cold environments had large quantities of ARGs, although their ARG profiles were highly dissimilar. Hence, the high prevalences of ARGs lend support to the fact that antibiotic resistance is a common issue worldwide, including environmentally fragile cold ecosystems.

Longitudinal monitoring reveals the emergence and spread of blaGES-5-harboring carbapenem-resistant Klebsiella quasipneumoniae in a Hong Kong hospital wastewater discharge line

Testing hospital wastewater (HWW) is potentially an effective, long-term approach for monitoring trends in antimicrobial resistance (AMR) patterns in health care institutions. Over a year, we collected wastewater samples from the clinical and non-clinical sites of a tertiary hospital and from a downstream wastewater treatment plant (WWTP). We focused on the extent of carbapenem resistance among Enterobacteriaceae isolates given their clinical importance. Escherichia coli and Klebsiella spp. were the most frequently isolated Enterobacteriaceae species at all sampling sites. Additionally, a small number of isolates belonging to ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species), except K. pneumoniae, were detected. Of the 232 Klebsiella spp. isolates, 100 (43.1 %) were multi-drug resistant (MDR), with 46 being carbapenem-resistant. Most of these carbapenem-resistant isolates were K. quasipneumoniae (CRKQ) (n = 44). All CRKQ isolates were isolated from the wastewater of a clinical site that includes intensive care units, which also yielded significantly more multi-drug resistant isolates compared to all other sampling sites. Among the CRKQ isolates, blaGES-5 genes (n = 42) were the primary genetic determinant of carbapenem resistance. Notably, three different CRKQ isolates, collected within the same month in HWW and the influent and effluent flow of the WWTP, shared >99 % sequence similarity between their blaGES-5 genes and between their flanking regions and upstream integron-integrase region. The influent isolate was phylogenetically close to K. quasipnuemoniae isolates from wastewater collected in Japan. Its blaGES-5 gene and surrounding sequences were > 99 % identical to blaGES-24 genes found in the Japanese isolates. Our results suggest that testing samples from sites located closer to hospitals could support antibiotic stewardship programs compared to samples collected further downstream. Moreover, testing samples collected regularly from WWTPs may reflect the local and global spread of pathogens and their resistances.

Distinctive hospital and community resistomes in Scottish urban wastewater: Metagenomics of a paired wastewater sampling design

The wastewater microbiome contains a multitude of resistant bacteria of human origin, presenting an opportunity for surveillance of resistance in the general population. However, wastewater microbial communities are also influenced by clinical sources, such as hospitals. Identifying signatures of the community and hospital resistome in wastewater is needed for interpretation and risk analysis. In this study, we compare the resistome and microbiome of hospital, community, and mixed municipal wastewater to investigate how and why the composition of these different sites differ. We conducted shotgun metagenomic analysis on wastewater samples from eight wastewater treatment plants (WWTPs), four hospitals, and four community sites in Scotland, using a paired sampling design. Cluster analysis and source attribution random forest models demonstrated that the hospital resistome was distinct from community and WWTP resistomes. Hospital wastewater had a higher abundance and diversity of resistance genes, in keeping with evidence that hospitals act as a reservoir and enricher of resistance. However, this distinctive 'hospital' signature appeared to be weak in the resistome of downstream WWTPs, likely due to dilution. We conclude that hospital and community wastewater resistomes differ, with the hospital wastewater representing a reservoir of patient- and hospital environment-associated bacteria. However, this 'hospital' signature is transient and does not overwhelm the community signature in the resistome of the downstream WWTP influent.

Genomic characterization of tigecycline-resistant Escherichia coli and Klebsiella pneumoniae isolates from hospital sewage

Introduction

The tigecycline-resistant Enterobacterales have emerged as a great public concern, and the mobile tet(X) variants and tmexCD-toprJ efflux pump are mainly responsible for the spread of tigecycline resistance. Hospital sewage is considered as an important reservoir of antimicrobial resistance, while tigecycline resistance in this niche is under-researched.

Methods

In this study, five Escherichia coli and six Klebsiella pneumoniae strains were selected from a collection of tigecycline-resistant Enterobacterales for further investigation by antimicrobial susceptibility testing, conjugation, whole-genome sequencing, and bioinformatics analysis.

Results

All five E. coli strains harbored tet(X4), which was located on different plasmids, including a novel IncC/IncFIA(HI1)/IncHI1A/IncHI1B(R27) hybrid structure. In addition, tet(X4)-bearing plasmids were able to transfer by conjugation and be stabilized in the recipient in the absence of antibiotics. tmexCD1-toprJ1 was identified in two K. pneumoniae (LZSFT39 and LZSRT3) and it was carried by a novel multidrug-resistance transposon, designated Tn7368, on a novel IncR/IncU hybrid plasmid. In addition, we found that two K. pneumoniae (LZSFZT3 and LZSRT3) showed overexpression of efflux genes acrB and oqxB, respectively, which was most likely to be caused by mutations in ramR and oqxR.

Discussion

In conclusion, the findings in this study expand our knowledge of the genetic elements that carry tigecycline resistance genes, which establishes a baseline for investigating the structure diversity and evolutionary trajectories of human, animal, and environmental tigecycline resistomes.

Removal of antibiotic resistant bacteria in wastewater by aggregation-induced emission photosensitizer

The spread of antibiotic resistant bacteria from wastewater to the environment will pose serious threats to human health. It is a potential solution to prepare photosensitizers with broad-spectrum antibacterial activity for use in the photo-oxidation process to supplement the wastewater treatment system. Here, an aggregation-induced emission photosensitizer with D-π-A structure (TBTPy) has been reasonably designed and successfully developed. TBTPy can generate singlet oxygen with extraordinarily high efficiency under white-light irradiation owing to the small singlet-triplet energy gap. TBTPy has a rapid and efficient photo-oxidative killing effect on bacteria and fungi (such as MRSA, S. aureus, E. coli and C. albicans). TBTPy kills bacteria by binding to bacterial surface and releasing singlet oxygen to destroy cell membrane, leading to leakage of bacterial genetic material. This successful case can provide practical guidance for the subsequent development of AIE photosensitizers.

