Ring-fused 2-pyridones effective against multidrug-resistant Gram-positive pathogens and synergistic with standard-of-care antibiotics.

The alarming rise of multidrug-resistant Gram-positive bacteria has precipitated a healthcare crisis, necessitating the development of new antimicrobial therapies. Here we describe a new class of antibiotics based on a ring-fused 2-pyridone backbone, which are active against vancomycin-resistant enterococci (VRE), a serious threat as classified by the Centers for Disease Control and Prevention, and other multidrug-resistant Gram-positive bacteria. Ring-fused 2-pyridone antibiotics have bacteriostatic activity against actively dividing exponential phase enterococcal cells and bactericidal activity against nondividing stationary phase enterococcal cells. The molecular mechanism of drug-induced killing of stationary phase cells mimics aspects of fratricide observed in enterococcal biofilms, where both are mediated by the Atn autolysin and the GelE protease. In addition, combinations of sublethal concentrations of ring-fused 2-pyridones and standard-of-care antibiotics, such as vancomycin, were found to synergize to kill clinical strains of VRE. Furthermore, a broad range of antibiotic resistant Gram-positive pathogens, including those responsible for the increasing incidence of antibiotic resistant healthcare-associated infections, are susceptible to this new class of 2-pyridone antibiotics. Given the broad antibacterial activities of ring-fused 2-pyridone compounds against Gram-positive (GmP) bacteria we term these compounds GmPcides, which hold promise in combating the rising tide of antibiotic resistant Gram-positive pathogens.

Therapeutics for Vancomycin-Resistant Enterococcal Bloodstream Infections.

Vancomycin-resistant enterococci (VRE) are common causes of bloodstream infections (BSIs) with high morbidity and mortality rates. They are pathogens of global concern with a limited treatment pipeline. Significant challenges exist in the management of VRE BSI, including drug dosing, the emergence of resistance, and the optimal treatment for persistent bacteremia and infective endocarditis. Therapeutic drug monitoring (TDM) for antimicrobial therapy is evolving for VRE-active agents; however, there are significant gaps in the literature for predicting antimicrobial efficacy for VRE BSIs. To date, TDM has the greatest evidence for predicting drug toxicity for the three main VRE-active antimicrobial agents daptomycin, linezolid, and teicoplanin. This article presents an overview of the treatment options for VRE BSIs, the role of antimicrobial dose optimization through TDM in supporting clinical infection management, and challenges and perspectives for the future.

Ursoricin, a bacteriocin of Streptococcus ursoris, has potent activity against methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci.

The emergence of drug-resistant bacteria, particularly methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE), has increased the need to discover novel antimicrobial agents that are effective against these species. Here, we describe the identification and purification of the mutacin BHT-B-like gene locus and bacteriocin peptide from Streptococcus ursoris, which is closely related to Streptococcus ratti; hence, we named this bacteriocin ursoricin. Ursoricin is a cationic, chromosome-encoded peptide that has potent antimicrobial effects against Gram-positive pathogens, including MRSA and VRE, with minimum inhibitory concentrations in the micromolar range. Ursoricin also inhibits the biofilm formation of high biofilm-forming S. aureus. Antibacterial activity was retained after treatment at 100°C for 60 min at a pH range of 3-9 and was partially reduced by treatment with proteinase K for 2 h (63% residual activity). The potent anti-MRSA, anti-VRE, and antibiofilm effects of ursoricin suggest that it is a possible candidate for the treatment of MRSA, VRE, and biofilm-associated infections. IMPORTANCE: The emergence of multidrug-resistant bacteria worldwide has posed a significant public health threat and economic burdens that make the identification and development of novel antimicrobial agents urgent. Bacteriocins are promising new agents that exhibit antibacterial activity against a wide range of human pathogens. In this study, we report that the bacteriocin produced by Streptococcus ursoris showed good antibacterial activity against a wide range of Staphylococcus aureus and enterococcus strains, particularly methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, and high biofilm-forming S. aureus. Interestingly, this bacteriocin had a stronger effect on S. aureus than on Staphylococcus epidermidis, which is a major commensal bacterium in human skin; this result is important when considering the disturbance of bacterial flora, especially on the skin, mediated by the application of antibacterial agents.

