Clinical Isolates Of Vancomycin-resistant Enterococci Research Articles

Oral vancomycin use and incidence of vancomycin-resistant enterococci: time-series analysis

SummaryBackgroundVancomycin exposure is a major risk factor for vancomycin-resistant enterococci (VRE) colonisation, but the relationship between oral vancomycin and the risk of VRE colonisation remains poorly understood without ecological evidence. In this study, we investigated the association between oral vancomycin usage and the incidence of hospital-acquired VRE using a time-series analysis.MethodsThis retrospective ecological study analysed monthly data on antibiotic usage and VRE incidence from January 2013 to December 2022 at a 2700-bed hospital in South Korea. Antibiotic usage was measured in days of therapy (DOT) per 1000 patient-days. Hospital-acquired VRE incidence was defined as the number of VRE isolates identified more than 48 h after admission per 1000 patient-days. The association between oral vancomycin use and VRE incidence was assessed using a multivariate autoregressive integrated moving average (ARIMA) regression model incorporating lag structures.ResultsOver 10 years, 5,763 clinical VRE isolates were identified, with 5,133 (89%) being hospital-acquired. Oral vancomycin usage and VRE incidence showed significant upward trends during the study period. In the final ARIMA model adjusting for various types of antibiotic use and baseline VRE carriage rate, a significant association was observed between oral vancomycin use and VRE incidence (coefficient: 0.0160, 95% CI: 0.0030 to 0.0290, P = 0.0162), with an R-squared value of 0.76. Sensitivity analyses demonstrated the robustness of the association between oral vancomycin use and VRE acquisition across various time lags between antibiotic use and VRE incidence.ConclusionsThere was a significant association between institutional oral vancomycin use and hospital-acquired VRE incidence, highlighting the need for antibiotic stewardship for oral vancomycin use to contain the nosocomial spread of VRE in addition to infection control measures.

Tolerance of clinical vancomycin-resistant Enterococcus faecium isolates against UV-C light from a mobile source

BackgroundAdmission to a room previously occupied by patients carrying environmentally robust pathogens implies an increased risk of acquiring those pathogens. Therefore, ‘No-touch’ automated room disinfection systems, including devices based on UV-C irradiation, are discussed to improve terminal cleaning. It is still unclear if clinical isolates of relevant pathogens behave differently under UV-C irradiation compared to laboratory strains used in the approval process of disinfection procedures. In this study we analysed the susceptibility of well characterized clonally divergent vancomycin-resistant enterococci (VRE) strains, including a linezolid-resistant isolate, against UV-C radiation.MethodsSusceptibility against UV-C of ten clonally divergent clinical isolates of VRE was determined in comparison to the commonly used test organism Enterococcus hirae ATCC 10541. Ceramic tiles contaminated with 105 to 106 colony forming units/25 cm² of the different enterococci were positioned at a distance of 1.0 and 1.5 m and irradiated for 20 s, resulting in a UV-C dose of 50 and 22 mJ/cm², respectively. Reduction factors were calculated after quantitative culture of the bacteria recovered from treated and untreated surfaces.ResultsSusceptibility to UV-C varied considerably among the strains studied, with the mean value of the most robust strain being up to a power of ten lower compared to the most sensitive strain at both UV-C doses. The two most tolerant strains belonged to MLST sequence types ST80 and ST1283. The susceptibility of the laboratory strain E. hirae ATCC 10541 ranged between the most sensitive and most tolerant isolates for both irradiation doses. However, for UV-C dose of 22 mJ/cm², the reduction of the most tolerant isolate of ST1283 was statistically significantly lower compared to E. hirae ATCC 10541. The most susceptible strains belonged to the MLST sequence types ST117 and ST203.ConclusionsThese results indicate that UV-C doses reported in the literature are sufficient for the reduction of commonly used reference strains of enterococci but could be insufficient for the reduction of tolerant patient VRE-isolates in a hospital setting. Therefore, for future studies, the most tolerant clinical isolates should be used to validate automated UV-C devices or longer exposure times should be expected to ensure efficacy in the real world.

