Vancomycin-resistant enterococci: mechanisms and clinical observations

''Myth Busting in Infectious Diseases'': A Comprehensive Review

Antibiotics have played a pivotal role in modern medicine, drastically reducing mortality rates associated with bacterial infections. Despite their significant contributions, the emergence of antibiotic resistance has become a formidable challenge, necessitating a re-evaluation of antibiotic use practices. The widespread belief in clinical practice that bactericidal antibiotics are inherently superior to bacteriostatic ones lacks consistent support from evidence in randomized controlled trials (RCTs). With the latest evidence, certain infections have demonstrated equal or even superior efficacy with bacteriostatic agents. Furthermore, within clinical practice, there is a tendency to indiscriminately order urine cultures for febrile patients, even in cases where alternative etiologies might be present. Consequently, upon obtaining a positive urine culture result, patients often receive antimicrobial prescriptions despite the absence of clinical indications warranting such treatment. Furthermore, it is a prevailing notion among physicians that extended durations of antibiotic therapy confer potential benefits and mitigate the emergence of antimicrobial resistance. Contrary to this belief, empirical evidence refutes such assertions. This article aims to address common myths and misconceptions within the field of infectious diseases.

Antibiotic resistance and virulence potentials of E. faecalis and E. faecium in hospital wastewater: a case study in Ardabil, Iran

Hospital wastewater can contaminate the environment with antibiotic-resistant and virulent bacteria. We analyzed wastewater samples from four hospitals in Ardabil province, Iran for Enterococcus faecium and Enterococcus faecalis using culture and molecular methods. We also performed antimicrobial susceptibility testing and polymerase chain reaction testing for resistance and virulence genes. Out of 141 enterococci isolates, 68.8% were E. faecium and 23.4% were E. faecalis. Ciprofloxacin and rifampicin showed the highest level of resistance against E. faecalis and E. faecium isolates at 65%. High-level gentamicin resistance (HLGR), high-level streptomycin resistance (HLSR), ampicillin, and vancomycin resistance were observed in 25, 5, 10, and 5.15% of E. faecium, and 15, 6, 15, and 3.03% of E. faecalis isolates, respectively. The ant(6')-Ia and ant(3')-Ia genes that were responsible for streptomycin resistance were observed in HLSR isolates and aph(3')-IIIa and aac(6') Ie-aph(2″)-Ia genes accounting for gentamicin resistance were detected in HLGR isolates. vanA was the predominant gene detected in vancomycin-resistant isolates. The majority of isolates were positive for gelE, asa1, esp, cylA, and hyl virulence genes. We found that drug-resistant and virulent E. faecalis and E. faecium isolates were prevalent in hospital wastewater. Proper treatment strategies are required to prevent their dissemination into the environment.

Prevalence of vancomycin-resistant Enterococci in India between 2000 and 2022: a systematic review and meta-analysis

BACKGROUND

Vancomycin-resistant Enterococci (VRE) infections are recurrently reported in different parts of India in the last two decades. However, an up-to-date, countrywide information concerning the prevalence and the rate of VRE in India is limited and hence this study aimed to estimate the pooled prevalence of VRE in India.

METHODS

A literature search was performed using various databases. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed throughout. Cross-sectional studies reporting the prevalence of VRE in India from human samples whereby at least two Enterococci were isolated between 1 January 2000 and 31 December 2022 were sought for inclusion. Data were extracted and analysed using Microsoft Excel and Comprehensive Meta-analysis version 4, respectively.

RESULTS

Nineteen studies were included in the analyses. A collective total of 3683 Enterococci isolates were examined, of which 368 were VRE strains. The pooled prevalence of VRE in India was calculated at 12.4% (95% CI: 8.6-17.5; Q = 189.69; I2 = 90.51%; p = < 0.001). E. faecalis was the most frequently isolated species (1450 [39.37%]) followed by E. faecium (724 [19.66%]). Amongst the VRE strains, E. faecium was the most prevalent (214 [58.15%]) followed by E. faecalis (134 [36.41%]). An upsurge in the rate of VRE infections was observed in India over time: VRE prevalence was estimated at 4.8% between 2000 and 2010 and 14.1% between 2011 and 2020.

CONCLUSION

This study presents the most up-to-date information on the rate of VRE infections in India. Though lower than the findings for some less developed countries, VRE prevalence in India is notable and on the rise.

Comprehensive genomic analysis of hypocholesterolemic probiotic Enterococcus faecium LR13 reveals unique proteins involved in cholesterol-assimilation

Hypercholesterolemia is a major risk factor for cardiovascular diseases (CVDs). Chemotherapeutic agents for CVDs exhibit several side effects. Specific probiotics with hypocholesterolemic effects can be safe and effective alternatives to chemotherapeutics. Here, we have analyzed and compared the genome of a novel rhizospheric Enterococcus faecium LR13 cholesterol-assimilating probiotic with other probiotic/pathogenic E. faecium strains to discern genetic factors underlying probiotic efficacy and cholesterol-assimilation. Genomic analyses of E. faecium probiotic strains revealed that LR13 and WEFA23 (cholesterol-assimilating probiotics) harbored 21 unique proteins absent in non-cholesterol-assimilating probiotics. Of these, 14 proteins could directly help in cholesterol-assimilation by producing short chain fatty acids, lipid (sterol) transport and membrane stabilization, and bile salt hydrolase activity. This suggests that cholesterol-assimilation is an intrinsic, strain-specific trait exhibited by probiotics with a specific genetic constitution. Moreover, the unique proteins identified in this study can serve as biomarkers for discerning/characterizing cholesterol-assimilating probiotics as novel biotherapeutics against CVDs.

Mitoxantrone targets both host and bacteria to overcome vancomycin resistance in Enterococcus faecalis

Antibiotic resistance critically limits treatment options for infection caused by opportunistic pathogens such as enterococci. Here, we investigate the antibiotic and immunological activity of the anticancer agent mitoxantrone (MTX) in vitro and in vivo against vancomycin-resistant Enterococcus faecalis (VRE). We show that, in vitro, MTX is a potent antibiotic against Gram-positive bacteria through induction of reactive oxygen species and DNA damage. MTX also synergizes with vancomycin against VRE, rendering the resistant strains more permeable to MTX. In a murine wound infection model, single-dose MTX treatment effectively reduces VRE numbers, with further reduction when combined with vancomycin. Multiple MTX treatments accelerate wound closure. MTX also promotes macrophage recruitment and proinflammatory cytokine induction at the wound site and augments intracellular bacterial killing in macrophages by up-regulating the expression of lysosomal enzymes. These results show that MTX represents a promising bacterium- and host-targeted therapeutic for overcoming vancomycin resistance.

A Review of Detection Methods for Vancomycin-Resistant Enterococci (VRE) Genes: From Conventional Approaches to Potentially Electrochemical DNA Biosensors

Vancomycin-resistant Enterococci (VRE) genes are bacteria strains generated from Gram-positive bacteria and resistant to one of the glycopeptides antibiotics, commonly, vancomycin. VRE genes have been identified worldwide and exhibit considerable phenotypic and genotypic variations. There are six identified phenotypes of vancomycin-resistant genes: VanA, VanB, VanC, VanD, VanE, and VanG. The VanA and VanB strains are often found in the clinical laboratory because they are very resistant to vancomycin. VanA bacteria can pose significant issues for hospitalized patients due to their ability to spread to other Gram-positive infections, which changes their genetic material to increase their resistance to the antibiotics used during treatment. This review summarizes the established methods for detecting VRE strains utilizing traditional, immunoassay, and molecular approaches and then focuses on potential electrochemical DNA biosensors to be developed. However, from the literature search, no information was reported on developing electrochemical biosensors for detecting VRE genes; only the electrochemical detection of vancomycin-susceptible bacteria was reported. Thus, strategies to create robust, selective, and miniaturized electrochemical DNA biosensor platforms to detect VRE genes are also discussed.