Risk factors and outcome associated with the acquisition of MDR linezolid-resistant Enterococcus faecium: a report from tertiary care centre.

OBJECTIVE: The aim of the study was to determine the resistance profile of linezolid-resistant Enterococcus faecium (LREfm) and to investigate risk factors and outcomes associated with LREfm infections. MATERIAL AND METHODS: A prospective case-control study was undertaken (2019 to 2022) and included 202 patients with LREfm infections (cases) and 200 controls with LSEfm infections. Clinical data was prospectively collected and analysed for risk factors and outcomes. Antimicrobial susceptibility was performed, and resistance profile was studied using WHOnet. RESULTS: Risk factors associated with LREfm infection were site of infection UTI (OR 5.87, 95% CI 2.59-13.29, p ≤ 0.001), prior use of carbapenem (OR 2.85 95% CI 1.62-5.02, p ≤ 0.001) and linezolid (OR 10.13, 95% CI 4.13-24.82, p ≤ 0.001), use of central line (OR 5.54, 95% CI 2.35-13.09, p ≤ 0.001), urinary catheter (OR 0.29, 95% CI 0.12-0.70, p ≤ 0.001) and ventilation (OR 14.87, 95% CI 7.86-28.11, p ≤ 0.007). The hospital stay 8-14 days (< 0.001) prior to infection and the mortality rate (p = 0.003) were also significantly high among patients with LREfm infections. Linezolid and vancomycin resistance coexisted; further, MDR, XDR and PDR phenotypes were significantly higher among LREfm. CONCLUSION: This study provided insight into epidemiology of MDR LREfm in a setting where linezolid use is high. The main drivers of infections with LREfm are multiple, including use of carbapenems and linezolid. Invasive procedures and increased hospital stay facilitate spread through breach in infection control practises. As therapeutic options are limited, ongoing surveillance of LREfm and VRE is critical to guide appropriate use of linezolid and infection control policies.

Synergistic properties of linezolid against Enterococcus spp. isolates: a systematic review from in vitro studies.

PURPOSE: Vancomycin-resistant enterococci (VRE) are a leading cause of hospital-acquired infections with limited therapeutic options. Combination of at least two antimicrobials is a possible strategy to obtain rapid and sustained bactericidal effects and overcome the emergence of resistance. We revised the literature on linezolid synergistic properties from in vitro studies to assess its activity in combination with molecules belonging to other antibiotic classes against Enterococcus spp. METHODS: We performed a systematic review of the literature from three peer-reviewed databases including papers evaluating linezolid synergistic properties in vitro against Enterococcus spp. isolates. RESULTS: We included 206 Enterococcus spp. isolates (92 E. faecalis, 90 E. faecium, 2 E. gallinarum, 3 E. casseliflavus, 19 Enterococcus spp.) from 24 studies. When an isolate was tested with different combinations, each combination was considered independently for further analysis. The most frequent interaction was indifferent effect (247/343, 72% of total interactions). The highest synergism rates were observed when linezolid was tested in combination with rifampin (10/49, 20.4% of interactions) and fosfomycin (16/84, 19.0%, of interactions). Antagonistic effect accounted for 7/343 (2.0%) of total interactions. CONCLUSION: Our study reported overall limited synergistic in vitro properties of linezolid with other antibiotics when tested against Enterococcus spp. The clinical choice of linezolid in combination with other antibiotics should be guided by reasoned empiric therapy in the suspicion of a polymicrobial infection or targeted therapy on microbiological results, rather than on an intended synergistic effect of the linezolid-based combination.

The epidemiology of multidrug-resistant organisms in persons diagnosed with cancer in Norway, 2008-2018: expanding surveillance using existing laboratory and register data.

