Occurrence of multidrug-resistant Enterococcus faecium isolated from environmental samples

The application prospect of metagenomic next-generation sequencing technology in diagnosing suspected lower respiratory tract infections

Objective

Lower respiratory tract infections present substantial diagnostic and therapeutic challenges, negatively impacting individual health. This study aims to utilize metagenomic next-generation sequencing (mNGS) technology to comprehensively explore the spectrum of pathogens, the detection of antibiotic resistance genes, and contributing factors associated with lung infections.

Method

The mNGS data of 217 patients with suspected lung infections attending the Respiratory Department of Nanjing Lishui People's Hospital and Gaochun People's Hospital from September 2022 to September 2023 were retrospectively analyzed. The study assessed the pathogenic spectrum of lung infections and compared the performance of patients with mNGS results from conventional microbiological techniques (CMT).

Results

The overall positivity rate of mNGS was 95.20%, demonstrating superior sensitivity (97.01% vs. 41.79%) and accuracy (75.56% vs. 56.67%) compared to CMT. Bacterial infections were the most prevalent, accounting for 60.76% of cases. And the most prevalent bacteria, fungus and virus were Mycobacterium tuberculosis (14.41%), Candida albicans (15.72%), and EB virus (14.85%), respectively. The primary resistance genes detected were tetM (17, 8.29%), mel (6, 2.93%), and PC1 beta-lactamase (blaZ) (3, 1.46%). Notably, TEM-183, PDC-5 and PDC-3 were exclusively detected in the Chronic Obstructive Pulmonary Disease (COPD) group. The multivariate binary logistic regression analysis revealed that there was no significant association between gender, presence of hypertension, or COPD with the type of infection in patients (p=0.679, p=0.229, p=0.345). However, the immune status was found to be statistically significant (p=0.009).

Conclusion

With the guidance of mNGS, patients with suspected respiratory tract infections can rapidly and accurately establish a pathogenic basis for their conditions. mNGS effectively identify mixed infections, enrich the pathogen spectrum of lung infections, and provide a large and reliable information base for the clinical realization of targeted medication.

Functional interplay between short antimicrobial peptides and model lipid membranes

Antimicrobial peptides (AMPs) are considered an attractive generation of novel antibiotics due to their advantageous properties such as a broad spectrum of antimicrobial activity against pathogens, low cytotoxicity, and drug resistance. Although they have common structural features and it has been widely demonstrated that bacterial membranes represent the main target of the peptide activity, the exact mechanism underlying the membrane perturbation by AMPs is not fully understood. Nevertheless, all the proposed modes of action implicate the preliminary interaction of AMPs with the negatively charged lipids in bacterial membranes. Recently, the structural and functional characterization of two AMPs, RiLK1 and RiLK3, was reported. Specifically, both peptides were revealed to be multitalented compounds capable of binding Gram-positive and Gram-negative liposome models with high affinity, but their mechanism of action remains elusive. In this paper, the effects of RiLK1 and RiLK3 on vesicles mimicking prokaryotic and eukaryotic cell membranes were further examined by using different approaches. Fluorescence and quenching assays either by acrylamide or lipophilic probes suggested that the peptides were mainly located at the interface of the negatively charged membranes that mimicked those of Salmonella Typhimurium and Staphylococcus aureus, possibly oriented in a parallel manner. Furthermore, RiLK1 and RiLK3 caused a significant leakage of carboxyfluorescein from bacterial liposomes, demonstrating that they can permeabilize the target membranes at high doses. Conversely, both peptides appear to behave like cell penetrating peptides (CPPs) at concentrations near their MIC values evaluated against the bacterial targets. Moreover, Dynamic Light Scattering provided further insights on the mechanisms of antimicrobial peptide against the bacterial liposomes. Conclusively, in vitro experiments indicated that RiLK1 and RiLK3 displayed potent bacteriostatic efficacy at low micromolar concentrations against an antibiotic-resistant ESKAPE pathogen, making them a valuable tool in preventing and treating infections caused by such bacteria.