Molecular Rapid Diagnostics Improve Time to Effective Therapy and Survival in Patients with Vancomycin-Resistant Enterococcus Bloodstream Infections

Delays in appropriate antibiotic therapy are a key determinant for deleterious outcomes among patients with vancomycin-resistant Enterococcus (VRE) bloodstream infections (BSIs). This was a multi-center pre/post-implementation study, assessing the impact of a molecular rapid diagnostic test (Verigene® GP-BC, Luminex Corporation, Northbrook, IL, USA) on outcomes of adult patients with VRE BSIs. The primary outcome was time to optimal therapy (TOT). Multivariable logistic and Cox proportional hazard regression models were used to determine the independent associations of post-implementation, TOT, early vs. delayed therapy, and mortality. A total of 104 patients with VRE BSIs were included: 50 and 54 in the pre- and post-implementation periods, respectively. The post- vs. pre-implementation group was associated with a 1.8-fold faster rate to optimized therapy (adjusted risk ratio, 1.841 [95% CI 1.234-2.746]), 6-fold higher likelihood to receive early effective therapy (<24 h, adjusted odds ratio, 6.031 [2.526-14.401]), and a 67% lower hazards for 30-day in-hospital mortality (adjusted hazard ratio, 0.322 [0.124-1.831]), after adjusting for age, sex, and severity scores. Inversely, delayed therapy was associated with a 10-fold higher risk of in-hospital mortality (aOR 10.488, [2.497-44.050]). Reduced TOT and in-hospital mortality were also observed in subgroups of immunosuppressed patients in post-implementation. These findings demonstrate that the addition of molecular rapid diagnostic tests (mRDT) to clinical microbiology and antimicrobial stewardship practices are associated with a clinically significant reduction in TOT, which is associated with lower mortality for patients with VRE BSIs, underscoring the importance of mRDTs in the management of VRE infections.

Factors associated with antimicrobial resistant enterococci in Canadian beef cattle: A scoping review

Introduction

Antimicrobial resistance (AMR) is a global health concern, occurring when bacteria evolve to render antimicrobials no longer effective. Antimicrobials have important roles in beef production; however, the potential to introduce AMR to people through beef products is a concern. This scoping review identifies factors associated with changes in the prevalence of antimicrobial-resistant Enterococcus spp. applicable to the Canadian farm-to-fork beef continuum.

Methods

Five databases (MEDLINE, BIOSIS, Web of Science, Embase, and CAB Abstracts) were searched for articles published from January 1984 to March 2022, using a priori inclusion criteria. Peer-reviewed articles were included if they met all the following criteria: written in English, applicable to the Canadian beef production context, primary research, in vivo research, describing an intervention or exposure, and specific to Enterococcus spp.

Results

Out of 804 screened articles, 26 were selected for inclusion. The included articles discussed 37 factors potentially associated with AMR in enterococci, with multiple articles discussing at least two of the same factors. Factors discussed included antimicrobial administration (n = 16), raised without antimicrobials (n = 6), metal supplementation (n = 4), probiotics supplementation (n = 3), pen environment (n = 2), essential oil supplementation (n = 1), grass feeding (n = 1), therapeutic versus subtherapeutic antimicrobial use (n = 1), feeding wet distiller grains with solubles (n = 1), nutritional supplementation (n = 1) and processing plant type (n = 1). Results were included irrespective of their quality of evidence.

Discussion

Comparability issues arising throughout the review process were related to data aggregation, hierarchical structures, study design, and inconsistent data reporting. Findings from articles were often temporally specific in that resistance was associated with AMR outcomes at sampling times closer to exposure compared to studies that sampled at longer intervals after exposure. Resistance was often nuanced to unique gene and phenotypic resistance patterns that varied with species of enterococci. Intrinsic resistance and interpretation of minimum inhibitory concentration varied greatly among enterococcal species, highlighting the importance of caution when comparing articles and generalizing findings.

Systematic Review Registration

[http://hdl.handle.net/1880/113592].

Heterologous Expression Reveals Ancient Properties of Tei3—A VanS Ortholog from the Teicoplanin Producer Actinoplanes teichomyceticus

Glycopeptide antibiotics (GPAs) are among the most clinically successful antimicrobials. GPAs inhibit cell-wall biosynthesis in Gram-positive bacteria via binding to lipid II. Natural GPAs are produced by various actinobacteria. Being themselves Gram-positives, the GPA producers evolved sophisticated mechanisms of self-resistance to avoid suicide during antibiotic production. These self-resistance genes are considered the primary source of GPA resistance genes actually spreading among pathogenic enterococci and staphylococci. The GPA-resistance mechanism in Actinoplanes teichomyceticus—the producer of the last-resort-drug teicoplanin—has been intensively studied in recent years, posing relevant questions about the role of Tei3 sensor histidine kinase. In the current work, the molecular properties of Tei3 were investigated. The setup of a GPA-responsive assay system in the model Streptomyces coelicolor allowed us to demonstrate that Tei3 functions as a non-inducible kinase, conferring high levels of GPA resistance in A. teichomyceticus. The expression of different truncated versions of tei3 in S. coelicolor indicated that both the transmembrane helices of Tei3 are crucial for proper functioning. Finally, a hybrid gene was constructed, coding for a chimera protein combining the Tei3 sensor domain with the kinase domain of VanS, with the latter being the inducible Tei3 ortholog from S. coelicolor. Surprisingly, such a chimera did not respond to teicoplanin, but indeed to the related GPA A40926. Coupling these experimental results with a further in silico analysis, a novel scenario on GPA-resistance and biosynthetic genes co-evolution in A. teichomyceticus was hereby proposed.

Detection and molecular characterization of VRE isolates in Slovakia from stool samples positive for Clostridioides difficile toxins

The study aimed to identify colonized patients as a possible source of eventual VRE (vancomycin-resistant enterococci) infection from stool samples positive for glutamate dehydrogenase antigen, as well as for Clostridioides difficile toxins A and B. The study was carried out from 7/2020 to 9/2021. Stool samples were grown in a brain heart infusion medium with a gram-positive non-spore-forming bacteria supplement under aerobic conditions. The samples for VRE identification were grown on CHROMID^® VRE agar, and the MICs for vancomycin and teicoplanin were also estimated. The presence of the vanA/vanB genes was tested using the PCR method. The total number of 113 stool samples positive for Clostridioides difficile toxins was analyzed. Of these samples, 44 isolates with VRE characters were identified. The most prevalent isolates in our set of isolates were Enterococcus faecium (27 isolates, 62%), Enterococcus faecalis (9 isolates, 21%), Enterococcus solitarius (4 isolates, 9%), Enterococcus durans (2 isolates, 4%), 1 isolate Enterococcus sulfurous (2%), and Enterococcus raffinosus (2%). In total, 26 isolates were detected in the study in the presence of vanA genes (24 isolates E. faecium, 2 isolates E. faecalis) and 18 isolates detected in the presence of vanB genes (7 isolates E. faecalis, 4 isolates E. solitarius, 3 isolates E. faecium, 2 isolates E. durans, 1 isolate E. sulfurous, and E. raffinosus). The results of this study showed the local dominance character of the vanA gene of hospital VRE isolates that were carriers of genes associated with high resistance to vancomycin, teicoplanin, and occasionally linezolid.

