In vitro activities of new quinolones and oxazolidinones against Actinomadura madurae

Actinomycetoma by Actinomadura madurae: Clinical Characteristics and Treatment of 47 Cases

Context:

Mycetoma is a chronic, granulomatous disease caused by fungi (eumycetoma) or aerobic filamentous actinomycetes (actinomycetoma). Actinomadura madurae is one of the most frequent actinomycetes.

Aim:

The study aims to provide an update on clinical, diagnostic, therapeutic, and outcome data for patients with actinomycetoma in a single center in Mexico.

Settings and Design:

This was a retrospective study of 47 cases diagnosed with actinomycetoma.

Subjects and Methods:

The cases were selected from a total of 536 mycetoma obtained during 35 years (from 1985 to 2019). Clinical data were retrieved from the clinical records of our department. Microbiological data were obtained from our Mycology laboratory.

Statistical Analysis:

Frequencies and percentages were used for categorical variables. Normality was determined with the Kolmogorov–Smirnov test. We used means and medians to describe the variables.

Results:

Forty-seven patients with actinomycetoma were included; female:male ratio 1.9:1; median age 38 years. The foot was the most affected region in 76.5% of cases. The bone invasion was observed in 89%. The time between symptoms onset and diagnosis was 5.5 years. Grain detection by direct examination was positive in 95% of cases. The most commonly used, as well as the most effective treatment scheme was streptomycin + sulfamethoxazole-trimethoprim with dapsone. Sixty-three percent (30 patients) achieved clinical and mycological cure, and 10.6% (5 patients) had treatment failure.

Conclusions:

We highlight the importance of designing therapeutic strategies to standardize treatments and gain more experience to improve the care of these patients.

Molecular identification of Actinomadura madurae isolated from a patient originally from Algeria; observations from a case report

Background

Mycetoma is a chronic granulomatous subcutaneous infection caused by anaerobic pseudofilamentous bacteria or fungi. It is commonly prevalent in tropical and subtropical countries. Men are more susceptible to the disease due to greater participation in agricultural works. Mycetoma commonly involves lower extremities, wherein untreated cases lead to aggressive therapeutic choices, such as amputation of the affected body organs and consequently lifelong disability.

Case presentation

In this report, we present the rare case of a 58-year-old man, originally from Algeria with a left foot chronic tumefaction of 5 years. In the initial clinical examination, mycetoma was diagnosed based on tumefaction and the presence of multiple sinuses with the emission of white grains. The latter was observed via direct examination. The histopathological analysis demonstrated an actinomycetoma caused by bacteria, as the etiological agent. Imaging showed a bone involvement with osteolysis at the levels of 2nd to 4th metatarsal diaphysis. The mycological and bacterial cultures were both negative. For an accurate diagnosis, the obtained grains were subjected to molecular analysis, targeting the 16S-rDNA gene. Molecular identification yielded Actinomadura madurae as the causal agent, and 800/160 mg of trimethoprim/sulfamethoxazole was prescribed twice a day for 1 year, as a treatment.

Conclusion

Considering low information about this disease, especially in non-endemic areas, it is of high importance to enhance the knowledge and awareness of clinicians and healthcare providers, in particular in the countries with immigration issues.

Actinomycetoma by Actinomadura madurae. Clinical and therapeutic characteristics of 18 cases with two treatment modalities

BACKGROUND

Actinomycetoma due to Actinomadura madurae is susceptible to numerous chemotherapeutic agents, however, the response to those treatments is variable and closely related to several factors.

OBJECTIVE

We aimed to evaluate the clinical-therapeutic characteristics of patients with actinomycetoma due to Actinomadura madurae with two treatment modalities.

METHODS

This was a retrospective study of eighteen patients with a diagnosis of actinomycetoma. The most widely used therapeutic scheme was streptomycin 1 g every third day plus TMP/SMX 800 mg/160 mg/12h, followed by TMP/SMX with DDS 100 mg/day. In six patients (33%), ciprofloxacin 500 mg every 12 h was used instead of DDS.

RESULTS

Conventional scheme achieved clinical and mycological cure in 58% of the cases, improvement in 16%, and 25% of the patients failed to treatment; in the cases treated with ciprofloxacin, clinical and microbiological cure was achieved in 83% of patients and clinical improvement in 16%. The treatment time to achieve clinical and mycological did not have a statistically significant difference (median 10 ± 1.38 vs. 12 ± 4.6).

CONCLUSION

Treatment based on streptomycin + TMP/SMX with ciprofloxacin was found to be effective in treating patients with actinomycetoma, and comparable to the conventional treatment with DDS in actinomycetoma due to A. madurae with minimal bone involvement.

Therapeutic effect of a novel oxazolidinone, DA-7867, in BALB/c mice infected with Nocardia brasiliensis

Background

Mycetoma is a chronic infectious disease of tropical and subtropical countries. It is produced by true fungi and actinobacteria. In México, Nocardia brasiliensis is the main causative agent of mycetoma, producing about 86% of the cases; the gold standard for the therapy of mycetoma by N. brasiliensis is the use of sulfonamides which give a 70% cure rate. The addition of amikacin to this regime increases to 95% the cure rate; however, the patients have to be monitored for creatinine clearance and audiometry studies because of the potential development of side effects. Because of that it is important to search for new active compounds. In the present work, we evaluated the in vivo effect of DA-7867, an experimental oxazolidinone, on the development of experimental mycetomas by N. brasiliensis in BALB/c mice.

