Therapeutic Options for Infections due to vanB Genotype Vancomycin-Resistant Enterococci

Infections in lung transplanted patients: A review

Lung transplantation can improve the survival of patients with severe chronic pulmonary disorders. However, the short- and long-term risk of infections can increase morbidity and mortality rates. A non-systematic review was performed to provide the most updated information on pathogen, host, and environment-related factors associated with the occurrence of bacterial, fungal, and viral infections as well as the most appropriate therapeutic options. Bacterial infections account for about 50% of all infectious diseases in lung transplanted patients, while viruses represent the second cause of infection accounting for one third of all infections. Almost 10% of patients develop invasive fungal infections during the first year after lung transplant. Pre-transplantation comorbidities, disruption of physical barriers during the surgery, and exposure to nosocomial pathogens during the hospital stay are directly associated with the occurrence of life-threatening infections. Empiric antimicrobial treatment after the assessment of individual risk factors, local epidemiology of drug-resistant pathogens and possible drug-drug interactions can improve the clinical outcomes.

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 Clinical Efficacy of Multidose Oritavancin: A Systematic Review

Oritavancin (ORI) is a semisynthetic lipoglycopeptide approved as a single 1200 mg dose intravenous infusion for the treatment of acute bacterial skin and skin structure infections (ABSSSIs) caused by Gram-positive organisms in adults. The pharmacokinetic/pharmacodynamic (PK/PD) linear kinetic profile and long terminal half-life (~393 h) of ORI make it therapeutically attractive for the treatment of other Gram-positive infections for which prolonged therapy is needed. Multidose regimens are adopted in real-world clinical practice with promising results, but aggregated efficacy data are still lacking. A comprehensive search on PubMed/Medline, Scopus, Cochrane and Google Scholar databases was performed to include papers published up to the end of January 2023. All articles on ORI multiple doses usage, including case reports, with quantitative data and relevant clinical information were included. Two reviewers independently assessed papers against the inclusion/exclusion criteria and for methodological quality. Differences in opinion were adjudicated by a third party. From 1751 potentially relevant papers identified by this search, a total of 16 studies met the inclusion criteria and were processed further in the final data analysis. We extracted data concerning clinical response, bacteriologic response, mortality and adverse events (AEs). From the 16 included papers, 301 cases of treatment with multidose ORIs were identified. Multidose regimens comprised an initial ORI dose of 1200 mg followed by 1200 mg or 800 mg subsequent doses with a varying total number and frequency of reinfusions. The most often treated infections and isolates were osteomyelitis (148; 54.4%), ABSSSI (35; 12.9%) and cellulitis (14; 5.1%); and MRSA (121), MSSA (66), CoNS (17), E. faecalis (13) and E. faecium (12), respectively. Clinical cure and improvement by multidose ORI regimens were observed in 85% (231/272) and 8% (22/272) patients, respectively. Multidose ORI was safe and well tolerated; the most frequent AEs were infusion-related reactions and hypoglycemia. A multidose ORI regimen may be beneficial in treating other Gram-positive infections besides ABSSSIs, with a good safety profile. Further studies are warranted to ascertain the superiority of one multidose ORI scheme or posology over the other.

In Vitro and In Vivo Studies of Oritavancin and Fosfomycin Synergism against Vancomycin-Resistant Enterococcus faecium

Therapeutic options for infections caused by vancomycin-resistant enterococci are currently suboptimal. Combination regimens where fosfomycin is used alongside existing treatments are emerging given the proven synergistic potential and PK/PD properties. In the studies presented here, we tested five vanA and five vanB clinical isolates of Enterococcus faecium using a combination of oritavancin + fosfomycin both in vitro (checkerboard, time killing) and in vivo (Galleria mellonella). The combination of oritavancin and fosfomycin increased drug susceptibility, showing a synergistic effect in 80% of isolates and an additive effect in the remaining isolates. The combination restored fosfomycin susceptibility in 85% of fosfomycin-resistant isolates. Time killing on four selected isolates demonstrated that the combination of oritavancin and fosfomycin provided a CFU/mL reduction > 2 log10 compared with the most effective drug alone and prevented the bacterial regrowth seen after 8−24 h at sub-inhibitory drug concentrations. In addition, the combination was also tested in a biofilm assay with two isolates, and a strong synergistic effect was observed in one isolate and an additive effect in the other. Finally, we demonstrated in vivo (Galleria mellonella) a higher survival rate of the larvae treated with the combination therapy compared to monotherapy (fosfomycin or oritavancin alone). Our study provides preclinical evidence to support trials combining oritavancin and fosfomycin for VRE BSI in humans, even when biofilm is involved.

Enterococcus Virulence and Resistant Traits Associated with Its Permanence in the Hospital Environment

Enterococcus are opportunistic pathogens that have been gaining importance in the clinical setting, especially in terms of hospital-acquired infections. This problem has mainly been associated with the fact that these bacteria are able to present intrinsic and extrinsic resistance to different classes of antibiotics, with a great deal of importance being attributed to vancomycin-resistant enterococci. However, other aspects, such as the expression of different virulence factors including biofilm-forming ability, and its capacity of trading genetic information, makes this bacterial genus more capable of surviving harsh environmental conditions. All these characteristics, associated with some reports of decreased susceptibility to some biocides, all described in this literary review, allow enterococci to present a longer survival ability in the hospital environment, consequently giving them more opportunities to disseminate in these settings and be responsible for difficult-to-treat infections.

Panorama of Bacterial Infections Caused by Epidemic Resistant Strains

Antimicrobial resistance (AMR) represents a critical obstacle to public health worldwide, due to the high incidence of strains resistant to available antibiotic therapies. In recent years, there has been a significant increase in the prevalence of resistant epidemic strains, associated with this, public health authorities have been alarmed about a possible scenario of uncontrolled dissemination of these microorganisms and the difficulty in interrupting their transmission, as nosocomial pathogens with resistance profiles previously considered sporadic. They become frequent bacteria in the community. In addition, therapy for infections caused by these pathogens is based on broad-spectrum antibiotic therapy, which favors an increase in the tolerance of remaining bacterial cells and is commonly associated with a poor prognosis. In this review, we present the current status of epidemic strains of methicillin-resistant Staphylococcus aureus (MRSA), Vancomycin-resistant Enterococcus (VRE), MDR Mycobacterium tuberculosis, extended-spectrum β-lactamase-producing Enterobacterales (ESBL), Klebsiella pneumoniae carbapenemase (KPC), and—New Delhi Metallo-beta-lactamase-producing Pseudomonas aeruginosa (NDM).

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.

Tuberculosis and pharmacological interactions: A narrative review

Even if major improvements in therapeutic regimens and treatment outcomes have been progressively achieved, tuberculosis (TB) remains the leading cause of death from a single infectious microorganism. To improve TB treatment success as well as patients' quality of life, drug-drug-interactions (DDIs) need to be wisely managed. Comprehensive knowledge of anti-TB drugs, pharmacokinetics and pharmacodynamic (PK/PD) parameters, potential patients' changes in absorption and distribution, possible side effects and interactions, is mandatory to built effective anti-TB regimens. Optimization of treatments and adherence to international guidelines can help bend the curve of TB-related mortality and, ultimately, decrease the likelihood of treatment failure and drop-out during anti-TB treatment. Aim of this paper is to describe the most relevant DDIs between anti-TB and other drugs used in daily clinical practice, providing an updated and "easy-to-use" guide to minimize adverse effects, drop-outs and, in the long run, increase treatment success.