In Vitro Evaluation of Phytobiotic Mixture Antibacterial Potential against Enterococcus spp. Strains Isolated from Broiler Chicken.

Enterococcus spp. are normal intestinal tract microflorae found in poultry. However, the last decades have shown that several species, e.g., Enterococcus cecorum, have become emerging pathogens in broilers and may cause numerous losses in flocks. In this study, two combinations (H1 and H2) of menthol, 1,8-cineol, linalool, methyl salicylate, γ-terpinene, p-cymene, trans-anethole, terpinen-4-ol and thymol were used in an in vitro model, analyzing its effectiveness against the strains E. cecorum, E. faecalis, E. faecium, E. hirae and E. gallinarum isolated from broiler chickens from industrial farms. To identify the isolated strains classical microbiological methods and VITEK 2 GP cards were used. Moreover for E. cecorum a PCR test was used.. Antibiotic sensitivity (MIC) tests were performed for all the strains. For the composition H1, the effective dilution for E. cecorum and E. hirae strains was 1:512, and for E. faecalis, E. faecium and E. gallinarum, 1:1024. The second mixture (H2) showed very similar results with an effectiveness at 1:512 for E. cecorum and E. hirae and 1:1024 for E. faecalis, E. faecium and E. gallinarum. The presented results suggest that the proposed composition is effective against selected strains of Enterococcus in an in vitro model, and its effect is comparable to classical antibiotics used to treat this pathogen in poultry. This may suggest that this product may also be effective in vivo and provide effective support in the management of enterococcosis in broiler chickens.

Insights into the novel Enterococcus faecalis phage: A comprehensive genome analysis.

Enterococcus faecalis, a Gram-positive bacterium, poses a significant clinical challenge owing to its intrinsic resistance to a broad spectrum of antibiotics, warranting urgent exploration of innovative therapeutic strategies. This study investigated the viability of phage therapy as an alternative intervention for antibiotic-resistant E. faecalis, with a specific emphasis on the comprehensive genomic analysis of bacteriophage SAM-E.f 12. The investigation involved whole-genome sequencing of SAM-E.f 12 using Illumina technology, resulting in a robust dataset for detailed genomic characterization. Bioinformatics analyses were employed to predict genes and assign functional annotations. The bacteriophage SAM-E.f 12, which belongs to the Siphoviridae family, exhibited substantial potential, with a burst size of 5.7 PFU/infected cells and a latent period of 20 min. Host range determination experiments demonstrated its effectiveness against clinical E. faecalis strains, positioning SAM-E.f 12 as a precise therapeutic agent. Stability assays underscore resilience across diverse environmental conditions. This study provides a comprehensive understanding of SAM-E.f 12 genomic composition, lytic lifecycle parameters, and practical applications, particularly its efficacy in murine wound models. These results emphasize the promising role of phage therapy, specifically its targeted approach against antibiotic-resistant E. faecalis strains. The nuanced insights derived from this research will contribute to the ongoing pursuit of efficacious phage therapies and offer valuable implications for addressing the clinical challenges associated with E. faecalis infections.

[A Thrombus in the Right Atrium Associated with Pyogenic Liver Abscess].

Hepatic abscesses are divided into bacterial and amoebic types. Although the prognosis of bacterial liver abscesses has improved owing to progress in drainage techniques and antimicrobial agents, poor outcomes remain common. While there have been some reports of amoebic liver abscesses complicated by thrombosis, bacterial liver abscesses and subsequent thrombus in the right atrium are very rare. We herein report the case of an 82-year-old man. He had suffered acute obstructive suppurative cholangitis 10 months previously, and bile culture yielded Enterococcus faecalis. In the present case, a right atrial thrombus caused by a bacterial liver abscess was observed and the causative organism was thought to be Enterococcus faecalis, for which was detected in a blood culture was positive. The patient was successfully treated with hepatic abscess drainage and surgical right atrial thrombectomy under cardiopulmonary bypass with a beating heart.

Enterococcus faecalis: implications for host health.

