Spatiotemporal distribution, interactions and toxic effect of microorganisms and ARGs/MGEs from the bioreaction tank in hospital sewage treatment facility

Antibiotic resistance genes (ARGs) can be emitted from wastewater to ambient air and impose unignorable inhalable hazards, which could be exacerbated in antibiotic-concentrated hospital sewage. However, whether the ARG-carrying pathogens are more likely to infect cells remains largely unknown. Here, this study investigated and analyzed the spatiotemporal distribution, interaction, and toxicity of airborne microorganisms and their hosting ARGs in a hospital sewage treatment facility. The average concentration of ARGs/MGEs in sewage of bioreaction tank (BRT-W) was 2.27 × 104 gene copies/L. In the air of bioreaction tank (BRT-A), the average concentration of ARGs/MGEs was 15.86 gene copies/m3. In the four seasons, the ARGs concentration of sewage gradually decreased over time; The concentration of ARGs in the air first decreased and then increased. In spring, the concentration of ARGs/MGEs (qacedelta1-01) in BRT-W was highest (1.05 × 105 gene copies/L); The concentration of ARGs/MGEs (strB) in BRT-A in winter was higher than other seasons (26.18 gene copies/m3). Different from the past, this study also paid attention to the pathogenic potential of ARGs/MGEs in the air. The results of cell experiments showed that the cytotoxicity of drug-resistant Escherichia coli could reach Grade V. This suggested that the longer the drug-resistant E. coli were exposed to cells, the greater the cytotoxicity. Moreover, the cytotoxicity of bacteria increased with the increase in exposure time. In spring, the toxic effect of ARGs/MGEs in sewage of BRT-W was highest. Traceability analysis proved that BRT-W was an essential source of microorganisms and ARGs/MGEs in BRT-A. Furthermore, the combined risk of people exposed to the air of BRT in spring was higher than that in other seasons.

Identification of TMexCD-TOprJ-producing carbapenem-resistant Gram-negative bacteria from hospital sewage

Carbapenems and tigecycline are crucial antimicrobials for the treatment of gram-negative bacteria infections. Recently, a novel resistance-nodulation-division (RND) efflux pump gene cluster, tmexCD-toprJ, which confers resistance to tigecycline, has been discovered in animals and clinical isolates. It was reported that hospital sewage could act as a reservoir for gram-negative bacteria with high antimicrobial resistance genes. In this study, we analyzed 84 isolates of carbapenem-resistant gram-negative bacteria (CR-GNB) from hospital sewage, and identified five isolates of TMexCD-ToprJ-producing CR-GNB, including one Raoultella ornithinolytica isolate and four Pseudomonas spp. isolates. All these five isolates carried at least one carbapenem resistance gene and were resistant to multiple antibiotics. Multiple tmexCD-toprJ clusters were detected, including tmexC2D2-toprJ2, tmexC3D3-toprJ3, tmexC3.2D3.3-toprJ1b and tmexC3.2D3-toprJ1b. Among these clusters, the genetic construct of tmexC3.2D3-toprJ1b showed 2-fold higher minimum inhibitory concentration (MIC) of tigecycline than other three variants. In addition, it was found that the tmexCD-toprJ gene cluster was originated from Pseudomonas spp. and mainly located on Tn6855 variants inserted in the same umuC-like genes on chromosomes and plasmids. This unit co-localized with blaIMP or blaVIM on IncHI5-, IncpJBCL41- and IncpSTY-type plasmids in the five isolates of TMCR-GNB. The IncHI5- and IncpSTY-type plasmids had the ability to conjugal transfer to E. coli J53 and P. aeruginosa PAO1, highlighting the potential risk of transfer of tmexCD-toprJ from Pseudomonas spp. to Enterobacterales. Importantly, genomic analysis showed that similar tmexCD-toprJ-harboring IncHI5 plasmids were also detected in human samples, suggesting transmission between environmental and human sectors. The emergence of TMCR-GNB from hospital sewage underscores the need for ongoing surveillance of antimicrobial resistance genes, particularly the novel resistance genes such as the tmexCD-toprJ gene clusters in the wastewater environment.

