Vancomycin-sensitive Enterococcus Research Articles

Measuring the efficacy of standard and novel disinfection methods on frequently used physical therapy equipment: a 2-phase prospective randomized controlled trial.

Frequently used physical therapy (PT) equipment is difficult to disinfect due to equipment material and shape. The efficacy of standard disinfection of PT equipment is poorly understood. We completed a 2-phase prospective microbiological analysis of fomites used in PT at our hospital from September 2022 to October 2023. For both phases, study fomites were obtained after usage and split into symmetrical halves for sampling. In phase 1, sides were sampled following standard disinfection. In phase 2, sides were randomized 1:1 to intervention or control. Samples were obtained before and after the intervention, a disinfection cabinet using Ultraviolet C (UV-C) and 6% nebulized hydrogen peroxide. We defined antimicrobial-resistant clinically important pathogens (AMR CIP) as methicillin-resistant staphylococcus aureus (MRSA), Vancomycin Resistant Enterococcus (VRE), and Multidrug resistant (MDR)-Gram-negatives and non-AMR CIP as methicillin-sensitive staphylococcus aureus (MSSA), Vancomycin sensitive Enterococcus (VSE), and Gram-negatives. Three assessments were made: 1) contamination following standard disinfection (phase 1), 2) contamination postintervention compared to no disinfection (phase 2) and, 3) contamination following standard disinfection compared to postintervention (phase 1 vs phase 2 intervention). The median total colony-forming units (CFU) from 122 study fomite samples was 1,348 (IQR 398-2,365). At the sample level, 52(43%) and 15(12%) of samples harbored any clinically important pathogens (CIPs) or AMR CIPs, respectively. The median CFU was 0 (IQR 0-55) in the intervention group and 977 (409-2,547) in the control group (P < .00001). Following standard disinfection, PT equipment remained heavily contaminated including AMR and non-AMR CIPs. Following the intervention, PT equipment was less contaminated and harbored no AMR CIPs compared to control sides supporting the efficacy of the intervention on difficult-to-disinfect PT fomites.

Characterization and Antimicrobial Susceptibility Patterns of Enterococcus Species Isolated from Nosocomial Infections in a Saudi Tertiary Care Hospital over a Ten-Year Period (2012-2021).

The Enterococcus genus is a common cause of nosocomial infections, with vancomycin-resistant enterococci (VRE) posing a significant treatment challenge. This retrospective study, spanning ten years (2012 to 2021), analyzes antimicrobial susceptibility patterns of Enterococcus species from clinical samples in a Saudi Arabian tertiary care hospital. A total of 1034 Enterococcus isolates were collected, 729 from general wards and 305 from intensive care unit (ICU) patients. VRE accounted for 15.9% of isolates. E. faecalis was the most common species (54.3% of isolates and 2.7% of VRE), followed by E. faecium (33.6% of isolates and 41.2% of VRE). E. faecium exhibited the highest resistance to ciprofloxacin (84.1%), ampicillin (81.6%), and rifampicin (80%), with daptomycin (0.6%) and linezolid (3.1%) showing the lowest resistance. In E. faecalis, ciprofloxacin resistance was highest (59.7%), followed by rifampicin (20.1%) and ampicillin (11.8%). Daptomycin (0%), linezolid (1.5%), and vancomycin (2.7%) had the lowest resistance. VRE cases had higher mortality rates compared to vancomycin-sensitive enterococci (VSE). Eight different strains of Enterocci were identified. E. faecalis was the most commonly identified strain, while E. faecium had the highest percentage of VRE. VRE cases had a significantly higher mortality rate than VSE cases.

New Frontier on Antimicrobial Therapy: Long-Acting Lipoglycopeptides.

Long-acting lipoglycopeptides (LGPs), such as dalbavancin and oritavancin, are semisynthetic antibiotics known for their strong effectiveness against a wide array of Gram-positive bacteria. This includes Staphylococcus aureus, both methicillin-sensitive (MSSA) and methicillin-resistant (MRSA) strains, coagulase-negative Staphylococci (CoNS), streptococci, and vancomycin-sensitive Enterococcus faecalis. A literature search was conducted on PubMed and on ClinicalTrials.gov to identify articles published until July 2023 investigating the use of oritavancin and dalbavancin in clinical practice. The review included case reports, case series, observational studies, and clinical studies. Although more consistent data are needed, LGPs seem to be a good alternative that may provide a quicker hospital discharge and reduce long-term intravenous access and therapy. This is attributed to their unique pharmacologic and pharmacokinetic characteristics. More quality data (i.e., number of patients treated with clinical success) are needed before clinicians may use these therapies more widely.