Resistance towards Critically Important Antimicrobials among Enterococcus faecalis and E. faecium in Poultry Farm Environments in Selangor, Malaysia

Multidrug resistant (MDR) enterococci pose significant public health challenges. However, the extent of resistance in the environment is less explored. This study aimed to determine the antibiotic resistance in a poultry farm environment. Eighty enterococcal isolates recovered from the soil and effluent water of 28 poultry farms in Selangor state were included in the study for further bacterial identification and antibiotic susceptibility testing using a VITEK 2 system. Data were analyzed using Statistical Package for Social Science (SPSS) version 27. The resistance rate and MDR of enterococcal isolates were reported. Out of 80 isolates recovered, 72 (90%) exhibited resistance to at least one antibiotic, with 50 isolates (62.5%) being found to be MDR. All linezolid-resistant enterococci (LRE) exhibit MDR, which constituted 40% of resistance among all the isolates recovered from poultry environment. Since linezolid is listed as critically important antibiotics for clinical use by the World Health Organization (WHO), the higher resistance towards it and other critically important antibiotic for human use is a serious concern. Hence, relevant agencies need to investigate the use of clinically important antimicrobials in poultry farms paying special attention towards linezolid or any other antibiotics that can facilitate the development of LRE.

Panorama of Bacterial Infections Caused by Epidemic Resistant Strains

Antimicrobial resistance (AMR) represents a critical obstacle to public health worldwide, due to the high incidence of strains resistant to available antibiotic therapies. In recent years, there has been a significant increase in the prevalence of resistant epidemic strains, associated with this, public health authorities have been alarmed about a possible scenario of uncontrolled dissemination of these microorganisms and the difficulty in interrupting their transmission, as nosocomial pathogens with resistance profiles previously considered sporadic. They become frequent bacteria in the community. In addition, therapy for infections caused by these pathogens is based on broad-spectrum antibiotic therapy, which favors an increase in the tolerance of remaining bacterial cells and is commonly associated with a poor prognosis. In this review, we present the current status of epidemic strains of methicillin-resistant Staphylococcus aureus (MRSA), Vancomycin-resistant Enterococcus (VRE), MDR Mycobacterium tuberculosis, extended-spectrum β-lactamase-producing Enterobacterales (ESBL), Klebsiella pneumoniae carbapenemase (KPC), and—New Delhi Metallo-beta-lactamase-producing Pseudomonas aeruginosa (NDM).

Comparative Analysis of Short- and Long-Read Sequencing of Vancomycin-Resistant Enterococci for Application to Molecular Epidemiology

Vancomycin-resistant enterococci (VRE) are nosocomial pathogens with genetic plasticity and widespread antimicrobial resistance (AMR). To prevent the spread of VRE in the hospital setting, molecular epidemiological approaches such as pulsed-field gel electrophoresis and multilocus sequence typing have been implemented for pathogen outbreak surveillance. However, due to the insufficient discriminatory power of these methods, whole-genome sequencing (WGS), which enables high-resolution analysis of entire genomic sequences, is being used increasingly. Herein, we performed WGS of VRE using both short-read next-generation sequencing (SR-NGS) and long-read next-generation sequencing (LR-NGS). Since standardized workflows and pipelines for WGS-based bacterial epidemiology are lacking, we established three-step pipelines for SR- and LR-NGS, as a standardized WGS-based approach for strain typing and AMR profiling. For strain typing, we analyzed single-nucleotide polymorphisms (SNPs) of VRE isolates and constructed SNP-based maximum-likelihood phylogenies. The phylogenetic trees constructed using short and long reads showed good correspondence. Still, SR-NGS exhibited higher sensitivity for detecting nucleotide substitutions of bacterial sequences. During AMR profiling, we examined AMR genes and resistance-conferring mutations. We also assessed the concordance between genotypic and phenotypic resistance, which was generally better for LR-NGS than SR-NGS. Further validation of our pipelines based on outbreak cases is necessary to ensure the overall performance of pipelines.

Multidrug-resistant infections in solid organ transplant recipients: a focus on risk factors, prevention and treatment strategies

Solid organ transplantation is the best therapeutic option for patients with end-stage organ disease and, according to the data from international registries, there has been a steady increase in numbers and results. However, post-transplant infections remain a fearsome complication with, in the last decade, an increasing incidence of episodes due to antibiotic-resistant bacteria and opportunistic agents. In this paper, we summarize the most relevant and updated knowledge concerning infections from multidrug-resistant germs in solid organ transplant recipients, focusing on risk factors, treatment and prevention strategies, and antimicrobial pharmacokinetics relevant to this particular population of patients.

Distinguishing Clinical Enterococcus faecium Strains and Resistance to Vancomycin Using a Simple In-House Screening Test

Vancomycin-resistant enterococci (VRE) are a major concern as microorganisms with antimicrobial resistance and as a public health threat contributing significantly to morbidity, mortality, and socio-economic costs. Among VREs, vancomycin-resistant Enterococcus faecium (VREfm) is frequently isolated and is resistant to many antibiotics used to treat patients with hospital-acquired infection. Accurate and rapid detection of VREfm results in effective antimicrobial therapy, immediate patient isolation, dissemination control, and appropriate disinfection measures. An in-house VREfm screening broth was developed and compared to the broth microdilution method and multiplex polymerase chain reaction for the detection of 105 enterococci, including 81 VRE isolates (61 E. faecium, 5 E. faecalis, 10 E. gallinarum, and 5 E. casseliflavus). Verification of this screening broth on 61 VREfm, 20 other VRE, and 24 non-VRE revealed greater validity for VREfm detection. The accuracy of this broth was 100% in distinguishing E. faecium from other enterococcal species. Our test revealed 93.3% accuracy, 97.5% sensitivity, and 79.2% specificity compared with broth microdilution and PCR detecting van genes. The kappa statistic to test interrater reliability was 0.8, revealing substantial agreement for this screening test to the broth microdilution method. In addition, the in-house VREfm screening broth produced rapid positivity after at least 8 h of incubation. Application of this assay to screen VREfm should be useful in clinical laboratories and hospital infection control units.

Surgical Antibiotic Prophylaxis in an Era of Antibiotic Resistance: Common Resistant Bacteria and Wider Considerations for Practice

The increasing incidence of antimicrobial resistance (AMR) presents a global crisis to healthcare, with longstanding antimicrobial agents becoming less effective at treating and preventing infection. In the surgical setting, antibiotic prophylaxis has long been established as routine standard of care to prevent surgical site infection (SSI), which remains one of the most common hospital-acquired infections. The growing incidence of AMR increases the risk of SSI complicated with resistant bacteria, resulting in poorer surgical outcomes (prolonged hospitalisation, extended durations of antibiotic therapy, higher rates of surgical revision and mortality). Despite these increasing challenges, more data are required on approaches at the institutional and patient level to optimise surgical antibiotic prophylaxis in the era of antibiotic resistance (AR). This review provides an overview of the common resistant bacteria encountered in the surgical setting and covers wider considerations for practice to optimise surgical antibiotic prophylaxis in the perioperative setting.

