Therapeutic Effect of a Novel Oxazolidinone, DA-7867, in BALB/c Mice Infected with Nocardia brasiliensis

Actinomycetoma is an infectious disease of tropical and subtropical regions produced by actinobacteria of the genera Nocardia, Streptomyces, and Actinomadura. Therapeutic alternatives are scarce and include trimethoprim-sulfamethoxazole, diaminodiphenylsulfone, amoxicillin-clavulanate, imipenem, and amikacin. Oxazolidinones are a new class of antimicrobials with a completely different cellular target; the first compound in the market, linezolid, was introduced in the year 2000. It is active against many species of Nocardia and other aerobic actinomycetes; however, the long-term application in human subjects produces side effects including peripheral neuropathy and mielossupression. Therefore, it is important to screen other oxazolidinones with higher activity and less toxicity. In the present work, we tested DA-7867, a new oxazolidinone, in an experimental mouse model. The drug is active in vivo and decreases the production of lesions using only one dose a day in contrast to linezolid, which needs to be injected three times a day. Although it was tested on N. brasiliensis, it can possibly be active (once it is accepted for its use in humans) against Actinomadura spp and Streptomyces spp, which are frequently found in places of Africa and India where actinomycetoma is also an important consult in dermatology

In Vivo Therapeutic Effect of Gatifloxacin on BALB/c Mice Infected with Nocardia brasiliensis▿

In the present work, we evaluated the effect of gatifloxacin on the evolution of experimental murine infection with Nocardia brasiliensis using linezolid as a control. Gatifloxacin was injected subcutaneously at 100 mg/kg body weight every 8 h for 4 weeks. This compound was equally as efficient as linezolid in reducing the production of lesions

In Vivo Activity of the Benzothiazinones PBTZ169 and BTZ043 against Nocardia brasiliensis.

BACKGROUND:Mycetoma is a neglected, chronic, and deforming infectious disease caused by fungi and actinomycetes. In Mexico, N. brasiliensis is the predominant etiologic agent. Therapeutic alternatives are necessary because the current drug regimens have several disadvantages. Benzothiazinones (BTZ) are a new class of candidate drugs that inhibit decaprenyl-phosphoribose-epimerase (DprE1), an essential enzyme involved in the cell wall biosynthesis of Corynebacterineae. METHODOLOGY/PRINCIPAL FINDINGS:In this study, the in vitro activity of the next generation BTZ, PBTZ169, was tested against thirty Nocardia brasiliensis isolates. The MIC50 and MIC90 values for PBTZ169 were 0.0075 and 0.03 μg/mL, respectively. Because Nocardia is a potential intracellular bacterium, a THP-1 macrophage monolayer was infected with N. brasiliensis HUJEG-1 and then treated with PBTZ169, resulting in a decrease in the number of colony-forming units (CFUs) at a concentration of 0.25X the in vitro value. The in vivo activity was evaluated after infecting female BALB/c mice in the right hind food-pad. After 6 weeks, treatment was initiated with PBTZ169 and its activity was compared with the first generation compound, BTZ043. Both BTZ compounds were administered at 100 mg/kg twice daily by gavage, and sulfamethoxazole/trimethoprim (SXT), at 100 mg/kg sulfamethoxazole, was used as a positive control. After 22 weeks of therapy, only PBTZ169 and SXT displayed statistically significant activity. CONCLUSION:These results indicate that DprE1 inhibitors may be useful for treating infections of Nocardia and may therefore be active against other actinomycetoma agents. We must test combinations of these compounds with other antimicrobial agents, such as linezolid, tedizolid or SXT, that have good to excellent in vivo activity, as well as new DprE1 inhibitors that can achieve higher plasma levels

Soluble factors in COVID-19 mRNA vaccine-induced myocarditis causes cardiomyoblast hypertrophy and cell injury: a case report