Seasonal analysis of commonly prescribed antibiotics in Istanbul city

Antibiotics are among the most common medicine groups since they are used to treat infectious diseases, as nutritional supplements in livestock breeding, and for preservation in the food industry. Turkey is among the highest antibiotic consumers in the world. In the present study, the most popular 14 antibiotics available in Turkey were monitored in one hospital sewage and two urban wastewater treatment plant influents and effluents seasonally in Istanbul province, the largest metropolitan center in Turkey. The present research aimed to develop a robust analytical method to determine 14 antibiotics, including six chemical groups, in environmental matrices which are considered significant antibiotic pollution sources, namely hospital sewage and urban wastewater. Solid-phase extraction (SPE) and UPLC-MS/MS analysis parameters included optimized column temperature, eluent, mobile phase, and flow rate. Three SPE cartridges were employed in recovery studies. The antibiotic recovery rates varied between 40 and 100%, and all analytes were identified within 3 min with UPLC-MS/MS under optimal conditions. It was determined that method detection limits (MDLs) varied between 0.07 and 2.72 µg/L for the antibiotics. In all seasons, the highest beta-lactam group antibiotic concentrations were identified in hospital sewage. The season with the greatest variety of antibiotics in urban wastewater was spring. Clarithromycin and ciprofloxacin were the antibiotics determined at the highest concentration in the influent and effluent of the wastewater treatment plant in all seasons. This study showed that the most widely used beta-lactam group antibiotics were found in high amounts in hospital sewage wastewater but in low concentrations in the treatment plants, and hence, it is seen that the degradability of beta-lactam group antibiotics was high. The presence of clarithromycin, ciprofloxacin, lincomycin, levofloxacin, and trimethoprim antibiotics in hospital sewage in higher amounts and also in inlet and outlet of wastewater treatment plants proves that those are resistant antibiotics.

Phage-based therapy against biofilm producers in gram-negative ESKAPE pathogens

Persistent antibiotic use results in the rise of antimicrobial resistance with limited or no choice for multidrug-resistant (MDR) and extensively drug resistant (XDR) bacteria. This necessitates a need for alternative therapy to effectively combat clinical pathogens that are resistant to last resort antibiotics. The study investigates hospital sewage as a potential source of bacteriophages to control resistant bacterial pathogens. Eighty-one samples were screened for phages against selected clinical pathogens. Totally, 10 phages were isolated against A. baumannii, 5 phages against K. pneumoniae, and 16 phages were obtained against P. aeruginosa. The novel phages were observed to be strain-specific with complete bacterial growth inhibition of up to 6 h as monotherapy without antibiotics. Phage plus colistin combinations reduced the minimum-biofilm eradication concentration of colistin up to 16 folds. Notably, a cocktail of phages exhibited maximum efficacy with complete killing at 0.5-1 μg/ml colistin concentrations. Thus, phages specific to clinical strains have a higher edge in treating nosocomial pathogens with their proven anti-biofilm efficacy. In addition, analysis of phage genomes revealed close phylogenetic relations with phages reported from Europe, China, and other neighbouring countries. This study serves as a reference and can be extended to other antibiotics and phage types to assess optimum synergistic combinations to combat various drug resistant pathogens in the ongoing AMR crisis.