Deciphering the impact of organic loading rate and digestate recirculation on the occurrence patterns of antibiotics and antibiotic resistance genes in dry anaerobic digestion of kitchen waste

Organic loading rate (OLR) is crucial for determining the stability of dry anaerobic digestion (AD). Digestate recirculation contributes to reactor stability and enhances methane production. Nevertheless, the understanding of how OLR and digestate recirculation affect the abundance and diversity of antibiotics and antibiotic resistance genes (ARGs), as well as the mechanisms involved in the dissemination of ARGs, remains limited. This study thoroughly investigated this critical issue through a long-term pilot-scale experiment. The metabolome analyses revealed the enrichment of various antibiotics, such as aminoglycoside, tetracycline, and macrolide, under low OLR conditions (OLR ≤ 4.0 g·VS/L·d) and the reactor instability. Antibiotics abundance decreased by approximately 19.66-31.69 % during high OLR operation (OLR ≥ 6.0 g·VS/L·d) with digestate recirculation. The metagenome analyses demonstrated that although low OLR promoted reactor stability, it facilitated the proliferation of antibiotic-resistant bacteria, such as Pseudomonas, and triggered functional profiles related to ATP generation, oxidative stress response, EPS secretion, and cell membrane permeability, thereby facilitating horizontal gene transfer (HGT) of ARGs. However, under stable operation at an OLR of 6.0 g·VS/L·d, there was a decrease in ARGs abundance but a notable increase in human pathogenic bacteria (HPB) and mobile genetic elements (MGEs). Subsequently, during reactor instability, the abundance of ARGs and HPB increased. Notably, during digestate recirculation at OLR levels of 6.0 and 7.0 g·VS/L·d, the process attenuated the risk of ARGs spread by reducing the diversity of ARGs hosts, minimizing interactions among ARGs hosts, ARGs, and MGEs, and weakening functional profiles associated with HGT of ARGs. Overall, digestate recirculation aids in reducing the abundance of antibiotics and ARGs under high OLR conditions. These findings provide advanced insights into how OLR and digestate recirculation affect the occurrence patterns of antibiotics and ARGs in dry AD.

Antibacterial, Antibiofilm, and Antioxidant Activities of Aqueous Crude Gymnema inodorum Leaf Extract against Vancomycin-Resistant Enterococcus faecium

Vancomycin-resistant Enterococcus faecium (VREF) causes nosocomial infections with high mortality and morbidity rates. This study aimed to evaluate the antibacterial and antibiofilm activities of aqueous crude Gymnema inodorum leaf extract (GIE) against the VREF ATCC 700221 strain. The antimicrobial activity of GIE against VREF was performed using disk diffusion and broth microdilution. The antibiofilm activities were evaluated using the crystal violet staining assay. The antioxidant potential was evaluated. Preliminary screening of the antimicrobial activity of 50 and 100 µg/disk of GIE against VREF revealed inhibition zones of 8.33 ± 0.58 mm and 8.67 ± 0.29 mm, respectively. Additionally, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values against VREF were 125 and ≥ 250 mg/mL, respectively. SEM analysis showed that treatment with GIE caused morphological changes, including incomplete cell division, damaged cell walls, and cell content leakage, suggesting a disruption of bacterial cells. GIE also inhibited and eradicated biofilms formed by VREF. The extract exhibited antioxidant activities in the DPPH and ABTS assays. While GIE shows potential as an antibacterial and antibiofilm agent, further studies are necessary to fully understand the underlying mechanisms and optimize its use for therapeutic applications.

Comparing antibiotic resistance and virulence profiles of Enterococcus faecium, Klebsiella pneumoniae, and Pseudomonas aeruginosa from environmental and clinical settings