Utility of Minimum Inhibitory Concentration values and Antibiotyping for Epidemiological study of Vancomycin Resistant Enterococci in a Tertiary Care Hospital

Vancomycin-resistant enterococci (VRE) have emerged as an important nosocomial infection. Three important vancomycin resistance types namely, VanA, VanB, VanC are very commonly found in enterococci. VanA and VanB are plasmid-encoded, transferable types of resistance and VanC is chromosomally mediated nontransferable resistance. So for infection control purpose, it is important to know the type of vancomycin resistance to prevent the spread of drug resistance. Enterococci isolated from clinical samples were tested for vancomycin resistance by disc diffusion and macro broth dilution (MIC) method. Vancomycin resistance gene was detected by the polymerase chain reaction (PCR) method. Antimicrobial susceptibility for penicillin, erythromycin, ciprofloxacin, high-level gentamicin, nitrofurantoin, tetracycline, teicoplanin and linezolid was performed by disc diffusion method. Antibiotyping of VRE strains was done based on their antimicrobial susceptibility pattern. Over a period of one year out of 246 clinical isolates of enterococci, seven (2.8%) isolates showed vancomycin resistance. Based on MICs and PCR, all the isolates demonstrated VanA type of resistance. Analysis of antibiogram showed three different antibiotype patterns for VRE labelled as 1,2,3. The majority of VRE isolates (72%) belonged to “Pattern 1”. Also clustering of cases of “Pattern 1” was observed in medicine ICU and medicine ward. These areas were identified as a potential reservoir for VRE infection and appropriate infection control measures were taken to curtail the spread of infection. The present study recommends a macro broth dilution method for detection of the type of vancomycin resistance in enterococci and “antibiotyping” as a basic typing method for VRE in resource-poor health care settings specifically in outbreak situations.

Increasing Trend of Vancomycin-resistant Enterococci Bacteremia in a Tertiary Care Hospital of South India: A Three-year Prospective Study

Introduction: Vancomycin-resistant enterococci (VRE) are emerging as an important multidrug-resistant pathogen causing nosocomial infections, predominantly bacteremia and urinary tract infections. VRE bacteremia has caused a significant increase in the duration of the hospital stay and mortality and had caused high public health threat due to limited treatment options.

Materials and methods: Between October 2017 and September 2020, all consecutive patients with culture-proven bloodstream infection with Enterococcus species, isolated for the first time, were included in the study. A total of 427 Enterococcus species were identified, and antimicrobial susceptibility tests were performed and interpreted using Clinical and Laboratory Standard Institute guidelines.

Results: Of the total 427 Enterococcus species isolated, 63 (45.6%) were VRE. Among them, 51/63 (81%) were Enterococcus faecium (E. faecium) and 5/63 (8%) were Enterococcus faecalis. There was an increased trend of VRE rate in the bloodstream infections of 6.12% (2018), 13.2% (2019), and 19.2% (2020). The majority of the VRE patients [43/63 (68%)] were admitted to the intensive care units (ICUs). Vancomycin A (VanA) is the most common phenotype isolated from 51/63(81%) patients.

Conclusion: This increasing trend of VRE bacteremia is a red alert to the clinicians and the infection control practitioners, so that strict antibiotic policies and proper adherence to the infection control practices can be initiated to reduce the VRE rate.

How to cite this article: Sivaradjy M, Gunalan A, Priyadarshi K, Madigubba H, Rajshekar D, Sastry AS. Increasing Trend of Vancomycin-resistant Enterococci Bacteremia in a Tertiary Care Hospital of South India: A Three-year Prospective Study. Indian J Crit Care Med 2021;25(8):881–885.

Vancomycin Use in Children and Neonates across Three Decades: A Bibliometric Analysis of the Top-Cited Articles

Vancomycin is frequently prescribed in pediatrics, especially in intensive care unit settings, to treat Gram-positive bacterial infections. This work aims to collect the top-cited articles of pediatric and infectious diseases areas to gather the current evidence and gaps of knowledge on the use of vancomycin in these populations. The most relevant journals reported in the "pediatrics" and "infectious diseases" categories of the 2019 edition of Journal Citation Reports were browsed. Articles with more than 30 citations and published over the last three decades were collected. A bibliometric analysis was performed and 115 articles were retrieved. They were published in 21 journals, with a median impact factor of 4.6 (IQR 2.9-5.4). Sixty-eight of them (59.1%) belonged to "infectious diseases" journals. The most relevant topic was "bloodstream/complicated/invasive infections", followed by "antibiotic resistance/MRSA treatment". As for population distribution, 27 articles were on children only and 27 on neonates, most of which were from intensive care unit (ICU) settings. The current literature mainly deals with vancomycin as a treatment for severe infections and antibiotic resistance, especially in neonatal ICU settings. Lately, attention to new dosing strategies in the neonatal and pediatric population has become a sensible topic.

Imaging Commensal Microbiota and Pathogenic Bacteria in the Gut

As a newly discovered organ, gut microbiota has been extensively studied in the last two decades, with their highly diverse and fundamental roles in the physiology of many organs and systems of the host being gradually revealed. However, most of the current research heavily relies on DNA sequencing-based methodologies. To truly understand the complex physiological and pathological functions demonstrated by commensal and pathogenic gut bacteria, we need more powerful methods and tools, among which imaging strategies suitable for approaching this ecosystem in different settings are one of the most desirable. Although the phrase gut "dark matter" is often used in referring to the unculturability of many gut bacteria, it is also applicable to describing the formidable difficulties in visualizing these microbes in the intestines. To develop suitable and versatile chemical and biological tools for imaging bacteria in the gut, great efforts have been devoted in the past several years.In this Account, we highlight the recent progress made by our group and other laboratories in the development of visualization strategies for commensal microbiota and pathogenic bacteria in the gut. First, we summarize our efforts toward the development of derivatized antibiotic staining probes that directly bind to specific bacterial surface structures for selective labeling of different groups of gut bacteria. Next, metabolic labeling-based imaging strategies, using unnatural amino acids, unnatural sugars, and stable isotopes, for imaging gut bacteria on various scales and in different settings are discussed in detail. We then introduce nucleic acid staining-based bacterial imaging, using either general nucleic acid-binding reagents or selective-labeling techniques (e.g., fluorescence in situ hybridization) to meet the diverse needs in gut microbiota research. This classical imaging strategy has witnessed a renaissance owing to a series of new technical advancements. Furthermore, despite the notorious difficulties of performing genetic manipulations in many commensal gut bacteria, great effort has been made recently in engineering gut bacteria with reporters like fluorescent proteins and acoustic response proteins.Our perspectives on the current limitations of the chemical tools and strategies and the future directions for improvement are also presented. We hope that this Account can offer valuable references to spark new ideas and invite new efforts to help decipher the complex biological and chemical interactions between commensal microbiota and pathogenic bacteria and the hosts.

ddcP, pstB, and excess D-lactate impact synergism between vancomycin and chlorhexidine against Enterococcus faecium 1,231,410

Vancomycin-resistant enterococci (VRE) are important nosocomial pathogens that cause life-threatening infections. To control hospital-associated infections, skin antisepsis and bathing utilizing chlorhexidine is recommended for VRE patients in acute care hospitals. Previously, we reported that exposure to inhibitory chlorhexidine levels induced the expression of vancomycin resistance genes in VanA-type Enterococcus faecium. However, vancomycin susceptibility actually increased for VanA-type E. faecium in the presence of chlorhexidine. Hence, a synergistic effect of the two antimicrobials was observed. In this study, we used multiple approaches to investigate the mechanism of synergism between chlorhexidine and vancomycin in the VanA-type VRE strain E. faecium 1,231,410. We generated clean deletions of 7 of 11 pbp, transpeptidase, and carboxypeptidase genes in this strain (ponA, pbpF, pbpZ, pbpA, ddcP, ldt_fm, and vanY). Deletion of ddcP, encoding a membrane-bound carboxypeptidase, altered the synergism phenotype. Furthermore, using in vitro evolution, we isolated a spontaneous synergy escaper mutant and utilized whole genome sequencing to determine that a mutation in pstB, encoding an ATPase of phosphate-specific transporters, also altered synergism. Finally, addition of excess D-lactate, but not D-alanine, enhanced synergism to reduce vancomycin MIC levels. Overall, our work identified factors that alter chlorhexidine and vancomycin synergism in a model VanA-type VRE strain.

