Vancomycin-resistant E. Faecium Research Articles

Bacteriophage and antibiotic combination therapy for recurrent Enterococcus faecium bacteremia.

Phage therapy is an emerging therapeutic approach for treating bacterial infections that do not respond to traditional antibiotics. The addition of phage therapy to systemic antibiotics to treat a patient with recurrent E. faecium infections that were non-responsive to antibiotics alone resulted in fewer hospitalizations and improved the patient's quality of life. Combination phage and antibiotic therapy reduced E. faecium and VRE abundance in the patient's stool. Eventually, an anti-phage antibody response emerged that was able to neutralize phage activity, which may have limited clinical efficacy. This study demonstrates the potential of phages as an additional option in the antimicrobial toolbox for treating invasive enterococcal infections and highlights the need for further investigation to ensure phage therapy can be deployed for maximum clinical benefit.

Antibiofilm and Antivirulence Properties of 6-Polyaminosteroid Derivatives against Antibiotic-Resistant Bacteria.

The emergence of multi-drug resistant pathogens is a major public health problem, leading us to rethink and innovate our bacterial control strategies. Here, we explore the antibiofilm and antivirulence activities of nineteen 6-polyaminosterol derivatives (squalamine-based), presenting a modulation of their polyamine side chain on four major pathogens, i.e., carbapenem-resistant A. baumannii (CRAB) and P. aeruginosa (CRPA), methicillin-resistant S. aureus (MRSA), and vancomycin-resistant E. faecium (VRE) strains. We screened the effect of these derivatives on biofilm formation and eradication. Derivatives 4e (for CRAB, VRE, and MRSA) and 4f (for all the strains) were the most potent ones and displayed activities as good as those of conventional antibiotics. We also identified 11 compounds able to decrease by more than 40% the production of pyocyanin, a major virulence factor of P. aeruginosa. We demonstrated that 4f treatment acts against bacterial infections in Galleria mellonella and significantly prolonged larvae survival (from 50% to 80%) after 24 h of CRAB, VRE, and MRSA infections. As shown by proteomic studies, 4f triggered distinct cellular responses depending on the bacterial species but essentially linked to cell envelope. Its interesting antibiofilm and antivirulence properties make it a promising a candidate for use in therapeutics.

2452. Prevalence of Antimicrobial ReSistanCE iN BloodStream Infections in HOspitalized (BSI) PatieNts in BRazil (ASCENSION-BR): Preliminary Results of a Multicenter Study

Abstract Background Carbapenem-resistant Enterobacterales (CRE), P. aeruginosa (CRPA), A. baumannii (CRAB), methicillin-resistant S. aureus (MRSA) and vancomycin-resistant E. faecium (VRE) are major multidrug-resistant (MDR) bacteria causing healthcare-associated infections. There is no multicenter study addressing the prevalence of these MDR bacteria in Brazil. We report the preliminary results of the ongoing ASCENSION-BR study evaluating the prevalence of these microorganisms in BSI in hospitalized patients in this country. Methods This prospective multicenter study has been conducted in 13 hospitals distributed in 4 of 5 Brazilian regions. From 15th August to 31st April (to be finished on 14th August 2023), each hospital recruited patients for a period of up to 6 months. Adult patients hospitalized for at least 48h, with positive blood cultures with Enterobacterales, P. aeruginosa, A. baumannii, S. aureus and Enterococcus spp. were eligible. More than one BSI of the same patients were included if caused by a distinct bacteria. MDR isolates were sent to a central laboratory where isolates were re-identified by MALDI-TOF-MS. Results A total of 10 hospitals recruited patients for 6 months(m), 1 for 5m, and 2 for 1m. 1231 bacterias were isolated from 1091 BSI episodes (118 were polymicrobial), and 442 (35.9%) were MDR. Enterobacterales were the most common isolates in BSIs (659, 75.3%), followed by S. aureus (221, 18.0%), A. baumannii (113, 12.9%), Enterococcus spp. (135, 11.0%: 48 [35.6%] E. faecium and 84 [62.2%] E. faecalis) and P. aeruginosa (103, 8.4%). Among Enterobacterales, the most frequent species were K. pneumoniae (275, 41.7%), E. coli (126, 19.1) and Enterobacter spp. (69, 10.5%). A total of 224 (34.0% of Enterobacterales) BSIs were caused by CRE (155 [69.2%] K. pneumoniae, 27 [12.1%] Serratia marcescens, 15 [6,7%] Enterobacter spp., and 27 [12.1%] other 11 species. A total of 100 (88.5% of A. baumannii) isolates recovered in BSIs were CRAB and 38 (36.9% of P. aeruginosa) were CRPA. Among Gram positives, 50 (22.6% of SA) were MRSA, and VRE represented 93.3% of E. faecium and 3.3% of E. faecalis isolates. Conclusion High prevalence of MDR in BSI, notably in A. baumannii, were found among hospitalized patients in Brazil. Disclosures João Telles, MD, PhD, MSD: Advisor/Consultant|MSD: Speaker|Pfizer: Advisor/Consultant|Pfizer: Speaker|União Química: Advisor/Consultant|União Química: Speaker Alexandre Zavascki, MD, PhD, Pfizer: Advisor/Consultant|Pfizer: Grant/Research Support

Antimicrobial and antibiofilm effects of essential fatty acids against clinically isolated vancomycin-resistant Enterococcus faecium.