Antibiotic resistance and virulence profiles of Enterococcus faecium, Klebsiella pneumoniae, and Pseudomonas aeruginosa, isolated from water sources collected in informal settlements, were compared to clinical counterparts. Cluster analysis using repetitive extragenic palindromic sequence-based polymerase chain reaction (REP-PCR) indicated that, for each respective species, low genetic relatedness was observed between most of the clinical and environmental isolates, with only one clinical P. aeruginosa (PAO1) and one clinical K. pneumoniae (P2) exhibiting high genetic similarity to the environmental strains. Based on the antibiograms, the clinical E. faecium Ef CD1 was extensively drug resistant (XDR); all K. pneumoniae isolates (n = 12) (except K. pneumoniae ATCC 13883) were multidrug resistant (MDR), while the P. aeruginosa (n = 16) isolates exhibited higher susceptibility profiles. The tetM gene (tetracycline resistance) was identified in 47.4 % (n = 6 environmental; n = 3 clinical) of the E. faecium isolates, while the blaKPC gene (carbapenem resistance) was detected in 52.6 % (n = 7 environmental; n = 3 clinical) and 15.4 % (n = 2 environmental) of the E. faecium and K. pneumoniae isolates, respectively. The E. faecium isolates were predominantly poor biofilm formers, the K. pneumoniae isolates were moderate biofilm formers, while the P. aeruginosa isolates were strong biofilm formers. All E. faecium and K. pneumoniae isolates were gamma (γ)-haemolytic, non-gelatinase producing (E. faecium only), and non-hypermucoviscous (K. pneumoniae only), while the P. aeruginosa isolates exhibited beta (β)-haemolysis and produced gelatinase. The fimH (type 1 fimbriae adhesion) and ugE (uridine diphosphate galacturonate 4-epimerase synthesis) virulence genes were detected in the K. pneumoniae isolates, while the P. aeruginosa isolates possessed the phzM (phenazine production) and algD (alginate biosynthesis) genes. Similarities in antibiotic resistance and virulence profiles of environmental and clinical E. faecium, K. pneumoniae, and P. aeruginosa, thus highlights the potential health risks posed by using environmental water sources for daily water needs in low-and-middle-income countries.

Dissemination of Enterococcal Genetic Lineages: A One Health Perspective

Enterococcus spp. are commensals of the gastrointestinal tracts of humans and animals and colonize a variety of niches such as water, soil, and food. Over the last three decades, enterococci have evolved as opportunistic pathogens, being considered ESKAPE pathogens responsible for hospital-associated infections. Enterococci's ubiquitous nature, excellent adaptative capacity, and ability to acquire virulence and resistance genes make them excellent sentinel proxies for assessing the presence/spread of pathogenic and virulent clones and hazardous determinants across settings of the human-animal-environment triad, allowing for a more comprehensive analysis of the One Health continuum. This review provides an overview of enterococcal fitness and pathogenic traits; the most common clonal complexes identified in clinical, veterinary, food, and environmental sources; as well as the dissemination of pathogenic genomic traits (virulome, resistome, and mobilome) found in high-risk clones worldwide, across the One Health continuum.

Enterococcus faecalis OG1RF Evolution at Low pH Selects Fusidate-Sensitive Mutants in Elongation Factor G and at High pH Selects Defects in Phosphate Transport

Enterococcus bacteria inhabit human and soil environments that show a wide range of pH values. Strains include commensals as well as antibiotic-resistant pathogens. We investigated the adaptation to pH stress in E. faecalis OG1RF by conducting experimental evolution under acidic (pH 4.8), neutral pH (pH 7.0), and basic (pH 9.0) conditions. A serial planktonic culture was performed for 500 generations and in a high-pH biofilm culture for 4 serial bead transfers. Nearly all of the mutations led to nonsynonomous codons, indicating adaptive selection. All of the acid-adapted clones from the planktonic culture showed a mutation in fusA (encoding elongation factor G). The acid-adapted fusA mutants had a trade-off of decreased resistance to fusidic acid (fusidate). All of the base-adapted clones from the planktonic cultures as well as some from the biofilm-adapted cultures showed mutations that affected the Pst phosphate ABC transporter (pstA, pstB, pstB2, pstC) and pyrR (pyrimidine biosynthesis regulator/uracil phosphoribosyltransferase). The biofilm cultures produced small-size colonies on brain heart infusion agar. These variants each contained a single mutation in pstB2, pstC, or pyrR. The pst and pyrR mutants outgrew the ancestral strain at pH 9.2, with a trade-off of lower growth at pH 4.8. Additional genes that had a mutation in multiple clones that evolved at high pH (but not at low pH) include opp1BCDF (oligopeptide ABC transporter), ccpA (catabolite control protein A), and ftsZ (septation protein). Overall, the experimental evolution of E. faecalis showed a strong pH dependence, favoring the fusidate-sensitive elongation factor G modification at low pH and the loss of phosphate transport genes at high pH. IMPORTANCE E. faecalis bacteria are found in dental biofilms, where they experience low pH as a result of fermentative metabolism. Thus, the effect of pH on antibiotic resistance has clinical importance. The loss of fusidate resistance is notable for OG1RF strains in which fusidate resistance is assumed to be a stable genetic marker. In endodontal infections, enterococci can resist calcium hydroxide therapy that generates extremely high pH values. In other environments, such as the soil and plant rhizosphere, enterococci experience acidification that is associated with climate change. Thus, the pH modulation of natural selection in enterococci is important for human health as well as for understanding soil environments.