Concomitant Vancomycin-Resistant Enterococcus faecium and Clostridium difficile Colitis

Colitis is a chronic gastrointestinal system disease characterized by inflammation of the inner lining of the colon. Infectious colitis is one of the most common causes of colitis and is associated with significant mortality and morbidity. One of the rare causes of colitis includes vancomycin-resistant Enterococcus faecium (VRE). Lately, the prevalence of VRE has significantly increased in hospitals. We present a case of a 32-year-old American man who was initially admitted because of bilateral lower extremity weakness. The hospital course was complicated, with acute hypoxic respiratory failure secondary to pneumonia. The patient was intubated and was started on broad-spectrum antibiotics. Later on, the patient had severe diarrhea and was found to have clostridium difficile infection. Patient symptoms persisted despite completing the course of antibiotics. Colonoscopy was performed, and the patient was found to have a diffuse area of severely altered vascular, congested, erythematous, friable with contact bleeding, hemorrhagic, inflamed, nodular, and ulcerated mucosa in the sigmoid colon, in the descending colon, and the transverse colon. A biopsy was sent, and the patient was found to be growing VRE. Currently, there is no effective treatment available for VRE. Hospitals need to have an active surveillance program to identify these patients so that the infection does not spread to other patients.

Prevalence of vancomycin-resistant enterococci in Asia-A systematic review and meta-analysis

WHAT IS KNOWN AND OBJECTIVE

The rise of vancomycin-resistant enterococci (VRE) has been a major health problem in most countries of the world including Asia, since its discovery. There is a paucity of data on VRE in many countries of Asia as well as limited pooled estimates. Therefore, we performed a systematic review and meta-analysis to estimate a pooled prevalence of VRE in Asia.

METHODS

A literature search in electronic databases like PubMed, Embase and Google Scholar and manual searching of references and grey literature, comprising the information on the prevalence of VRE with at least two species of enterococci, conducted in different countries of Asia from January 1, 2000, to September 20, 2020, was done. The random-effect model and 95% CIs was used to calculate the pooled prevalence. Subgroup, sensitivity and meta-regression analyses were performed to address heterogeneity while Egger's test for publication bias.

RESULTS AND DISCUSSIONS

We identified 39 studies, comprising a total of 11,875 enterococcal isolates. The result of the analysis showed that the pooled prevalence of VRE in Asia was 8.10% (95% CI; 7-9; I²  = 93.79%; p < 0.001). Resistance to vancomycin was greater among strains of E. faecium compared to the strains of E. faecalis (22.40% vs. 3.70%). Amongst various regions of Asia, the highest prevalence of VRE was found in the Western Asian region and the lowest in the South-east Asian region. Moreover, the rate of VRE was higher than most European countries and lower than USA.

WHAT IS NEW AND CONCLUSIONS

With an upsurge of VRE in Asia in recent years, efficient infection control programmes, robust surveillance systems and adherence to antibiotic stewardship are paramount to halt the further rise of VRE.

Emergence and Transmission of Daptomycin and Vancomycin-Resistant Enterococci Between Patients and Hospital Rooms

BACKGROUND

Vancomycin-resistant enterococci (VRE) are a major cause of morbidity and mortality in immunocompromised patients. Tracking the dissemination of VRE strains is crucial to understand the dynamics of emergence and spread of VRE in the hospital setting.

METHODS

Whole genome sequencing (WGS) and phylogenetic analyses were performed to identify dominant VRE strains and potential transmission networks between 35 patients with VRE-positive rectal swabs and their rooms (main rooms and bathrooms) on the leukemia (LKM) and the hematopoietic cell transplant (HCT) floors. Sequence types (STs), drug resistance genes, and patients' outcomes were also determined.

RESULTS

A total of 89 VRE strains grouped into 10 different STs, of which newly described STs were isolated from both floors (ST736, ST494, ST772, and ST1516). We observed highly genetically related strains transmitted between rooms, floors, and time periods in an average period of 39 days (ranging from 3 to 90 days). Of 5 VRE bacteremia events, 3 strains were lacking the pili operon fms14-17-13 (ST203) and the remaining 2 were resistant to daptomycin (DAP; ST736, ST664). Of 10 patients harboring DAP-resistant strains, only 2 were exposed to DAP within 4 months before strain recovery.

CONCLUSION

Our comparisons of VRE strains derived from the environment and immunocompromised patients confirmed horizontal transfer of highly related genetic lineages of multidrug-resistant (particularly to DAP) VRE strains between HCT and LKM patients and their room environment. Implementing WGS can be useful in distinguishing VRE reservoirs where interventions can be targeted to prevent and control the spread of highly resistant organisms.

High-Level Antibiotic Tolerance of a Clinically Isolated Enterococcus faecalis Strain

Bacteria can survive antibiotic treatment both by acquiring antibiotic resistance genes and through mechanisms of tolerance that are based on phenotypic changes and the formation of metabolically inactive cells. Here, we report an Enterococcus faecalis strain (E. faecalis UM001B) that was isolated from a cystic fibrosis patient and had no increase in resistance but extremely high-level tolerance to ampicillin, vancomycin, and tetracycline. Specifically, the percentages of cells that survived 3.5-h antibiotic treatment (at 100 μg · ml^-1) were 25.4% ± 4.3% and 51.9% ± 4.0% for ampicillin and tetracycline, respectively; vancomycin did not exhibit any significant killing. Consistent with the changes in antibiotic susceptibility, UM001B was found to have reduced penetration of ampicillin and vancomycin and accumulation of tetracycline compared to the reference strain ATCC 29212. Based on whole-genome sequencing, four amino acid substitutions were identified in one of the tetracycline efflux pump repressors (TetRs), compared to ATCC 29212. Results of molecular simulations and experimental assays revealed that these mutations could lead to higher levels of tetracycline efflux activity. Consistently, replicating these mutations in Escherichia coli MG1655 increased its tolerance to tetracycline. Overall, these findings provide new insights into the development of multidrug tolerance in E. faecalis, which can facilitate future studies to better control enterococcal infections.IMPORTANCE Enterococcus faecalis represents a major group of pathogens causing nosocomial infections that are resistant to multiple classes of antibiotics. An important challenge associated with E. faecalis infection is the emergence of multidrug-tolerant strains, which have normal MICs but do not respond to antibiotic treatment. Here, we report a strain of E. faecalis that was isolated from a cystic fibrosis patient and demonstrated high-level tolerance to ampicillin, vancomycin, and tetracycline. Whole-genome sequencing revealed critical substitutions in one of the tetracycline efflux pump repressors that are consistent with the increased tolerance of E. faecalis UM001B to tetracycline. These findings provide new information about bacterial antibiotic tolerance and may help develop more effective therapeutics.

Resistance in Vancomycin-Resistant Enterococci

Serious infections owing to vancomycin-resistant enterococci have historically proven to be difficult clinical cases, requiring combination therapy and management of treatment-related toxicity. Despite the introduction of new antibiotics with activity against vancomycin-resistant enterococci to the therapeutic armamentarium, significant challenges remain. An understanding of the factors driving the emergence of resistance in vancomycin-resistant enterococci, the dynamics of gastrointestinal colonization and microbiota-mediated colonization resistance, and the mechanisms of resistance to the currently available therapeutics will permit clinicians to be better prepared to tackle these challenging hospital-associated pathogens.