Detection and Characterization of Carbapenemase-Producing Escherichia coli and Klebsiella pneumoniae from Hospital Effluents of Ouagadougou, Burkina Faso

Hospital wastewater is a recognized reservoir for resistant Gram-negative bacteria. This study aimed to screen for carbapenemase-producing Escherichia coli and Klebsiella pneumoniae and their resistance determinants in two hospital effluents of Ouagadougou. Carbapenem-resistant E. coli and K. pneumoniae were selectively isolated from wastewater collected from two public hospitals in Ouagadougou, Burkina Faso. Bacterial species were identified via MALDI-TOF mass spectrometry. Carbapenemase production was studied phenotypically using antibiotic susceptibility testing via the disk diffusion method. The presence of carbapenemases was further characterized by PCR. A total of 14 E. coli (13.59%) and 19 K. pneumoniae (17.92%) carbapenemase-producing isolates were identified with different distributions. They were, respectively, blaNDM (71.43%), blaVIM (42.86%), blaIMP (28.57%), blaKPC (14.29%), blaOXA-48 (14.29%); and blaKPC (68.42%), blaNDM (68.42%), blaIMP (10.53%), blaVIM (10.53%), and blaOXA-48 (5.26%). In addition, eight (57.14%) E. coli and eleven (57.89%) K. pneumoniae isolates exhibited more than one carbapenemase, KPC and NDM being the most prevalent combination. Our results highlight the presence of clinically relevant carbapenemase-producing isolates in hospital effluents, suggesting their presence also in hospitals. Their spread into the environment via hospital effluents calls for intensive antimicrobial resistance (AMR) surveillance.

Genetic plurality of blaKPC-2-harboring plasmids in high-risk clones of Klebsiella pneumoniae of environmental origin

International high-risk clones of Klebsiella pneumoniae are important human pathogens that are spreading to the environment. In the COVID-19 pandemic scenario, the frequency of carbapenemase-producing strains increased, which can contribute to the contamination of the environment, impacting the surrounding and associated ecosystems. In this regard, KPC-producing strains were recovered from aquatic ecosystems located in commercial, industrial, or agricultural areas and were submitted to whole-genome characterization. K. pneumoniae and Klebsiella quasipneumoniae subsp. quasipneumoniae strains were assigned to high-risk clones (ST11, ST340, ST307) and the new ST6325. Virulome analysis showed genes related to putative hypervirulence. Strains were resistant to almost all antimicrobials tested, being classified as extensively drug-resistant or multidrug-resistant. In this context, a broad resistome (clinically important antimicrobials and hazardous metal) was detected. Single replicon (IncX5, IncN-pST15, IncU) and multireplicon [IncFII(K1)/IncFIB(pQil), IncFIA(HI1)/IncR] plasmids were identified carrying the bla_KPC-2 gene with Tn4401 and non-Tn4401 elements. An unusual association of bla_KPC-2 and qnrVC1 and the coexistence of bla_KPC-2 and mer operon (mercury tolerance) was found. Comparative analysis revealed that bla_KPC-2-bearing plasmids were most similar to plasmids from Enterobacterales of Brazil, China, and the United States, evidencing the long persistence of plasmids at the human-animal-environmental interface. Furthermore, the presence of uncommon plasmids, displaying the interspecies, intraspecies, and clonal transmission, was highlighted. These findings alert for the spread of high-risk clones producing bla_KPC-2 in the environmental sector and call attention to rapid dispersion in a post-pandemic world.

Molecular Characterization of Antibiotic Resistance Determinants in Klebsiella pneumoniae Isolates Recovered from Hospital Effluents in the Eastern Cape Province, South Africa

Klebsiella pneumoniae (K. pneumoniae) is an opportunistic bacteria responsible for many nosocomial and community-acquired infections. The emergence and spread of antibiotic resistances have resulted in widespread epidemics and endemic dissemination of multidrug-resistant pathogens. A total of 145 K. pneumoniae isolates were recovered from hospital wastewater effluents and subjected to antibiogram profiling. Furthermore, the antibiotic resistance determinants were assessed among phenotypic resistant isolates using polymerase chain reaction (PCR). The isolates showed a wide range of antibiotic resistance against 21 selected antibiotics under 11 classes, with the most susceptible shown against imipenem (94.5%) and the most resistant shown against ampicillin (86.2%). The isolates also showed susceptibility to piperacillin/tazobactam (89.0%), ertapenem (87.6%), norfloxacin (86.2%), cefoxitin (86.2%), meropenem (76.6%), doripenem (76.6%), gentamicin (76.6%), chloramphenicol (73.1%), nitrofurantoin (71.7%), ciprofloxacin (79.3%), amikacin (60.7%), and amoxicillin/clavulanic acid (70.4%). Conversely, resistance was also recorded against tetracycline (69%), doxycycline (56.6%), cefuroxime (46.2%), cefotaxime (48.3%), ceftazidime (41.4%). Out of the 32 resistance genes tested, 28 were confirmed, with [tetA (58.8%), tetD (47.89%), tetM (25.2%), tetB (5.9%)], [sul1 (68.4%), sul1I (66.6%)], and [aadA (62.3%), strA (26%), aac(3)-IIa(aacC2)^a (14.4%)] genes having the highest occurrence. Strong significant associations exist among the resistance determinants screened. About 82.7% of the K. pneumoniae isolates were multidrug-resistant (MDR) with a multiple antibiotics resistance index (MARI) range of 0.24 to 1.0. A dual presence of the resistant genes among K. pneumoniae was also observed to occur more frequently than multiple presences. This study reveals a worrisome presence of multidrug-resistant K. pneumoniae isolates and resistance genes in hospital waste effluent, resulting in higher public health risks using untreated surface water for human consumption. As a result, adequate water treatment and monitoring initiatives designed to monitor antimicrobial resistance patterns in the aquatic ecosystem are required.