Repositioning of Disulfiram in Association with Vancomycin Against Enterococcus spp. MDR and XDR.

The identification of molecules that exhibit potent antibacterial activity and are capable of circumventing resistance mechanisms is an unmet need. The repositioning of approved drugs is considered an advantageous alternative in this case, and has gained prominence. In addition, drug synergism can reduce morbidity and mortality in the treatment of nosocomial infections caused by multi-drug resistant microorganisms (MDR). Whole cell growth inhibition assays were used to define the in vitro antibacterial activity of disulfiram against two standard American Type Culture Collection (ATCC) strains and 35 clinical isolates of vancomycin-resistant enterococci (VRE). The ability of disulfiram to synergize with vancomycin was determined by fractional inhibitory concentration index, preceded by the checkerboard test. The cytotoxicity of drugs alone and in combination was tested against Raw 264.7 cells. Disulfiram exhibited potent antibacterial activity against VRE (MIC 16-64µgmL-1). Results: Associated with vancomycin, disulfiram it had a reduction in MIC of up to 64 times, with values of 0.5-4µgmL-1. Vancomycin had a MIC of 128-1024µgmL-1; combined, reduced this value by up to 124 times (8µgmL-1), with synergy occurring against all strains. Disulfiram and vancomycin alone and in combination did not show cytotoxicity against the eukaryotic cell line. Based on these results, we suggest that the redirection of disulfiram may be promising in the treatment of infections caused by VRE, since it was able to potentiate the activity of vancomycin against the strains, being able to act as an adjuvant in cases of serious infections caused by Enterococcus.

In vitro and in vivo activities of the carbonic anhydrase inhibitor, dorzolamide, against vancomycin-resistant enterococci.

Vancomycin-resistant enterococci (VRE) are a serious public health threat and a leading cause of healthcare-associated infections. Bacterial resistance to antibiotics recommended for the treatment of enterococcal infections complicates the management of these infections. Hence, there is a critical need for the discovery of new anti-VRE agents. We previously reported carbonic anhydrase inhibitors (CAIs) as new potent VRE inhibitors. In the present study, the activity of the CAI, dorzolamide was evaluated against VRE both in vitro and in vivo. Dorzolamide exhibited potent activity against a panel of clinical VRE isolates, with minimum inhibitory concentration (MIC) values ranging from 1 µg/mL to 8 µg/mL. A killing kinetics experiment determined that dorzolamide exhibited a bacteriostatic effect against VRE, which was similar to the drug of choice (linezolid). Dorzolamide interacted synergistically with gentamicin against four strains of VRE, and exhibited an additive interaction with gentamicin against six VRE strains, reducing gentamicin’s MIC by several folds. Moreover, dorzolamide outperformed linezolid in an in vivo VRE colonization reduction mouse model. Dorzolamide significantly reduced the VRE burden in fecal samples of mice by 2.9-log10 (99.9%) and 3.86-log10 (99.99%) after 3 and 5 days of treatment, respectively. Furthermore, dorzolamide reduced the VRE count in the cecal (1.74-log10 (98.2%) reduction) and ileal contents (1.5-log10 (96.3%)) of mice, which was superior to linezolid. Collectively, these results indicate that dorzolamide represents a promising treatment option that warrants consideration as a supplement to current therapeutics used for VRE infections.

Optimization of Linezolid Dosing Regimens for Treatment of Vancomycin-Resistant Enterococci Infection.