Enterococcus faecium is a leading cause of hospital-acquired infections, which has become a serious public health concern. The increasing incidence of vancomycin-resistant E. faecium (VRE-fm) raises an urgent need to find new antimicrobial agents as a complement to traditional antibiotics. The study aimed to evaluate the antimicrobial and antibiofilm activity of essential fatty acids (EFAs) against VRE-fm, and further explore the molecular mechanism of the antibiofilm activity of EFAs. The microdilution broth method was used for antimicrobial susceptibility testing with traditional antibiotics and EFAs, including α-linolenic acid (ALA), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), linoleic acid (LOA), γ-linolenic acid (GLA), and arachidonic acid (AA). The effect of EFAs on cell morphology of VRE-fm was investigated by scanning electron microscopy. The crystal violet method was used to evaluate the antibiofilm activities of EFAs against VRE-fm. Furthermore, the expression of biofilm-related genes (acm, atlA, esp, and sagA) of VRE-fm isolates under the action of GLA was analyzed using quantitative reverse transcription PCR (qRT-PCR) assay. VRE-fm isolates were highly resistant to most traditional antibiotics, only highly susceptible to quinupristin-dalfopristin (90.0%), tigecycline (100%), and linezolid (100%). EPA, DHA, and GLA exhibited excellent antimicrobial activity. The MIC50/90 of EPA, DHA, and GLA were 0.5/1, 0.25/0.5, and 0.5/1 mM, respectively. SEM imaging showed that strain V27 adsorbed a large number of DHA molecules. Furthermore, all EFAs exhibited excellent inhibition and eradication activities against VRE-fm biofilms. The biofilm inhibition rates of EFAs ranged from 45.3% to 58.0%, and eradication rates ranged from 54.1% to 63.4%, against 6 VRE-fm isolates with moderate biofilm formation ability. GLA exhibited remarkable antibiofilm activity against VRE-fm isolates. The qRT-PCR analysis showed that GLA could significantly down-regulate the expression of the atlA gene (P < 0.01) of VRE-fm. DHA showed the strongest antibacterial activity, while GLA showed the strongest antibiofilm effect among the EFAs with antibacterial activity. Our novel findings indicate that the antibiofilm activity of GLA may be through down-regulating the atlA gene expression in VRE-fm. Therefore, DHA and GLA had the potential to be developed as therapeutic agents to treat infections related to multiple antimicrobial-resistant E. faecium.

Phage-Antibiotic Cocktail Rescues Daptomycin and Phage Susceptibility against Daptomycin-Nonsusceptible Enterococcus faecium in a Simulated Endocardial Vegetation Ex Vivo Model.

Enterococcus faecium is a difficult-to-treat pathogen with emerging resistance to most clinically available antibiotics. Daptomycin (DAP) is the standard of care, but even high DAP doses (12 mg/kg body weight/day) failed to eradicate some vancomycin-resistant strains. Combination DAP-ceftaroline (CPT) may increase β-lactam affinity for target penicillin binding proteins (PBP); however, in a simulated endocardial vegetation (SEV) pharmacokinetic/pharmacodynamic (PK/PD) model, DAP-CPT did not achieve therapeutic efficacy against a DAP-nonsusceptible (DNS) vancomycin-resistant E. faecium (VRE) isolate. Phage-antibiotic combinations (PAC) have been proposed for resistant high-inoculum infections. We aimed to identify PAC with maximum bactericidal activity and prevention/reversal of phage and antibiotic resistance in an SEV PK/PD model against DNS isolate R497. Phage-antibiotic synergy (PAS) was evaluated with modified checkerboard MIC and 24-h time-kill analyses (TKA). Human-simulated antibiotic doses of DAP and CPT with phages NV-497 and NV-503-01 were then evaluated in 96-h SEV PK/PD models against R497. Synergistic and bactericidal activity was identified with the PAC of DAP-CPT combined with phage cocktail NV-497-NV-503-01, demonstrating a significant reduction in viability down to 3-log10 CFU/g (-Δ, 5.77-log10 CFU/g; P < 0.001). This combination also demonstrated isolate resensitization to DAP. Evaluation of phage resistance post-SEV demonstrated prevention of phage resistance for PACs containing DAP-CPT. Our results provide novel data highlighting bactericidal and synergistic activity of PAC against a DNS E. faecium isolate in a high-inoculum ex vivo SEV PK/PD model with subsequent DAP resensitization and prevention of phage resistance. IMPORTANCE Our study supports the additional benefit of standard-of-care antibiotics combined with a phage cocktail compared to antibiotic alone against a daptomycin-nonsusceptible (DNS) E. faecium isolate in a high-inoculum simulated endocardial vegetation ex vivo PK/PD model. E. faecium is a leading cause of hospital-acquired infections and is associated with significant morbidity and mortality. Daptomycin is considered the first-line therapy for vancomycin-resistant E. faecium (VRE), but the highest published doses have failed to eradicate some VRE isolates. The addition of a β-lactam to daptomycin may result in synergistic activity, but previous in vitro data demonstrate that daptomycin plus ceftaroline failed to eradicate a VRE isolate. Phage therapy as an adjunct to antibiotic therapy has been proposed as a salvage therapy for high-inoculum infections; however, pragmatic clinical comparison trials for endocarditis are lacking and difficult to design, reinforcing the timeliness of such analysis.