Molecular Characterization and Prevalence of Antimicrobial-Resistant Escherichia coli Isolates Derived from Clinical Specimens and Environmental Habitats

Antibiotic-resistant bacteria (ARB) are present in wastewaters as their elimination during treatment in wastewater treatment plants (WWTPs) is often impossible. Water plays an important role in the spread of these microorganisms among humans, animals and the environment. This study aimed to assess the antimicrobial resistance patterns, resistance genes and molecular genotypes by means of phylogenetic groups of E. coli isolates in aquatic habitats, including sewage and receiving water bodies, as well as clinical settings in the Boeotia regional district of Greece. The highest resistance rates among both environmental and clinical isolates were observed to be for penicillins, ampicillin and piperacillin. Resistance patterns related to extended spectrum β-lactamases (ESBL) production and ESBL genes were also detected in both environmental and clinical isolates. Phylogenetic group B2 was predominant in clinical settings and the second most frequent among wastewaters, whereas group A was dominant in all environmental isolates. In conclusion, the studied river water and wastewaters may serve as reservoirs of resistant E. coli isolates that pose potential threats to both human and animal health.

Performance of a Pilot-Scale Continuous Flow Ozone-Based Hospital Wastewater Treatment System

Antimicrobial resistance (AMR) is becoming a global concern. Recently, research has emerged to evaluate the human and environmental health implications of wastewater from medical facilities and to identify acceptable wastewater treatment methods. In this study, a disinfection wastewater treatment system using an ozone-based continuous flow system was installed in a general hospital located in Japan. The effectiveness of antimicrobial-resistant bacteria (ARB) and antimicrobials in mitigating the environmental impact of hospital wastewater was evaluated. Metagenomic analysis was conducted to characterize the microorganisms in the wastewater before and after treatment. The results demonstrated that ozone treatment enables effective inactivation of general gut bacteria, including Bacteroides, Prevotella, Escherichia coli, Klebsiella, DNA molecules, and ARGs, as well as antimicrobials. Azithromycin and doxycycline removal rates were >99% immediately after treatment, and levofloxacin and vancomycin removal rates remained between 90% and 97% for approximately one month. Clarithromycin was more readily removed than the other antimicrobials (81-91%), and no clear removal trend was observed for ampicillin. Our findings provide a better understanding of the environmental management of hospital wastewater and enhance the effectiveness of disinfection wastewater treatment systems at medical facilities for mitigating the discharge of pollutants into aquatic environments.

Antimicrobial Resistance Is Prevalent in E. coli and Other Enterobacterales Isolated from Public and Private Drinking Water Supplies in the Republic of Ireland

High levels of bacterial antimicrobial resistance (AMR) have been reported in many environmental studies conducted in Ireland and elsewhere. The inappropriate use of antibiotics in both human and animal healthcare as well as concentrations of residual antibiotics being released into the environment from wastewaters are thought to be contributing factors. Few reports of AMR in drinking water-associated microbes are available for Ireland or internationally. We analysed 201 enterobacterales from group water schemes and public and private water supplies, only the latter having been surveyed in Ireland previously. The organisms were identified using conventional or molecular techniques. Antimicrobial susceptibility testing for a range of antibiotics was performed using the ARIS 2X interpreted in accordance with EUCAST guidelines. A total of 53 Escherichia coli isolates, 37 Serratia species, 32 Enterobacter species and enterobacterales from seven other genera were identified. A total of 55% of isolates were amoxicillin resistant, and 22% were amoxicillin-clavulanic acid resistant. A lower level of resistance (<10%) was observed to aztreonam, chloramphenicol, ciprofloxacin, gentamicin, ceftriaxone and trimethoprim-sulfamethoxazole. No resistance to amikacin, piperacillin/tazobactam, ertapenem or meropenem was detected. The level of AMR detected in this study was low but not insignificant and justifies ongoing surveillance of drinking water as a potential source of antimicrobial resistance.

The shared NDM-positive strains in the hospital and connecting aquatic environments

The spread of antibiotic-resistant priority pathogens outside hospital settings is, both, a significant public health concern and an environmental problem. In recent years, New Delhi Metallo-β-lactamase (NDM)-positive strains have caused nosocomial infections with high mortality and poor prognosis worldwide. Our study investigated the links of NDM-positive strains between the hospital and the connecting river system in Jinan city, Eastern China by using NDM-producing Escherichia coli (NDM-EC) as an indicator via whole genome sequencing. Thirteen NDM-EC isolates were detected from 187 river water and sediment samples, while 9 isolates were identified from patients at the local hospital. All NDM-EC isolates were resistant to imipenem, meropenem, cefotaxime, cefoxitin, ampicillin, tetracycline, fosfomycin, piperacillin-tazobactam. The bla_NDM-5 (n = 20) and bla_NDM-9 (n = 2) genes were identified, which were predominantly on IncX3 plasmids (n = 13), followed by IncFII plasmids (n = 5) and IncFIA plasmids (n = 2). Conjugation experiments showed that 21 isolates could transfer NDM-harboring plasmids. The well-conserved bla_NDM-5 genetic environment (ISAba125-bla_NDM-5/9-ble_MBL-trpF-dsbD-IS26) of these plasmids suggested a common genetic origin. Nine sequence types (STs) were detected, including three international high-risk clones ST167 (n = 8), ST410 (n = 1), and ST617 (n = 1). Phylogenetic analysis showed ST167 E. coli from the river was genotypically related to clinical isolates recovered from patients. Furthermore, ST167 isolates showed high genetic similarities with other clinical strains from geographically distinct regions. The genetic concordance between isolates from different sampling sites in the same river (ST218 clone), and different rivers (ST448 clone) raises concerns regarding the rapid dissemination of NDM-EC in the aquatic environment. The emergence and spread of the clinically relevant NDM-positive strains, especially for E. coli ST167 clone, an international high-risk clone associated with multi-resistance and virulence capacity, within and between the hospital and aquatic environments were elucidated, highlighting the need for attention and action.