BackgroundLinezolid, an oxazolidinone antibiotic, is recommended for vancomycin-resistant enterococci (VRE). However, 100% free-drug concentration above the minimum inhibitory concentration (fT>MIC) and an area under the curve of free drug to MIC ratio (fAUC24/MIC) >100 were associated with favorable clinical outcome with less emerging resistance. A plasma trough concentration (Ctrough) of linezolid ≥9 µg/mL was also related to hematologic toxicity. Thus, linezolid dose optimization is needed for VRE treatment. The study aimed to determine the in vitro linezolid activity against clinical VRE isolates and linezolid dosing regimens in critically ill patients who met the target pharmacokinetics/pharmacodynamics (PK/PD) for VRE treatment.Materials and MethodsEnterococcal isolates from enterococcal-infected patients were obtained between 2014 and 2018 at Phramongkutklao Hospital. We used Monte Carlo simulation to calculate the probability of target attainment, and the cumulative fraction of response (CFR) of the free area under the curve to MIC ratio (fAUIC24) was used to calculate the fAUC24/MIC 80 - 100 and fT/MIC >85 - 100% of the interval time of administration for clinical response and microbiological eradication as well as the Ctrough ≥9 µg/mL for the probability of hematologic toxicity.ResultsFor linezolid MIC determination, the MIC median (MIC50), MIC for 90% growth (MIC90), and range for linezolid were 1.5 µg/mL, 2 µg/mL, and 0.72 - 2 µg/mL, respectively. A dosing regimen of 1,200 mg either once daily or as a divided dose every 12 h gave target attainments of fAUC24/MICs >80 and >100, which exceeded 90% for MICs ≤1 and ≤1 µg/mL, respectively, with a rate of hematologic toxicity <15%. If the expected fT>MICs were >85% and 100%, a 1,200-mg divided dose every 12 h could cover VRE isolates having linezolid MICs ≤1 µg/mL and ≤0.75 µg/mL. Even 600 mg every 8 h and 1,200 mg as a continuous infusion gave a higher target attainment of fAUC24/MIC and a fT>MIC and the target CFR, but those regimens gave Ctrough ≥9 µg/mL rates of 40.7% and 99.6%.ConclusionThe current dosing of 1,200 mg/day might be optimal treatment for infection by VRE isolates with documented MICs ≤1 µg/mL. For treatment of VRE with a MIC of 2 µg/mL or to achieve the target CFR, the use of linezolid with other antibiotic combinations might help achieve the PK/PD target, provide better clinical outcome, and prevent resistance.

Rektal Tarama Örnekleri ile Klinik Örneklerde Üreyen Vankomisine Dirençli Enterokokların İrdelenmesi: Yedi Yıllık Sürveyans, Retrospektif Kesitsel Bir Çalışma

Vancomycin-resistant enterococci (VRE) are multidrug-resistant microorganisms that cause nosocomial infections, prolong hospital stay and cause mortality. Current recommendations are active surveillance, screening and contact isolation to prevent the spread of VRE positivity among patients. It has been observed that the failure of the systematic screening caused the spread of VRE and increased costs. It was aimed to determine vancomycin resistance rates in Enterococcus spp., which was grown from rectal swab samples and clinical samples sent for screening of hospitalized patients between January 2013 and May 2019, to investigate the distribution of resistant isolates to departments. A rectal swab sample for VRE screening was obtained from each patient admitted to intensive care units in our hospital, and subcultured onto VRE chromogenic medium (Gül Laboratories, Turkey). The susceptibility of the isolates to vancomycin (30 μg) was detected by Kirby-Bauer disk diffusion method in accordance with the Clinical and Laboratory Standards Institute (CLSI) criteria. The VITEK2 Compact automated system was used to determine the vancomycin susceptibility of enterococci isolated from clinical samples. VRE growth was detected in 316 (6 %) of the 5249 rectal swab samples sent to the laboratory, and vancomycin resistance was detected in 51 (3.9 %) of 1306 Enterococcus spp. from clinical specimens. Of the 51 isolates with vancomycin resistance, 80 % were isolated from urine, 14 % from blood, 4 % from wound, and 2% from joint fluid. While the VRE rate in rectal swab samples was 5.5 % in 2013, it increased to 11.6 % in 2019. Vancomycin resistance was 1.6 % in 2013 and peaked at 7.7 % in 2017 in Enterococcus spp. Twenty nine percent of the 51 clinical VRE isolates were grown from patients with VRE positive rectal swabs. The highest rate of VRE growth in rectal swab samples and culture samples was observed in the Anesthesia Intensive Care Unit. No relationship was found between VRE positivity decrease and increase rates of rectal swab and clinical samples over the years. In order to prevent the spread of VRE in the hospital environment, it is necessary to take surveillance cultures regularly in centers, to provide necessary training to hospital staff, to control the use of antimicrobials, and to ensure good cooperation between the microbiology laboratory and services.