Abstract Background Inflammation affecting the heart and surrounding tissues is a clinical condition recently reported following COVID-19 mRNA vaccination. Assessing trends of these events related to immunization will improve vaccine safety surveillance and best practices for forthcoming vaccine campaigns. However, the causality is unknown, and the mechanisms associated with cardiac myocarditis are not understood. Case presentation After the first dose, we reported an mRNA vaccine-induced perimyocarditis in a young patient with a history of recurrent myocardial inflammation episodes and progressive loss of cardiac performance. We tested this possible inflammatory cytokine-mediated cardiotoxicity after vaccination in the acute phase (ten days), and we found a significant elevation of MCP-1, IL-18, and IL-8 inflammatory mediators. Still, these cytokines decreased considerably at the recovery phase (42 days later). We used the cardiomyoblasts cell line to test the effect of serum on cell viability, observing that serum from the acute phase reduced the cell viability to 75%. We did not detect this toxicity in cells when we tested serum from the patient in the recovery phase. We also tested serum-induced hypertrophy, a phenomenon in myocarditis and heart failure. We found that acute phase-serum has hypertrophy effects, increasing 25% of the treated cardiac cells’ surface and significantly increasing B-type natriuretic peptide. However, we did not observe the hypertrophic effect in the recovery phase or sera from healthy controls. Conclusion Our results opened the possibility of the inflammatory cytokines or serum soluble mediators as key factors for vaccine-associated myocarditis. In this regard, identifying anti-inflammatory molecules that reduce inflammatory cytokines could help avoid vaccine-induced myocardial inflammation

Efficacy of Ciprofloxacin and Moxifloxacin against Nocardia brasiliensis In Vitro and in an Experimental Model of Actinomycetoma in BALB/c Mice▿

The efficacy of ciprofloxacin and moxifloxacin against Nocardia brasiliensis was evaluated by applying 25 mg of each drug/kg subcutaneously every 8 h in BALB/c mice infected with N. brasiliensis. A statistically significant difference was observed only with moxifloxacin. A moxifloxacin-trimethoprim-sulfamethoxazole combination was as active as when each compound was used alone

Intracellular activity of PBTZ169 against <i>Nocardia brasiliensis</i> HUJEG-1 after 8 h of replication inside THP-1 macrophages.

<p>The measurements were performed in triplicate. Each point represents the mean of the assays and error bars represent the standard deviations. There were significant differences at all concentrations for PBTZ169 (open diamonds) (<i>P</i>  =  0.021) (MIC = 0.0037 μg/mL). As a control, we used tedizolid (closed circles) (MIC = 8 μg/mL).</p

Alignment of <i>M</i>. <i>tuberculosis</i> DprE1 ortholog proteins in <i>Nocardia spp</i>. We observe that all species have orthologs with the susceptible genotype, a cysteine at position 368.

<p>This analysis included common <i>Nocardia</i> pathogens, such as <i>N</i>. <i>brasiliensis</i>, <i>N</i>. <i>cyryiacigeorgica</i>, <i>N</i>. <i>farcinica</i>, <i>N</i>. <i>transvalensis</i>, and <i>N</i>. <i>otitidiscaviarum</i>. We also included rarely pathogenic species, such as <i>N</i>. <i>tenerifensis</i>, <i>N</i>. <i>terpenica</i>, and <i>N</i>. <i>carnea</i>.</p

Effect of PBTZ169, BTZ043, and SXT on the development of mycetoma lesions in BALB/c mice infected with <i>N</i>. <i>brasiliensis</i> HUJEG-1.

<p>The Y axis is an arbitrary scale we developed to measure the degree of infection (14) and goes from the total absence of lesions (0.0 +) to the presence of abundant inflammation, abscesses and fistulae. Each dot represents the reading of one animal; all the groups were compared statistically against the saline control group by using the Variance test,. According to this analysis, significant differences were found for treatment with PBTZ169 (<i>P</i> = 0.017) but not BTZ043 (<i>P</i> = 0.667). The positive control group treated with SXT yielded a statistically significant value (<i>P</i> = 0.007).</p

Plasma levels observed in BALB/c mice after applying, by gavage, PBTZ169 (left) and trimethoprim-sulfomethoxazole (right), both at 100 mg/kg.

<p>Three mice were bled and sacrificed at each point. Bars represent the standard deviation.</p

Protein sequence alignment of <i>M</i>. <i>tuberculosis</i> H37Rv DprE1 (A) and two orthologs in the genome of <i>N</i>. <i>brasiliensis</i> HUJEG-1.

<p>In red, we show Cys387. B: <i>N</i>. <i>brasilie</i>nsis YP_006807368 has 97% query cover and 62% identity to MTB DprE1. C: <i>N</i>. <i>brasiliensis</i> YP_006805098, presents a 99% query cover and 74% identity to MTB DprE1.</p