Ertapenem Supplemented Selective Media as a New Strategy to Distinguish β-Lactam-Resistant Enterobacterales: Application to Clinical and Wastewater Samples

The increase in carbapenem-resistant Enterobacterales (CRE) is mostly driven by the spread of carbapenemase-producing (CP) strains. In New Caledonia, the majority of carbapenemases found are IMP-type carbapenemases that are difficult to detect on routine selective media. In this study, a culture-based method with ertapenem selection is proposed to distinguish non-CRE, non-CP-CRE, and CP-CRE from samples with very high bacterial loads. Firstly, assays were carried out with phenotypically well-characterized β-lactam-resistant Enterobacterales isolates. Then, this approach was applied to clinical and environmental samples. Presumptive CP-CRE isolates were finally identified, and the presence of a carbapenemase was assessed. In a collection of 27 phenotypically well-characterized β-lactam-resistant Enterobacterales, an ertapenem concentration of 0.5 µg·mL^-1 allowed distinguishing CRE from non-CRE. A concentration of 4 µg·mL^-1 allowed distinguishing CP-CRE from non-CP-CRE after nine hours of incubation. These methods allowed isolating 18 CP-CRE from hospital effluents, including the first detection of a KPC in New Caledonia. All these elements show that this cost-effective strategy to distinguish β-lactam-resistant Enterobacterales provides fast and reliable results. This could be applied in the Pacific islands or other resource-limited settings, where limited data are available.

Rapid culture-independent loop-mediated isothermal amplification detection of antimicrobial resistance markers from environmental water samples

Environmental water is considered one of the main vehicles for the transmission of antimicrobial resistance (AMR), posing an increasing threat to humans and animals health. Continuous efforts are being made to eliminate AMR; however, the detection of AMR pathogens from water samples often requires at least one culture step, which is time-consuming and can limit sensitivity. In this study, we employed comparative genomics to identify the prevalence of AMR genes within among: Escherichia coli, Klebsiella, Salmonella enterica and Acinetobacter, using publicly available genomes. The mcr-1, blaKPC (KPC-1 to KPC-4 alleles), blaOXA-48, blaOXA-23 and blaVIM (VIM-1 and VIM-2 alleles) genes are of great medical and veterinary significance, thus were selected as targets for the development of isothermal loop-mediated amplification (LAMP) detection assays. We also developed a rapid and sensitive sample preparation method for an integrated culture-independent LAMP-based detection from water samples. The developed assays successfully detected the five AMR gene markers from pond water within 1 h and were 100% sensitive and specific with a detection limit of 0.0625 μg/mL and 10 cfu/mL for genomic DNA and spiked bacterial cells, respectively. The integrated detection can be easily implemented in resource-limited areas to enhance One Health AMR surveillances and improve diagnostics.

Candida auris Discovery through Community Wastewater Surveillance during Healthcare Outbreak, Nevada, USA, 2022

Candida auris transmission is steadily increasing across the United States. We report culture-based detection of C. auris in wastewater and the epidemiologic link between isolated strains and southern Nevada, USA, hospitals within the sampled sewershed. Our results illustrate the potential of wastewater surveillance for containing C. auris.

Research progress of electrochemical oxidation and self-action of electric field for medical wastewater treatment

A large number of pathogenic microorganisms exist in medical wastewater, which could invade the human body through the water and cause harm to human health. With the global pandemic coronavirus (COVID-19), public health safety become particularly important, and medical wastewater treatment is an important part of it. In particular, electrochemical disinfection technology has been widely studied in medical wastewater treatment due to its greenness, high efficiency, convenient operation, and other advantages. In this paper, the development status of electrochemical disinfection technology in the treatment of medical wastewater is reviewed, and an electrochemical three-stage disinfection system is proposed for the treatment of medical wastewater. Moreover, prospects for the electrochemical treatment of medical wastewater will be presented. It is hoped that this review could provide insight and guidance for the research and application of electrochemical disinfection technology to treat medical wastewater.GRAPHICAL ABSTRACT.

Frequency and diversity of carbapenemase-producing Enterobacterales recovered from untreated wastewater impacted by selective media containing cefotaxime and meropenem in Ohio, USA

As safe agents of last resort, carbapenems are reserved for the treatment of infections caused by multidrug-resistant organisms. The impact of β-lactam antibiotics, cefotaxime, and meropenem on the frequency and diversity of carbapenemase-producing organisms recovered from environmental samples has not been fully established. Therefore, this methodological study aimed at determining β-lactam drugs used in selective enrichment and their impact on the recovery of carbapenemase-producing Enterobacterales (CPE) from untreated wastewater. We used a longitudinal study design where 1L wastewater samples were collected weekly from wastewater treatment plant (WWTP) influent and quarterly from contributing sanitary sewers in Columbus, Ohio USA with 52 total samples collected. Aliquots of 500 mL were passed through membrane filters of decreasing pore sizes to enable all the water to pass through and capture bacteria. For each sample, the resulting filters were placed into two modified MacConkey (MAC) broths, one supplemented with 0.5 μg/mL of meropenem and 70 μg/mL of ZnSO4 and the other supplemented with 2 μg/mL cefotaxime. The inoculated broth was then incubated at 37° C overnight, after which they were streaked onto two types of correspondingly-modified MAC agar plates supplemented with 0.5 μg/mL and 1.0 μg/mL of meropenem and 70 μg/mL of ZnSO4 and incubated at 37°C overnight. The isolates were identified based on morphological and biochemical characteristics. Then, up to four distinct colonies of each isolate's pure culture per sample were tested for carbapenemase production using the Carba-NP test. Matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry (MS) MALDI-TOF MS was used to identify carbapenemase-producing organisms. In total 391 Carba-NP positive isolates were recovered from the 52 wastewater samples: 305 (78%) isolates had blaKPC, 73 (19%) carried blaNDM, and 14 (4%) harbored both blaKPC and blaNDM resistance genes. CPE genes of both blaKPC and blaNDM were recovered in both types of modified MAC broths, with 84 (21%) having a blaKPC gene, 22 (6%) carrying blaNDM and 9 (2%) harbored both a blaKPC and blaNDM of isolates recovered from MAC medium incorporated with 0.5ug/mL meropenem and 70ug/mL ZnSO4. The most prevalent isolates were Klebsiella pneumoniae, Escherichia coli, and Citrobacter spp.

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.