Trends in Antibiotic Resistance of Nosocomial and Community-Acquired Infections in Italy.

The World Health Organization has recently identified three categories of pathogens, namely: critical, high, and medium priority, according to the need for new antibiotics. Critical priority pathogens include carbapenem-resistant microorganism (CPO) such as A. baumannii and P. aeruginosa, K. pneumoniae, and Enterobacter spp., whereas vancomycin-resistant E. faecium (VRE), methicillin and vancomycin-resistant S. aureus (MRSA) are in the high priority list. We compared the trend of antimicrobial resistants (AMRs) in clinical isolates, divided by year and bacteria spp., of samples obtained from nosocomial and community patients. Patient records were collected, including age, sex, site of infection, isolated organisms, and drug susceptibility patterns. From 2019 to 2022, a total of 113,635 bacterial isolates were tested, of which 11,901 resulted in antimicrobial resistants. An increase in the prevalence of several antibiotics resistant bacteria was observed. Specifically, the percentage of CPO cases increased from 2.62% to 4.56%, the percentage of MRSA increased from 1.84% to 2.81%, and the percentage of VRE increased from 0.58% to 2.21%. AMRs trend resulted in increases in CPO and MRSA for both community and nosocomial. Our work aims to highlight the necessity of preventive and control measures to be adopted in order to reduce the spread of multidrug-resistant pathogens.

Vancomycin Resistance in Enterococcus faecium from the Dallas, Texas, Area Is Conferred Predominantly on pRUM-Like Plasmids.

Vancomycin-resistant E. faecium (VREfm) is a significant public health concern because of limited treatment options. Genomic surveillance can be used to monitor VREfm transmission and evolution. Genomic analysis of VREfm has not been reported for the Dallas/Fort Worth/Arlington, TX, area, which is currently the 4th largest metropolitan area in the United States. Our study aimed to address this gap in knowledge by analyzing the genomes of 46 VREfm strains and 1 vancomycin-sensitive comparator collected during routine fecal surveillance of high-risk patients upon admission to a Dallas, TX, hospital system (August to October 2015). Thirty-one complete and 16 draft genome sequences were generated. The closed VREfm genomes possessed up to 12 extrachromosomal elements each. Overall, 251 closed putative plasmid sequences assigned to previously described and newly defined rep family types were obtained. Phylogenetic analysis identified 10 different sequence types (STs) among the isolates, with the most prevalent being ST17 and ST18. Strikingly, all but three of the VREfm isolates encoded vanA-type vancomycin resistance within Tn1546-like elements on a pRUM-like (rep17) plasmid backbone. Relative to a previously reported typing scheme for the vanA-carrying Tn1546, new variants of the Tn1546 were identified that harbored a combination of 7 insertion sequences (IS), including 3 novel IS elements reported here (ISEfa16, ISEfa17, and ISEfa18). We conclude that pRUM-like plasmids are important vectors for vancomycin resistance in the Dallas, TX, area and should be a focus of plasmid surveillance efforts. IMPORTANCE Vancomycin is an antibiotic used to treat infections caused by multidrug-resistant Gram-positive bacteria. Vancomycin resistance is common in clinical isolates of the Gram-positive pathogen Enterococcus faecium. Among E. faecium strains, vancomycin resistance genes can be disseminated by plasmids with different host ranges and transfer efficiencies. Surveillance of resistance plasmids is critical to understanding antibiotic resistance transmission. This study analyzed the genome sequences of VREfm isolates collected from the Dallas, TX, area, with particular focus on the mobile elements associated with vancomycin resistance genes. We found that a single plasmid family, the pRUM-like family, was associated with vancomycin resistance in the majority of isolates sampled. Our work suggests that the pRUM-like plasmids should continue to be studied to understand their mechanisms of maintenance, transmission, and evolution in VREfm.

Emergence of OptrA Gene Mediated Linezolid Resistance among Enterococcus Faecium: A Pilot Study from a Tertiary Care Hospital, India.

E. faeciumis the third most common cause of nosocomial infections. Linezolid (LNZ) is a reserve antibiotic recommended for infections caused by vancomycin resistant E. faecium (VREfm).The aim of the present study was to investigate the prevalence of optrAgene among linezolid resistant E. faecium (LREfm) and to study the molecular epidemiology using pulse field gel electrophoresis (PFGE).Clinically significant LREfm were identified and antimicrobial susceptibility was performed by disc diffusion. Minimum inhibitory concentration (MIC) of linezolid, vancomycin, daptomycin and quinupristin/dalfopristin was determined by E-test.PCR and PCR-RFPL were performed for the detection of optrA/cfrgene and G2576T mutation respectively. Molecular epidemiology was studied by PFGE. A total of 1081 clinically significant Enterococci species were isolated which included E. faecium 63.5% (n=687) and E. faecalis 36.5% (n=394). LREfm (30/687) were further studied. Multidrug resistance and vancomycin resistance was 100% and 80%, respectively. Linezolid MIC range was 8-256µg/ml and the most common mechanism of resistance was optrA gene (83.3%) followed by G2576T mutation (33.3%). PFGE analysis demonstrated 4 major clones. The optrAgene mediated linezolid resistance was high and PFGE suggests resistance was emerging in the different background strains irrespective of resistance mechanism. Studies are required to investigate factors driving the emergence of linezolid resistance. The review suggests that this is the first report of optrA-mediated resistance in E. faecium from India.