The microbiota represents a crucial area of research in maintaining human health due to its potential for uncovering novel biomarkers, therapies, and molecular mechanisms relevant to population identification and experimental model characterization. Among these microorganisms, Enterococcus faecalis, a Gram-positive bacterium found in the gastrointestinal tract of humans and animals, holds particular significance. Strains of this bacterial species have sparked considerable debate in the literature due to their dual nature; they can either be utilized as probiotics in the food industry or demonstrate resistance to antibiotics, potentially leading to severe illness, disability, and death. Given the diverse characteristics of Enterococcus faecalis strains, this review aims to provide a comprehensive understanding of their impact on various systems within the host, including the immunological, cardiovascular, metabolic, and nervous systems. Furthermore, we summarize the bacterium-host interaction characteristics and molecular effects to highlight their targets, features, and overall impact on microbial communities and host health.

Genomic epidemiology reveals multiple mechanisms of linezolid resistance in clinical enterococci in China.

BACKGROUND: Infections caused by linezolid-resistant enterococci (LRE) are clinically difficult to treat and threaten patient health. However, there is a lack of studies on long time-span LRE strains in China. For this reason, our study comprehensively revealed the resistance mechanisms of LRE strains collected in a Chinese tertiary care hospital from 2011 to 2022. METHODS: Enterococcal strains were screened and verified after retrospective analysis of microbial data. Subsequently, 65 LRE strains (61 Enterococcus faecalis and 4 Enterococcus faecium, MIC ≥ 8 µg/ml), 1 linezolid-intermediate Enterococcus faecium (MIC = 4 µg/ml) and 1 linezolid-susceptible Enterococcus faecium (MIC = 1.5 µg/ml) were submitted for whole-genome sequencing (WGS) analysis and bioinformatics analysis. RESULTS: The optrA gene was found to be the most common linezolid resistance mechanism in our study. We identified the wild-type OptrA and various OptrA variants in 98.5% of LRE strains (61 Enterococcus faecalis and 3 Enterococcus faecium). We also found one linezolid-resistant Enterococcus faecium strain carried both optrA and cfr(D) gene, while one linezolid-resistant Enterococcus faecium only harbored the poxtA gene. Most optrA genes (55/64) were located on plasmids, with impB-fexA-optrA, impB-fexA-optrA-erm(A), fexA-optrA-erm(A), and fexA-optrA segments. A minority of optrA genes (9/64) were found on chromosomes with the Tn6674-like platform. Besides, other possible linezolid resistance-associated mechanisms (mutations in the rplC and rplD genes) were also found in 26 enterococcal strains. CONCLUSIONS: Our study suggested that multiple mechanisms of linezolid resistance exist among clinical LRE strains in China.

Identification of an Enterococcus faecium strain isolated from raw bovine milk co-harbouring the oxazolidinone resistance genes optrA and poxtA in China.

Oxazolidinones are potent antimicrobial agents used to treat human infections caused by multidrug-resistant Gram-positive bacteria. The growing resistance to oxazolidinones poses a significant threat to public health. In August 2021, a linezolid-resistant Enterococcus faecium BN83 was isolated from a raw milk sample of cow in Inner Mongolia, China. This isolate exhibited a multidrug resistance phenotype and was resistant to most of drugs tested including linezolid and tedizolid. PCR detection showed that two mobile oxazolidinones resistance genes, optrA and poxtA, were present in this isolate. Whole genome sequencing analysis revealed that the genes optrA and poxtA were located on two different plasmids, designated as pBN83-1 and pBN83-2, belonging to RepA_N and Inc18 families respectively. Genetic context analysis suggested that optrA gene on plasmid pBN83-1 was located in transposon Tn6261 initially found in E. faecalis. Comprehensive analysis revealed that Tn6261 act as an important horizontal transmission vector for the spread of optrA in E. faecium. Additionally, poxtA-bearing pBN83-2 displayed high similarity to numerous plasmids from Enterococcus of different origin and pBN83-2-like plasmid represented a key mobile genetic element involved in movement of poxtA in enterococcal species. The presence of optrA- and poxtA-carrying E. faecium in raw bovine milk represents a public health concern and active surveillance is urgently warranted to investigate the prevalence of oxazolidinone resistance genes in animal-derived food products.

