Gentamicin induced ototoxicity during treatment of enterococcal endocarditis: resolution with substitution by netilmicin

Arginine-Rich Peptidomimetic Ampicillin/Gentamicin Conjugate To Tackle Nosocomial Biofilms: A Promising Strategy To Repurpose First-Line Antibiotics

Combined therapy with penicillins and aminoglycosides has been proved beneficial to address many persistent bacterial infections with possible synergistic effects. However, the different pharmacokinetic profiles of these two antibiotic classes may not guarantee a concerted spatio-temporal delivery at the site of action, decreasing the efficacy of this combination and promoting resistance. Herein, we propose a multifunctional antibiotic-polymer conjugate, designed to colocalize ampicillin and gentamicin to tackle persistent biofilm infections. The two antibacterial molecules were grafted along with the amino acid l-arginine to a biocompatible polymer backbone with peptidomimetic hydrophilic structure, obtaining the antimicrobial poly(argilylaspartamide-co-aspartic) acid-ampicillin, gentamicin (PAA-AG) conjugate. The PAA-AG conjugate displayed excellent biocompatibility on human cell lines if compared with free drugs, potentially enlarging their therapeutic window and safety, and suitable mucoadhesive characteristics which may help local treatments of mucosal infections. Studies on planktonic cultures of clinical and reference strains of S. aureus, P. aeruginosa, and E. coli revealed that PAA-AG holds a broad-spectrum antibacterial efficacy, revealing high potency in inhibiting the growth of the tested strains. More interestingly, PAA-AG exhibited excellent antibiofilm activity on both Gram+ and Gram- communities, showing inhibition of their formation at subMIC concentrations as well as inducing the regression of mature biofilms. Given the high biocompatibility and broad antibiofilm efficacy, combined with the opportunity for synchronous co-delivery, the PAA-AG conjugate could be a valuable tool to increase the success of ampicillin/gentamicin-based antibiotic multitherapy.

Ameliorative effect of taxifolin on gentamicin-induced ototoxicity via down-regulation of apoptotic pathways in mouse cochlear UB/OC-2 cells

BACKGROUND

Taxifolin is a flavanonol with efficacious cytoprotective properties, such as anti-inflammatory, antioxidant, anticancer, hepatoprotective, and nephroprotective effects. However, the potential protective effects of taxifolin against gentamicin-induced ototoxicity have not been confirmed. In this study, the possible mechanisms underlying the effects of taxifolin on gentamicin-induced death of UB/OC-2 cochlear cells were investigated.

METHODS

Mouse cochlear UB/OC-2 cells with or without taxifolin pretreatment were exposed to gentamicin, and the effects on cytotoxicity, reactive oxygen species (ROS) production, mitochondrial permeability transition, and apoptotic marker expression were examined using biochemical techniques, flow cytometry, western blotting, and fluorescent staining.

RESULTS

Little or no apparent effect of taxifolin on cell viability was observed at concentrations less than 40 μM. Further investigations showed that gentamicin significantly inhibited cell viability in a concentration-dependent manner. Pretreatment with taxifolin attenuated gentamicin-induced lactate dehydrogenase release, as well as cellular cytotoxicity. In addition, taxifolin significantly prevented gentamicin-induced cell damage by decreasing ROS production, stabilizing mitochondrial membrane potential, and downregulating the mitochondrial pathway of apoptosis.

CONCLUSION

In summary, pretreatment with taxifolin is effective for mitigating gentamicin-induced apoptotic cell death mediated by the mitochondrial pathway. Our data suggest that taxifolin provides a new approach to combat gentamicin-induced ototoxicity.

Time to abandon ampicillin plus gentamicin in favour of ampicillin plus ceftriaxone in Enterococcus faecalis infective endocarditis? A meta-analysis of comparative trials

Background

Current guidelines recommend either ampicillin plus ceftriaxone (AC) or amoxicillin/ampicillin plus gentamicin (AG) with an equivalent class IB recommendation in Enterococcus faecalis endocarditis. However, previous observational studies suggest that AC might be favourable in terms of adverse events.

Objectives

To investigate whether AC is non-inferior to AG, and if it is associated with less adverse events.

Methods

In June 2021, a systematic literature search using the databases PubMed/MEDLINE, CDSR, CENTRAL, CCAs, EBM Reviews, Web of Science and LILACS was conducted by two independent reviewers. Studies were considered eligible if (P) patients included were ≥ 18 years of age and had IE with E. faecalis, (I) treatment with AC was compared to (C) treatment with AG and (O) outcomes on in-hospital mortality, nephrotoxicity and adverse events requiring drug withdrawal were reported. Odds ratios and 95% confidence intervals were calculated using random-effects models with the Mantel–Haenszel method, the Sidik–Jonkman estimator for τ² and the Hartung–Knapp adjustment.

Results

Treatment with AC was non-inferior to AG, as depicted by no significant differences in-hospital mortality, 3-month mortality, relapses or treatment failure. Furthermore, AC was associated with a lower prevalence of nephrotoxicity (OR 0.45 [0.26–0.77], p = 0.0182) and drug withdrawal due to adverse events (OR 0.11 [0.03–0.46], p = 0.0160) than AG.

Conclusions

Treatment with AC was non-inferior to treatment with AG, and it was associated with a reduced prevalence of nephrotoxicity and drug withdrawal due to adverse events. Thus, combination therapy with AC appears favourable over AG in patients with E. faecalis IE.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s00392-021-01971-3.

Synthesis, ribosomal selectivity, and antibacterial activity of netilmicin 4'-derivatives

Halogenation of a suitably protected netilmicin derivative enables preparation of 4'-chloro-, bromo-, and iodo derivatives of netilmicin after deprotection. Suzuki coupling of a protected 4'-bromo derivative with phenylboronic acid or butyltrifluoroborate affords the corresponding 4'-phenyl and 4'-butyl derivatives of netilmicin. Sulfenylation of suitably protected netilmicin derivative with ethanesulfenyl chloride followed by deprotection affords 4'-ethylsulfanylnetilmicin. All netilmicin 4'-derivatives displayed reduced levels of inhibition for prokaryotic ribosomes and reduced antibacterial activity against typical Gram-positive and Gram-negative strains. None of the derivatives displayed enhanced target selectivity.