Investigation of a vanA linezolid- and vancomycin-resistant Enterococcus faecium outbreak in the Southwest Indian Ocean (Reunion Island)

IntroductionDual resistance to linezolid and glycopeptides is a milestone reached by certain extensively drug-resistant (XDR) enterococci. This paper describes the molecular and epidemiological investigations of a linezolid-resistant and vancomycin-resistant Enterococcus faecium (E. faecium) (LVREf) outbreak in the French overseas territory of Reunion Island (Indian Ocean). MethodsAll vancomycin-resistant Enterococcus (VRE) isolates detected on Reunion Island between 2015 and 2019 were included in the study. The VRE isolates were phenotypically characterised and genetically explored by whole-genome sequencing (WGS). ResultsSixteen vancomycin-resistant E. faecium (VREf) isolates were retrieved between 2015 and 2019. Seven isolates obtained in 2019 were involved in the outbreak. These seven LVREf isolates from the 2019 outbreak at the University Hospital of Reunion Island (UHRI) were suspected to be related to a linezolid-susceptible VREf strain imported from India. An epidemiological link was highlighted for six of the seven outbreak cases. All the LVREf outbreak isolates were obtained from rectal swabs (colonisation) and resistant to vancomycin (MIC > 128 mg/L) and linezolid (MIC 8–32 mg/L); one isolate was also resistant to daptomycin (MIC 8 mg/L). The seven outbreak isolates were positive for the vanA and optrA genes and belonged to ST761. ConclusionsThese results argue for the strict application of control and prevention measures for VRE clones at high risk of spread, particularly in areas such as Reunion Island where the risk of importation from the Indian subcontinent is high. The regional spread of optrA linezolid-resistance genes in VRE isolates is a matter of concern, due to possibility of treatment failure.

Molecular Detection of Some Vancomycin and Virulence Factor Genes in Enterococcus faecium

Multidrug-resistant (MDR) and pathogenic E. faecium is a crisis in healthcare settings. This survey aimed at antibiotic susceptibility profiling and virulence determinants of E. faecium. This study pooled 100 fecal E. faecium isolates identified by phenotypic and molecular tests. Antibiotic susceptibility and ampicillin MIC were determined according to clinical and laboratory standards institute (CLSI) 2017. Moreover, biofilm formation was assayed by a microtiter tissue plate assay. Virulence genes pattern was performed by polymerase chain reaction (PCR) method. Among 460 fecal samples, 100 isolates of E. faecium were identified, among which the highest resistance was related to penicillin (81%), cephalothin (78%), cefazolin (76%), tetracycline and cefepime (69%). In contrast, 83% of them were susceptible to vancomycin. Moreover, four vancomycin-resistant isolates had vancomycin MIC&gt;32µg/mL, and 11 isolates had MIC&gt;8µg/mL. Of 32 ampicillin-resistant isolates, 18 (56%) produced strong biofilm, and 14 isolates (44%) produced moderate biofilm. Among 17 vancomycin-resistant E. faecium (VREfa), 15 (88.23%) isolates produced strong biofilms, and two of them produced moderate-level biofilms, which was significantly higher than susceptible isolates (p=0.0144). The vanA (vancomycin MIC: 16-64µg/mL) and vanB (vancomycin MIC: 8-64µg/mL) genes were detected in twelve and five isolates, respectively. The rate of adhesin genes ace, esp and ebp included 68%, 97% and 82%, respectively. All the VREfa harbored the ace, esp and ebp genes. The antibiotic resistance rate of E. faecium was low. Biofilm formation was significantly different between VREfa and vancomycin-susceptible isolates but not between k9ampicillin-resistant and ampicillin-susceptible isolates. All the VREfa harbored the ace, esp and ebp genes. The virulence adhesin genes were not significantly associated with biofilm formation. Further studies are essential to appreciate better the relation between biofilm formation, drug non-susceptibility and adhesin genes. Keywords: E. faecium, antibiotic resistance, biofilm formation, virulence genes

The Timing and Epidemiology of Enterococcus Faecium and E. Faecalis Bloodstream Infections (BSI) in Patients with Acute Leukemia Receiving Chemotherapy