Genomic landscape of blaGES-5- and blaGES-24-harboring Gram-negative bacteria from hospital wastewater: emergence of class 3 integron-associated blaGES-24 genes

OBJECTIVES

This study aimed to characterize Gram negative bacteria carrying bla_GES carbapenemase genes detected in wastewater from a hospital with no history of detection of clinical isolates producing GES carbapenemases.

METHODS

Six hospital effluent samples were screened for carbapenemase-producing organisms (CPO) using CHROMagar mSuperCARBA and MacConkey agar with 1 µg/mL imipenem. Polymerase chain reaction (PCR) amplification and sequencing of carbapenemase genes, multilocus sequence typing, antimicrobial susceptibility testing, and whole-genome sequencing were performed.

RESULTS

Among 21 CPO isolates, 11 Klebsiella spp. and 5 Enterobacter kobei isolates carried bla_GES-24, and 4 E. roggenkampii and 1 Pseudomonas aeruginosa isolates carried bla_GES-5. Genomic analysis of 8 representative isolates comprising 6 bla_GES-24-positive and 2 bla_GES-5-positive revealed that class 3 integrons with complete or defective Tn402-like transposition modules were predominantly associated with two tandem copies of bla_GES-24. Furthermore, a total of 5 new class 3 integrons, In3-18 to In3-22, were identified among 5 bla_GES-24 and 1 bla_GES-5 plasmids. One strain each of K. pneumoniae subsp. pneumoniae and K. quasipneumoniae subsp. similipneumoniae harboring bla_GES-24 plasmids also carried a rare bla_VEB-1-positive class 1 integron on a non-typeable plasmid, where these bla_VEB-1 plasmids had high sequence similarity. Virulence gene profiles differed between Klebsiella spp. and Enterobacter spp.; the former harbored type III fimbriae cluster, salmochelin, and T6SS type i2 gene clusters, while the latter had curli pili operon, aerobactin, T2SS gene clusters, and T6SS type i3 gene clusters.

CONCLUSION

Our findings confirmed the linkage of bla_GES-24 with rare Tn402-like class 3 integrons and the structural diversity of their gene cassette arrays.

Evaluation of culturable 'last-resort' antibiotic resistant pathogens in hospital wastewater and implications on the risks of nosocomial antimicrobial resistance prevalence

Antimicrobial resistance has been recognized as an important emerging environmental pollutant. 'Last-resort' antibiotics including tigecycline, polymyxin E, daptomycin, vancomycin and linezolid are the 'last line of defence' for antibiotic resistant pathogen infections. Therefore, the presence of 'last-resort' antibiotic resistant pathogens in hospital environments and the nosocomial transmission of 'last-resort' antibiotic resistance poses a grave threat to the well-being of patients. In this work, the extent of resistance to 'last-resort' antibiotics in culturable pathogens in hospital wastewater was investigated. Resistance to 'last-resort' antibiotics were quantified for 1384 culturable Enterobacteriaceae, Enterococcus, Staphylococcus, and Pseudomonas strains. With these investigations, several significant findings were made: (1) a very high level of resistance to 'last-resort' antibiotics was found; (2) multiple resistance to antibiotics, including 'last-resort' antibiotics, was prevalent; (3) a high level of 'last-resort' antibiotic resistance phenotype-genotype inconsistency was found, suggesting knowledge gap for resistance mechanisms; 4) tet(X4)-containing tigecycline-resistant Gram-positive pathogens were found for the first time; 5) wastewater treatment processes are effective in preventing the release of 'last-resort' antibiotic resistant pathogens to the environment. This investigation reveals the severe situation on 'last-resort' resistance in the hospital environment, and implies high risk for nosocomial transmission of 'last-resort' antibiotic resistant pathogens.

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.

Occurrence of Antimicrobial-Resistant Escherichia coli in Marine Mammals of the North and Baltic Seas: Sentinels for Human Health

Antimicrobial resistance is a global health threat that involves complex, opaque transmission processes in the environment. In particular, wildlife appears to function as a reservoir and vector for antimicrobial-resistant bacteria as well as resistance genes. In the present study, the occurrence of antimicrobial-resistant Escherichia coli was determined in marine mammals and various fish species of the North and Baltic Seas. Rectal or faecal swabs were collected from 66 live-caught or stranded marine mammals and 40 fish specimens. The antimicrobial resistance phenotypes and genotypes of isolated E. coli were determined using disk diffusion tests and PCR assays. Furthermore, isolates were assigned to the four major phylogenetic groups of E. coli. Additionally, post mortem examinations were performed on 41 of the sampled marine mammals. The investigations revealed resistant E. coli in 39.4% of the marine mammal samples, while no resistant isolates were obtained from any of the fish samples. The obtained isolates most frequently exhibited resistance against aminoglycosides, followed by β-lactams. Of the isolates, 37.2% showed multidrug resistance. Harbour porpoises (Phocoena phocoena) mainly carried E. coli isolates belonging to the phylogenetic group B1, while seal isolates were most frequently assigned to group B2. Regarding antimicrobial resistance, no significant differences were seen between the two sampling areas or different health parameters, but multidrug-resistant isolates were more frequent in harbour porpoises than in the sampled seals. The presented results provide information on the distribution of antimicrobial-resistant bacteria in the North and Baltic Seas, and highlight the role of these resident marine mammal species as sentinels from a One Health perspective.

Microbial Resistance to Carbapenems in Effluents from Gynaecological, Paediatric and Surgical Hospital Units

The aim of this work is to identify and count antimicrobial resistance (AMR) in hospital effluents (HEs) of 2 units of the University Hospital Mohamed VI the Mother and Child Hospital (MCH) and the Ar-razi Surgical Hospital (ArzH), and to compare the two hospital units in terms of ARMs and seasonal variation. Each HE was sampled during 2016 and 2017. After identification of the pathogenic strains and determination of AMR, the results were reported for 24 ABs, including 3 carbapenems (CBP), and their consumption rates. The Predicted environmental concentration (PEC) rate of carbapenems in the HE of the study sites is calculated. A comparative analysis of the AMR of the isolated bacterial species was performed and related to the evolution of PEC in HEs. In the ArzH effluents:15 strains isolated, 7 are carbanepenem-resistant Enterobacteria (CRE) and are resistant to at least one of the 3 carbapenems tested. ArzH and MCH effluents respectively show some similarities: 26.87% and 28.57% of isolated bacteria are resistant to ertapenem while 43.48% and 57.14% are resistant to meropenem. However, for imipenem, the MCH effluent has a higher percentage of bacterial antibiotic resistance than ArzH. In addition, the percentage of resistance in each hospital unit effluent is mainly in relation with the increasing antibiotic consumption and predicted environmental values PEC for very antibiotic in each unit in the same period.