Necrotising fasciitis with extensive necrosis caused by Lactobacillus: a case report.

BACKGROUND: Necrotising fasciitis (NF) is a life-threatening soft-tissue infection that rapidly destroys the epidermis, subcutaneous tissue, and fascia. Despite their low virulence, Lactobacillus spp. can cause NF, and because of its rare incidence, there is limited information about its molecular and clinicopathological characteristics. We report a rare case of NF in a patient with type 2 diabetes mellitus diagnosed on admission and severe obesity due to infection with two types of Lactobacillus spp. that manifested in extensive necrosis. CASE PRESENTATION: A 48-year-old woman was referred to our hospital with a complaint of difficulty walking due to severe bilateral thigh pain. She presented with mild erythema, swelling, and severe skin pain extending from the pubic region to the groin. The patient was morbidly obese, had renal dysfunction, and had diabetes mellitus diagnosed on admission.; her LRINEC (Laboratory Risk Indicator for Necrotising Fasciitis) score was 9, indicating a high risk of NF. An exploratory surgical incision was made, and NF was diagnosed based on fascial necrosis. Emergent surgical debridement was performed, and cultures of the tissue culture and aspirated fluid/pus revealed two types of Lactobacillus spp.: Lactobacillus salivarius and L. iners. The patient was admitted to the intensive care unit (ICU), where antibiotics were administered and respiratory and circulatory management was performed. Diabetic ketoacidosis was detected, which was treated by controlling the blood glucose level stringently via intravenous insulin infusion. The patient underwent a second debridement on day 11 and a skin suture and skin grafting on day 36. The patient progressed well, was transferred from the ICU to the general ward on day 41, and was discharged unassisted on day 73. CONCLUSIONS: Lactobacillus spp. are rarely pathogenic to healthy individuals and can scarcely trigger NF. However, these bacteria can cause rare infections such as NF in immunocompromised individuals, such as those with diabetes and obesity, and an early diagnosis of NF is imperative; surgical intervention may be required for the prevention of extensive necrosis. The LRINEC score may be useful for the early diagnosis of NF, even for less pathogenic bacteria such as Lactobacillus.

Bosutinib Stimulates Macrophage Survival, Phagocytosis, and Intracellular Killing of Bacteria.

Host-acting compounds are emerging as potential alternatives to combating antibiotic resistance. Here, we show that bosutinib, an FDA-approved chemotherapeutic for treating chronic myelogenous leukemia, does not possess any antibiotic activity but enhances macrophage responses to bacterial infection. In vitro, bosutinib stimulates murine and human macrophages to kill bacteria more effectively. In a murine wound infection with vancomycin-resistant Enterococcus faecalis, a single intraperitoneal bosutinib injection or multiple topical applications on the wound reduce the bacterial load by approximately 10-fold, which is abolished by macrophage depletion. Mechanistically, bosutinib stimulates macrophage phagocytosis of bacteria by upregulating surface expression of bacterial uptake markers Dectin-1 and CD14 and promoting actin remodeling. Bosutinib also stimulates bacterial killing by elevating the intracellular levels of reactive oxygen species. Moreover, bosutinib drives NF-κB activation, which protects infected macrophages from dying. Other Src kinase inhibitors such as DMAT and tirbanibulin also upregulate expression of bacterial uptake markers in macrophages and enhance intracellular bacterial killing. Finally, cotreatment with bosutinib and mitoxantrone, another chemotherapeutic in clinical use, results in an additive effect on bacterial clearance in vitro and in vivo. These results show that bosutinib stimulates macrophage clearance of bacterial infections through multiple mechanisms and could be used to boost the host innate immunity to combat drug-resistant bacterial infections.

Psychrobacter raelei sp. nov., isolated from a dog with peritonitis.