Enterococcal BSI occurs frequently in patients with acute leukemia and causes significant morbidity and mortality. Daptomycin non-susceptible Enterococcus (DNSE) infection has emerged as a threat that has limited treatment options. However, the timing of enterococcal BSI in relationship to chemotherapy is unknown. In addition, previous studies have focused on the epidemiology of vancomycin-resistant E. faecium (VRE) BSI. The present study investigates the timing of enterococcal BSI in relationship to chemotherapy and the epidemiology of both E. faecium and E. faecalis BSI in patients with acute leukemia. We hypothesize that most BSIs are gut derived, mucosal barrier injury infections that occur in patients who undergo intensive chemotherapy that causes prolonged neutropenia and chemotherapy-induced mucositis leading to febrile neutropenia and antimicrobial-induced gut dysbiosis.We conducted a retrospective cohort study of patients with acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) admitted to Duke University for infusional chemotherapy from 2010-15. BSI was adjudicated by CDC criteria. Appropriate enterococcal therapy was defined as receipt of an antibiotic with in vitro activity against the BSI isolate. BSI clearance was defined by negative follow-up blood cultures obtained within 72 hours after positive blood cultures. Recurrent BSI was defined by positive blood cultures for Enterococcus after BSI clearance. Bivariate analysis was performed using chi-squared test.Three hundred twelve patients were evaluated for this study, 83 of whom had enterococcal BSI during the study period (27%; Table 1). Eight-seven percent had BSI due to E. faecium while 13% had BSI due to E. faecalis . Most were febrile (82%) and neutropenic (96%) on broad-spectrum antimicrobials at the time of BSI. All patients had an indwelling central line and had received intensive chemotherapy prior to BSI. Median time from acute leukemia diagnosis to BSI was 30 days. BSI occurred most frequently during the first cycle of induction chemotherapy (47%), but a combined 52% of BSIs occurred during the 2nd-5rd cycles of induction chemotherapy. Sixty-six percent of BSIs qualified as mucosal barrier injury infections. Only 2 patients had metastatic sites of infection: 1 with empyema and 1 with CNS infection, both due to VRE. In terms of clinical response to therapy, 61% of patients achieved cure, and 10% died with BSI. Twenty-eight percent suffered recurrent BSI, and 29% of these patients had DNSE BSI after previous daptomycin exposure. Fifty-one percent of patients underwent central line removal for BSI. Failure to remove the central line for BSI did not increase risk of recurrent BSI (p=0.38).Enterococcal BSI typically occurs as a mucosal barrier injury infection in febrile neutropenic patients with acute leukemia receiving intensive chemotherapy. Many cases take place during re-induction chemotherapy in patients with relapsed or refractory disease. VRE is the most common infecting pathogen, but E. faecalis is not an insignificant cause of BSI (13%). In addition, some E. faecium isolates maintain ampicillin or vancomycin susceptibility. These results support empiric anti-VRE therapy with daptomycin upon initial suspicion for enterococcal BSI, but this therapy could be switched to ampicillin or vancomycin depending on isolate susceptibility to conserve daptomycin susceptibility. The risk of recurrent enterococcal BSI is notable as is the emergence of DNSE following daptomycin therapy. However, failure to remove the central line does not appear to be associated with recurrent BSI. Future study of changes to the gut enterococcal microbiome over the course of chemotherapy for acute leukemia will be critical in ultimately preventing enterococcal BSI. [Display omitted] DisclosuresSung:Cellective: Research Funding; Novartis: Research Funding; Merck: Research Funding.

Attributable mortality of vancomycin resistance in ampicillin-resistant Enterococcus faecium bacteremia in Denmark and the Netherlands: A matched cohort study.

To study whether replacement of nosocomial ampicillin-resistant Enterococcus faecium (ARE) clones by vancomycin-resistant E. faecium (VRE), belonging to the same genetic lineages, increases mortality in patients with E. faecium bacteremia, and to evaluate whether any such increase is mediated by a delay in appropriate antibiotic therapy. Retrospective, matched-cohort study. The study included 20 Dutch and Danish hospitals from 2009 to 2014. Within the study period, 63 patients with VRE bacteremia (36 Dutch and 27 Danish) were identified and subsequently matched to 234 patients with ARE bacteremia (130 Dutch and 104 Danish) for hospital, ward, length of hospital stay prior to bacteremia, and age. For all patients, 30-day mortality after bacteremia onset was assessed. The risk ratio (RR) reflecting the impact of vancomycin resistance on 30-day mortality was estimated using Cox regression with further analytic control for confounding factors. The 30-day mortality rates were 27% and 38% for ARE in the Netherlands and Denmark, respectively, and the 30-day mortality rates were 33% and 48% for VRE in these respective countries. The adjusted RR for 30-day mortality for VRE was 1.54 (95% confidence interval, 1.06-2.25). Although appropriate antibiotic therapy was initiated later for VRE than for ARE bacteremia, further analysis did not reveal mediation of the increased mortality risk. Compared to ARE bacteremia, VRE bacteremia was associated with higher 30-day mortality. One explanation for this association would be increased virulence of VRE, although both phenotypes belong to the same well-characterized core genomic lineage. Alternatively, it may be the result of unmeasured confounding.

Time to positivity as a prognostic factor in bloodstream infections with Enterococcus spp.