Evaluating the potential of vancomycin-modified magnetic beads as a tool for sample preparation in diagnostic assays.

Vancomycin-functionalized micro- or nanoparticles are frequently used for isolation and enrichment of bacteria from various samples. Theoretically, only Gram-positive organisms should adhere to the functionalized surfaces as vancomycin is an antibiotic targeting a peptidoglycan precursor in the cell wall, which in Gram-negative bacteria is shielded by the outer cell membrane. In the literature, however, it is often reported that Gram-negative bacteria also bind efficiently to the vancomycin-modified particles. The goal of our study was to identify the underlying cause for these different findings. For each species several strains, including patient isolates, were investigated, and effects such as day-to-day reproducibility, particle type, and the antimicrobial effect of vancomycin-coupled beads were explored. Overall, we found that there is a strong preference for binding Gram-positive organisms, but the specific yield is heavily influenced by the strain and experimental conditions. For Staphylococcus aureus average yields of approximately 100% were obtained. Respectively, yields of 44% for Staphylococcus cohnii, 22% for Staphylococcus warneri, 17% for Enterococcus faecalis and 5% for vancomycin-sensitive Enterococcus faecium were found. Yields for Gram-negative species (Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii) and vancomycin-resistant Enterococcus faecium were below 3%. Our results indicate that the interaction between vancomycin and the D-alanine-D-alanine terminus of the peptidoglycan precursor in the bacterial cell wall is the dominant force responsible for the adherence of the bacteria to the particle surface. It needs to be considered though, that other factors, such as the specific molecules presented on the bacterial surface, as well as the pH, and the ion concentrations in the surrounding medium will also play a role, as these can lead to attractive or repulsive electrostatic forces. Last but not least, when using colony forming unit-based quantification for determining the yields, the influence of cell cluster formation and different sensitivities towards the antimicrobial effect of the vancomycin beads between species and strains needs to be considered.

Vancomycin-sensitive Enterococcus faecium bacteraemia - hospital transmission and mortality in a Danish University Hospital.

Introduction. The emergence of vancomycin-resistant Enterococcus faecium (VREfm) has left the vancomycin-sensitive E. faecium (VSEfm) strains almost unnoticed.Hypothesis. Molecular characteristics, hospital transmission patterns and clinical impact of VSEfm have changed, and VSEfm is a predictor of VREfm introduction.Aim. We wanted to do a molecular characterization of VSEfm to identify hospital transmissions and links between VSEfm and VREfm, and to investigate the demographics, treatment and impact on mortality of VSEfm bacteraemia.Methodology. VSEfm and VREfm blood culture isolates from Odense University Hospital, Denmark, from 2015 to 2019 were characterized using whole-genome sequencing and core-genome multilocus sequence typing (cgMLST). Clonal shifts and diversity of the VREfm isolates were compared to the VSEfm isolates. Hospital records were used for clinical data and transmission investigation of VSEfm cases.Results. Six-hundred and thirty VSEfm isolates from 599 patients belonged to 42 sequence types (STs) and 131 complex types (CTs) in several clusters. Multiple types were involved in putative transmission, occurring over the entire period. Twenty-seven VREfm bacteraemia cases were included. No correlation between the VSEfm and VREfm clones was identified. The 30 day mortality was 40 %, but only in 6.3 % of the cases, VSEfm bacteraemia was the likely cause of death.Conclusion. The molecular types of VSEfm bacteraemia isolates are changing and diverse. No direct correlation between VSEfm and the introduction of VREfm was found, but widespread hospital transmission indicates a presence of risk factors that could facilitate transmission of other micro-organisms as well. VSEfm bacteraemia is rarely the cause of death, indicating that 30 day mortality does not reflect the cause of death.

Prevalence, Microbiological Profile, and Risk Factors of Surgical Site Infections in Saudi Patients with Colorectal Cancer.

