Risk factors and outcome associated with the acquisition of linezolid-resistant Enterococcus faecalis

The Impact of Enterococcus spp. in the Immunocompromised Host: A Comprehensive Review

The immunocompromised host is usually vulnerable to infectious diseases due to broad-spectrum treatments and immunological dysregulation. The Enterococcus genus consists of normal gut commensals, which acquire a leading role in infective processes among individuals with compromised immune systems. These microorganisms may express a potential virulence and resistance spectrum, enabling their function as severe pathogens. The Enterococcus spp. infections in immunocompromised hosts appear to be difficult to resolve due to the immunological response impairment and the possibility of facing antimicrobial-resistant strains. As regards the related risk factors, several data demonstrated that prior antibiotic exposure, medical device insertion, prolonged hospitalization and surgical interventions may lead to Enterococcus overgrowth, antibiotic resistance and spread among critical healthcare settings. Herein, we present a comprehensive review of Enterococcus spp. in the immunocompromised host, summarizing the available knowledge about virulence factors, antimicrobial-resistance mechanisms and host-pathogen interaction. The review ultimately yearns for more substantial support to further investigations about enterococcal infections and immunocompromised host response.

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.

Risk exploration and prediction model construction for linezolid-resistant Enterococcus faecalis based on big data in a province in southern China

BACKGROUND

Enterococcus faecalis is a common cause of healthcare-associated infections. Its resistance to linezolid, the antibiotic of last resort for vancomycin-resistant enterococci, has become a growing threat in healthcare settings.

METHODS

We analyzed the data of E. faecalis isolates from 26 medical institutions between 2018 and 2020 and performed univariate and multivariate logistic regression analyses to determine the independent predictors for linezolid-resistant E. faecalis (LREFs). Then, we used the artificial neural network (ANN) and logistic regression (LR) to build a prediction model for linezolid resistance and performed a performance evaluation and comparison.

RESULTS

Of 12,089 E. faecalis strains, 755 (6.25%) were resistant to linezolid. Among vancomycin-resistant E. faecalis, the linezolid-resistant rate was 24.44%, higher than that of vancomycin-susceptible E. faecalis (p < 0.0001). Univariate and multivariate regression analyses showed that gender, age, specimen type, length of stay before culture, season, region, GDP (gross domestic product), number of beds, and hospital level were predictors of linezolid resistance. Both the ANN and LR models constructed in the study performed well in predicting linezolid resistance in E. faecalis, with AUCs of 0.754 and 0.741 in the validation set, respectively. However, synthetic minority oversampling technique (SMOTE) did not improve the prediction ability of the models.

CONCLUSION

E. faecalis linezolid-resistant rates varied by specimen site, geographic region, GDP level, facility level, and the number of beds. At the same time, community-acquired E. faecalis with linezolid resistance should be monitored closely. We can use the prediction model to guide clinical medication and take timely prevention and control measures.

Dose Optimization of Combined Linezolid and Fosfomycin against Enterococcus by Using an In Vitro Pharmacokinetic/Pharmacodynamic Model

The rapid spread of antibiotic resistance among Enterococcus has prompted considerable interest in determining the dosage regimen of linezolid combined with fosfomycin. A checkerboard assay was employed to evaluate whether linezolid combined with fosfomycin had a synergistic effect on Enterococcus isolates from the hospital, including three drug-resistant strains (MIC of linezolid [MIC_LZD], ≥8 mg/L; MIC of fosfomycin [MIC_FOF], ≥256 mg/L). The in vitro static time-kill assay, dynamic pharmacokinetic (PK)/pharmacodynamic (PD) model, and semimechanistic PK/PD model were used to explore and predict effective combined dosage regimens. The checkerboard assay and in vitro static time-kill assay demonstrated that linezolid combined with fosfomycin has a synergistic effect on drug-resistant and sensitive Enterococcus. In the in vitro PK/PD model, the dosage regimen of linezolid (8 mg/L or 12 mg/L, steady-state concentration) combined with fosfomycin (6 g or 8 g) via a 0.5-h infusion every 8 h effectively suppressed bacterial growth at 24 h with a 3 log₁₀ CFU/mL decrease compared with the initial inocula against two resistant and one sensitive Enterococcus isolates. The semimechanistic PK/PD model predicted that linezolid (more than 16 mg/L) combined with fosfomycin (6 g or 10 g) via a 0.5-h infusion every 8 h was required to achieve a 4 log₁₀ CFU/mL decrease at 24 h against Enterococcus isolates (MIC_LZD ≥ 8 mg/L and MIC_FOF ≥ 256 mg/L). According to the prediction of the semimechanical PK/PD model, the effect of the combination was driven by linezolid, with fosfomycin enhancing the effect. Our study is the first to explore the synergistic effects of these two drugs from a qualitative and quantitative perspective and provides a simulation tool for future studies.