Time to positivity (TTP) is the delay of time from incubation to blood culture positivity. Short TTP can predict mortality and source of infection. The aim of this study was to investigate the value of TTP of patients with bloodstream infections with enterococci (E-BSI).In a single centre retrospective cohort study in Germany, the data of 244 patients with monomicrobial E-BSI were analyzed with hospital mortality as the primary outcome of interest from January 1 2014 to December 31 2016. Mortality rate of patients with bloodstream infections (BSI) with E. faecalis was 16.7%, Vancomycin sensitive E. faecium (VSEfm) 26.7% and Vancomycin resistant E. faecium (VREfm) 38.2%. Cut-offs showed a significantly higher mortality rate when compared to longer TTP (E. faecalis: P=0.047; VSEfm: P=0.02), but were not risk factors in survival analysis (E.faecalis: HR (hazard ratio): 2.73; P=0.17; VSEfm: HR: 1.63; P=0.15; VREfm: HR: 1.24; P=0.63). TTP≤10.5 hours with E. faecalis BSI was a discriminator for cardiovascular source of infection (AUC: 0.75). A short TTP could predict mortality rates and source of infection but was not an independent parameter for risk of death in survival analysis.

Antimicrobial resistance of &lt;i&gt;Enterococcus faecium&lt;/i&gt; and &lt;i&gt;Enterococcus faecalis&lt;/i&gt;, isolated from blood culture of patients with hematological malignancies during different study periods

Objective: to determine antimicrobial resistance of Enterococcus faecium and Enterococcus faecalis isolated from blood culture of hematological patients during different study periods.Materials and methods. Antimicrobial susceptibility of Enterococcus spp., collected as part of the multicenter study was tested by the broth microdilution method (USA Clinical and Laboratory Standards Institute (CLSI), 2018), to daptomycin by Etest (bioMeriéux, France). High-level gentamicin resistance (HLGR) and high-level streptomycin resistance (HLSR) was performed by the agar dilution method (CLSI (Oxoid, UK), 2018).Results. The susceptibility of 366 E. faecium (157 in 2002-2009 and 209 in 2010-2017) and 86 E. faecalis (44 in 20022009 and 42 in 2010-2017) was studied. In the second study period (2010-2017) the rise of vancomycin-resistant E. faecium (VREF) increased from 8.3 % to 23.4 % (p = 0.0001), and two linezolid-resistant (LREF) were identified. All VREF and LREF remained susceptible to daptomycin and tigecycline. The rate of susceptible to tetracycline E. faecium remained the same (73.9 and 74.6 %), and an increase in susceptibility to chloramphenicol (74.5 and 82.3 %) was observed. Susceptibility of E. faecium to tetracycline was detected with almost the same rate and in a part of isolates, the increase of susceptibility to chloramphenicol was registered during the analyzed periods. The rise of E. faecium susceptible to HLGR and HLSR has increased significantly in 2010-2017 compared to 2002-2009. Erythromycin, levofloxacin, ampicillin and penicillin had the least activity against E. faecium (less than 5 %).All E. faecalis were susceptible to tigecycline, linezolid, and teicoplanin. Only one of E. faecalis had intermediate resistance to vancomycin. High susceptibility to ampicillin in E. faecalis remained unchanged (97.7 and 97.6 %, respectively). In the second period of the study the rise of susceptible E. faecalis decreased significantly to penicillin (from 97.7 % to 76.2 %), to levofloxacin (from 59.1 % to 31 %), to HLSR (from 52.3 % до 31 %), and to HLGR (from 47.7 % to 26.2 %), remained unchanged to chloramphenicol (52.3 % and 50 %) and was minimal to erythromycin and tetracycline.Conclusion. The study demonstrated higher rates of antibiotic resistance among E. faecium, which consisted of an increase in VREF and the appearance of linezolid-resistant strains. High susceptibility to ampicillin remained in E. faecalis, but there was an increase in resistance to penicillin and aminoglycosides.

Mode and dynamics of vanA-type vancomycin resistance dissemination in Dutch hospitals

BackgroundEnterococcus faecium is a commensal of the gastrointestinal tract of animals and humans but also a causative agent of hospital-acquired infections. Resistance against glycopeptides and to vancomycin has motivated the inclusion of E. faecium in the WHO global priority list. Vancomycin resistance can be conferred by the vanA gene cluster on the transposon Tn1546, which is frequently present in plasmids. The vanA gene cluster can be disseminated clonally but also horizontally either by plasmid dissemination or by Tn1546 transposition between different genomic locations.MethodsWe performed a retrospective study of the genomic epidemiology of 309 vancomycin-resistant E. faecium (VRE) isolates across 32 Dutch hospitals (2012–2015). Genomic information regarding clonality and Tn1546 characterization was extracted using hierBAPS sequence clusters (SC) and TETyper, respectively. Plasmids were predicted using gplas in combination with a network approach based on shared k-mer content. Next, we conducted a pairwise comparison between isolates sharing a potential epidemiological link to elucidate whether clonal, plasmid, or Tn1546 spread accounted for vanA-type resistance dissemination.ResultsOn average, we estimated that 59% of VRE cases with a potential epidemiological link were unrelated which was defined as VRE pairs with a distinct Tn1546 variant. Clonal dissemination accounted for 32% cases in which the same SC and Tn1546 variants were identified. Horizontal plasmid dissemination accounted for 7% of VRE cases, in which we observed VRE pairs belonging to a distinct SC but carrying an identical plasmid and Tn1546 variant. In 2% of cases, we observed the same Tn1546 variant in distinct SC and plasmid types which could be explained by mixed and consecutive events of clonal and plasmid dissemination.ConclusionsIn related VRE cases, the dissemination of the vanA gene cluster in Dutch hospitals between 2012 and 2015 was dominated by clonal spread. However, we also identified outbreak settings with high frequencies of plasmid dissemination in which the spread of resistance was mainly driven by horizontal gene transfer (HGT). This study demonstrates the feasibility of distinguishing between modes of dissemination with short-read data and provides a novel assessment to estimate the relative contribution of nested genomic elements in the dissemination of vanA-type resistance.