A strain belonging to the genus Psychrobacter, named PraFG1T, was isolated from the peritoneal effusion of a stray dog during necropsy procedures. The strain was characterized by the phylogenetic analyses based on the nucleotide sequences of 16S and 23S rRNA genes and of gyrB, which placed the strain in the genus Psychrobacter. The nucleotide sequence of the chromosome confirmed the placement, showing an average nucleotide identity of 72.1, 77.7, and 77.5 % with the closest related species, namely Psychrobacter sanguinis, Psychrobacter piechaudii, and Psychrobacter phenylpyruvicus, respectively, thus indicating a novel species. The polyphasic characterization by biochemical and fatty acid profiling as well as MALDI-TOF supported those findings. The strain was halotolerant, capable of growing within a temperature range between 4 and 37 °C, it was positive for catalase and oxidase, indole producing, nitrate reducing, and not able to use 5-keto-d-gluconic acid as a carbon source. Taken together, the data suggest that strain PraFG1T could be considered as representing a novel species, with the name Psychrobacter raelei sp. nov. (type strain PraFG1T=CIP 111873T=LMG 32233T).

Investigation of some changes and clonal relationship in enterococci isolates due to relocation of a hospital.

Objectives: To investigate the isolation rates, antimicrobial resistance rates, minimum inhibitory concentration values of antimicrobial agents, and clonal relationships of Enterococcus faecalis and Enterococcus faeciumdue to the relocation of a hospital to a newly constructed building. METHODS: The comparative, prospective study was conducted at adult general intensive care units of the Mus State Hospital, Mus, Turkey, in two phases; before the relocation from January 25 to December 1, 2014, and after the relocation from February 10 to May 24, 2015. Rectal swab samples were collected 72 hours post-hospitalisation. Identification of Enterococcus faecalis and Enterococcus faeciumisolates was determined by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, and antimicrobial resistance with minimum inhibitory concentration values was detected with Vitek 2 system. The clonal relatedness among the strains was investigated by pulsed-field gel electrophoresis. Data was analysed using SPSS 23. RESULTS: Of the 69 patients, 37(53.62%) were related to pre-relocation phase; 20(54.1%) females and 17(45.9%) males with mean age 62.81±21.71 years. There were 32(46.37%) patients in the post-relocation phase; 13(40.6%) females and 19(59.4%) males with mean age 62.69±21.35 years (p>0.05). Of the 84 enterococci strains isolated, 51(60.7%) were Enterococcus faecium; 28(55%) before relocation and 23(45%) after relocation (p=0.77). The remaining 33(39.3%) isolates were Enterococcus faecalis; 16(48.5%) before relocation and 17(51.5%) after relocation (p=0.73). Multiple strains were located in 7(18.9%) patients before relocation and in 7(21.9%) after relocation. In 1(3.1%) patient after relocation, 2(8.7%) Enterococcus faecium isolates with different resistance and pulsed-field gel electrophoresis patterns were detected. There were no significant differences between the isolation and antibiotic resistance rates before and after relocation (p>0.05), and a clonal relation between the isolates was not detected (p>0.05). Decreased minimum inhibitory concentration values were noted for some antibiotics. CONCLUSIONS: Clonal relationship between the isolates and change in the rates of isolation and antimicrobial resistance of Enterococcus faecalis and Enterococcus faecium was not detected due to relocation. Minimum inhibitory concentration values could be used to reveal relocation-related changes in isolates obtained from patients hospitalised in intensive care units.

CCR2-dependent CX3CR1+ colonic macrophages promote Enterococcus faecalis dissemination.

Enterococci are common commensal bacteria that colonize the gastrointestinal tracts of most mammals, including humans. Importantly, these bacteria are one of the leading causes of nosocomial infections. This study examined the role of colonic macrophages in facilitating Enterococcus faecalis infections in mice. We determined that depletion of colonic phagocytes resulted in the reduction of E. faecalis dissemination to the gut-draining mesenteric lymph nodes. Furthermore, we established that trafficking of monocyte-derived CX3CR1-expressing macrophages contributed to E. faecalis dissemination in a manner that was not reliant on CCR7, the conventional receptor involved in lymphatic migration. Finally, we showed that E. faecalis mutants with impaired intracellular survival exhibited reduced dissemination, suggesting that E. faecalis can exploit host immune cell migration to disseminate systemically and cause disease. Our findings indicate that modulation of macrophage trafficking in the context of antibiotic therapy could serve as a novel approach for preventing or treating opportunistic infections by disseminating enteric pathobionts like E. faecalis.