Sewage from a secondary hospital in Ribeirão Preto, southeastern Brazil: a source of multidrug-resistant Enterobacteriaceae

Antimicrobial resistance is one of the severe threats to global health. Hospital sewage can serve as a reservoir for multi-resistant bacteria and promote the spread of antimicrobial resistance. This study aimed to investigate the antimicrobial susceptibility and the pathogenic potential of Enterobacteriaceae isolated from the sewage of a secondary hospital in Ribeirão Preto, a city in southeastern Brazil. The strains were isolated by membrane filtration and identified by matrix-assisted laser desorption ionization-time of flight (MALDI-TOF). The antimicrobial susceptibility profile was performed by disk diffusion. Polymerase chain reaction (PCR) assays were used to detect virulence genes among the strains. Twenty-eight isolates were obtained, with Klebsiella pneumoniae being the predominant species (71.4%, n = 20). All isolates were classified as multidrug-resistant, including four isolates that were non-susceptible to at least 50% of the tested antibiotics. All isolates were also non-susceptible to cefuroxime and sulfonamides antibiotics; however, they were susceptible to norfloxacin, ofloxacin, amikacin, gentamicin, netilmicin, ertapenem, cefazolin, cefaclor, and cefotetan. The virulence genes ycfM, fimH, mrkD, kfu, and entB were detected in several isolates. Our study showed that even in a secondary hospital, without the routine of major surgeries and intensive care admissions, the hospital sewage can harbor a high percentage of multidrug-resistant bacteria with pathogenic potential. This leads to the worrying risk of public health and environmental contamination.

Multidrug-resistant and potentially pathogenic Enterobacteriaceae found in a tertiary hospital sewage in southeastern Brazil

Hospital sewage is considered an environment with the potential to favor the spread and increase of multidrug-resistant bacteria (MDR). The increase in antimicrobial resistance is one of the greatest global threats today. Therefore, this study aimed to evaluate the profile of antimicrobial susceptibility and virulence factors in Enterobacteriaceae isolated from the sewage of a tertiary hospital located in southeastern Brazil. For bacterial isolation, membrane filtering, serial dilution, and spread-plate techniques were used. The bacterial isolates were identified using the MALDI-TOF (matrix-assisted laser desorption ionization-time of flight) technique. Antimicrobial susceptibility profile was performed by disk-diffusion test. Virulence genes were screened by Polymerase Chain Reaction (PCR) and the hypermucoviscosity phenotype by string test. In total, 13 enterobacteria distributed in three species were identified (Klebsiella pneumoniae, Escherichia coli, and Citrobacter freundii) and 76.9% (n = 10) were classified as MDR. Two K. pneumoniae demonstrated the hypermucoviscosity phenotype. The virulence genes ycfM and entB were detected in all K. pneumoniae isolates (other genes found were fimH, mrkD, and kfu). The results indicated that the sewage from the analyzed hospital receives MDR bacteria and has the potential to contaminate and spread through the environment.

Monitoring of hospital sewage shows both promise and limitations as an early-warning system for carbapenemase-producing Enterobacterales in a low-prevalence setting

Carbapenemase-producing Enterobacterales (CPE) constitute a significant threat to healthcare systems. Continuous surveillance is important for the management and early warning of these bacteria. Sewage monitoring has been suggested as a possible resource-efficient complement to traditional clinical surveillance. It should not least be suitable for rare forms of resistance since a single sewage sample contains bacteria from a large number of individuals. Here, the value of sewage monitoring in early warning of CPE was assessed at the Sahlgrenska University Hospital in Gothenburg, Sweden, a setting with low prevalence of CPE. Twenty composite hospital sewage samples were collected during a two-year period. Carbapenemase genes in the complex samples were analyzed by quantitative PCR and the CPE loads were assessed through cultures on CPE-selective agar followed by species determination as well as phenotypic and genotypic tests targeting carbapenemases of presumed CPE. The findings were related to CPE detected in hospitalized patients. A subset of CPE isolates from sewage and patients were subjected to whole genome sequencing. For three of the investigated carbapenemase genes, bla_NDM, bla_OXA-48-like and bla_KPC, there was concordance between gene levels and abundance of corresponding CPE in sewage. For the other two analyzed genes, bla_VIM and bla_IMP, there was no such concordance, most likely due to the presence of those genes in non-Enterobacterales populating the sewage samples. In line with the detection of OXA-48-like- and NDM-producing CPE in sewage, these were also the most commonly detected CPE in patients. NDM-producing CPE were detected on a single occasion in sewage and isolated strains were shown to match strains detected in a patient. A marked peak in CPE producing OXA-48-like enzymes was observed in sewage during a few months. When levels started to increase there were no known cases of such CPE at the hospital but soon after a few cases were detected in samples from patients. The OXA-48-like-producing CPE from sewage and patients represented different strains, but they carried similar bla_OXA-48-like-harbouring mobile genetic elements. In conclusion, sewage analyses show both promise and limitations as a complement to traditional clinical resistance surveillance for early warning of rare forms of resistance. Further evaluation and careful interpretation are needed to fully assess the value of such a sewage monitoring system.