Optimizing the Dosing Regimens of Daptomycin Based on the Susceptible Dose-Dependent Breakpoint against Vancomycin-Resistant Enterococci Infection.

Daptomycin, a lipopeptide antibiotic, is one of the therapeutic options used for the treatment of vancomycin-resistant enterococci (VRE). Recently, the Clinical and Laboratory Standards Institute (CLSI) M100 30th edition has removed the susceptibility (S) breakpoint for Enterococcus faecium and replaced it with a susceptible dose-dependent (SDD) breakpoint of ≤4 μg/mL, with a suggested dosage of 8–12 mg/kg/day. Herein, we aimed to determine the minimum inhibitory concentration (MIC) values of daptomycin against clinical VRE isolates and to study the appropriate daptomycin dosing regimens among critically ill patients based on the new susceptibility CLSI breakpoint. The MIC determination of daptomycin was performed using E-test strips among clinical VRE strains isolated from patients at the Phramongkutklao Hospital. We used Monte Carlo simulation to calculate the probability of target attainment (PTA) and the cumulative fraction of response (CFR) of the ratio of the free area under the curve to MIC (fAUC0–24/MIC) > 27.4 and fAUC0–24/MIC > 20 for survival and microbiological response, respectively, at the first day and steady state. Further, we determined that the simulated daptomycin dosing regimen met the minimum concentration (Cmin) requirements for safety of being below 24.3 mg/L. All of the 48 VRE isolates were E. faecium strains, and the percentiles at the 50th and 90th MIC of daptomycin were 1 and 1.5 μg/mL, respectively. At MIC ≤ 2 μg/mL, a daptomycin dosage of 12 mg/kg/day achieved the PTA target of survival and microbiological response at the first 24 h time point and steady state. For a MIC of 4 μg/mL, none of the dosage regimens achieved the PTA target. For CFR, a dosage of 8–12 mg/kg/day could achieve the 90% CFR target at the first day and steady state. All dosing regimens had a low probability of Cmin being greater than 24.3 mg/L. In conclusion, the MIC of VRE against daptomycin is quite low, and loading and maintenance doses with 8 mg/kg/day were determined to be optimal and safe.

New semisynthetic teicoplanin derivatives have comparable in vitro activity to that of oritavancin against clinical isolates of VRE.

Ten analogues of a teicoplanin pseudoaglycon derivative have been synthesized with the aim of optimizing the in vitro activity of the compound against VanA type vancomycin resistant enterococci (VRE) isolated from hospitalized patients. Teicoplanin, vancomycin, and oritavancin were used as reference antibiotics for the antibacterial evaluations. One of the new derivatives exhibited far superior activity than the original compound. The in vitro MICs measured were comparable to that of oritavancin against the investigated VRE strains.

Overview of Prevalence, Characteristics, Risk Factors, Resistance, and Virulence of Vancomycin-Resistant Enterococci in Saudi Arabia.

Vancomycin-resistant enterococci (VRE) are Gram-positive bacteria that are resistant to vancomycin. Infections caused by VRE are associated with adverse outcomes such as extended length of hospital stay, increased cost, and high mortality rate. Clinical and surveillance VRE isolates have been reported from Saudi Arabia. In this review, prevalence, characteristics, risk factors, resistance, and virulence of VRE isolates associated with infection and colonization in Saudi Arabia are described.

A novel bacteriocin from Enterococcus faecalis 478 exhibits a potent activity against vancomycin-resistant enterococci.