The virtue of training: extending phage host spectra against vancomycin-resistant Enterococcus faecium strains using the Appelmans method.

Phage therapy has (re)emerged as a serious possibility for combating multidrug-resistant bacterial infections, including those caused by vancomycin-resistant Enterococcus faecium strains. These opportunistic pathogens belong to a specific clonal complex 17, against which relatively few phages have been screened. We isolated a collection of 21 virulent phages growing on these vancomycin-resistant isolates. Each of these phages harbored a typical narrow plaquing host range, lysing at most 5 strains and covering together 10 strains of our panel of 14 clinical isolates. To enlarge the host spectrum of our phages, the Appelmans protocol was used. We mixed four out of our most complementary phages in a cocktail that we iteratively grew on eight naive strains from our panel, of which six were initially refractory to at least three of the combined phages. Fifteen successive passages permitted to significantly improve the lytic activity of the cocktail, from which phages with extended host ranges within the E. faecium species could be isolated. A single evolved phage able to kill up to 10 of the 14 initial E. faecium strains was obtained, and it barely infected nearby species. All evolved phages had acquired point mutations or a recombination event in the tail fiber genetic region, suggesting these genes might have driven phage evolution by contributing to their extended host spectra.

Genomic analysis of inter-hospital transmission of vancomycin-resistant Enterococcus faecium sequence type 80 isolated during an outbreak in Hiroshima, Japan.

Outbreaks caused by vancomycin-resistant enterococci that transcend jurisdictional boundaries are occurring worldwide. This study focused on a vancomycin-resistant enterococcus outbreak that occurred between 2018 and 2021 across two cities in Hiroshima, Japan. The study involved genetic and phylogenetic analyses using whole-genome sequencing of 103 isolates of vancomycin-resistant enterococci to identify the source and transmission routes of the outbreak. Phylogenetic analysis was performed using core genome multilocus sequence typing and core single-nucleotide polymorphisms; infection routes between hospitals were inferred using BadTrIP. The outbreak was caused by Enterococcus faecium sequence type (ST) 80 carrying the vanA plasmid, which was derived from strain A10290 isolated in India. Of the 103 isolates, 93 were E. faecium ST80 transmitted across hospitals. The circular vanA plasmid of the Hiroshima isolates was similar to the vanA plasmid of strain A10290 and transferred from E. faecium ST80 to other STs of E. faecium and other Enterococcus species by conjugation. The inferred transmission routes across hospitals suggest the existence of a central hospital serving as a hub, propagating vancomycin-resistant enterococci to multiple hospitals. Our study highlights the importance of early intervention at the key central hospital to prevent the spread of the infection to small medical facilities, such as nursing homes, with limited medical resources and a high number of vulnerable individuals.

Characterization of Weissella Species during a 3-Year Observational Study - An Emerging Threat.

Weissella species are mistaken for Lactobacillus or Leuconostoc because of their Gram-staining property and resistance to vancomycin. In this study, we aimed to evaluate the demographic pattern, presenting symptoms, risk factors, associated pathologies, and clinical outcomes in patients with Weissella infection. We also analyzed the antibiotic susceptibility pattern of the Weissella species isolated. This retrospective observational study was done from January 2021 to August 2023 in a tertiary care referral center in Uttar Pradesh. All Weissella species isolated from blood cultures or cerebrospinal fluid (CSF) samples during this period were included in the study. Twenty-four-hour growth from a positive blood culture or CSF sample was identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Demographic and clinical details of the patients were extracted from the hospital information system. Kirby-Bauer disk diffusion was used for antibiotic susceptibility testing. During the 3-year study, 13 isolates of Weissella species were identified in our laboratory. Among the patients, male predominance was seen. The age range of the patients was 5-53 years. The samples were blood samples (n = 11) and CSF samples (n = 2). Of these isolates, 12 (92.3%) were identified as Weissella confusa and 1 (7.69%) was identified as Weissella viridescens. Common risk factors were anemia, prolonged hospital stay, indwelling catheter, chemotherapy, and chronic kidney disease. All the isolates in this study were sensitive to amikacin, daptomycin, amoxicillin-clavulanate, minocycline, and linezolid. Death was attributed to Weissella infection in three patients. Weissella species are opportunistic organisms that need to be identified quickly and precisely to guarantee the right course of treatment.