Survivor microbial populations in post-chlorinated wastewater are strongly associated with untreated hospital sewage and include ceftazidime and meropenem resistant populations

Wastewater treatment plant (WWTP) effluent has been implicated in the spread of antibiotic resistant bacteria (ARB), including pathogens, as the WWTP environment contains multiple selective pressures that may increase mutation rates, pathogen survivability, and induce gene transfer between bacteria. In WWTPs receiving hospital sewage, this selective effect may be more pronounced due to increased concentrations of antibiotics, ARB, and clinical pathogens from hospital sewage. To determine the extent to which hospital sewage contributes to the microbial community of disinfected wastewater which is released into the environment, we used 16S rRNA sequencing of hospital sewage, WWTP influent, primary effluent, Post-Chlorinated Effluent, and receiving sediments in a combined sewage system to track changes in microbial community composition. We also sequenced the culturable survivor community resistant to β-lactam antibiotics within disinfected effluent. Using molecular source tracking, we found that the hospital sewage microbiome contributes an average of 11.49% of the microbial community in Post-Chlorinated Effluents, suggesting microorganisms identified within hospital sewage can survive or are enriched by the chlorination disinfection process. Additionally, we identified 28 potential pathogens to the species level, seven of which remained detectable in Post-Chlorinated Effluent and environmental sediments. When Post-Chlorinated Effluents were cultured on media containing β-lactam antibiotics ceftazidime and meropenem, a diverse antibiotic resistant survivor community was identified including potential human pathogens Bacillus cereus, Bacillus pumilus, and Chryseobacterium indologenes. Together, these results indicate that although wastewater treatment does significantly reduce pathogenic loads and ARBs, their continual presence in disinfected wastewater and receiving sediments suggests additional treatment and microbial tracking systems are needed to reduce human and animal health risks.

Detection of extended-spectrum beta-lactamase-producing E. coli and Klebsiella spp. in effluents of different hospitals sewage in Biratnagar, Nepal

Objective

This study was aimed to determine prevalence and resistance pattern like multidrug resistant (MDR) or ESBL nature of E. coli and Klebsiella spp. from various sewage drain samples with an idea to deliver baseline information that could be utilized for defining guidelines for the treatment of hospital sewages.

Results

Of 10 sewage samples analyzed, 7 (70%) contained E. coli while 6 (60%) contained Klebsiella. Except one sample, all positive samples contained both E. coli and Klebsiella spp. E. coli isolates were resistant to ampicillin, amoxicillin, cefoxitin, cefuroxime, and cefpodoxime; while 85.7% were resistant to amoxicillin/clavulanate, ceftazidime, cefotaxime and ceftriaxone. 71.4%, 57.1%, 42.9%, and 28.6% were resistant to aztreonam, trimethoprim/sulfamethoxazole, nitrofurantoin, and gentamicin. Most were sensitive to chloramphenicol, ofloxacin, ciprofloxacin, and azithromycin. 85.7% and 57.1% of E. coli were MDR and ESBL isolates, respectively. Klebsiella were resistant to ampicillin, amoxicillin, and amoxicillin/clavulanate. 83.4% of Klebsiella were resistant to cefoxitin. 66.7% of strains were resistant to cefuroxime, ceftazidime, cefotaxime, ceftriaxone, and cefpodoxime. Klebsiella showed 50% resistant to aztreonam and trimethoprim/sulfamethoxazole, while 33.3% were resistant to chloramphenicol, nitrofurantoin, ofloxacin, and ciprofloxacin. Klebsiella were sensitive to azithromycin and gentamicin. 66.7% and 33.3% of Klebsiella were MDR and ESBL isolates, respectively.