The emergence of multidrug-resistant enterococci (MDRE) and particularly vancomycin-resistant enterococci (VRE) is considered a serious health problem worldwide, causing the need for new antimicrobials. The aim of this study was to discover and characterize bacteriocin against clinical isolates of MDRE and VRE. Over 10,000 bacterial isolates from water, environment and clinical samples were screened. E. faecalis strain 478 isolated from human feces produced the highest antibacterial activity against several MDRE and VRE strains. The optimum condition for bacteriocin production was cultivation in MRS broth at 37°C, pH 5–6 for 16 hours. The bacteriocin-like substance produced from E. faecalis strain EF478 was stable at 60°C for at least 1 hour and retained its antimicrobial activity after storage at -20°C for 1 year, at 4°C for 6 months, and at 25°C for 2 months. A nano-HPLC electrospray ionization multi-stage tandem mass spectrometry (nLC-ESI-MS/MS) analysis showed that the amino acid sequences of the bacteriocin-like substance was similar to serine protease of E. faecalis, gi|488296663 (NCBI database), which has never been reported as a bacteriocin. This study reported a novel bacteriocin with high antibacterial activity against VRE and MDRE.

Draft Genome Sequences of Nine Clinical Isolates of Vancomycin-Resistant Enterococci.

In 2012, there was an increase in vancomycin-resistant enterococci (VRE) isolated from the intensive care unit at the University Hospital of Cologne. Using whole-genome sequencing it was possible to establish that bloodstream infections with VRE were not the result of an outbreak or cross infections.

Enhancing the Anti-Enterococci Activity of Different Antibiotics by Combining With Metal Oxide Nanoparticles

BackgroundEnterococci have emerged as more virulent and multidrug-resistant in community and hospital settings. The emergence of vancomycin resistant enterococci (VRE) in hospitals has posed a serious threat to public health. The widespread use of antibiotics to treat VRE infections has resulted in the development of resistant forms of these organisms.ObjectivesPresent study deals with the efficacy of antibiotic-nanoparticle combination against clinical isolates of VRE. This study has effectively evaluated the anti-enterococcal activity of metallic nanoparticles and their combination with antibiotics with the aim to search for new biocidal combinations.Materials and MethodsInitially, the isolates were identified by various biochemical tests and also by PCR, targeting ddl, vanA and vanB genes. Antibiotic susceptibility testing was carried out by disc diffusion method. Minimum inhibitory concentration (MIC) of both antibiotics and metal nanoparticles against VRE was done using broth dilution method. On the basis of MICs, a combination of both antibiotics and nanoparticles was used by physical mixing of antibiotics and different concentrations of nanoparticles.ResultsThe MIC of metal nanoparticles were found in the range of 0.31 - 30 mM. The combination of both antibiotics and nanoparticles has effectively reduced the MICs of ciprofloxacin from 16 - 256 μg/mL to 2 - 16 μg/mL, erythromycin 1024 - 2048 μg/mL to 128 - 512 μg/mL, methicillin 32 - 256 μg/mL to 8 - 64 μg/mL and vancomycin 2 - 512 μg/mL to 0.5 - 64 μg/mL.ConclusionsAmong the nanoparticles, ZnO was found as a potent metallic nanoparticle which effectively reduced the MIC upon combination with the antibiotics. The combination exhibited enhanced bactericidal activity against multidrug resistant clinical strains of VRE with dose dependency. Further extensive study on this aspect can prove their beneficial clinical use against resistant pathogens to combat increasing resistance to antibiotics.

Emergence of linezolid resistance in clinical isolates of vancomycin-resistant enterococci

Emergence of linezolid resistance in clinical isolates of vancomycin-resistant enterococci

Synthesis and biological evaluation of novel peptide BF2 as an antibacterial agent against clinical isolates of vancomycin-resistant enterococci.