Nutritional Strategies To Improve VRE Control.

The rise of Vancomycin-resistant enterococci (VRE) strains among cellular therapy recipients raises concerns due to increased morbidity, mortality, and hospitalization costs, particularly impacting transplanted patients with diminished survival expectations. Recent research linking lactose to Enterococcus growth and graft-versus-host disease (GVHD) emphasizes the need for data on reducing lactose in the diets of VRE-carrying patients, especially in cellular therapy contexts like CAR-T or allogeneic hematopoietic stem cell transplantation. Responding to elevated VRE positivity rates in rectal swabs among patients in our BMT Unit, a unique nutritional strategy was implemented, introducing lactose-free milk and strictly enforcing lactose-free diets. This approach resulted in a significant reduction in VRE carriers, with a 16% positivity rate in the Lactose Group versus 3.6% in the Lactose-Free Group, as of June 2023. These results indicate the potential efficacy of this innovative nutritional strategy in high-risk departments, such as BMT Units and Intensive Care Units, with implications for reducing isolation strategies and inappropriate antibiotic use in cases of VRE colonization.

Assessing the Risk of Antimicrobial Resistant Enterococcal Infections in Humans Due to Bacitracin Usage in Poultry.

Bacitracin is an antimicrobial used in the feed or water of poultry in the U.S. for the prevention, treatment, and control of clostridial diseases such as necrotic enteritis. Concern has been raised that bacitracin can select for antimicrobial-resistant bacteria that can be transmitted to humans and subsequently cause disease that is more difficult to treat because of the resistance. The objective of the present study was to perform a quantitative risk assessment (QRA) to estimate the potential risk in the U.S. of human infection with antimicrobial-resistant Enterococcus faecalis and E. faecium derived from chicken and turkey products as a result of bacitracin usage in U.S. poultry. The modeling approach estimated the annual number of healthcare-associated enterococcal infections in the U.S. that would be resistant to antimicrobial therapy and that would be derived from poultry sources because of bacitracin use in poultry. Parameter estimates were developed to be "maximum risk" to overestimate the risk to humans. While approximately 60% of E. faecalis and E. faecium derived from poultry were predicted to possess bacitracin resistance based on the presence of the bcrABDR gene locus, very few human-derived isolates possessed this trait. Furthermore, no vancomycin or linezolid-resistant strains of E. faecalis or E. faecium were detected in poultry sources between the years 2002 and 2019. The model estimated the number of antimicrobial-resistant E. faecalis and E. faecium cases per year that might resist therapy due to bacitracin use in poultry as 0.86 and 0.14, respectively, which translates to an annual risk estimate for E. faecalis of less than 1 in 350 million and for E. faecium of less than 1 in 2 billion for members of the U.S. population. Even with the use of risk-maximizing assumptions, the results indicate that there is a high probability that the use of bacitracin according to label instructions in U.S. poultry presents a negligible risk to human health.

Promiscuous, persistent and problematic: insights into current enterococcal genomics to guide therapeutic strategy.

Vancomycin-resistant enterococci (VRE) are major opportunistic pathogens and the causative agents of serious diseases, such as urinary tract infections and endocarditis. VRE strains mainly include species of Enterococcus faecium and E. faecalis which can colonise the gastrointestinal tract (GIT) of patients and, following growth and persistence in the gut, can transfer to blood resulting in systemic dissemination in the body. Advancements in genomics have revealed that hospital-associated VRE strains are characterised by increased numbers of mobile genetic elements, higher numbers of antibiotic resistance genes and often lack active CRISPR-Cas systems. Additionally, comparative genomics have increased our understanding of dissemination routes among patients and healthcare workers. Since the efficiency of currently available antibiotics is rapidly declining, new measures to control infection and dissemination of these persistent pathogens are urgently needed. These approaches include combinatory administration of antibiotics, strengthening colonisation resistance of the gut microbiota to reduce VRE proliferation through commensals or probiotic bacteria, or switching to non-antibiotic bacterial killers, such as bacteriophages or bacteriocins. In this review, we discuss the current knowledge of the genomics of VRE isolates and state-of-the-art therapeutic advances against VRE infections.