Surveillance has revealed an increase of multidrug-resistant organisms (MDROs), even in low-prevalent settings such as Norway. MDROs pose a particular threat to at-risk populations, including persons with cancer. It is necessary to include such populations in future infection surveillance. By combining existing data sources, we aimed to describe the epidemiology of MDROs in persons diagnosed with cancer in Norway from 2008 to 2018. A cohort was established using data from the Cancer Registry of Norway, which was then linked to notifications of methicillin-resistant Staphylococcus aureus (MRSA), vancomycin- and/or linezolid-resistant enterococci (V/LRE), and carbapenemase-producing Gram-negative bacilli (CP-GNB) from the Norwegian Surveillance System for Communicable Diseases, and laboratory data on third-generation cephalosporin-resistant Enterobacterales (3GCR-E) from Oslo University Hospital (OUH). We described the incidence of MDROs and resistance proportion in Enterobacterales from 6 months prior to the person's first cancer diagnosis and up to 3 years after. The cohort included 322,005 persons, of which 0.3% (878) were diagnosed with notifiable MDROs. Peak incidence rates per 100,000 person-years were 60.9 for MRSA, 97.2 for V/LRE, and 6.8 for CP-GNB. The proportion of 3GCR-E in Enterobacterales in blood or urine cultures at OUH was 6% (746/12,534). Despite overall low MDRO incidence, there was an unfavourable trend in the incidence and resistance proportion of Gram-negative bacteria. To address this, there is a need for effective infection control and surveillance. Our study demonstrated the feasibility of expanding the surveillance of MDROs and at-risk populations through the linkage of existing laboratory and register data.

Epidemiological trends and susceptibility patterns of bloodstream infections caused by Enterococcus spp. in six German university hospitals: a prospectively evaluated multicentre cohort study from 2016 to 2020 of the R-Net study group.

PURPOSE: To analyse recent epidemiological trends of bloodstream infections (BSI) caused by Enterococcus spp. In adult patients admitted to tertiary care centres in Germany. METHODS: Epidemiological data from the multicentre R-NET study was analysed. Patients presenting with E. faecium or E. faecalis in blood cultures in six German tertiary care university hospitals between October 2016 and June 2020 were prospectively evaluated. In vancomycin-resistant enterococci (VRE), the presence of vanA/vanB was confirmed via molecular methods. RESULTS: In the 4-year study period, 3001 patients with BSI due to Enterococcus spp. were identified. E. faecium was detected in 1830 patients (61%) and E. faecalis in 1229 patients (41%). Most BSI occurred in (sub-) specialties of internal medicine. The pooled incidence density of enterococcal BSI increased significantly (4.0-4.5 cases per 10,000 patient days), which was primarily driven by VRE BSI (0.5 to 1.0 cases per 10,000 patient days). In 2020, the proportion of VRE BSI was > 12% in all study sites (range, 12.8-32.2%). Molecular detection of resistance in 363 VRE isolates showed a predominance of the vanB gene (77.1%). CONCLUSION: This large multicentre study highlights an increase of BSI due to E. faecium, which was primarily driven by VRE. The high rates of hospital- and ICU-acquired VRE BSI point towards an important role of prior antibiotic exposure and invasive procedures as risk factors. Due to limited treatment options and high mortality rates of VRE BSI, the increasing incidence of VRE BSI is of major concern.

Synthetic antimicrobial peptides: activity against vancomycin-resistant Enterococcus faecalis and modulation of chloramphenicol antibacterial activity.

AIMS: Enterococcus faecalis (E. faecalis) is a leading cause of nosocomial infection and presents a wide spectrum of antibiotic resistance, being vancomycin-resistant Enterococcus (VRE) one of the most relevant. Synthetic antimicrobial peptides (SAMPs) are currently a promising option to overcome antimicrobial resistance. Thus, the purpose of this study was to assess the effect of eight SAMPs against vancomycin-resistant E. faecalis, as well as to investigate their mechanism of action and synergy with conventional antibiotics. METHODS AND RESULTS: Here, eight SAMPs, Mo-CBP3-PepI, Mo-CBP3-PepII, Mo-CBP3-PepIII, RcAlb-PepI, RcAlb-PepII, RcAlb-PepIII, PepGAT, and PepKAA, were tested for antibacterial activity in vitro against E. faecalis (ATCC® 51299) through broth microdilution. A maximum of 48% of E. faecalis growth inhibition was achieved by treatment with SAMPs alone. However, when these peptides were combined with the antibiotic chloramphenicol, assessed by checkerboard method, the inhibition increased to 55%-76% of inhibition, two to three-folds of increase if compared to the effects of the compounds alone. Microscopic analysis showed that E. faecalis cells treated with a combination of SAMPs and chloramphenicol resulted in bacterial membrane damage. The biofilm inhibition maximum was 22% for SAMPs alone, when combined with chloramphenicol, the maximum increased to 33%. CONCLUSIONS: SAMPs and their combination with chloramphenicol demonstrate antibacterial activity against E. faecalis, possibly by inducing bacterial membrane damage.