Association of early immune-related adverse events with treatment efficacy of neoadjuvant Toripalimab in resectable advanced non-small cell lung cancer

Background

Neoadjuvant immunotherapy with anti-PD-1 was proved promising in resectable non-small cell lung cancer (NSCLC). Immune-related adverse events (irAEs) have been preliminarily implicated their association with treatment efficacy. Here we elucidated the early onset of irAEs associated with better clinical outcomes in a prospective study (Renaissance study).

Methods

We conducted the prospective study of NSCLC patients treated by neoadjuvant Toripalimab (240mg, every 3 weeks) plus double platinum-based chemotherapy from December 2020 to March 2022 at Peking University Cancer Hospital. Patients were enrolled if they have resectable IIB-IIIB NSCLC without EGFR/ALK mutation. Data were analyzed to explore the relationship between clinical outcome and irAEs after neoadjuvant treatment. A multidisciplinary team including physicians, surgeons, and radiologists, confirmed the irAEs according to the clinical manifestation. The relationship between irAEs and pathological outcomes was analyzed. The Renaissance study was approved by the Peking University Ethic board (2020YJZ58) and registered at https://clinicaltrials.gov/ as NCT04606303.

Results

Fifty-five consecutive patients were enrolled with a male-to-female ratio of 10:1, the median age was 62 years old (IQR: 45-76), of which 44 patients (80%) were diagnosed with squamous cell carcinoma. Forty-eight of 55 patients finally received thoracic surgery with a median preoperative waiting time of 67 days (IQR 39-113 days). Pathological results demonstrated that 31 (64.6%) patients achieved major pathological response (MPR) and 24 (50.0%) achieved complete pathological response (pCR). Among 48 patients who received R0 resection, immunotherapy-related thyroid dysfunction, rash/pruritus and enteritis occurred in 11 patients (22.9%), 7 patients (14.6%), and 1 patient (2.1%), respectively. Six patients (54.5%) with thyroid dysfunction achieved MPR with 5 (45.5%) achieved pCR, and a median time to onset was 45 days (IQR 21-91 days). Six patients (85.7%) with rash or pruritus achieved MPR and 5 patients (71.4%) achieved pCR, with median time to onset being 8 days (IQR 6-29 days). Furthermore, irAEs had no significant influence on operation time (170.6 min vs 165.7 min, P=0.775), intraoperative blood loss (67.4 mL vs 64.3 mL, P=0.831) and preoperative waiting time (93 days vs 97 days, P=0.630) when comparing with patients without irAEs (Figure 1).Figure 1Comparison of operation time (A), intraoperative blood loss (B), and preoperative waiting time (C) between "with irAEs" and "without irAEs".

Conclusion

The immunotherapy-related rash is potentially associated with pathological outcomes in NSCLC patients after neoadjuvant chemo-immunotherapy, suggesting easy-to-find irAEs, such as rash, can be used as indicators to predict response to neoadjuvant chemo-immunotherapy.Clinical trial registration: clinicaltrials.gov/, identifier NCT04606303.

Detection of optrA and poxtA genes in linezolid resistant Enterococcus isolates from fur animals in China

The emergence of linezolid-resistant (LR) enterococci found in food of animal origin arouses attention, but little is known about LR enterococci in fur animals. A total of 342 E. faecalis and 265 E. faecium strains isolated from fur animals in China from 2015 to 2017 were investigated to determine if linezolid-resistant (LR) enterococci (≥16 μg ml^-1 ) are present. Overall, two E. faecalis and twelve E. faecium among these isolates were resistant to linezolid. In addition, all LR isolates were classified as multidrug-resistant (MDR) isolates. We further explore the resistance genes of the LR enterococci, four E. faecalis and two E. faecium isolates contained optrA gene. Two of them co-harbored optrA and poxtA genes. We detected virulence genes in LR enterococci were the following: asa1, cylA, esp, gelE and hyl, among which the highest carrying rate gene was asa1. Besides, all of the LR enterococci we tested had the biofilm-forming ability. It is worth noting that we detected a novel ST type ST2010 from E. faecium 82-2. These data show LR enterococci exist in fur animals and have unique characteristics.