Characterization of a vancomycin-resistant Enterococcus faecium isolate and a vancomycin-susceptible E. faecium isolate from the same blood culture.

To characterize two Enterococcus faecium isolates with different resistance phenotypes obtained from the same blood culture. The isolates were identified by MALDI-TOF MS and antimicrobial susceptibility testing (AST) was performed using a VITEK® 2 AST P592 card and Etest. WGS was performed on the MiSeq and MinION sequencer platforms. Core-genome MLST (cgMLST) and seven-loci MLST were performed. Plasmid analysis was performed using S1-PFGE followed by Southern-blot hybridization. Both E. faecium isolates were ST203. AST revealed that one was a vancomycin-resistant E. faecium (VREfm) isolate and the other was a vancomycin-susceptible E. faecium (VSEfm) isolate. The VREfm isolate harboured the vanA gene cluster as part of a Tn1546-type transposon encoded on a 49 kb multireplicon (rep1, rep2 and rep7a) plasmid (pAML0157.1). On the same plasmid, ant(6)-Ia, cat-like and erm(B) were encoded. The VSEfm isolate harboured a rep2 plasmid (pAML0158.1), 12 kb in size, which was present in full length as part of pAML0157.1 from the VREfm isolate. The vanA-encoding pAML0157.1 was a chimera of the rep2 pAML0158.1 and a second DNA segment harbouring vanA, ant(6)-Ia, erm(B) and cat-like, as well as the replicons rep1 and rep7a. By cgMLST analysis, the VREfm and VSEfm isolates were identical. Our results demonstrate that the VREfm and VSEfm blood culture isolates represented ST203 and were identical. The investigated heterogeneous resistance phenotypes resulted from the acquisition or loss of plasmid segments in the enterococcal isolates. These data illustrate that mobile genetic elements may contribute to the spread of vancomycin resistance among enterococci and to the genotypic and phenotypic variation within clonal isolates.

Value of Nontargeted Screening for Highly Resistant Microorganisms: The MOVE Study

Background: In the Erasmus MC University Medical Center, Rotterdam, the Netherlands, patients considered at risk for carrying highly resistant microorganisms (HRMO) are placed in isolation on admission, until tested negative for HRMO (ie, targeted screening). Patients without risk factors are not routinely screened (ie, nontargeted screening). However, nontargeted screening could identify patients colonized with HRMO missed by targeted screening. To determine the additional value of nontargeted screening, we compared the outcomes of the nontargeted screening approach with all available clinical cultures. Objective: We aim to identify patients colonized with HRMO, but missed by targeted screening, and to determine whether non-targeted screening has additional value. Methods: For the MOVE study, nontargeted admission and discharge cultures (nose and perianal) were obtained from randomly selected patients admitted to specific wards, regardless of HRMO risk factors. This study was part of a research initiative to identify the relation of a contaminated environment with the risk of becoming infected or colonized on a patient level. All bacteriological clinical samples positive for at least 1 HRMO from January 1, 2018, until August 31, 2019, were compared with the nontargeted screening samples. Samples were screened for methicillin-susceptible Staphylococcus aureus (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA) as well as highly resistant Pseudomonas aeruginosa, Acinetobacter baumannii, Enterococcus faecium, and Enterobacteriales. Broth enrichment was used for all cultures. Results: During the study period, 50,653 patients were admitted. 706 patients (1%) had a clinical sample positive for at least 1 HRMO during their hospital stay. 936 (1.8%) patients were included in the nontargeted screening for the MOVE study, and 40 patients were found to have at least 1 culture positive for HRMO (4.3%). Among these 40 patients, 28 were positive at admission and 12 were positive at discharge. Extended-spectrum β-lactamase (ESBL)–producing Enterobacteriales were most prevalent (n = 36, 90.0%) both at admission and discharge (n = 26 and n = 10, respectively). At admission, 1 patient was identified with MRSA and 1 patient was positive for vancomycin-resistant E. faecium (VRE). At discharge, 1 patient was identified with VRE and 1 had Verona Integron-encoded Metallo-β-lactamase (VIM)–positive P. aeruginosa. Conclusions: Our results show that the current targeted screening does not identify all HRMO carriers. Furthermore, patients who acquire an HRMO during admission are missed. The nontargeted screening identified 40 unknown carriers (4.3%). The limitations of the study are the restricted number of sample sites and the fact that we were unable to culture all patients. Therefore, it is likely that our study shows an underestimation of the true number of patients with HRMO.Funding: NoneDisclosures: None

100% Single-Patient Rooms and Environmental Contamination With Highly Resistant Microorganisms: The MOVE Study

