Linezolid Toxicity and Mitochondrial Susceptibility: A Novel Neurological Complication in a Lebanese Patient

What’s old is new again: Insights into diabetic foot microbiome

Diabetes is a chronic disease that is considered one of the most stubborn global health problems that continues to defy the efforts of scientists and physicians. The prevalence of diabetes in the global population continues to grow to alarming levels year after year, causing an increase in the incidence of diabetes complications and health care costs all over the world. One major complication of diabetes is the high susceptibility to infections especially in the lower limbs due to the immunocompromised state of diabetic patients, which is considered a definitive factor in all cases. Diabetic foot infections continue to be one of the most common infections in diabetic patients that are associated with a high risk of serious complications such as bone infection, limb amputations, and life-threatening systemic infections. In this review, we discussed the circumstances associated with the high risk of infection in diabetic patients as well as some of the most commonly isolated pathogens from diabetic foot infections and the related virulence behavior. In addition, we shed light on the different treatment strategies that aim at eradicating the infection.

Linezolid-Associated Neuropathy in Patients with MDR/XDR Tuberculosis in Shenzhen, China

Objective

Linezolid is one of the key drugs for the treatment of multidrug-resistant/extensively drug-resistant tuberculosis (MDR/XDR-TB). We aimed to describe the incorporation of the Michigan Neuropathy Screening Instrument (MNSI) and serum trough concentration as screening tools for neurotoxicity in the management of MDR/XDR-TB patients receiving a linezolid-based treatment regimen in Shenzhen, China.

Methods

A total of 73 patients on a linezolid-containing anti–MDR/XDR-TB regimen were prospectively enrolled. The MNSI was used for peripheral neuropathy screening. Optic neuropathy was diagnosed by ophthalmologists. Serum trough concentration was recorded and its relationship with neuropathy analyzed.

Results

Of all patients, neuropathy was observed in 40% (29) during anti-TB treatment. Of these, 20 (69%) had peripheral neuritis, seven (24%) optic neuritis, and two (7%) both. Serum trough concentration >2 mg/L was observed in 17 (59%) patients with neuropathy and 13 (30%) patients without neuropathy. There was a significant statistical difference between the two groups (P=0.013). Time to onset of neuropathy from initiation of the linezolid-containing regimen was within 2 months for eight (28%) patients, 2–6 months for 18 (62%) patients, and >6 months for three (10%) patients. Sixteen (55%) patients were adjusted to a lower dose of 300 mg linezolid daily. Four (14%) patients had linezolid permanently removed from their regimen.

Conclusion

Neuropathy is a commonly reported adverse event associated with long-term use of linezolid. MNSI and serum trough–concentration monitoring can be adopted as simple screening tools for early detection of neuropathy to balance linezolid efficacy and tolerability.

UPLC-MS/MS Determination of Linezolid and Heme in Plasma of Infected Patients and Correlation Analysis

Linezolid can cause serious haematological toxicity, such as thrombocytopenia and aneamia. Heme, composed of iron and porphyrin, is an important component of hemoglobin. In order to investigate the relationship between the concentration of linezolid and heme in the plasma of infected patients, a UPLC-MS/MS method that can determine the concentrations of linezolid and heme simultaneously was developed and validated. A total of 96 healthy subjects and 81 infected patients, who received blood routine blood tests, were included and determined by the UPLC-MS/MS method. The results showed that the concentration of linezolid was 5.08 ± 3.46 μg/mL in infected patients who were treated with linezolid. The heme in healthy subjects was 7.05 ± 8.68 μg/mL, and it was significantly decreased to 0.88 ± 0.79 μg/mL in infected patients (P < 0.01). Spearman correlation analysis showed that linezolid had a high negative correlation with platelet (PLT) (R = -0.309). Heme had a high positive correlation with hemoglobin (Hb) (R = 0.249) in healthy subjects and infected patients. The ROC analysis showed that heme had diagnostic value to distinguish low Hb (110 g/L). In conclusion, there was a positive correlation between heme and Hb, and this correlation was also observed in infected patients. A high concentration of linezolid was inclined to decrease PLT. Monitoring of heme and linezolid helps in the early diagnose of low Hb and PLT.