Enterococci are the leading cause of nosocomial infections worldwide and acquired resistance to a variety of antibiotics. Antimicrobial peptides represent a promising molecule against the antibiotic resistance in bacteria and an indispensable component of the innate immune system. The aim of the study was to develop an antimicrobial peptide against vancomycin-resistant enterococci (VRE). We have designed a series of peptides based on Sapecin B as template. An in vitro antibacterial study of synthetic peptide BF2 against the clinical isolates of vancomycin-resistant and control strains of enterococci showed rapid killing effect on enterococci by killing 99.9% of bacterial cells in 60 min and susceptibility at minimum inhibitory concentration (MIC) range of 6.25-12.5 μg/mL. Synergy of BF2 was observed in combination with vancomycin and teicoplanin. The peptide was bactericidal and nontoxic to mammalian cells. An in vivo study also revealed the antibacterial activity against enterococci-infected Wistar albino rats. BF2 may be used synergistically with antibiotics.

Evaluation of the antimicrobial activity of daptomycin and linezolid against vancomycin-resistant Enterococcus spp. isolates in south India.

Vancomycin-resistant enterococci (VRE) have emerged as a major nosocomial pathogen. Alternatives for the treatment of infection with VRE include linezolid and daptomycin. Experience with these agents, especially daptomycin, is limited in India. The minimum inhibitory concentration of linezolid and daptomycin against 98 clinical isolates of VRE was tested by E-test. Daptomycin and linezolid showed good activity, with susceptibility rates of 93.9% and 96.9%, respectively.

Correlation between antimicrobial consumption and incidence of health-care-associated infections due to methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci at a university hospital in Taiwan from 2000 to 2010

ObjectivesThis study was conducted to investigate the correlation between antibiotic consumption and the incidence of health-care-associated infections (HCAIs) caused by methicillin-resistant Staphylococcus aureus (MRSA) (HCAI-MRSA) and vancomycin-resistant enterococci (VREs) (HCAI-VREs) at a university hospital in Taiwan during the period from 2000 to 2010.MethodsData on annual patient-days and annual consumption (defined daily dose/1000 patient-days) of glycopeptides (vancomycin and teicoplanin), linezolid, fusidic acid, tigecycline, and daptomycin were analyzed. Yearly aggregated data on the number of nonduplicate clinical MRSA and VRE isolates causing HCAI were collected.ResultsOverall, the consumption of teicoplanin and linezolid significantly increased during the study period. A significant decrease in the incidence of HCAI-MRSA and a significant increase in the incidence of HCAI-VRE were found during the study period. A significant correlation was found between the increased use of teicoplanin and linezolid and the decreased incidence of HCAI-MRSA. By contrast, positive correlations were found between the consumption of teicoplanin and tigecycline and the incidence of HCAI-VRE.ConclusionThis study identified various correlations between the consumption of antibiotics and the incidence of HCAI-MRSA and HCAI-VRE. Strict implementation of infection-control guidelines and reinforcement of administering appropriate antibiotic agents would be helpful in decreasing the incidence of MRSA and VRE in hospitals.

Molecular characterization of vancomycin-resistant enterococci in Serbia: Intensive care unit as the source

The purpose of this study was to evaluate the molecular relatedness of clinical isolates of vancomycin-resistant enterococci (VRE) collected from patients of the Clinic for Infectious and Tropical Diseases in Belgrade. Among 40 isolates available for the investigation, 36 were identified as Enterococcus faecium, whereas 2 were Enterococcus faecalis and Enterococcus raffinosus, respectively. Pulsed-field gel electrophoresis (PFGE) typing revealed 21 strain types, comprising 7 clusters which contained at least two isolates and 14 unique PFGE patterns. Although we searched for pathogenicity factor genes (gelE, cylB, asa1, efaAfs, esp, cpd, cob) in representatives of all macro-restriction patterns, they have been confirmed in only one clone of E. faecalis. Genes esp and hyl, commonly found in E. faecium, were yilded in 10 macro-restriction patterns of this species, and their presence could not be ascribed to clonally related strains (p = 0.05). All VRE isolates were multiresistant and positive for vanA gene. Twenty strains of VRE and 6 clusters obtained from Intensive care unit (ICU) are proof of intensive transmission of these microorganisms at this department. The results of this study suggest wide genotypic variability among the clinical VRE isolates, but also intrahospital dissemination of some of them.