Resection surgery in patients with colorectal cancer (CRC) patients is associated with potential complications, including surgical site infection (SSI). To estimate the prevalence rate of SSI, identify the common pathogens responsible for SSI, and determine potential risk factors for SSI development in a cohort from Saudi Arabia. Patients with CRC who underwent bowel resection surgery at King Abdulaziz Medical City, Riyadh, between January 01, 2016, and December 31, 2019, were retrospectively included. Demographics, comorbidities, surgical procedure data, and the results of preoperative laboratory tests were retrospectively collected from medical records through the health information system. The study population was divided into two groups: those who developed SSI and those who did not. A total of 92 patients with CRC who underwent resection surgery were included, of which 54 (58.7%) were males. The median age was 65 (IQR 55.5-75.0) years. SSI was observed in 25 (27.2%) patients. The most frequently isolated organisms were Escherichia coli and Pseudomonas aeruginosa, followed by Klebsiella pneumoniae, vancomycin-sensitive Enterococcus faecium, and methicillin-resistant Staphylococcus aureus. Three E. coli isolates were producers of extended-spectrum beta-lactamases, and two K. pneumoniae isolates exhibited a multidrug resistance profile. Low preoperative serum albumin level was identified as a significant independent risk factor for developing SSI (AOR = 0.853, 95% CI = 0.748-0.973, P = 0.0181). The study found a notable prevalence of SSI among the included patients. Gram-negative bacteria were more involved in SSI events and were also associated with drug-resistance patterns. Gut microbiota bacteria were most commonly involved in SSIs. Low preoperative serum albumin levels predicted the development of postoperative SSI, and thus its close monitoring and management before surgery could reduce the SSIs.

Check the melting temperature of the FilmArray BCID panel to avoid missed detection of vanM-type enterococci

PurposeWe aimed to evaluate whether the FilmArray blood culture identification (BCID) panel holds the ability to detect vanM-type vancomycin-resistant enterococci (VRE) clinical isolates effectively. MethodsTwenty VRE clinical strains, including 10 vanA-type VRE and 10 vanM-type VRE, were collected from patients in five tertiary hospitals, Shanghai, China. By conventional PCR and sequencing, the strains were identified and van genotypes were confirmed. All VRE strains were investigated using the FilmArray BCID panel. All results, including enterococcus assay, vanA/B assay, DNA melting curves and melting temperature (Tm), were recorded. We also compared these results with those obtained via the conventional PCR and sequencing. ResultsAccording to the instructions of the FilmArray BCID panel, the Enterococcus assay is used to identify species and vanA/B assay is used to detect van genes. In all vanA-type VRE, the Enterococcus assay and vanA/B assay were positive. The results correctly showed that the tested strains were VRE. However, in 10 vanM-type VRE, the Enterococcus assay was positive and vanA/B assay were negative. The results mistakenly showed that the tested strains were vancomycin-sensitive enterococci (VSE). In the vanA/B assay, the melting curves of vanM-type VRE were similar to that of vanA-type VRE, but the Tm values were lower. The Tm values were then compared against the expected Tm range for the vanA/B assay. The Tm values of vanM-type VRE fall outside the assay-specific Tm range, resulting in negative reports. Thus, by adjusting the expected Tm range for the Enterococcus assay, the FilmArray BCID panel holds the ability to detect vanM-type VRE. ConclusionsThe vanM-type VRE isolates can be effectively detected by optimizing the expected Tm range for the vanA/B assay.

Streptomyces thinghirensis sp. nov. as a promising path for green synthesis of silver nanoparticles: High eradication of multidrug-resistant bacteria and catalytic activity

Biological and non-biological pollutants are posing a major health and environmental threat worldwide. For this reason, we reported on the synthesis and investigations of the silver nanoparticle (ST-AgNPs), using Streptomyces thinghirensis sp. (ST) as an original Streptomyces species deposited in GenBank under the accession number DSM 41919 T. Various techniques such as UV-Vis spectroscopy, Fourier transform infrared (FTIR) spectroscopy, particle-size analyzer, scanning electron microscopy (SEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM) for the characterization of the structure and morphology of biosynthesized ST-AgNPs, thereby, the evaluation of their catalyst and antimicrobial behaviors. ST-AgNPs nanoparticles are spherical, crystallizing with a size ranging from 10 to 30 nm, and are stable (−27.2 mV). They were able to reduce 4-nitrophenol to 4-aminophenol within 15 min. ST-AgNPs exhibited excellent antibacterial activities against Vancomycin-resistant Enterococcus faecium ATCC 700221vanA, Cefoxitin-resistant Staphylococcus aureus NCTC 12493 and Ceftazidime-resistant Pseudomonas aeruginosa ATCC BAA-2108, as well as Vancomycin-sensitive Enterococcus faecalis ATCC 29212, Cefoxitin-sensitive Staphylococcus aureus ATCC 29213 and Ceftazidime-sensitive Pseudomonas aeruginosa ATCC 27853, with the minimal inhibitory concentration ranging from 3.125 to 12.5 µg/mL. In conclusion the green synthesis approaches using ST would be the most important path in biomaterial sciences, which enrich their biological, medical and pharmaceutical applications.