In vitro and in vivo activities of the carbonic anhydrase inhibitor, dorzolamide, against vancomycin-resistant enterococci

Vancomycin-resistant enterococci (VRE) are a serious public health threat and a leading cause of healthcare-associated infections. Bacterial resistance to antibiotics recommended for the treatment of enterococcal infections complicates the management of these infections. Hence, there is a critical need for the discovery of new anti-VRE agents. We previously reported carbonic anhydrase inhibitors (CAIs) as new potent VRE inhibitors. In the present study, the activity of the CAI, dorzolamide was evaluated against VRE both in vitro and in vivo. Dorzolamide exhibited potent activity against a panel of clinical VRE isolates, with minimum inhibitory concentration (MIC) values ranging from 1 µg/mL to 8 µg/mL. A killing kinetics experiment determined that dorzolamide exhibited a bacteriostatic effect against VRE, which was similar to the drug of choice (linezolid). Dorzolamide interacted synergistically with gentamicin against four strains of VRE, and exhibited an additive interaction with gentamicin against six VRE strains, reducing gentamicin’s MIC by several folds. Moreover, dorzolamide outperformed linezolid in an in vivo VRE colonization reduction mouse model. Dorzolamide significantly reduced the VRE burden in fecal samples of mice by 2.9-log₁₀ (99.9%) and 3.86-log₁₀ (99.99%) after 3 and 5 days of treatment, respectively. Furthermore, dorzolamide reduced the VRE count in the cecal (1.74-log₁₀ (98.2%) reduction) and ileal contents (1.5-log₁₀ (96.3%)) of mice, which was superior to linezolid. Collectively, these results indicate that dorzolamide represents a promising treatment option that warrants consideration as a supplement to current therapeutics used for VRE infections.

Postmortem magnetic resonance imaging revealed bilateral globi pallidi lesions in a death associated with prolonged carbon monoxide poisoning: a case report

A man and a woman were found dead in the same car with a burned coal briquette. The cause of death of the woman was assigned to acute carbon monoxide (CO) poisoning without difficulty based on typical findings associated with this condition, including elevation of carboxyhaemoglobin (COHb). However, the man had an unremarkable elevation of COHb and a higher rectal temperature compared to that of the woman. Postmortem computed tomography (PMCT) revealed ambiguous low-density areas in the bilateral globi pallidi. Further analysis by postmortem magnetic resonance (PMMR) imaging showed these lesions more clearly; the lesions appeared as marked high signal intensity areas on both the T2-weighted images and the fluid-attenuated inversion recovery sequences. A subsequent autopsy revealed signs of pneumonia, dehydration, starvation, and hypothermia, suggesting that the man died from prolonged CO poisoning. Both globi pallidi contained grossly ambiguous lesions, and a detailed neuropathologic investigation revealed these lesions to be coagulative necrotic areas; this finding was compatible with a diagnosis of prolonged CO poisoning. This case report shows that postmortem imaging, especially PMMR, is useful for detecting necrotic lesions associated with prolonged CO poisoning. This report further exemplifies the utility of PMMR for detecting brain lesions, which may be difficult to detect by macroscopic analysis.

Development of Biphenylthiazoles Exhibiting Improved Pharmacokinetics and Potent Activity Against Intracellular Staphylococcus aureus

Exploring the structure-activity relationship (SAR) at the cationic part of arylthiazole antibiotics revealed hydrazine as an active moiety. The main objective of the study is to overcome the inherited toxicity associated with the free hydrazine. A series of hydrocarbon bridges was inserted in between the groups, to separate the two amino groups. Hence, the aminomethylpiperidine-containing analog 16 was identified as a new promising antibacterial agent with efficient antibacterial and pharmacokinetic profiles. Briefly, compound 16 outperformed vancomycin in terms of the antibacterial spectrum against vancomycin-resistant staphylococcal and enterococcal strains with minimum inhibitory concentrations (MICs) ranging from 2 to 4 μg/mL, which is a faster bactericidal mode of action, completely eradicating the high staphylococcal burden within 6-8 h, and it has a unique ability to completely clear intracellular staphylococci. In addition, the initial pharmacokinetic assessment confirmed the high metabolic stability of compound 16 (biological half-life >4 h); it had a good extravascular distribution and maintained a plasma concentration higher than the average MIC value for over 12 h. Moreover, compound 16 significantly reduced MRSA burden in an in vivo MRSA skin infection mouse experiment. These attributes collectively suggest that compound 16 is a good therapeutic candidate for invasive staphylococcal and enterococcal infections. From a mechanistic point of view, compound 16 inhibited undecaprenyl diphosphate phosphatase (UppP) with an IC₅₀ value of 29 μM.