Surveillance of vancomycin-resistant enterococci reveals shift in dominating clusters from vanA to vanB Enterococcus faecium clusters, Denmark, 2015 to 2022.

BackgroundVancomycin-resistant enterococci (VRE) are increasing in Denmark and Europe. Linezolid and vancomycin-resistant enterococci (LVRE) are of concern, as treatment options are limited. Vancomycin-variable enterococci (VVE) harbour the vanA gene complex but are phenotypically vancomycin-susceptible.AimThe aim was to describe clonal shifts for VRE and VVE in Denmark between 2015 and 2022 and to investigate genotypic linezolid resistance among the VRE and VVE.MethodsFrom 2015 to 2022, 4,090 Danish clinical VRE and VVE isolates were whole genome sequenced. We extracted vancomycin resistance genes and sequence types (STs) from the sequencing data and performed core genome multilocus sequence typing (cgMLST) analysis for Enterococcus faecium. All isolates were tested for the presence of mutations or genes encoding linezolid resistance.ResultsIn total 99% of the VRE and VVE isolates were E. faecium. From 2015 through 2019, 91.1% of the VRE and VVE were vanA E. faecium. During 2020, to the number of vanB E. faecium increased to 254 of 509 VRE and VVE isolates. Between 2015 and 2022, seven E. faecium clusters dominated: ST80-CT14 vanA, ST117-CT24 vanA, ST203-CT859 vanA, ST1421-CT1134 vanA (VVE cluster), ST80-CT1064 vanA/vanB, ST117-CT36 vanB and ST80-CT2406 vanB. We detected 35 linezolid vancomycin-resistant E. faecium and eight linezolid-resistant VVEfm.ConclusionFrom 2015 to 2022, the numbers of VRE and VVE increased. The spread of the VVE cluster ST1421-CT1134 vanA E. faecium in Denmark is a concern, especially since VVE diagnostics are challenging. The finding of LVRE, although in small numbers, ia also a concern, as treatment options are limited.

Evaluation of Antimicrobial Resistancein Clinical Isolates of Enterococcus spp. Obtained from Hospital Patients in Latvia.

Background and Objective: Enterococci are typically found in a healthy human gastrointestinal tract but can cause severe infections in immunocompromised patients. Such infections are treated with antibiotics. This study addresses the rising concern of antimicrobial resistance (AMR) in Enterococci, focusing on the prevalence of vancomycin-resistant enterococcus (VRE) strains. Materials and Methods: The pilot study involved 140 Enterococci isolates collected between 2021 and 2022 from two multidisciplinary hospitals (with and without local therapeutic drug monitoring protocol of vancomycin) in Latvia. Microbiological assays and whole genome sequencing were used. AMR gene prevalence with resistance profiles were determined and the genetic relationship and outbreak evaluation were made by applying core genome multi-locus sequence typing (cgMLST). Results: The acquired genes and mutations were responsible for resistance against 10 antimicrobial classes, including 25.0% of isolates expressing resistance to vancomycin, predominantly of the vanB type. Genetic diversity among E. faecalis and E. faecium isolates was observed and seven potential outbreak clusters were identified, three of them containing sequence types ST6, ST78 and ST80. The prevalence of vancomycin resistance was highest in the hospital without a therapeutic drug-monitoring protocol and in E. faecium. Notably, a case of linezolid resistance due to a mutation was documented. Conclusions: The study illustrates the concerning prevalence of multidrug-resistant Enterococci in Latvian hospitals, showcasing the rather widespread occurrence of vancomycin-resistant strains. This highlights the urgency of implementing efficient infection control mechanisms and the need for continuous VRE surveillance in Latvia to define the scope and pattern of the problem, influencing clinical decision making and planning further preventative measures.