English

Enterococcus faecalis has emerged as an important nosocomial pathogen worldwide, infections and outbreaks of Vancomycin-resistant enterococci (VRE) still appear to be rare in Baghdad. In the present study, 20 isolates of E. faecalis were collected from 252 clinical samples (151 urine and 101 blood) from different hospitals in Baghdad and 3 isolates from 50 stool samples from healthy people during the period 1/10/2010 to 1/12/2010. All isolates were identified through morphological, cultural and biochemical tests using Rapid ID-32 strep. Vancomycin-resistance phenotype was determined by the agar diffusion method; results showed that five clinical isolates (25%) and two faecal isolates (66.7%)were resistant to vancomycin. Minimum inhibitory concentrations (MIC) of clinical VRE isolates ranged between 4 to 512 µg/ml and the MICs for isolates of faecal origin were 64 and 128 µg/ml. Seven vancomycin-resistant E. faecalis isolates were examined for their drug resistance and plasmid DNAs. Of the 5 clinical isolates, 2 isolates exhibited resistance to azlocillin (Azl) and ofloxacillin (Ofx). All clinical and stool isolates were resistant to oxacillin (Ox), cefepime (Fep), rifampicin (Ra) and tetracycline (Te). Imipenem and ampicillin were found to be the most effective agents against the isolates. The detection of plasmid DNA by gel electrophoresis showed that some E. faecalis isolates carried a high molecular weight plasmid that was transferred to the recipient by filter mating. The putative presence of vanA gene was examined by PCR, using specific primers. Positive PCR amplifications were obtained in all 7 isolates for vanA gene.Vancomycin resistant E. faecalis increased gradually in Baghdad hospitals and high dissemination of vanA gene, which encoded high resistance level to vancomycin. Continued surveillance is required to prevent further spread of these serious resistances. Key words: Bacteria, vancomycin, Enterococcus faecalis

Photoinactivation of vancomycin-resistant Enterococci and Bacillus subtilis by a novel norvancomycin–rhodamine B conjugate

In order to accumulate photosensitizers on the cell walls of vancomycin-sensitive and vancomycin-resistant bacterial strains for labeling or/and photoinactivation of bacteria upon light irradiation, a simple and novel norvancomycin–rhodamine B (Van–Rh) conjugate was synthesized, characterized and confirmed using MALDI-TOF mass spectrometry. The properties of Van–Rh in photodynamic inactivation and fluorescent imaging of vancomycin-sensitive and vancomycin-resistant Enterococci (VRE) strains were investigated. The photodynamic assay indicated that Van–Rh effectively inactivated Bacillus subtilis (ATCC 6633), clinical isolates of VRE and Enterococcus faecalis (ATCC 51299, Van B genotype) with inactivation rates of 71, 54 and 47% at 9 μM upon 3 min of light exposure, respectively. Van–Rh enabled the fluorescent imaging of B. subtilis at 5 μM and two VRE strains at 20 μM, but not E. coli. The phototoxicity and binding affinity of rhodamine B were enhanced by conjugation with norvancomycin as an affinity ligand.

Performance Characteristics of the Cepheid Xpert vanA Assay for Rapid Identification of Patients at High Risk for Carriage of Vancomycin-Resistant Enterococci

We compared the performance characteristics of culture and the Cepheid Xpert vanA assay for routine surveillance of vancomycin-resistant enterococci (VRE) from rectal swabs in patients at high risk for VRE carriage. The Cepheid Xpert vanA assay had a limit of detection of 100 CFU/ml and correctly detected 101 well-characterized clinical VRE isolates with no cross-reactivity in 27 non-VRE and related culture isolates. The clinical sensitivity, specificity, positive predictive value, and negative predictive value of the Xpert vanA PCR assay were 100%, 96.9%, 91.3%, and 100%, respectively, when tested on 300 consecutively collected rectal swabs. This assay provides excellent predictive values for prompt identification of VRE-colonized patients in hospitals with relatively high rates of VRE carriage.