High Rates of Multidrug-Resistant Escherichia coli in Great Cormorants (Phalacrocorax carbo) of the German Baltic and North Sea Coasts: Indication of Environmental Contamination and a Potential Public Health Risk

Antimicrobial-resistant bacteria pose a serious global health risk for humans and animals, while the role of wildlife in the dynamic transmission processes of antimicrobial resistance in environmental settings is still unclear. This study determines the occurrence of antimicrobial-resistant Escherichia coli in the free-living great cormorants (Phalacrocorax carbo) of the North and Baltic Sea coasts of Schleswig-Holstein, Germany. For this, resistant E.coli were isolated from cloacal or faecal swabs and their antimicrobial resistance pheno- and genotypes were investigated using disk diffusion tests and PCR assays. The isolates were further assigned to the four major phylogenetic groups, and their affiliation to avian pathogenic E. coli (APEC) was tested. Resistant E. coli were isolated from 66.7% of the 33 samples, and 48.9% of all the resistant isolates showed a multidrug resistance profile. No spatial differences were seen between the different sampling locations with regard to the occurrence of antimicrobial resistance or multidrug resistance. Most commonly, resistance percentages occurred against streptomycin, followed by tetracycline and sulfonamides. More than half of the isolates belonged to the phylogenetic group B1. Of all the isolates, 24.4% were classified as APEC isolates, of which almost 82% were identified as multidrug-resistant. These results add information on the dispersal of antimicrobial-resistant bacteria in wild birds in Germany, thereby allowing conclusions on the degree of environmental contamination and potential public health concerns.

Monitoring Carbapenem-Resistant Enterobacterales in the Environment to Assess the Spread in the Community

The usefulness of wastewater-based epidemiology (WBE) was proven during the COVID-19 pandemic, and the role of environmental monitoring of emerging infectious diseases has been recognized. In this study, the prevalence of carbapenem-resistant Enterobacterales (CRE) in Japanese environmental samples was measured in the context of applying WBE to CRE. A total of 247 carbapenem-resistant isolates were obtained from wastewater, treated wastewater, and river water. Treated wastewater was shown to be an efficient target for monitoring CRE. The results of the isolate analysis showed that WBE may be applicable to Escherichia coli-carrying New Delhi metallo-β-lactamase (NDM)-type carbapenemase, the Enterobacter cloacae complex and Klebsiella pneumoniae complex-carrying IMP-type carbapenemase. In addition, a certain number of CRE isolated in this study carried Guiana extended spectrum (GES)-type carbapenemase although their clinical importance was unclear. Only a few isolates of Klebsiella aerogenes were obtained from environmental samples in spite of their frequent detection in clinical isolates. Neither the KPC-type, the oxacillinase (OXA)-type nor the VIM-type of carbapenemase was detected in the CRE, which reflected a low regional prevalence. These results indicated the expectation and the limitation of applying WBE to CRE.

Occurrence of antibiotics and bacterial resistance genes in wastewater: resistance mechanisms and antimicrobial resistance control approaches

Antimicrobial pharmaceuticals are classified as emergent micropollutants of concern, implying that even at low concentrations, long-term exposure to the environment can have significant eco-toxicological effects. There is a lack of a standardized regulatory framework governing the permissible antibiotic content for monitoring environmental water quality standards. Therefore, indiscriminate discharge of antimicrobials at potentially active concentrations into urban wastewater treatment facilities is rampant. Antimicrobials may exert selective pressure on bacteria, leading to resistance development and eventual health consequences. The emergence of clinically important multiple antibiotic-resistant bacteria in untreated hospital effluents and wastewater treatment plants (WWTPs) has been linked to the continuous exposure of bacteria to antimicrobials. The levels of environmental exposure to antibiotics and their correlation to the evolution and spread of resistant bacteria need to be elucidated to help in the formulation of mitigation measures. This review explores frequently detected antimicrobials in wastewater and gives a comprehensive coverage of bacterial resistance mechanisms to different antibiotic classes through the expression of a wide variety of antibiotic resistance genes either inherent and/or exchanged among bacteria or acquired from the reservoir of antibiotic resistance genes (ARGs) in wastewater systems. To complement the removal of antibiotics and ARGs from WWTPs, upscaling the implementation of prospective interventions such as vaccines, phage therapy, and natural compounds as alternatives to widespread antibiotic use provides a multifaceted approach to minimize the spread of antimicrobial resistance.

Carbapenemase producing Enterobacteriaceae: Environmental reservoirs as primary targets for control and prevention strategies

Carbapenemase-producing Enterobacteriaceae (CPE) have become one of the greatest public health challenges globally. In the past decade, antimicrobial resistance (AMR) was viewed as a clinical problem in many parts of the world; hence, the role and magnitude of the contribution of the environment were not well appreciated. This review article was done with online published articles extracted from different databases using search terms related to the work. Evidence has shown that there exists the presence of carbapenemase genes in the environment, consequently fuelling the dissemination with alarming consequences. CPE when acquired causes life-threatening infections in humans. The health and economic impact of these infections are numerous, including treatment failure due to limited therapeutic options which hamper the containment of infectious diseases, further contaminating the environment and worsening the public health challenge. It is a well-known fact that the rate of emergence of resistant genes has outpaced the production of new antimicrobial agents, so it is pertinent to institute effective environmental measures to combat the spread of AMR organisms before it will completely gain a foothold and take us back to 'the pre-antibiotic era'. Environmental sources and reservoirs of resistant genes should therefore be amongst the primary targets for the control and prevention of the spread of resistant genes in the environment. This calls for the effective implementation of the 'one health' strategy with stakeholders committed to the design and enforcement of environmental mitigation policies and guidelines.