Prevalence of vancomycin-resistant enterococcus in Africa in one health approach: a systematic review and meta-analysis

Vancomycin-resistant enterococci are a global challenge currently as reported by the World Health Organization. It is also important to recognize that combating antimicrobial resistance needs to recognize the interconnections between people, animals, plants and their shared environment in creating public health, the so-called One Health approach. Although the presence of VRE has been described in many regions of the world, there is a lack of comprehensive data indicating their prevalence of in Africa. Therefore, this study aimed to aggregate the result of studies describing VRE reported across multiple regions in Africa. A literature search was conducted on PubMed, Google scholar, and Hinari with the term “Vancomycin resistance enterococcus in Africa” on August 1–3, 2019. All available articles were downloaded to “Endnote version 7.1” then to Microsoft Word 2013. Articles determined to meet our criteria for the review was extracted to Microsoft Excel 2013. Those articles that reported the prevalence of vancomycin resistance Enterococcus obtained from all sample types and published from 2010 to 2019 in the English language were included for the review. A meta-analysis was conducted with OpenMetaAnalyst version R.3.1.0 software. The effect size was determined using a binary random effect model and statically significant considered when p < 0.05. Heterogeneity determined with the inconsistency index. A leave one out analysis used to perform the sensitivity analysis. There were 151 articles identified from the database searches; of this, 36 articles included after extensive review with two independent authors. Out of 4073 samples collected, 1488 isolates identified with an overall pooled prevalence of VRE 26.8% (95% CI; 10.7–43.0%) in Africa with a one-health perspective. The analysis showed that considerable heterogeneity among the studies (I² = 99.97%; p < 0.001). Subgroup analysis in-country, African region, laboratory method, year of publication, and sample source showed that a high prevalence was identified from South Africa (74.8%), South African regions (74.8%), PCR (959.2%), 2010–2015 years (30.3%) and environmental (52.2%), respectively. This meta-analysis indicates that there was a high-pooled prevalence of vancomycin-resistant enterococci in African. A lot should be done to prevent and control the transmission of vancomycin resistance enterococci to a human being from the environment in the continent.

Antibiotic resistance levels in soils from urban and rural land uses in Great Britain

Although soil is one of the largest microbial diversity reservoirs, the processes that define its microbial community dynamics are not fully understood. Improving our understanding of the levels of antibiotic resistance in soils with different land uses in Great Britain is not only important for the protection of animal health (including humans), but also for gaining an insight into gene transfer levels in microbial communities. This study looked at the levels of antibiotic-resistant bacteria (ARB) able to survive inhibitory concentrations of chloramphenicol, erythromycin and vancomycin, as well as subinhibitory (10 µg ml⁻¹) erythromycin concentrations. Soils from nine different sites across Great Britain with three distinct land uses (agricultural, urban and semi-natural) were sampled and the percentage of ARB was calculated for each site. Statistical analyses confirmed a significant difference in the level of ARB found in agricultural land compared to urban or semi-natural sites. The results also showed that resistance levels to vancomycin and chloramphenicol in the agricultural and urban sites sampled were significantly higher than those for erythromycin, whilst in semi-natural sites all three antibiotics show similar resistance levels. Finally, although the levels of resistance to a subinhibitory (10 µg ml⁻¹) erythromycin concentration were significantly higher across land use types when compared to the levels of resistance to an inhibitory (20 µg ml⁻¹) concentration, these were much less marked in soil from agricultural land compared to that from urban or semi-natural land use soil.

Therapeutic Options for Infections due to vanB Genotype Vancomycin-Resistant Enterococci

Enterococci are ubiquitous, facultative, anaerobic Gram-positive bacteria that mainly reside, as part of the normal microbiota, in the gastrointestinal tracts of several animal species, including humans. These bacteria have the capability to turn from a normal gut commensal organism to an invasive pathogen in patients debilitated by prolonged hospitalization, concurrent illnesses, and/or exposed to broad-spectrum antibiotics. The majority of vancomycin-resistant enterococcus (VRE) infections are linked to the vanA genotype; however, outbreaks caused by vanB-type VREs have been increasingly reported, representing a new challenge for effective antimicrobial treatment. Teicoplanin, daptomycin, fosfomycin, and linezolid are useful antimicrobials for infections due to vanB enterococci. In addition, new drugs have been developed (e.g., dalbavancin, telavancin, and tedizolid), new molecules will soon be available (e.g., eravacycline, omadacycline, and oritavancin), and new treatment strategies are progressively being used in clinical practice (e.g., combination therapies and bacteriophages). The aim of this article is to discuss the pathogenesis of infections due to enterococci harboring the vanB operon (vanBVRE) and their therapeutic, state-of-the-art, and future treatment options and provide a comprehensive and easy to use review for clinical purposes.

Probiotic Cocktail Identified by Microbial Network Analysis Inhibits Growth, Virulence Gene Expression, and Host Cell Colonization of Vancomycin-Resistant Enterococci

The prevalence of vancomycin resistant enterococcus (VRE) carrier-state has been increasing in patients of intensive care unit and it would be a public health threat. Different research groups conducted decolonizing VRE with probiotic and the results were controversial. Therefore, a systemic approach to search for the probiotic species capable of decolonizing VRE is necessary. Thus, VRE was co-cultured with ten probiotic species. The fluctuations of each bacterial population were analyzed by 16S rRNA sequencing. Microbial network analysis (MNA) was exploited to identify the most critical species in inhibiting the VRE population. The MNA-selected probiotic cocktail was then validated for its efficacy in inhibiting VRE, decolonizing VRE from Caco-2 cells via three approaches: exclusion, competition, and displacement. Finally, the expression of VRE virulence genes after co-incubation with the probiotic cocktail were analyzed with quantitative real-time PCR (qRT-PCR). The MNA-selected probiotic cocktail includes Bacillus coagulans, Lactobacillus rhamnosus GG, Lactobacillus reuteri, and Lactobacillus acidophilus. This probiotic combination significantly reduces the population of co-cultured VRE and prevents VRE from binding to Caco-2 cells by down-regulating several host-adhesion genes of VRE. Our results suggested the potential of this four-strain probiotic cocktail in clinical application for the decolonization of VRE in human gut.

Effect of the lantibiotic nisin on inhibitory and bactericidal activities of antibiotics used against vancomycin-resistant enterococci

OBJECTIVES

Antibiotic resistance is a serious issue facing clinicians all over the world. Vancomycin-resistant enterococci (VRE) are amongst the most common resistant pathogens that are isolated from patients suffering from infections in our locality. New antimicrobial agents such as the lantibiotic nisin have been previously examined against resistant bacteria as it has strong antibacterial action with no chance of resistance development. This study aimed to explore the effect of nisin in combination with the conventional antibiotics against VRE, with a view to using it as an auxiliary therapy with such antibiotics for combating resistant isolates.

METHODS

Twenty-three VRE had been examined for the combined effect of nisin with the routine sets of antibiotics using the microplate dilution technique for minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) testing. Checkerboard microbroth assay was conducted for inspection of synergism between nisin and either ampicillin or chloramphenicol.

RESULTS

An obvious improvement of inhibitory and bactericidal activities of the tested antibiotics after addition of lantibiotic nisin was observed, with a remarkable reduction in the MIC values of vancomycin against all of the isolates. Nisin recorded a synergistic outcome when combined with either ampicillin or chloramphenicol using the checkerboard assay.

CONCLUSION

Nisin could be effectively considered as a supplementary agent to traditional antibiotics in the management of VRE-associated infections, as it had a synergistic outcome with commonly prescribed antibiotics such as ampicillin and chloramphenicol.

Diversity and antimicrobial resistance of Enterococcus from the Upper Oconee Watershed, Georgia

AIM

It is well-known that enterococci are abundant in the environment; however, the role of surface water as a reservoir of antimicrobial-resistant enterococci remains largely undefined. In this study, surface water samples were collected over a 2-year period from the Upper Oconee watershed, Athens, GA to examine enterococci and their antimicrobial resistance.