Microbial Interspecies Associations in Fracture-Related Infection.

Describe co-occurrence or clustering of microbial taxa in fracture-related infections to inform further exploration of infection-related interactions among them. Retrospective review. Level 1 trauma center. Four hundred twenty-three patients requiring surgical intervention for deep surgical site infection between January 2006 and December 2015. None. Connection between microbial taxa. Methicillin-resistant Staphylococcus aureus, methicillin-sensitive Staphylococcus aureus, and coagulase-negative Staphylococcus represented the majority of monomicrobial observations (71%). Gram-negative rods, gram-positive rods, and anaerobes presented more frequently in polymicrobial infections. Enterobacter, vancomycin-sensitive Enterococcus, and Pseudomonas are present in polymicrobial infections with the highest frequencies and represent the top 3 most important nodes within the microorganism framework, with the highest network centrality scores. The present study indicates that there are common microbial taxa (Enterobacter, Enterococcus, and Pseudomonas) that tend to co-occur with other microbes greater than 75% of the time. These commonly co-occurring microbes have demonstrated interactive relationships in other disease pathologies, suggesting that there may be similar important interactions in fracture-related infections. It is possible that these microbial communities play a role in the persistently high failure rate associated with management of infection after trauma. Future studies are needed to study the intermicrobial interactions that explain the frequency at which taxa co-occur. Understanding and potentially disrupting these intermicrobial relationships could inform improvements in the treatment of established infections and in the prevention of infection in high-risk patients. Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Prevalence of Vancomycin Resistant Enterococcus in Wastewater Treatment Plants and Their Recipients for Reuse Using PCR and MALDI-ToF MS

The World Health Organization in 2017 listed vancomycin-resistant enterococci (VRE) among those with high priority for research. This study determined the efficiency of two wastewater treatment plants (WWTPs) in removing both vancomycin-resistant enterococci (VRE) and vancomycin-sensitive enterococci (VSE) from wastewater and the effect of their effluents on the receiving water bodies being reused. VRE and total enterococci (TE) respectively were isolated using Slanetz and Bartley agar with and without vancomycin from wastewater and river samples. Isolate speciation was confirmed by PCR and Matrix-Assisted Laser Desorption/Ionization-Time of Flight (MALDI-TOF) mass spectrometry (MS). Molecular methods were used for confirmation of presumptive VRE and for detection of van genes. Resistance to antibiotics was determined by the disk diffusion method. The TE and VRE counts of the two WWTPs influents ranged from 6.1 to 7.2 log10 CFU/100 ml and 4.3 to 6.7 log10 CFU/100 ml respectively while the effluent counts ranged from 0 to 4.4 log10 CFU/100 ml and 0 to 3.4 log10 CFU/100 ml for the chlorinated effluents. The TE and VRE counts of the recipient river samples were higher than the effluents. Exactly 186 (80.1%) isolates tallied with PCR as Enterococcus while 22 (9.5%) were positive by PCR but negative with MALDI-TOF. Enterococcus faecium and E. faecalis were the most abundant species. The isolates showed 34–100% resistance to quinopristin-dalfopristin, streptomycin, doxycycline, tetracycline, ciprofloxacin and cefixime. VanA (73.8%) were dominant among the isolates. The two WWTPs were efficient in reducing the VRE counts. Thus, the VRE in the river is most likely due to contamination from other sources and it may result in threat to human health when reused.

Real-Time PCR Assay for Rapid and Simultaneous Detection of vanA and vanB Genes in Clinical Strains.

Here, we develop a robust and sensitive real-time PCR assay which allows the simultaneous detection of vanA and vanB genes using common primers. The system was designed using the Primer3 online software. The specificity of primers and probes was first checked by in silico PCR and by BlastN analysis. The genomic DNA of 255 bacterial isolates, including Enterococcus spp., Gram-negative, and Gram-positive strains, as well as a collection of 50 stool and 50 rectal swab samples, were tested to evaluate the specificity of the new real-time PCR (RT-PCR) system. The results of the designed RT-PCR were 100% specific and 100% positive on tested vancomycin resistant isolates harboring either the vanA or vanB gene. RT-PCR assays were negative for all other bacterial species tested including vancomycin-sensitive Enterococci and Enterococcus strains harboring vanC genes. The limit of detection of vanA and vanB genes by RT-PCR assay was 47 CFU/mL and 32 CFU/mL, respectively. The rapid and accurate detection of vancomycin-resistant Enterococci is the cornerstone for minimizing the risk of nosocomial transmissions and outbreaks. We believe that this assay will strengthen routine diagnostics and surveillance programs.