Multisite Detection of Tn1549-Mediated vanB Vancomycin Resistance in Multidrug-Resistant Enterococcus faecalis ST6 in Texas and Florida.

In the United States, vanB-mediated resistance in enterococci is rare. We characterized three sequence type (ST) 6, vancomycin-resistant Enterococcus faecalis isolates causing bacteremia in unique patients in spatiotemporally distinct settings. Isolates were recovered between 2018 and 2020 in two cities in the United States (Houston, TX; Miami, FL). The isolates harbored the vanB operon on a chromosomally located Tn1549 transposon, and epidemiological data suggested multiple introductions of the vanB gene cluster into ST6 E. faecalis.

Assessment of antibiotic resistance and biofilm formation of Enterococcus species isolated from different pig farm environments in Poland.

BACKGROUND: Enteroccocus spp. are human opportunistic pathogens causing a variety of serious and life-threating infections in humans, including urinary tract infection, endocarditis, skin infection and bacteraemia. Farm animals and direct contact with them are important sources of Enterococcus faecalis (EFA) and Enterococcus faecium (EFM) infections among farmers, veterinarians and individuals working in breeding farms and abattoirs. The spread of antibiotic-resistant strains is one of the most serious public health concerns, as clinicians will be left without therapeutic options for the management of enterococcal infections. The aim of the study was to evaluate the occurrence and antimicrobial susceptibility of EFA and EFM strains isolated from a pig farm environment and to determine the biofilm formation ability of identified Enterococcus spp. strains. RESULTS: A total numer of 160 enterococcal isolates were obtained from 475 samples collected in total (33.7%). Among them, 110 of genetically different strains were identified and classified into EFA (82; 74.5%) and EFM (28; 25.5%). Genetic similarity analysis revealed the presence of 7 and 1 clusters among the EFA and EFM strains, respectively. The highest percentage of EFA strains (16; 19.5%) was resistant to high concentrations of gentamicin. Among the EFM strains, the most frequent strains were resistant to ampicillin and high concentrations of gentamicin (5 each; 17.9%). Six (7.3%) EFA and 4 (14.3%) EFM strains showed vancomycin resistance (VRE - Vancomycin-Resistant Enterococcus). Linezolid resistance was found in 2 strains of each species. The multiplex PCR analysis was performed to identify the vancomycin resistant enterococci. vanB, vanA and vanD genotypes were detected in 4, 1 and 1 EFA strains, respectively. Four EFA VRE-strains in total, 2 with the vanA and 2 with the vanB genotypes, were identified. The biofilm analysis revealed that all vancomycin-resistant E. faecalis and E. faecium strains demonstrated a higher biofilm-forming capacity, as compared to the susceptible strains. The lowest cell count (5.31 log CFU / cm2) was reisolated from the biofilm produced by the vancomycin-sensitive strain EFM 2. The highest level of re-isolated cells was observed for VRE EFA 25 and VRE EFM 7 strains, for which the number was 7 log CFU / cm2 and 6.75 log CFU / cm2, respectively. CONCLUSIONS: The irrational use of antibiotics in agriculture and veterinary practice is considered to be one of the key reasons for the rapid spread of antibiotic resistance among microorganisms. Owing to the fact that piggery environment can be a reservoir of antimicrobial resistance and transmission route of antimicrobial resistance genes from commensal zoonotic bacteria to clinical strains, it is of a great importance to public health to monitor trends in this biological phenomenon.

Differences in Pharmacokinetic/Pharmacodynamic Parameters of Tedizolid Against VRE and MRSA.