METHODS AND RESULTS

Approximately 97% (445/458) of the samples were positive for enterococci and a total of 637 enterococci were isolated. The predominant species were Enterococcus casseliflavus (33·6%) followed by Enterococcus faecalis (26·5%) and Enterococcus hirae (13·2%). Regardless of species, the highest levels of resistance were to lincomycin (88·5%) and tetracycline (13%); isolates also exhibited resistance to newer antimicrobials, daptomycin (8·9%) and tigecycline (6·4%). Multidrug resistance (resistance ≥3 antimicrobial classes) was observed to as many as five classes of antimicrobials. Resistant enterococci appeared to be randomly dispersed over the seasons rather than clustered by species or antimicrobial resistance.

CONCLUSIONS

This study demonstrated that surface waters contain a large population of diverse species of antimicrobial-resistant enterococci, including resistance to new antimicrobials.

SIGNIFICANCE AND IMPACT OF THE STUDY

These results may indicate the potential of human intestinal illness and/or colonization of the human gut with resistant enterococci as enterococci correlate with increased disease risk to humans during recreational exposure to water.

Design and synthesis of biaryloxazolidinone derivatives containing amide or acrylamide moiety as novel antibacterial agents against Gram-positive bacteria

A series of novel biaryloxazolidinone derivatives containing amide and acrylamide structure were designed, synthesized and evaluated for their antibacterial activity. Most compounds generally exhibited potent antibacterial activity with MIC values of 1 μg/mL against S. aureus, MRSA, MSSA, LREF and VRE pathogens, using linezolid and radezolid as positive controls. Compound 17 exhibited good antibacterial activity with MIC values of 0.5 μg/mL against S. aureus, MRSA, MSSA and VRE and 0.25 μg/mL against LREF. The results indicated that compound 17 might serve as a potential hit-compound for further investigation.

Characterization of antibiotic resistance genes in the species of the rumen microbiota

Infections caused by multidrug resistant bacteria represent a therapeutic challenge both in clinical settings and in livestock production, but the prevalence of antibiotic resistance genes among the species of bacteria that colonize the gastrointestinal tract of ruminants is not well characterized. Here, we investigate the resistome of 435 ruminal microbial genomes in silico and confirm representative phenotypes in vitro. We find a high abundance of genes encoding tetracycline resistance and evidence that the tet(W) gene is under positive selective pressure. Our findings reveal that tet(W) is located in a novel integrative and conjugative element in several ruminal bacterial genomes. Analyses of rumen microbial metatranscriptomes confirm the expression of the most abundant antibiotic resistance genes. Our data provide insight into antibiotic resistange gene profiles of the main species of ruminal bacteria and reveal the potential role of mobile genetic elements in shaping the resistome of the rumen microbiome, with implications for human and animal health.

Eradication of Vancomycin-Resistant Enterococci by Combining Phage and Vancomycin

Currently, effective options are needed to fight vancomycin-resistant Enterococcus faecalis (VRE). The present study shows that combinations of phage and vancomycin are highly efficient against VRE, despite being resistant to the antibiotic. Vancomycin-phage EFLK1 (anti-E. faecalis phage) synergy was assessed against VRE planktonic and biofilm cultures. The effect of the combined treatment on VRE biofilms was determined by evaluating the viable counts and biomass and then visualized using scanning electron microscopy (SEM). The cell wall peptidoglycan was stained after phage treatment, visualized by confocal microscopy and quantified by fluorescence activated cell sorting (FACS) analysis. The combined treatment was synergistically effective compared to treatment with phage or antibiotic alone, both in planktonic and biofilm cultures. Confocal microscopy and FACS analysis showed that fluorescence intensity of phage-treated bacteria increased eight-fold, suggesting a change in the peptidoglycan of the cell wall. Our results indicate that with combined treatment, VRE strains are not more problematic than sensitive strains and thus give hope in the continuous struggle against the current emergence of multidrug resistant pathogens.

Emergence of High-level Gentamicin Resistance among Enterococci Clinical Isolates from Burn Patients in South-west of Iran: Vancomycin Still Working

Enterococcus faecalis and Enterococcus faecium are among the main agents associated with nosocomial infections with high mortality in immunocompromised patients. Antibiotic resistance, especially against gentamicin and vancomycin among Enterococci, is a risk factor that could increase the morbidity and mortality rate. 179 Enterococci isolates from burn patients were included in this study. Antibiotic susceptibility testing was done using the disk diffusion test and minimum inhibitory concentration (MIC) was evaluated by agar microdilution. Vancomycin and gentamicin resistance associated genes including vanA, vanB, vanC, aac (6’)-Ie aph(2’’), aph(3’)-IIIa and ant(4’)-Ia were detected by PCR and their statistical relation with antibiotic resistance was evaluated. E. faecalis was the more prevalent strain among our local isolates and showed a higher antibiotic resistance in comparison to E. faecium. Vancomycin had a good antibacterial effect on the Enterococcus spp. isolates; however, resistance to this antibiotic and a high-level gentamicin resistance (HLGR) phenotype were observed. Among van operon genes, vanA was the most prevalent gene and among the gentamicin resistance genes, aph (3’)-IIIa was more frequent. The HLGR Enterococci are a real challenge in nosocomial infections. Vancomycin is a key antibiotic to treat such infections but emergence of VRE in our region could be a real concern and, therefore, phenotypic and molecular surveillance must be considered.

Species, antibiotic susceptibility profiles and van gene frequencies among enterococci isolated from patients at Mulago National Referral Hospital in Kampala, Uganda

Background

The increase in drug resistance to affordable antibiotics used to treat Gram positive bacterial infections has complicated the management of enterococcal infections. Resistance to vancomycin, one of the most powerful antibiotics, is of utmost concern as both intrinsic and acquired forms of resistance do occur in enterococci. This cross-sectional study aimed to determine the species, antibiotic susceptibility profiles and vanA/vanB gene frequencies among enterococci isolated from patients at Mulago Hospital in Kampala, Uganda.

Methods

Between November 2011 and October 2012, stool, urine, sputum and blood samples, as well as vaginal, endocervical, pus, ear and urethra swabs from 3229 patients were processed for isolation of bacteria, yielding 162 enterococci of which 115 were available for analysis (one isolate per specimen/patient). Species-level confirmation and susceptibility testing were determined with the Phoenix™ AST/ID Automated System, while vanA/vanB gene carriage was determined by PCR.

Results

Species-level identification revealed 72 isolates of E. faecalis, 20 E. gallinarum/casseliflavus, 5 E. faecium, 4 E. raffinosus and 2 isolates each for E. hirae and E. durans. Ten isolates could not be identified to species level. Antibiotic resistance was generally low especially to ampicillin, quinolones, nitrofurantoin, glycopeptides and linezolid, but high for erythromycin and tetracycline. Equally, vanA and vanB gene frequencies were low (i.e. 15.8 and 7.9%, respectively) and detected only in E. casseliflavus/gallinarum species that are intrinsically resistant to vancomycin. Vancomycin resistant isolates of E. faecalis and E. faecium were not detected.

Conclusions

Enterococcus species are frequent in clinical specimens at Mulago Hospital but they are highly susceptible to common antibiotics especially ampicillin. While vancomycin resistant enterococcal (VRE) isolates of E. faecium and E. faecalis are rare in the hospital and frequency of multidrug resistance is low, non-faecium and non-faecalis VRE isolates (i.e. E. gallinarum/casseliflavus) are frequent, some with VanA/VanB (high-level) vancomycin resistance. Therefore, species-level identification of enterococci is necessary in resource limited settings to guide infection control and treatment of enterococcal infections.