Isolation and characterization of new phenolic siderophores with antimicrobial properties from Pseudomonas sp. UIAU-6B.

Five new phenolic siderophores 1–5 were isolated from the organic extract of a culture broth in a modified SGG medium of Pseudomonas sp. UIAU-6B, obtained from sediments collected from the Oyun river in North Central Nigeria. The structure of the new compounds, pseudomonin A–C (1–3) and pseudomobactin A and B (4 and 5) isolated alongside two known compounds, pseudomonine (6) and salicylic acid (7), were elucidated based on high-resolution mass spectrometry, 1D and 2D NMR analyses. The absolute configuration of the threonine residue in compounds 1–5 was determined by Marfey analysis. The antimicrobial evaluation of compound 4 exhibited the most potent activity against vancomycin-sensitive Enterococcus faecium VS144754, followed by 3 and 5, with MIC values ranging from 8 to 32 µg/mL. Compounds 2 and 3 exhibited moderate activity against Mycobacterium tuberculosis H37Rv, with MIC values of 7.8 and 15.6 µg/mL, respectively. Plausible biosynthetic hypotheses toward the new compounds 1–5 were proposed.

Effect of Vancomycin on Cytoplasmic Peptidoglycan Intermediates and van Operon mRNA Levels in VanA-Type Vancomycin-Resistant Enterococcus faecium.

Resistance in VanA-type vancomycin-resistant Enterococcus faecium (VREfm) is due to an inducible gene cassette encoding seven proteins (vanRSHAXYZ). This provides for an alternative peptidoglycan (PG) biosynthesis pathway whereby D-Ala-D-Ala is replaced by D-Ala-d-lactate (Lac), to which vancomycin cannot bind effectively. This study aimed to quantify cytoplasmic levels of normal and alternative pathway PG intermediates in VanA-type VREfm by liquid chromatography-tandem mass spectrometry before and after vancomycin exposure and to correlate these changes with changes in vanA operon mRNA levels measured by real-time quantitative PCR (RT-qPCR). Normal pathway intermediates predominated in the absence of vancomycin, with low levels of alternative pathway intermediates. Extended (18-h) vancomycin exposure resulted in a mixture of the terminal normal (UDP-N-acetylmuramic acid [NAM]-l-Ala-D-Glu-l-Lys-D-Ala-D-Ala [UDP-Penta]) and alternative (UDP-NAM-l-Ala-γ-D-Glu-l-Lys-D-Ala-D-Lac [UDP-Pentadepsi]) pathway intermediates (2:3 ratio). Time course analyses revealed normal pathway intermediates responding rapidly (peaking in 3 to 10 min) and alternative pathway intermediates responding more slowly (peaking in 15 to 45 min). RT-qPCR demonstrated that vanA operon mRNA transcript levels increased rapidly after exposure, reaching maximal levels in 15 min. To resolve the effect of increased van operon protein expression on PG metabolite levels, linezolid was used to block protein biosynthesis. Surprisingly, linezolid dramatically reduced PG intermediate levels when used alone. When used in combination with vancomycin, linezolid only modestly reduced alternative UDP-linked PG intermediate levels, indicating substantial alternative pathway presence before vancomycin exposure. Comparison of PG intermediate levels between VREfm, vancomycin-sensitive Enterococcus faecium, and methicillin-resistant Staphylococcus aureus after vancomycin exposure demonstrated substantial differences between S. aureus and E. faecium PG biosynthesis pathways. IMPORTANCE VREfm is highly resistant to vancomycin due to the presence of a vancomycin resistance gene cassette. Exposure to vancomycin induces the expression of genes in this cassette, which encode enzymes that provide for an alternative PG biosynthesis pathway. In VanA-type resistance, these alternative pathway enzymes replace the D-Ala-D-Ala terminus of normal PG intermediates with D-Ala-D-Lac terminated intermediates, to which vancomycin cannot bind. While the general features of this resistance mechanism are well known, the details of the choreography between vancomycin exposure, vanA gene induction, and changes in the normal and alternative pathway intermediate levels have not been described previously. This study comprehensively explores how VREfm responds to vancomycin exposure at the mRNA and PG intermediate levels.