Background: Studies have shown that patients colonized with highly resistant microorganisms (HRMO) contaminate the hospital environment, and that transmission from contaminated environments to patients occurs. In May 2018, the Erasmus MC University Medical Center, Rotterdam, moved from a hospital with mostly multiple-occupancy rooms to a new hospital with 100% single-patient rooms with private bathrooms. This move provided the unique opportunity to determine environmental contamination before the new hospital was open for admissions and thereafter and to compare the environmental contamination to the number of patients colonized with HRMO. Method: Environmental sampling took place twice in the old building and 12 times in the new building, from 2 weeks before to 15 months after relocating patients. At each moment, ~306 samples were taken from 13 locations (eg, nightstands, sinks) in 40 patient rooms. Samples were screened for Staphylococcus aureus (methicillin-susceptible [MSSA] and methicillin resistant [MRSA]) and highly resistant Pseudomonas aeruginosa, Acinetobacter baumannii, Enterococcus faecium, and Enterobacteriales. During the study period, January 1, 2018, until August 31, 2019, all clinical samples positive for HRMO were included. Results: Environmental sampling revealed that 29 of 724 (4.0%) locations were positive for HRMO in the old building, whereas 4 of 3,358 (0.1%) samples in the new building were positive for HRMO (P &lt; .001). In the old building, 14 of 29 locations were positive for extended-spectrum β-lactamase (ESBL)–producing bacteria and 15 were positive for carbapenemase-producing bacteria. In the new building, 3 of 4 positive samples were positive for vancomycin-resistant E. faecium (VRE), 1 was positive for ESBL-producing K. pneumoniae. For both HRMO, no carriers were detected. In the old building, 145 of 12,256 adult patients (1.2%) had clinical samples positive for HRMO, compared to 561 of 38,397 (1.5%) in the new building, a small but significant increase (P = .02). Conclusions: The transition from mainly 2- and 4-person rooms to 100% single-patient rooms resulted in a significant decrease in environmental contamination, even though the number of patients colonized with HRMO slightly increased. No molecular typing to determine transfer from environment to patients and vice versa has yet been performed. Future sampling is needed to determine whether the low environmental contamination is a long-term effect of the transition to single rooms.Funding: NoneDisclosures: None

Trends in the Incidence and Antibiotic Resistance of Enterococcal Bloodstream Isolates: A 7-Year Retrospective Multicenter Epidemiological Study in Italy

The spread of resistance to vancomycin and other last-resort drugs in Enterococcus spp. remains of concern. In Italy, surveillance data for enterococcal bloodstream isolates in humans are scant. The aim of our study was to assess the incidence trends of bacteremias due to Enterococcus species and their prevalence trends of antimicrobial resistance. We retrospectively included all consecutive not-duplicate Enterococcus species isolated from blood cultures, in patients from 11 Italian hospitals (2011-2017). Incidence was defined as the number of isolates per 10,000 patient-days, while resistance prevalence was defined as the number of resistant strains divided by the number of tested strains. We included 4,858 isolates (59%, 36%, and 5% due to Enterococcus faecalis, E. faecium, and other Enterococcus spp., respectively). Over the study period, the incidence of bacteremias due to E. faecalis (incidence rate ratio [IRR]: 1.02, 95% confidence interval [CI]: 1.00-1.04, p = 0.008) and E. faecium increased (IRR: 1.03, 95% CI: 1.01-1.05, p < 0.001) alongside with the whole enterococcal bacteremias trend (IRR: 1.02, 95% CIs: 1.01-1.04, p = 0.002). A progressive increase in vancomycin-resistant E. faecium (VREfm) bacteremias was observed. Resistance to tigecycline and linezolid was rarely reported. The incidence of enterococcal bloodstream isolates is increasing in Italy, together with the prevalence of VREfm. Resistance to linezolid, a cornerstone drug used in the treatment of VRE bloodstream infection, remains negligible.

Comprehensive integrated NGS-based surveillance and contact-network modeling unravels transmission dynamics of vancomycin-resistant enterococci in a high-risk population within a tertiary care hospital.

Vancomycin-resistant E. faecium (VRE) are an important cause of nosocomial infections, which are rapidly transmitted in hospitals. To identify possible transmission routes, we applied combined genomics and contact-network modeling to retrospectively evaluate routine VRE screening data generated by the infection control program of a hemato-oncology unit. Over 1 year, a total of 111 VRE isolates from 111 patients were collected by anal swabs in a tertiary care hospital in Southern Germany. All isolated VRE were whole-genome sequenced, followed by different in-depth bioinformatics analyses including genotyping and determination of phylogenetic relations, aiming to evaluate a standardized workflow. Patient movement data were used to overlay sequencing data to infer transmission events and strain dynamics over time. A predominant clone harboring vanB and exhibiting genotype ST117/CT469 (n = 67) was identified. Our comprehensive combined analyses suggested intra-hospital spread, especially of clone ST117/CT469, despite of extensive screening, single room placement, and contact isolation. A new interactive tool to visualize these complex data was designed. Furthermore, a patient-contact network-modeling approach was developed, which indicates both the periodic import of the clone into the hospital and its spread within the hospital due to patient movements. The analyzed spread of VRE was most likely due to placement of patients in the same room prior to positivity of screening. We successfully demonstrated the added value for this combined strategy to extract well-founded knowledge from interdisciplinary data sources. The combination of patient-contact modeling and high-resolution typing unraveled the transmission dynamics within the hospital department and, additionally, a constant VRE influx over time.