KPC-3-, GES-5-, and VIM-1-Producing Enterobacterales Isolated from Urban Ponds

Carbapenems are antibiotics of pivotal importance in human medicine, the efficacy of which is threatened by the increasing prevalence of carbapenem-resistant Enterobacterales (CRE). Urban ponds may be reservoirs of CRE, although this hypothesis has been poorly explored. We assessed the proportion of CRE in urban ponds over a one-year period and retrieved 23 isolates. These were submitted to BOX-PCR, PFGE, 16S rDNA sequencing, antibiotic susceptibility tests, detection of carbapenemase-encoding genes, and conjugation assays. Isolates were affiliated with Klebsiella (n = 1), Raoultella (n = 11), Citrobacter (n = 8), and Enterobacter (n = 3). Carbapenemase-encoding genes were detected in 21 isolates: bla_KPC (n = 20), bla_GES-5 (n = 6), and bla_VIM (n = 1), with 7 isolates carrying two carbapenemase genes. Clonal isolates were collected from different ponds and in different campaigns. Citrobacter F6, Raoultella N9, and Enterobacter N10 were predicted as pathogens from whole-genome sequence analysis, which also revealed the presence of several resistance genes and mobile genetic elements. We found that bla_KPC-3 was located on Tn4401b (Citrobacter F6 and Enterobacter N10) or Tn4401d (Raoultella N9). The former was part of an IncFIA-FII pBK30683-like plasmid. In addition, bla_GES-5 was in a class 3 integron, either chromosomal (Raoultella N9) or plasmidic (Enterobacter N10). Our findings confirmed the role of urban ponds as reservoirs and dispersal sites for CRE.

Population-based variations of a core resistome revealed by urban sewage metagenome surveillance

Sewage-based surveillance is widely employed to understand the occurrence and distribution of antimicrobial resistance (AMR) in urban community. However, there are limited studies which investigated the sewage of different sources within community. The present study used metagenomics to decipher the AMR profiles in five sources: local residence's source, animal source, migrant workers' source, clinical source , and urban wastewater treatment plant influent. A core resistome of ARGs was found across all samples, accounting for 81.4%-93.3% of the abundance of total resistome with only 17.3% diversity, irrespective of the sewage sources. Clinically relevant ARGs were identified in the core resistome across all wastewater sources. This included genes conferring resistance to beta-lactams as biomarkers of hospital sewage. The pet center wastewater showed a high abundance of genes encoding resistance to tetracycline, which is a commonly used veterinary antibiotic. The resistome profile of sewage from the migrant workers' dormitories showed a slight variation to that of the local residential population, suggesting possible differences in the human gut resistome of the foreign/migrant population, with biomarkers of genes encoding resistance to fosfomycin, fosmidomycin, kasugamycin, MLS, and polymyxin. The co-localization of ARGs and plasmid, MGEs and integrative and conjugative elements (ICEs) could explain variations in the core resistome, presumably a result of high antibiotic selection pressure. Further analysis showed a specific host-associated resistance pattern, in which core hosts mediated the core resistome profile. The core BMRGs were also co-localized with MGEs/ICEs and carried by core potential bacterial hosts. Local healthy population carried the lowest ARG load (copy number discharged by each person per day) but contributed the highest ARG burden (copy number discharged by the population). This study elucidates population-based variations of a core resistome, and further provides important insights into source tracking and management of AMR in urban environments.

High burden and diversity of carbapenemase-producing Enterobacterales observed in wastewater of a tertiary care hospital in Germany

Hospitals are one of the main reservoirs of multi-resistant Enterobacterales (MRE). As MRE are resistant to the most frequently used antibiotics, therapy for patients with MRE infections is challenging. It has been previously described that MRE from hospital wastewater can pass into municipal wastewater and even surface water. In this study, we investigated the diversity and epidemiology of MRE in the wastewater of a large tertiary care hospital. Wastewater samples were collected for a four-day period and tested for the presence of Enterobacterales resistant to 3rd gen. cephalosporins. Representative isolates were further characterized by whole genome sequencing. In 120 β-glucuronidase-producing isolates, 68 Escherichia coli and, interestingly, also 52 Citrobacter freundii were identified. In 120 β-glucosidase-producing isolates 45 Serratia marcescens, 34 Klebsiella oxytoca, 32 Enterobacter cloacae and 9 Klebsiella pneumoniae were observed. For all species various MLST sequence types and different clusters of resistance genes were determined, showing a great diversity within the different Enterobacterales, further corroborated by clonal analysis performed by cgMLST. The most prominent clone was wastewater associated E. coli ST635, which accounted for 47.1% of all E. coli isolates. Interestingly, 45.6% of E. coli, 88.5% of C. freundii, 95.6% of S. marcescens, 91.2% of K. oxytoca, 96.9% of E. cloacae and 88.9% of K. pneumoniae isolates carried a carbapenemase gene, indicating a high burden with carbapenemase-producing Enterobacterales. Comparison with clinical isolates from the same hospital displayed few clonal matches. One wastewater isolate of K. pneumoniae was identified to be closely related compared to a clone that had been introduced into the hospital during an outbreak four years earlier. One E. coli isolate was identified as identical to an isolate from a patient, with inpatient stay during the sampling period. The data obtained in this study highlight the problem of antibiotic resistance of Enterobacterales in hospital wastewater. In particular, the clustered occurrence of carbapenemase genes is of great concern and underscores the problem of increasingly scarce antibiotic options against these bacteria.