Occurrence and characteristics of extended-spectrum β-lactamase- and carbapenemase- producing bacteria from hospital effluents in Singapore

One of the most important resistance mechanisms in Gram-negative bacteria today is the production of enzymes causing resistance to cephalosporin and carbapenem antibiotics. The spread of extended-spectrum β-lactamases (ESBL)- and carbapenemase- producing Gram-negative bacteria is an emerging global public health problem. The aim of the present study was to (i) assess the prevalence of carbapenem-resistant bacteria (CRB) and ESBL-producing strains in sewage effluents from two major hospitals in Singapore, (ii) characterize the isolated strains and (iii) identify some of the ESBL and carbapenemase genes responsible for the resistance. CHROMagar ESBL and KPC plates were used to rapidly screen for ESBL-producing bacteria and those expressing reduced susceptibility to carbapenems, respectively. The abundance of ESBL-producers and CRB in hospital wastewater ranged between 10³ and 10⁶CFU/mL. Out of the 66 isolates picked from ESBL and KPC plates, 95%, 82%, 82% and 76% were resistant to ceftriaxone, ceftazidime (3rd generation cephalosporin family), ertapenem and meropenem (carbapenem family), respectively. Among the resistant isolates, the most predominant taxa identified were Pseudomonas spp. (28.2%), Klebsiella spp. (28.2%), Enterobacter spp. (18.3%) and Citrobacter spp. (11.3%). PCR and sequencing analysis showed that the predominant β-lactamase genes were bla_SHV (41.1%) followed by bla_NDM-1 (35.6%), bla_CTX (35.6%) and bla_KPC (28.8%). The results of this study show a high prevalence of bacteria resistant to modern extended-spectrum cephalosporins and carbapenems and the presence of ESBL- and carbapenemase producers in hospital effluents. These findings support the need to improve management of hospital wastewater in order to minimize the spread of antimicrobial resistant microorganisms from this source.

Distribution of coliphages against four e. Coli virotypes in hospital originated sewage sample and a sewage treatment plant in bangladesh

The distribution of coliphages infecting different Escherichia coli virotypes (EHEC, EIEC, EPEC, ETEC) and an avirulent strain (K-12) in sewage system of a hospital and a sewage treatment plant (STP) was investigated by culture-based agar overlay methods. Coliphages were found in all the samples except stool dumping site in the sewage system of the hospital and lagoon of the STP. Bacteriophage count (pfu/ml) infecting E. coli strains showed the following ascending pattern (EHEC < EIEC < EPEC < ETEC < E coli K-12) in all the collected samples except one. Phages capable of infecting avirulent E. coli K-12 strains were present in the highest number among all the examined locations. Phages specific for E. coli K-12 presented high diversity in plaque size on the bacterial lawn. Virulent E. coli specific coliphages rarely produced plaques with diameter of 1-2 mm or over. Conventional agar overlay method was found to be not satisfactory for phage community analysis from primary stool dumping site of the hospital, probably due to the presence of high concentration of antimicrobial substances. The gradual decrease seen in the five groups of coliphage quantity with the ongoing treatment process and then the absolute absence of coliphages in the outlet of the examined treatment plant is indicative of the usefulness of the treatment processes practiced there.