PURPOSE: Vancomycin-resistant enterococci (VRE) have recently become a major cause of nosocomial infections and a global public health concern. Tedizolid exhibits powerful antibacterial activity against VRE in vitro, but its pharmacokinetic/pharmacodynamic (PK/PD) parameters remain unclear. Therefore, we aimed to determine the PK/PD indices of tedizolid action on VRE and the mechanisms underlying the PK/PD indices differences of tedizolid against VRE and methicillin-resistant Staphylococcus aureus (MRSA). METHODS: Optimal PK/PD target values of tedizolid were determined in vitro, based on time-kill curves and post-antibiotic effects (PAEs), and in vivo, using mouse models of thigh infection with VRE and MRSA strains. RESULTS: The tedizolid bactericidal activity on VRE and MRSA was time-dependent. Correlations were closest between fAUC24/MIC and the tedizolid PK/PD index against MRSA and VRE. To achieve 1 log10 kill tedizolid fAUC24/MIC in neutropenic mouse models of thigh infection with VRE and MRSA should be 14.2 and 138.5, respectively. The PAEs of tedizolid against VRE and MRSA were 2.39 and 0.99 h, respectively. CONCLUSION: Tedizolid showed bactericidal effects against VRE even in neutropenic mice unlike MRSA, which could be attributed to its longer PAE against VRE. Hence, we hypothesize that tedizolid treatment against VRE infections is promising for achieving therapeutic success in clinical.

Intestinal colonization of vancomycin-resistant Enterococcus in children admitted to Mofid children's hospital intensive care unit at admission and at discharge.

BACKGROUND: This study aimed to investigate the frequency of intestinal colonization by vancomycin-resistant Enterococcus (VRE) carrying vanA and vanB genes in patients at ICU admission and at discharge from ICU in Mofid children's Hospital, Tehran, Iran. METHOD: Sampling was performed using rectal swabs and vancomycin susceptibility testing for Enterococcus spp. was carried out using a minimum inhibitory concentration (MIC) assay on Muller Hinton Agar (MHA) medium using an E-test kit. The molecular detection of VRE isolates was performed by the PCR method using the vanA and vanB resistance genes. RESULTS: A total of 234 and 186 non-duplicate rectal swab samples were collected from patients at ICU admission and at discharge from ICU, respectively. Enterococcus spp. was detected in 34.6% (n = 81/234) of rectal swab samples collected from patients at ICU admission, of which 44.4% (n = 36/81) were VRE isolates. In contrast, the prevalence of Enterococcus spp. and VRE isolates among patients at discharge from ICU was 17.7% (n = 33/186) and 57.6% (n = 19/33), respectively. Out of 19 VRE isolated from patients at ICU admission, 4 (21%) and 1 (5.3%) contained vanA and vanB genes, respectively. In contrast, out of 36 VRE isolated from patients at discharge from ICU, 11 (30.5%) were positive for the vanA gene. CONCLUSION: Results revealed that the prevalence of Enterococcus spp. among patients at ICU admission was high. However, VRE was frequently isolated from patients who were hospitalized for several days in ICUs. The implementation of proper infection control strategies and the use of suitable protocols to guide the appropriate prescribing of antibiotics are necessary.

Development of a workflow for the detection of vancomycin-resistant Enterococcus faecium and Enterococcus faecalis from rectal swabs using the spectra VRE medium.

BACKGROUND: Spectra™ VRE agar (Remel, Lenexa, KS) is a chromogenic agar that is FDA approved for screening patients for VRE colonization. The package insert recommends confirming isolates with identification and susceptibility testing, but confirming every culture delays time to result. Given the agar's historic high specificity for E. faecium isolates, we theorized the agar could be utilized as a stand-alone screening to minimize reagents and time. AIM: Our laboratory sought to develop a workflow to optimize the use of the medium. METHODS: We plated 3,815 rectal swabs to the Spectra VRE agar and compared results to traditional identification and susceptibility testing. RESULTS: Dark blue or purple colonies on the agar demonstrated a sensitivity of 98% and specificity of 85% for detection of VRE faecium, but light blue colonies were significantly less specific for E. faecalis. CONCLUSIONS: We streamlined our workflow to accept dark blue or purple colonies as VRE faecium and plan to perform additional testing only on light blue colonies. Interestingly, higher quantity of growth increased the accuracy of the agar. In the future, growth quantity may be used to further streamline the workflow once more data is obtained.

The intestinal carrier status of Enterococcus spp. in children: clonal diversity and alterations in resistance phenotypes before and after admission to a pediatric intensive care unit.