Epidemiology and outcomes associated with enterococcal blood stream infection among liver and kidney transplant recipients.

Bloodstream infections (BSIs) account for 18% of bacterial infections in the first year after solid organ transplantation (SOT). Enterococcus accounts for up to 20% of BSIs in this population, with vancomycin-resistant enterococcus (VRE) posing a particular risk. This is a retrospective, case-control study of adult liver and kidney transplant recipients between 01/01/2016 and 06/30/2021 that characterizes the epidemiology and outcomes of enterococcal BSIs in liver and kidney transplantations at a single institution. Subjects with an enterococcal BSI within the first 6 months post-transplant were compared to those with non-enterococcal BSIs in the same period. We identified 26 subjects with enterococcal BSIs and 28 controls with non-enterococcal BSIs (n = 54; 10.3%). Cases were mostly liver transplant recipients (n = 20; 77%) with a median MELD at transplant of 33 (range 14-43); controls included 14 KT recipients (50%). Groups differed significantly (all p < .05) by factors including perioperative transfusion requirements, need for reoperation, and number of interventions post-transplant. Cases had a median time of 25.5 days to infection and controls 100.5 days (p < .0001). There were no differences in 1-year mortality between the groups. Enterococcus faecium was the predominant species of Enterococcus (n = 23; 88.5%), with a majority (91.3%) of the isolates being VRE. In our liver and kidney transplants, enterococcal BSIs occurred early among liver transplant recipients. The high incidence of VRE among E. faecium isolates in this population warrants further investigation into the optimal approach to empiric antimicrobials for bacteremia in the early post-transplant period.

Discovery of Gambogic acid as an antibacterial adjuvant against vancomycin-resistant enterococci in vitro and in vivo.

BACKGROUND: The emergence and spread of vancomycin-resistant enterococci (VRE) have posed a significant challenge to clinical treatment, underscoring the need to develop novel strategies. As therapeutic options for VRE are limited, discovering vancomycin enhancer is a feasible way of combating VRE. Gambogic acid (GA) is a natural product derived from the resin of Garcinia hanburyi Hook.f. (Clusiaceae), which possesses antibacterial activity. PURPOSE: This study aimed to investigate the potential of GA as an adjuvant to restore the susceptibility of VRE to vancomycin. METHODS: In vitro antibacterial and synergistic activities were evaluated against vancomycin-susceptible and resistant strains by the broth microdilution method for the Minimal Inhibitory Concentrations (MICs) determination, and checkerboard assay and time-kill curve analysis for synergy evaluation. In vivo study was conducted on a mouse multi-organ infection model. The underlying antibacterial mechanism of GA was also explored. RESULTS: GA showed a potent in vitro activity against all tested strains, with MICs ranging from 2 to 4 µg/ml. The combination of GA and vancomycin exhibited a synergistic effect against 18 out of 23 tested VRE strains, with a median fractional inhibitory concentration index (FICI) of 0.254, and demonstrated a synergistic effect in the time-kill assay. The combination therapy exhibited a significant reduction in tissue bacterial load compared with either compound used alone. GA strongly binds to the ParE subunit of topoisomerase IV, a bacterial type II DNA topoisomerase, and suppresses its activity. CONCLUSIONS: The study suggests that GA has a significant antibacterial activity against enterococci, and sub-MIC concentrations of GA can restore the activity of vancomycin against VRE in vitro and in vivo. These findings indicate that GA has the potential to be a new antibacterial adjuvant to vancomycin in the treatment of infections caused by VRE.