Evaluation of the Correspondence between the Concentration of Antimicrobials Entering Sewage Treatment Plant Influent and the Predicted Concentration of Antimicrobials Using Annual Sales, Shipping, and Prescriptions Data

The accuracy and correspondence between the measured concentrations from the survey and predicted concentrations on the basis of the three types of statistical antimicrobial use in Japan was evaluated. A monitoring survey of ten representative antimicrobials: ampicillin (APL), cefdinir (CDN), cefpodoxime proxetil (CPXP), ciprofloxacin (CFX), clarithromycin (CTM), doxycycline (DCL), levofloxacin (LFX), minocycline (MCL), tetracycline (TCL), and vancomycin (VMC), in the influent of sewage treatment plant (STP) located in urban areas of Japan, was conducted. Then, the measured values were verified in comparison with the predicted values estimated from the shipping volumes, sales volumes, and prescription volumes based on the National Database of Health Insurance Claims and Specific Health Checkups of Japan (NDB). The results indicate that the correspondence ratios between the predicted concentrations calculated on the basis of shipping and NDB volumes and the measured concentrations (predicted concentration/measured concentration) generally agreed for the detected concentration of antimicrobials in the STP influent. The correspondence ratio on the basis of shipping volume was, for CFX, 0.1; CTM, 2.9; LFX, 0.5; MCL, 1.9; and VMC, 1.7, and on the basis of NDB volume the measured concentration was CFX, 0.1; CTM, 3.7; DCL, 0.4; LFX, 0.7; MCL, 1.9; TCL, 0.6; and VMC, 1.6. To our knowledge, this is the first report to evaluate the accuracy of predicted concentrations based on sales, shipping, NDB statistics and measured concentrations for antimicrobials in the STP influent.

Reflections on a national public health emergency response to carbapenemase-producing Enterobacterales (CPE)

Carbapenemase-producing Enterobacterales (CPE) are important globally. In 2017, Ireland declared a national public health emergency to address CPE in acute hospitals. A National Public Health Emergency Team and an expert advisory group (EAG) were established. The EAG has identified key learnings to inform future strategies. First, there is still an opportunity to prevent CPE becoming endemic. Second, damp environmental reservoirs in hospitals are inadequately controlled. Third, antibiotic stewardship remains important in control. Finally, there is no current requirement to extend screening to detect CPE outside of acute hospitals. These conclusions and their implications may also be relevant in other countries.

Dissemination of carbapenem resistant bacteria from hospital wastewater into the environment

Infections with antibiotic resistant pathogens threaten lives and cause substantial costs. For effective interventions, knowledge of the transmission paths of resistant bacteria to humans is essential. In this study, carbapenem resistant bacteria were isolated from the wastewater of a maximum care hospital during a period of two years, starting in the patient rooms and following the sewer system to the effluent of the wastewater treatment plant (WWTP). The bacteria belonged to six different species and 44 different sequence types (STs). The most frequent STs, ST147 K. pneumoniae (bla_NDM/bla_OXA-48) and ST235 P. aeruginosa (bla_VIM) strains, were present at nearly all sampling sites from the hospital to the WWTP effluent. After core genome multi-locus sequence typing (cgMLST), all ST147 K. pneumoniae strains presented a single epidemiological cluster. In contrast, ST235 P. aeruginosa formed five cgMLST clusters and the largest cluster contained the strain from the WWTP effluent, indicating without doubt, a direct dissemination of both high-risk clones into the environment. Thus, there are - at least two - possible transmission pathways to humans, (i) within the hospital by contact with the drains of the sanitary installations and (ii) by recreational or irrigation use of surface waters that have received WWTP effluent. In conclusion, remediation measures must be installed at both ends of the wastewater system, targeting the drains of the hospital as well as at the effluent of the WWTP.

Natural recreational waters and the risk that exposure to antibiotic resistant bacteria poses to human health

Antimicrobial resistance (AMR) is widely recognised as a considerable threat to human health, wellbeing and prosperity. Many clinically important antibiotic resistance genes are understood to have originated in the natural environment. However, the complex interactions between humans, animals and the environment makes the health implications of environmental AMR difficult to quantify. This narrative review focuses on the current state of knowledge regarding antibiotic resistant bacteria (ARB) in natural bathing waters and implications for human health. It considers the latest research focusing on the transmission of ARB from bathing waters to humans. The limitations of existing evidence are discussed, as well as research priorities. The authors are of the opinion that future studies should include faecally contaminated bathing waters and people exposed to these environments to accurately parameterise environment-to-human transmission.

Slaughterhouse wastewater as a reservoir for extended-spectrum β-lactamase (ESBL)-producing, and colistin-resistant Klebsiella spp. and their impact in a "One Health" perspective

Klebsiella spp. are ubiquitous bacteria capable of colonizing humans and animals, and sometimes leading to severe infections in both. Due to their high adaptability against environmental/synthetic conditions as well as their potential in aquiring antimicrobial/metal/biocide resistance determinants, Klebsiella spp. are recognized as an emerging threat to public health, worldwide. Currently, scarce information on the impact of livestock for the spread of pathogenic Klebsiella spp. is available. Thus, the phenotypic and genotypic properties of extended-spectrum β-lactamase-producing, and colistin-resistant Klebsiella strains (n = 185) from process- and wastewater of two poultry and pig slaughterhouses as well as their receiving municipal wastewater treatment plants (mWWTPs) were studied to determine the diversity of isolates that might be introduced into the food-production chain or that are released into the environment by surviving the wastewater treatment. Selectively-isolated Klebsiella spp. from slaughterhouses including effluents and receiving waterbodies of mWWTPs were assigned to various lineages, including high-risk clones involved in human outbreaks, and exhibited highly heterogeneous antibiotic-resistance patterns. While isolates originating from poultry slaughterhouses showed the highest rate of colistin resistance (32.4%, 23/71), carbapenem-resistant Klebsiella spp. were only detected in mWWTP samples (n = 76). The highest diversity of resistance genes (n = 77) was detected in Klebsiella spp. from mWWTPs, followed by isolates from pig (n = 56) and poultry slaughterhouses (n = 52). Interestingly, no carbapenemase-encoding genes were detected and mobile colistin resistance genes were only obeserved in isolates from poultry and pig slaughterhouses. Our study provides in-depth information into the clonality of livestock-associated Klebsiella spp. and their determinants involved in antimicrobial resistance and virulence development. On the basis of their pathogenic potential and clinical importance there is a potential risk of colonization and/or infection of wildlife, livestock and humans exposed to contaminated food and/or surface waters.