BACKGROUND: This study aimed to investigate the intestinal carrier status of Enterococcus spp. among children in a pediatric intensive care unit (PICU) and reveal the role of hospitalization in the alteration of resistance phenotypes and clonal diversity of the isolates during admission and discharge periods. METHODS: Two separate stool samples were collected from hospitalized patients in the pediatric intensive care unit at admission and discharge times. The culture was done, and Enterococcus species were tested for antimicrobial susceptibility and carriage of vanA-D gene subtypes. Random Amplified Polymorphic DNA (RAPD)-PCR was used for a phylogenetic study to check the homology of pairs of isolates. RESULTS: The results showed carriage of Enterococci at admission, discharge, and at both time points in 31%, 28.7%, and 40.1% of the cases, respectively. High frequencies of the fecal Enterococcus isolates with vancomycin-resistance (VR, 32.6% and 41.9%), high-level of gentamicin-resistance (HLGR, 25.6% and 27.9%), and multi-drug resistance phenotypes (MDR, 48.8% and 65.1%) were detected at admission and discharge times, respectively. Resistance to vancomycin, ampicillin, and rifampicin was higher among E. faecium, but resistance to ciprofloxacin was higher in E. faecalis isolates. The increased length of hospital stay was correlated with the carriage of resistant strains to vancomycin, ampicillin, and ciprofloxacin. While the homology of the isolates was low among different patients during hospitalization, identical (9%) and similar (21%) RAPD-PCR patterns were detected between pairs of isolates from each patient. CONCLUSIONS: The high rate of intestinal carriage of VR, HLGR-, and MDR-Enterococci at admission and during hospitalization in the PICU, and the impact of increased length of hospital stay on the fecal carriage of the resistant strains show the importance of antibiotic stewardship programs to control their transmission and spread in children.

Enterococcal Membrane Vesicles as Vaccine Candidates.

Enterococcus faecium is a leading cause of nosocomial infections, particularly in immunocompromised patients. The rise of multidrug-resistant E. faecium, including Vancomycin-Resistant Enterococci (VRE), is a major concern. Vaccines are promising alternatives to antibiotics, but there is currently no vaccine available against enterococci. In a previous study, we identified six protein vaccine candidates associated with extracellular membrane vesicles (MVs) produced by nosocomial E. faecium. In this study, we immunized rabbits with two different VRE-derived MV preparations and characterized the resulting immune sera. Both anti-MV sera exhibited high immunoreactivity towards the homologous strain, three additional VRE strains, and eight different unrelated E. faecium strains representing different sequence types (STs). Additionally, we demonstrated that the two anti-MV sera were able to mediate opsonophagocytic killing of not only the homologous strain but also three unrelated heterologous VRE strains. Altogether, our results indicate that E. faecium MVs, regardless of the purification method for obtaining them, are promising vaccine candidates against multidrug-resistant E. faecium and suggest that these naturally occurring MVs can be used as a multi-antigen platform to elicit protective immune responses against enterococcal infections.

Half-Sandwich Type Platinum-Group Metal Complexes of C-Glucosaminyl Azines: Synthesis and Antineoplastic and Antimicrobial Activities.