Analysis of the Restriction of Vancomycin Use in Hospitals Before, During and After the Implementation of the Antimicrobial Resistance Control Program (ARCP)

Background: A policy restricting the use of vancomycin was a pilot project for the implementation of the Antimicrobial Resistance Control Program (ARCP) in RSUD Nusa Tenggara Barat in 2018. There were three phases of the ARCP in hospitals, namely preparation, execution, and monitoring. This research aimed to evaluate the quality of vancomycin prescribing before, during, and after the implementation of ARCP in 2017–2019. Method: Descriptive analysis was conducted of all the vancomycin prescriptions before, during, and after the implementation of ARCP in 2018. All medical records of cases requiring vancomycin prescriptions during the research period was evaluated: patient characteristics, culture test results, and clinical diagnoses. The quality of vancomycin prescriptions, which was expressed as follows: “Vancomycin prescriptions are intended only for infections caused by Gram-positive pathogens, particularly Staphylococcus aureus, that are resistant to methicillin (MRSA), Enterococcus sp (Vancomycin-sensitive enterococci)” was evaluated. Results: There were sixty-one cases of vancomycin prescribing; 21 female and 40 male patients, with a mean age of 23 years (0–82 years). Overall, there were 41 positive cultures, 5 negative cultures, and 15 no-cultures. The diagnoses were moderate to severe infections: sepsis, pneumonia, post-surgery infections, CNS infections, low birth weight, septic shocks, and chronic obstructive lung diseases. The urinary tract infection was present as a mild infection. The prescription quality indicators ‘vancomycin is prescribed only for moderate to severe infections’ and ‘prescribed only for Gram-positive pathogens’ altogether increased. Conclusion: There was improvement in the vancomycin prescription quality after the implementation of the vancomycin restriction policy.

Emergence of Vancomycin Resistance after Treatment of Enterococcus: Risk Factors for Subsequent Pathogen Resistance

Background: Vancomycin-resistant Enterococcus (VRE) is a leading cause of nosocomial infections that carries an increased risk of mortality when compared to vancomycin-sensitive Enterococcus (VSE). Data on the frequency of conversion between VSE and VRE in patients are scarce. Among patients presenting with VSE infections, little is known about the subsequent risk of conversion to VRE in the initial treatment period. Methods: A descriptive analysis of VSE to VRE conversion and a retrospective case-control study were performed examining cases of VSE that had subsequent cultures positive for VRE within 90 days within a quaternary healthcare system. Cases were obtained from June 2013 through December 2018. Controls were patients who had VSE culture followed by another VSE culture and were matched by organism (E. faecalis or E. faecium), time between cultures, and initial culture site. Age, gender, healthcare, antibiotic, Clostridiodes difficile, proton pump inhibitor (PPI) exposure, and H2 blocker exposures, and prior VRE infection or colonization were abstracted from the electronic medical record. A univariate analysis with the Fisher exact test was performed with significance considered for P &lt; .05. Results: In total, 8,913 cases of E. faecalis and 2,322 cases of E. faecium were included in the study. Of 8,913 cases of E. faecalis, 51 of 8,503 (0.6%) cultured VRE after VSE, and 47 of 403 (11.7%) cultured VSE after initial VRE. Of E. faecium, 51 of 783 (6.5%) cultured VRE after VSE, and 76 of 1,532 (5.0%) cultured VSE after initial VRE. In total, 76 cases were matched with 99 controls. Patients converting from VSE to VRE were more likely to have prior admission to an intensive care unit (P = .0207), prior positive swab or culture for VRE (P = .0114), previous C. difficile infection (P = .0155), prior vancomycin (P = .0022) and cefepime (P = .0089) exposure. Patients receiving vancomycin after initial VSE culture were more likely to have subsequent cultures positive for VRE (P = .0053). There was no difference in age (P = .966) or male sex (P = .7588). Conclusions: Conversion from VSE to VRE is common, and E. faecium is more likely to become resistant than E. faecalis. Reversion to a vancomycin-sensitive phenotype is also common, and E. faecalis is more likely to show subsequent sensitivity than E. faecium. Previous admission to an intensive care unit, prior colonization or infection with VRE, prior C. difficile infection, and exposure to vancomycin and cefepime are risk factors for emergence of VRE after treatment for vancomycin-sensitive Enterococcus.Funding: NoneDisclosures: None

Diagnostic utility of bronchoscopy in newly diagnosed acute leukemia patients.