IMPORTANCE In this study, we found that linezolid combined with fosfomycin could kill Enterococcus in vitro and that the administered dose was significantly lower after the combination treatment, which could reduce adverse effects and the development of drug resistance. The potential mechanism of the two-drug combination against Enterococcus was revealed from a quantitative perspective, which is an important step toward dose optimization in simulated humans. We hope that our research will help build a better relationship between clinicians and patients as we work together to address the challenges of antibiotic resistance in the 21st century.

The Global Prevalence of Daptomycin, Tigecycline, and Linezolid-Resistant Enterococcus faecalis and Enterococcus faecium Strains From Human Clinical Samples: A Systematic Review and Meta-Analysis

Background and Aim: The predominant species of the Enterococcus, Enterococcus faecalis (E. faecalis) and Enterococcus faecium (E. faecium) cause great variety of infections. Therefore, the expansion of antimicrobial resistance in the Enterococcus is one of the most important global concerns. This study was conducted to investigate the prevalence of resistance to linezolid, tigecycline, and daptomycin among enterococcal strains isolated from human clinical specimens worldwide.

Methods: Several databases including Web of Science, EMBASE, and Medline (via PubMed), were carefully searched and reviewed for original research articles available in databases and published between 2000 and 2020. A total of 114 studies worldwide that address E. faecalis and E. faecium resistance to linezolid, tigecycline, and daptomycin were analyzed by STATA software.

Results: The overall prevalence of antibiotic-resistant E. faecalis and E. faecium was reported to be 0.9 and 0.6%, respectively. E. faecalis and E. faecium were more resistant to the linezolid (2.2%) and daptomycin (9%), respectively. The prevalence of tigecyline-resistant E. facium (1%) strains was higher than E. faecalis strains (0.3%). Accordingly, the prevalence of linezolid-resistant E. faecalis was higher in Asia (2.8%), while linezolid-resistant E. faecium was higher in the America (3.4%). Regarding tigecycline-resistance, a higher prevalence of E. faecalis (0.4%) and E. faecium (3.9%) was reported in Europe.

Conclusion: In conclusion, this meta-analysis shows that there is an emerging resistance in Enterococcus strains. Despite the rising resistance of enterococci to antibiotics, our results demonstrate that tigecycline, daptomycin, and linezolid can still be used for the treatment of enterococcal infections worldwide.

Moringa oleifera polysaccharides regulates caecal microbiota and small intestinal metabolic profile in C57BL/6 mice

This study investigated the effects of Moringa oleifera polysaccharides (MOP) on the serum indexes, small intestinal morphology, small intestinal metabolic profile, and caecal microbiota of mice. A new type of polysaccharides with 104,031 Da molecular weight and triple helix structure was isolated from M. oleifera leaves for in vivo experiment. Forty male SPF C57BL/6 mice aged 4 weeks were average divided into four groups randomly according to the MOP gavaged daily (0, 20, 40 and 60 mg/kg body weight MOP). After a 7-day preliminary trial period and a 28-day official trial period, the mice were slaughtered. Results showed that MOP reduced glucose, total cholesterol, and malondialdehyde. It also improved superoxide dismutase and catalase in serum (P < 0.05). For small intestinal morphology, MOP improved the villi length and crypt depth in both ileum and jejunum (P < 0.05); the ratio of villi length to crypt depth in jejunum increased (P < 0.05). MOP could cause the increase of beneficial bacteria and the decrease of harmful bacteria in caecum, further affecting the function of microbiota. In addition, MOP regulated 114 metabolites enriched in the pathway related to the synthesis and metabolism of micromolecules. In sum, MOP exerted positive effects on the serum indexes and intestinal health of mice.