New Antibiotics for the Treatment of Acute Bacterial Skin and Soft Tissue Infections in Pediatrics

Acute bacterial skin and soft tissue infections (aSSTIs) are a large group of diseases that can involve exclusively the skin or also the underlying subcutaneous tissues, fascia, or muscles. Despite differences in the localization and severity, all these diseases are due mainly to Gram-positive bacteria, especially Staphylococcus aureus and Streptococcus pyogenes. aSSTI incidence increased considerably in the early years of this century due to the emergence and diffusion of community-acquired methicillin-resistant S. aureus (CA-MRSA). Despite the availability of antibiotics effective against CA-MRSA, problems of resistance to these drugs and risks of significant adverse events have emerged. In this paper, the present knowledge on the potential role new antibiotics for the treatment of pediatric aSSTIs is discussed. The most recent molecules that have been licensed for the treatment of aSSTIs include ozenoxacin (OZ), ceftaroline fosamil (CF), dalbavancin (DA), oritavancin (OR), tedizolid (TD), delafloxacin (DL), and omadacycline (OM). However, only OZ and CF have been licensed for use in children with aSSTIs, although the superiority of these antibiotics to those routinely used for the treatment of aSSTIs should be further demonstrated. Waiting for additional studies, OZ and CF should be prescribed for aSSTI treatment in the presence of the potential failure of old molecules.

Structural variety of heterosynthons in linezolid cocrystals with modified thermal properties

In a search for new crystalline forms of linezolid with modified thermal properties five cocrystals of this wide range antibiotic with aromatic acids were obtained via mechanochemical grinding and analyzed with single crystal X-ray diffraction, solid-state NMR spectroscopy, powder X-ray diffraction and DSC measurements. The coformers used in this study were benzoic acid, p-hydroxybenzoic acid, protocatechuic acid, γ-resorcylic acid and gallic acid. In each of the cocrystals distinct structural features have been found, including a variable amount of water and different heterosynthons, indicating that there is more than one type of intermolecular interaction preferred by the linezolid molecule. Basing on the frequency of the observed supramolecular synthons, the proposed hierarchy of the hydrogen-bond acceptor sites of linezolid (LIN) is C=O_amide > C=O_oxazolidone > C-O-C_morpholine > C-N-C_morpholine > C-O-C_oxazolidone. In addition, aromatic-aromatic interactions were found to be important in the stabilization of the analyzed structures. The obtained cocrystals show modified thermal properties, with four of them having melting points lower than the temperature of the phase transition from linezolid form II to linezolid form III. Such a change in this physicochemical property allows for the future application of melting-based techniques of introducing linezolid into drug delivery systems. In addition a change in water solubility of linezolid upon cocrystalization was evaluated, but only in the case of the cocrystal with protocatechuic acid was there a significant (43%) improvement in solubility in comparison with linezolid.

Pinacho D. Personalized Medicine for Antibiotics: The Role of Nanobiosensors in Therapeutic Drug Monitoring

Due to the high bacterial resistance to antibiotics (AB), it has become necessary to adjust the dose aimed at personalized medicine by means of therapeutic drug monitoring (TDM). TDM is a fundamental tool for measuring the concentration of drugs that have a limited or highly toxic dose in different body fluids, such as blood, plasma, serum, and urine, among others. Using different techniques that allow for the pharmacokinetic (PK) and pharmacodynamic (PD) analysis of the drug, TDM can reduce the risks inherent in treatment. Among these techniques, nanotechnology focused on biosensors, which are relevant due to their versatility, sensitivity, specificity, and low cost. They provide results in real time, using an element for biological recognition coupled to a signal transducer. This review describes recent advances in the quantification of AB using biosensors with a focus on TDM as a fundamental aspect of personalized medicine.