Methodology/Principal Findings

In order to determine the optimal dose utilized to apply to the animals, we first determined by HPLC the plasma levels using several concentrations of the compounds. Based on these results, we used 10 and 25 mg/kg subcutaneously every 24 hr; DA-7867 was also supplied in the drinking water at a calculated dose of 25 mg/kg. As a control we utilized linezolid at 25 mg/kg, a compound active in murine and human infections, three times a day. The mice were infected in the right footpad with a young culture of N. brasiliensis HUJEG-1, and one week later we started the application of the antimicrobials for six more weeks. After that we compared the development of lesions in the groups injected with saline solution or with the antimicrobials; the results were analyzed by the variance ANOVA test. DA-7867 was able to reduce the production of lesions at 25 mg/kg, when given either subcutaneously or in the drinking water.

Conclusions/Significance

The experimental oxazolidinone DA-7867 is active in vivo against N. brasiliensis, which opens the possibility of using this drug once it is accepted for human application. Since oxazolidinones seem to be active against a wide spectrum of actinobacteria, it is possible they could be used in human cases of mycetoma by other actinomycetales, such as Streptomyces somaliensis, highly prevalent in Sudan, or Actinomadura madurae and A. pelletieri, which are commonly observed in Africa and India.

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.

Prodrugs for the treatment of neglected diseases

Recently, World Health Organization (WHO) and Medicins San Frontieres (MSF) proposed a classification of diseases as global, neglected and extremely neglected. Global diseases, such as cancer, cardiovascular and mental (CNS) diseases represent the targets of the majority of the R&D efforts of pharmaceutical companies. Neglected diseases affect millions of people in the world yet existing drug therapy is limited and often inappropriate. Furthermore, extremely neglected diseases affect people living under miserable conditions who barely have access to the bare necessities for survival. Most of these diseases are excluded from the goals of the R&D programs in the pharmaceutical industry and therefore fall outside the pharmaceutical market. About 14 million people,mainly in developing countries, die each year from infectious diseases. From 1975 to 1999,1393 new drugs were approved yet only 1% were for the treatment of neglected diseases[3]. These numbers have not changed until now, so in those countries there is an urgent need for the design and synthesis of new drugs and in this area the prodrug approach is a very interesting field. It provides, among other effects, activity improvements and toxicity decreases for current and new drugs, improving market availability. It is worth noting that it is essential in drug design to save time and money, and prodrug approaches can be considered of high interest in this respect. The present review covers 20 years of research on the design of prodrugs for the treatment of neglected and extremely neglected diseases such as Chagas' disease (American trypanosomiasis), sleeping sickness (African trypanosomiasis), malaria, sickle cell disease, tuberculosis, leishmaniasis and schistosomiasis.

Mycetoma

Mycetoma is a granulomatous infection affecting mainly the feet and lower extremities. It can be caused either by aerobic, branched actinomycetes or by eumycetes. Most cases are found in tropical and subtropical regions. The infection is usually produced by the introduction of the etiologic agents through minor wounds caused by thorns and wood splinters. Clinically the disease begins as small, firm nodules that can enlarge to form extensive lesions with fistulae and abscesses with pus containing granules of the causative microorganisms. Antimicrobials and surgery are used in the management of mycetoma. The actinomycetomas generally respond well to antimicrobials. For eumycetomas, surgery may be required. New therapeutic options for drug-resistant cases are discussed.

In vitro activities of DA-7157 and DA-7218 against Mycobacterium tuberculosis and Nocardia brasiliensis

The in vitro activities of DA-7157, a novel oxazolidinone, against clinical isolates of Nocardia brasiliensis and Mycobacterium tuberculosis were determined. Equal MIC(50)s and MIC(90)s (0.25 and 0.5 microg/ml, respectively) were found for susceptible and multidrug-resistant isolates of M. tuberculosis. The N. brasiliensis isolates showed an MIC(90) of 1 microg/ml and an MIC(50) of 1 microg/ml. The DA-7157 prodrug, DA-7218, exhibited similar MICs for M. tuberculosis but fivefold-higher MICs for N. brasiliensis.

In vitro activities of the novel oxazolidinones DA-7867 and DA-7157 against rapidly and slowly growing mycobacteria

DA-7867 and DA-7157 are oxazolidinones active against pathogenic aerobic actinomycetes including Nocardia spp. and Mycobacterium tuberculosis. However, the activity of these drugs against nontuberculous mycobacterium (NTM) species is not known. In this work, we compared the susceptibilities of 122 clinical isolates and 29 reference species of both rapidly growing and slowly growing mycobacteria to linezolid, DA-7867, and DA-7157 by the broth microdilution method. The MICs for 50 and 90% of the strains tested (MIC50s and MIC90s, respectively) of DA-7867 and DA-7157 were lower than those of linezolid. In all of the cases, a MIC90 of <8 microg/ml was observed for all of the species tested in both groups of NTM. For M. kansasii and M. marinum isolates, the MIC90s of both DA-7867 and DA-7157 were less than 0.5 microg/ml. These results demonstrate the potential of these compounds to treat NTM infections.