e19510 Background: Over 40% of newly diagnosed acute leukemia patients receiving induction therapy develop acute respiratory failure. Bronchoscopy is a valuable tool for evaluating airway disease, but its diagnostic yield in this setting has not been fully explored. Methods: We performed a retrospective chart review of 75 newly diagnosed acute leukemia patients who had bronchoscopies. Data recorded prior to bronchoscopy included age, diagnosis, induction treatment regimen, chest imaging, assisted ventilation, duration of neutropenia and antibiotic therapy and microbiological studies. Bronchoalveolar lavage (BAL) cultures were sorted by organism, as well as by other pathologic findings. The primary outcome was antibiotic change supported by culture data. Results: The study population is summarized in the table. Induction regimen backbones included 7+3 (51), 7+4+ATRA (2), decitabine (12), hyperCVAD (2), AYA (3), other (1) and none (4); 18 patients were treated on clinical trial. Average days of neutropenia was 10.92 and average days of antibiotic therapy was 10.57. Thirty-eight patients had chest infiltrates, 11 received NIPPV, and 17 were mechanically ventilated. We identified 24 patients with +BAL studies. Of these, 37.5% (9) had + blood, urine or sputum studies before bronchoscopy, but only 3 had cultures positive for the same organism as the BAL. Of 51 patients with –BAL studies, 33.3% (17) had prior negative cultures. Infections were most commonly bacterial (15, 62.5%), followed by viral (5, 20.8%) and fungal (4, 16.7%). The most common organisms were rhinovirus, vancomycin sensitive Enterococcus (4, 16.7% each) followed by VRE, Candida albicans and MRSA (2, 8.3% each). Five patients (6.7%) had alveolar hemorrhage. Of the 24 patients with +BAL cultures, bronchoscopy findings supported changing antibiotics in 18. In contrast, antibiotics were changed in 16 patients without +BAL cultures. Conclusions: We investigated the utility of bronchoscopy on AL patients during their initial admission. BAL cultures were positive in 32% of newly diagnosed AL patients undergoing bronchoscopy. However, +BAL cultures identified a new organism in 87.5% and guided antibiotic therapy in 75% of these patients. Further studies will be needed to establish predictors of bronchoscopy findings in this patient population. [Table: see text]

Unravelling the benefits and barriers to utilising whole-genome sequencing in the investigation of outbreaks

Background This prospective study was established to develop and evaluate methods to harness pathogen sequencing in the clinical microbiology environment. We describe new insights into the clinical benefits of using whole-genome sequencing (WGS) for outbreak investigation with solutions for the practical barriers to implementation in clinical settings. Methods Surveillance software (ICNet) and statistical process control charts (SPCs) detected potential outbreaks of meticillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), carbapenem-resistant Enterobacteriaceae (CRE), Enterobacteriaceae producing extended spectrum β-lactamases (ESBLs), Listeriaspp. and optrAgene positive enterococci. Isolates were sent to reference laboratories for conventional typing and the Infection Group, School of Medicine, University of St Andrews for WGS (Illumina Inc, San Diego, CA, USA) and bioinformatic data analysis. Results Over 400 isolates have been sequenced to date. WGS replaced multiple typing techniques in a Pseudomonas aeruginosa ICU outbreak. It confirmed two patient’s Listeria spp. isolates were indistinguishable prompting hospital kitchen inspections, identified a patient to be carrying two strains of VRE and confirmed that vancomycin-sensitive Enterococcus faecium isolates related to a VRE cluster. We observed five main barriers to implementing WGS (infrastructure, performance/quality assessment of data, isolate selection, clinical result interpretation and database management). Conclusion WGS is beneficial in outbreaks of uncommon organisms and when conventional typing cannot show whether isolates are linked or not. Identifying barriers assisted us in developing a clinical decision aid that can be used by clinicians when applying WGS to outbreak investigations.