Electronic supplementary material

The online version of this article (10.1186/s12879-019-4136-7) contains supplementary material, which is available to authorized users.

Vancomycin-resistant Enterococcus in solid organ transplant recipients: Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

These updated guidelines from the Infectious Diseases Community of Practice of the American Society of Transplantation address vancomycin-resistant enterococci (VRE) infections in SOT candidates and recipients. VRE are an important cause of infection and have been named by the CDC as a serious public threat. Typically, a commensal of the gastrointestinal tract, VRE may become pathogenic after abdominal organ manipulation like transplantation. This guideline reviews the microbiology, antimicrobial resistance mechanisms, epidemiology, and clinical manifestations of VRE infection in the context of solid organ transplantation. Treatment regimens including combination therapies and novel investigational agents are also reviewed. Finally, an updated appraisal of infection control measures relevant to VRE infection and colonization is presented.

Antimicrobial Activities of Dictyostelium Differentiation-Inducing Factors and Their Derivatives

At the end of its life cycle, the cellular slime mold Dictyostelium discoideum forms a fruiting body consisting of spores and a multicellular stalk. Originally, the chlorinated alkylphenone differentiation-inducing factors (DIFs) -1 and -3 were isolated as stalk cell inducers in D. discoideum. Later, DIFs and their derivatives were shown to possess several biologic activities including antitumor and anti-Trypanosoma properties. In this study, we examined the antibacterial activities of approximately 30 DIF derivatives by using several bacterial species. Several of the DIF derivatives strongly suppressed the growth of the Gram-positive bacteria Staphylococcus aureus, Bacillus subtilis, and Enterococcus faecalis and Enterococcus faecium, at minimum inhibitory concentrations (MICs) in the sub-micromolar to low-micromolar range. In contrast, none of the DIF derivatives evaluated had any noteworthy effect on the growth of the Gram-negative bacterium Escherichia coli (MIC, >100 µM). Most importantly, several of the DIF derivatives strongly inhibited the growth of methicillin-resistant S. aureus and vancomycin-resistant E. faecalis and E. faecium. Transmission electron microscopy revealed that treatment with DIF derivatives led to the formation of distinct multilayered structures consisting of cell wall or plasma membrane in S. aureus. The present results suggest that DIF derivatives are good lead compounds for developing novel antimicrobials.

Promising Recent Strategies with Potential Clinical Translational Value to Combat Antibacterial Resistant Surge

Multiple drug resistance (MDR) for the treatment of bacterial infection has been a significant challenge since the beginning of the 21st century. Many of the small molecule-based antibiotic treatments have failed on numerous occasions due to a surge in MDR, which has claimed millions of lives worldwide. Small particles (SPs) consisting of metal, polymer or carbon nanoparticles (NPs) of different sizes, shapes and forms have shown considerable antibacterial effect over the past two decades. Unlike the classical small-molecule antibiotics, the small particles are less exposed so far to the bacteria to trigger a resistance mechanism, and hence have higher chances of fighting the challenge of the MDR process. Until recently, there has been limited progress of clinical treatments using NPs, despite ample reports of in vitro antibacterial efficacy. In this review, we discuss some recent and unconventional strategies that have explored the antibacterial efficacy of these small particles, alone and in combination with classical small molecules in vivo, and demonstrate possibilities that are favorable for clinical translations in near future.

Targeting Metalloenzymes for Therapeutic Intervention

Metalloenzymes are central to a wide range of essential biological activities, including nucleic acid modification, protein degradation, and many others. The role of metalloenzymes in these processes also makes them central for the progression of many diseases and, as such, makes metalloenzymes attractive targets for therapeutic intervention. Increasing awareness of the role metalloenzymes play in disease and their importance as a class of targets has amplified interest in the development of new strategies to develop inhibitors and ultimately useful drugs. In this Review, we provide a broad overview of several drug discovery efforts focused on metalloenzymes and attempt to map out the current landscape of high-value metalloenzyme targets.

Comparative genome analysis reveals key genetic factors associated with probiotic property in Enterococcus faecium strains

BACKGROUND

Enterococcus faecium though commensal in the human gut, few strains provide a beneficial effect to humans as probiotics while few are responsible for the nosocomial infection. Comparative genomics of E. faecium can decipher the genomic differences responsible for probiotic, pathogenic and non-pathogenic properties. In this study, we compared E. faecium strain 17OM39 with a marketed probiotic, non-pathogenic non-probiotic (NPNP) and pathogenic strains.

RESULTS

E. faecium 17OM39 was found to be closely related with marketed probiotic strain T110 based on core genome analysis. Strain 17OM39 was devoid of known vancomycin, tetracycline resistance and functional virulence genes. Moreover, E. faecium 17OM39 genome was found to be more stable due to the absence of frequently found transposable elements. Genes imparting beneficial functional properties were observed to be present in marketed probiotic T110 and 17OM39 strains. Genes associated with colonization and survival within gastrointestinal tract was also detected across all the strains.

CONCLUSIONS

Beyond shared genetic features; this study particularly identified genes that are responsible for imparting probiotic, non-pathogenic and pathogenic features to the strains of E. faecium. Higher genomic stability, absence of known virulence factors and antibiotic resistance genes and close genomic relatedness with marketed probiotics makes E. faecium 17OM39 a potential probiotic candidate. The work presented here demonstrates that comparative genome analyses can be applied to large numbers of genomes, to find potential probiotic candidates.

Clinical Evaluation of the iCubate iC-GPC Assay for Detection of Gram-Positive Bacteria and Resistance Markers from Positive Blood Cultures

The iC-GPC Assay (iCubate, Huntsville, AL) is a qualitative multiplex test for the detection of five of the most common Gram-positive bacteria (Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, Enterococcus faecalis, and Enterococcus faecium) responsible for bacterial bloodstream infections, performed directly from positive blood cultures. The assay also detects the presence of the mecA, vanA, and vanB resistance determinants.

The iC-GPC Assay (iCubate, Huntsville, AL) is a qualitative multiplex test for the detection of five of the most common Gram-positive bacteria (Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, Enterococcus faecalis, and Enterococcus faecium) responsible for bacterial bloodstream infections, performed directly from positive blood cultures. The assay also detects the presence of the mecA, vanA, and vanB resistance determinants. This study comparatively evaluated the performance of the iC-GPC Assay against the Verigene Gram-positive blood culture (BC-GP) assay (Luminex Corp., Austin, TX) for 1,134 patient blood culture specimens positive for Gram-positive cocci. The iC-GPC Assay had an overall percent agreement with the BC-GP assay of 95.5%. Discordant specimens were further analyzed by PCR and a bidirectional sequencing method. The results indicate that the iC-GPC Assay together with the iCubate system is an accurate and reliable tool for the detection of the five most common Gram-positive bacteria and their resistance markers responsible for bloodstream infections.

Cyclic Peptides that Govern Signal Transduction Pathways: From Prokaryotes to Multi-Cellular Organisms

Cyclic peptide scaffolds are key components of signal transduction pathways in both prokaryotic and eukaryotic organisms since they act as chemical messengers that activate or inhibit specific cognate receptors. In prokaryotic organisms these peptides are utilized in non-essential pathways, such as quorum sensing, that are responsible for virulence and pathogenicity. In the more evolved eukaryotic systems, cyclic peptide hormones play a key role in the regulation of the overall function of multicellular organisms, mainly through the endocrine system. This review will highlight several prokaryote and eukaryote systems that use cyclic peptides as their primary signals and the potential associated with utilizing these scaffolds for the discovery of novel therapeutics for a wide range of diseases and illnesses.