Prevalence of ESKAPE pathogens in the environment: Antibiotic resistance status, community-acquired infection and risk to human health

The ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.) pathogens are characterised by increased levels of resistance towards multiple classes of first line and last-resort antibiotics. Although these pathogens are frequently isolated from clinical environments and are implicated in a variety of life-threatening, hospital-associated infections; antibiotic resistant ESKAPE strains have been isolated from environmental reservoirs such as surface water, wastewater, food, and soil. Literature on the persistence and subsequent health risks posed by the ESKAPE isolates in extra-hospital settings is however, limited and the current review aims to elucidate the primary reservoirs of these pathogens in the environment, their antibiotic resistance profiles, and the link to community-acquired infections. Additionally, information on the current state of research regarding health-risk assessments linked to exposure of the ESKAPE pathogens in the natural environment, is outlined.

Descriptive Analysis of Circulating Antimicrobial Resistance Genes in Vancomycin-Resistant Enterococcus (VRE) during the COVID-19 Pandemic

COVID-19 offers ideal premises for bacteria to develop antimicrobial resistance. In this study, we evaluated the presence of several antimicrobial resistance genes (ARG) in vancomycin-resistant Enterococcus (VRE) isolated from rectal swabs from patients at a hospital in Cluj-Napoca, Romania. Rectal swabs were cultivated on CHROMID^® VRE (bioMérieux, Marcy—l’ Étoile, France) and positive isolates were identified using MALDI-TOF Mass Spectrometry (Bruker Daltonics, Bremen, Germany) and further analyzed using the PCR technique for the presence of the following ARGs: van A, van B, tet(M), tet(L), ermB, msrA, mefA, aac(6′)-Im, aph(2)-Ib, ant(4′)-Ia, sul1, sul2, sul3, and NDM1. We isolated and identified 68 isolates of Enterococcus faecium and 11 isolates of Enterococcus faecalis. The molecular analysis showed 66 isolates positive for the vanA gene and eight positive for vanB. The most frequent association of ARG in VRE was vanA-tet(M)-ermB. There was no statistically significant difference between Enterococcus faecium and Enterococcus faecalis regarding ARGs. Our work proves that during the COVID-19 pandemic, highly resistant isolates of Enterococcus were present in patients in the intensive care unit; thus, better healthcare policies should be implemented for the management and control of these highly resistant isolates in the future.

Fate, mobility, and pathogenicity of drinking water treatment plant resistomes deciphered by metagenomic assembly and network analyses

Antibiotic resistance genes (ARGs) have been regarded as emerging environmental contaminants. The profile of resistome (collection of all ARGs) in drinking water and its fate during drinking water treatment remain unclear. This study applied metagenomic assembly combined with network analysis to decipher the profile, mobility, host, and pathogenicity of resistomes in two full-scale drinking water treatment plants (DWTPs), each applying conventional treatment and advanced treatment of ozonation followed by biological activated carbon filtration. In source waters and effluents of each treatment process collected from both DWTPs, 215 ARGs belonging to 20 types were detected with total concentration ranging from 6.30 ± 1.83 to 5.20 ± 0.26 × 10⁴ copies/mL. Both the conventional and advanced DWTPs were revealed to effectively reduce the concentration of total ARGs, with the average removal efficiency of 3.61-log₁₀ and 2.21-log₁₀, respectively. Multiple statistical analyses (including network analysis) indicated drinking water resistome correlated tightly with mobile gene elements (MGEs) and bacterial community, with the latter acting as the premier driver of resistome alteration in DWTPs. Further analysis of ARG-carrying contigs (ACCs) assembled from drinking water metagenomes (i) tracked down potential bacterial hosts of ARGs (e.g., Proteobacteria phylum as the major pool of resistome), (ii) provided co-localization information of ARGs and MGEs (e.g., MacB-E7196 plasmid1), and (iii) identified ARG-carrying human pathogens (e.g., Enterococcus faecium and Ralstonia pickettii). This work firstly determined the concentration, mobility incidence, and pathogenicity incidence of DWTP resistomes, based on which the actual health risk regarding antibiotic resistance could be quantitatively assessed in further study, providing a useful direction for decision-making concerning the risk control of ARGs in DWTPs.