While platinum-based compounds such as cisplatin form the backbone of chemotherapy, the use of these compounds is limited by resistance and toxicity, driving the development of novel complexes with cytostatic properties. In this study, we synthesized a set of half-sandwich complexes of platinum-group metal ions (Ru(II), Os(II), Ir(III) and Rh(III)) with an N,N-bidentate ligand comprising a C-glucosaminyl group and a heterocycle, such as pyridine, pyridazine, pyrimidine, pyrazine or quinoline. The sugar-containing ligands themselves are unknown compounds and were obtained by nucleophilic additions of lithiated heterocycles to O-perbenzylated 2-nitro-glucal. Reduction of the adducts and, where necessary, subsequent protecting group manipulations furnished the above C-glucosaminyl heterocycles in their O-perbenzylated, O-perbenzoylated and O-unprotected forms. The derived complexes were tested on A2780 ovarian cancer cells. Pyridine, pyrazine and pyridazine-containing complexes proved to be cytostatic and cytotoxic on A2780 cells, while pyrimidine and quinoline derivatives were inactive. The best complexes contained pyridine as the heterocycle. The metal ion with polyhapto arene/arenyl moiety also impacted on the biological activity of the complexes. Ruthenium complexes with p-cymene and iridium complexes with Cp* had the best performance in ovarian cancer cells, followed by osmium complexes with p-cymene and rhodium complexes with Cp*. Finally, the chemical nature of the protective groups on the hydroxyl groups of the carbohydrate moiety were also key determinants of bioactivity; in particular, O-benzyl groups were superior to O-benzoyl groups. The IC50 values of the complexes were in the low micromolar range, and, importantly, the complexes were less active against primary, untransformed human dermal fibroblasts; however, the anticipated therapeutic window is narrow. The bioactive complexes exerted cytostasis on a set of carcinomas such as cell models of glioblastoma, as well as breast and pancreatic cancers. Furthermore, the same complexes exhibited bacteriostatic properties against multiresistant Gram-positive Staphylococcus aureus and Enterococcus clinical isolates in the low micromolar range.

Effects of Melaleuca alternifolia Chell (Tea Tree) and Eucalyptus globulus Labill. Essential Oils on Antibiotic-Resistant Bacterial Biofilms.

In the present investigation, the anti-biofilm potential of two essential oils (EOs), Melaleuca alternifolia Chell (Tea-Tree) (TTO) and Eucalyptus globulus Labill. (EEO) was characterized and tested "in vitro" against both mature biofilms and biofilms in the process of formation, produced by strains belonging to three main categories of antibiotic resistant bacteria (ARB): Vancomycin-resistant enterococci (VRE), methicillin-resistant Staphylococcus aureus (MRSA) and broad-spectrum ß-lactamase-producing Escherichia coli (ESBL). The study was carried out in 96-well microtiter-plates using EOs alone, in association with each other and in combination with antibiotics against both single and multi-species biofilm. The study demonstrated the ability of TTO and EEO to counteract the ARB strains in sessile form, with promising results in particular against the biofilm in formation. Mature biofilm by ESBL E. coli was the most sensitive in the results from the quantification study of viable cells performed in multi-species biofilms. Lastly, in all tests, carried out using TTO/EEO associations and EOs/antibiotic combinations, the synergistic effect which emerged from the FIC-index has been confirmed, and both the reduction of biofilm in formation, and the removal of mature structure was obtained at very low concentrations, with values from 4 to >512-fold lower than the minimum inhibitory concentration (MIC) of the single compounds.

Ultraviolet-C Light Evaluation as Adjunct Disinfection to Remove Multidrug-Resistant Organisms.

BACKGROUND: Our objective was to determine if the addition of ultraviolet-C (UV-C) light to daily and discharge patient room cleaning reduces healthcare-associated infection rates of vancomycin-resistant enterococci (VRE) and Clostridioides difficile in immunocompromised adults. METHODS: We performed a cluster randomized crossover control trial in 4 cancer and 1 solid organ transplant in-patient units at the Johns Hopkins Hospital, Baltimore, Maryland. For study year 1, each unit was randomized to intervention of UV-C light plus standard environmental cleaning or control of standard environmental cleaning, followed by a 5-week washout period. In study year 2, units switched assignments. The outcomes were healthcare-associated rates of VRE or C. difficile. Statistical inference used a two-stage approach recommended for cluster-randomized trials with <15 clusters/arm. RESULTS: In total, 302 new VRE infections were observed during 45787 at risk patient-days. The incidence in control and intervention groups was 6.68 and 6.52 per 1000 patient-days respectively; the unadjusted incidence rate ratio (IRR) was 0.98 (95% confidence interval [CI], .78 - 1.22; P = .54). There were 84 new C. difficile infections observed during 26118 at risk patient-days. The incidence in control and intervention periods was 2.64 and 3.78 per 1000 patient-days respectively; the unadjusted IRR was 1.43 (95% CI, .93 - 2.21; P = .98). CONCLUSIONS: When used daily and at post discharge in addition to standard environmental cleaning, UV-C disinfection did not reduce VRE or C. difficile infection rates in cancer and solid organ transplant units.