2412. Oral Vancomycin Prophylaxis Against Recurrent Clostridioides difficile Infection: Efficacy and Side-effects: Two Hospitals Experience

Background Clostridioides difficile is the most common hospital-acquired pathogen with an unchanged infection prevalence between 2011–2015. The data regarding the effectiveness of chemical prophylaxis to prevent recurrent C. difficile infection (CDI) are conflicting.MethodsWe conducted a retrospective study of hospitalized patients with CDI history in 2 New York academic hospitals over a 4.5-year period to determine the effectiveness of vancomycin prophylaxis for CDI prevention. The participating hospitals implemented an automated alert to providers recommending oral vancomycin 125 mg twice daily in patients with a history of CDI scheduled to receive any systemic antimicrobials for the duration of therapy and 5 days thereafter. Measured outcomes included the rate of breakthrough and recurrent CDI, defined as CDI during and in the one-month following prophylaxis, respectively. A self-controlled, before and after study design was employed to examine whether the use of oral vancomycin was associated with an increase in the prevalence of vancomycin-resistant Enterococcus species (VRE) both in absolute numbers and in comparison to vancomycin-sensitive Enterococcus species (VSE) in the period following vancomycin prophylaxis.Results264 patients were included in the final analysis. Breakthrough CDI was identified in 17 (6.4%; 95% CIs 3.8%–10.1%) and recurrent CDI in 22 (8.3%; 95% CIs 5.3%–12.3%) patients. Of the 102 patients with a history of CDI within the 3 months preceding the administration of prophylaxis 4 (3.9%, 95% CIs 1.1%-9.7%) had breakthrough CDI and 9 had recurrent disease (8.3%, 95% CIs 5.3%–12.3%). In the 3 months following vancomycin prophylaxis there was an increase in both the absolute number of VRE and the ratio of VRE to VSE isolates compared with the combined period of 1.5 months preceding and the 3–4.5 months following the administration of prophylaxis. The increase in the absolute number of VRE colonized patients remained in the extended period of 6 months following prophylaxis.ConclusionProphylactic vancomycin is an effective strategy to prevent CDI recurrence, but is associated with an increase in VRE colonization in the immediate period after administration. The risk of VRE infection should lead to careful selection of patients at the highest risk for CDI recurrence.Disclosures All authors: No reported disclosures.

A nonclonal outbreak of vancomycin-sensitive Enterococcus faecalis bacteremia in a neonatal intensive care unit.

To describe an outbreak of bacteremia caused by vancomycin-sensitive Enterococcus faecalis (VSEfe). An investigation by retrospective case control and molecular typing by whole-genome sequencing (WGS). A tertiary-care neonatal unit in Melbourne, Australia. Risk factors for 30 consecutive neonates with VSEfe bacteremia from June 2011 to December 2014 were analyzed using a case control study. Controls were neonates matched for gestational age, birth weight, and year of birth. Isolates were typed using WGS, and multilocus sequence typing (MLST) was determined. Bacteremia for case patients occurred at a median time after delivery of 23.5 days (interquartile range, 14.9-35.8). Previous described risk factors for nosocomial bacteremia did not contribute to excess risk for VSEfe. WGS typing results designated 43% ST179 as well as 14 other sequence types, indicating a polyclonal outbreak. A multimodal intervention that included education, insertion checklists, guidelines on maintenance and access of central lines, adjustments to the late onset sepsis antibiotic treatment, and the introduction of diaper bags for disposal of soiled diapers after being handled inside the bed, led to termination of the outbreak. Typing using WGS identified this outbreak as predominately nonclonal and therefore not due to cross transmission. A multimodal approach was then sought to reduce the incidence of VSEfe bacteremia.

Assessment of vancomycin resistance transfer among enterococci of clinical importance in milk matrix

Dissemination of vancomycin resistance in enterococci has been associated with horizontal transfer of mobile genetic elements. Aim of the study was to evaluate if milk matrix is a suitable environment to support transferability of vancomycin resistance (vanA) gene from clinical vancomycin-resistant Enterococcus faecium to vancomycin-sensitive Enterococcus faecalis. Enterococci strains were firstly screened for the presence of cpd (inducible sex pheromone determinant) gene, vanA and tetL genes (vancomycin and tetracycline resistance markers, respectively) and the gelE (extracellular metalloendopeptidase) gene to define the mating pairs. Based on these selection markers, we investigated the transferability of eight plasmid-borne vanA harbored by E. faecium (vanA+, cpd-, tetL- and gelE-) into two E. faecalis (vanA-, cpd+, tetL + and gelE+) recipient strains in milk matrix. The strains were mated in a 1:1 ratio in 7% reconstituted milk and incubated at 37 °C. Transconjugants emerged from all 16 matings within 2 h of incubation and were evidenced by dual antibiotic resistance (vancomycin and tetracycline). The vancomycin-resistance of trasconjugants was maintained even after ten subsequent passages on nonselective medium. Transconjugants were positive for vanA, tetL and gelE genes. This study indicates milk matrix as suitable environment to support gene exchange between Enterococcus species.