The role of tedizolid in skin and soft tissue infections

PURPOSE OF REVIEW

Tedizolid is a second-generation oxazolidinone with activity against Gram-positive bacteria, including MRSA isolates resistant to linezolid. Pivotal clinical trials showed that tedizolid at 200 mg once-daily for 6 days is not inferior to linezolid 600 mg twice daily for 10 days in patients with SSTI. The comparison of adverse events is favorable to tedizolid under the circumstances of the clinical trials. This is a review of recent literature on tedizolid, its use in special populations and potential adverse effects.

RECENT FINDINGS

Findings suggest that tedizolid can be used in SSTI in adolescents, those older than 65 years, obese individuals and patients with diabetic foot infections. Forthcoming research to determine the future uses of this drug in other clinical syndromes requires demonstration of tolerance whenever tedizolid is administered for longer than 6 days.We also speculate on missing data and potential future indications of tedizolid in the highly competitive field of the treatment of severe Gram-positive infections other than SSTI.

SUMMARY

Tedizolid is a second-generation oxazolidinone, very convenient for treatment of SSTI, in search for other indications including nosocomial pneumonia and bone and joint infections. VIDEO ABSTRACT.

Linezolid-Induced Lactic Acidosis Sets Stage for Surgery to Rule Out Mesenteric Ischemia: A Case Report

An 81-year-old woman with extensive peripheral vascular and coronary artery disease was admitted to the intensive care unit with a deep heel abscess and urinary tract infection. When cultures from the heel ulcer yielded vancomycin-resistant enterococci, she was started on the antibiotic linezolid. After several days of intravenous linezolid therapy, she developed severe lactic acidosis (pH 6.89) and elevation of pancreatic enzymes. An emergent exploratory laparotomy was performed to rule out mesenteric ischemia. Findings from the laparotomy were negative, and after elimination of other differential diagnoses, the metabolic acidosis was ultimately attributed to linezolid. Acidosis resolved after discontinuation of linezolid.

The risk factors of linezolid-induced lactic acidosis: A case report and review

BACKGROUND

In recent years, linezolid is increasingly used in multidrug-resistant bacteria therapy. At the same time, linezolid-induced lactic acidosis has been continually reported as a serious side effect. Notably, to our knowledge, there are limited available literatures that evaluate risk factors for linezolid-induced lactic acidosis, and there is no highly reliable study on the relationship between linezolid-induced lactic acidosis and age or gender. However, clinicians need relevant information to advice on the use of linezolid. Therefore, we report on a case of life-threatening lactic acidosis after 3 doses of linezolid exposure and evaluate the risk factors of linezolid-induced lactic acidosis.

METHODS

Cases of linezolid-induced lactic acidosis reported in PubMed were searched. Several characteristics and data of case numbers and deaths were extracted for analysis.

RESULTS

A total of 35 articles including 47 cases were included in this study. Twelve patients (25.5%) died due to linezolid-induced lactic acidosis. At the cut-offs of 7, 14, and 28 days, the mortalities were 27.3%, 20%, and 27.3%. No statistically significant difference was observed according to age and gender. However, the proportion (27.7% and 29.8%) and mortality (30.8% and 35.7%) of male patients were much higher than females in both ≥65 and <65 years old groups (proportion: 15.2% and 23.9%; mortality: 14.3% and 18.2%).

CONCLUSION

The mortality of linezolid-induced lactic acidosis was relatively high. The duration of linezolid use and age might not be risk factors. Gender (specifically, male) might be related to the mortality of linezolid-induced lactic acidosis.

Nocardia spp. Pneumonia in a Solid Organ Recipient: Role of Linezolid

We describe a rare infection with Nocardia spp. (N. pseudobrasiliensis species identification based on high-performance liquid chromatography analysis) in a 68-year-old renal transplant recipient. He presented with pneumonia complicated by hypoxic respiratory failure. He was allergic to sulphonamides. He was initially successfully treated with linezolid. However, he suffered severe sensory neuropathy after 4 months of therapy, necessitating linezolid cessation and completion of treatment with azithromycin. He had clinical and radiological resolution of his pneumonia and was disease free at subsequent follow-up 4 years later. This case highlights the need for alternative therapies for nocardiosis for patients that cannot be treated with sulphonamides due to allergies or/and infection with multidrug-resistant pathogens. It also illustrates the treatment limiting side effects of long-term therapy with linezolid.