Longistylin A from Cajanus cajan (L.) Millsp. disturbs glycerophospholipid metabolism and cytokinin biosynthesis of Nocardia seriolae.

ETHNOPHARMACOLOGICAL RELEVANCE: Nocardiosis is an uncommon infectious disease that bears certain similarities to tuberculosis, with a continuous increase in its incidence and a poor prognosis. In traditional Chinese medicine, the leaves of Cajanus cajan (L.) Millsp. are employed to treat wounds, malaria, coughs, and abdominal pain. AIM OF THE STUDY: In this study, we investigated the effects and mechanisms of longistylin A (LGA), a natural stilbene isolated from C. cajan, as a potential antibiotic against nocardiosis. MATERIALS AND METHODS: LGA was isolated from the leaves of C. cajan and assessed using a minimum bactericidal concentration (MBC) determination against Nocardia seriolae. Multi-omics analysis encompassing genes, proteins, and metabolites was conducted to investigate the impact of LGA treatment on N. seriolae. Additionally, quantitative analysis of 40 cytokinins in N. seriolae mycelium was performed to assess the specific effects of LGA treatment on cytokinin levels. Cryo-scanning electron microscopy was utilized to examine morphological changes induced by LGA treatment, particularly in the presence of exogenous trans-zeatin-O-glucoside (tZOG). The therapeutic effect of LGA was investigated by feeding N. seriolae-infected largemouth bass. RESULTS: LGA exhibited significant efficacy against N. seriolae, with MBC value of 2.56 µg/mL. Multi-omics analysis revealed that LGA disrupted glycerophospholipid metabolism and hormone biosynthesis by notably reducing the expression of glycerol-3-phosphate dehydrogenase and calmodulin-like protein. Treatment with LGA markedly disrupted 12 distinct cytokinins in N. seriolae mycelium. Additionally, the addition of exogenous tZOG counteracted the inhibitory effects of LGA on filamentous growth, resulting in mycelial elongation and branching. Furthermore, LGA treatment improved the survival rate of largemouth bass infected with N. seriolae. CONCLUSIONS: We found for the first time that LGA from C. cajan exhibited significant efficacy against N. seriolae by interfering with glycerophospholipid metabolism and cytokinin biosynthesis.

Disseminated actinomycetoma due to Nocardia wallacei.

BACKGROUND: Actinomycetoma caused by Nocardia usually responds well to antibiotics. Emerging species of Nocardia, such as N. wallacei, can be a therapeutic challenge. AIMS: Confirm the therapeutic effectivity of linezolid in multidrug resistant Nocardia Wallacei actinomycetoma. MATERIALS AND METHODS: We evaluated the medical management of an 18-year-old man with multidrug resistant actinomycetoma of the left leg caused by N. transvalensis complex treated 17 years ago with linezolid 1200 mg a day. This bacteria was recently reclassified as Nocardia Wallacei by specific molecular biology technique. RESULTS: The infection was cured after 3 months of treatment; the patient remained asymptomatic for the past 17 years. No adverse effects were found. DISCUSSION: Frequently, strains of N. transvalensis complex have aminoglycoside resistance; in this case, we highlight the effectiveness of linezolid for the successful medical management of multidrug resistant actinomycetoma. CONCLUSION: Linezolid can be an alternative for the treatment of multidrug resistant Nocardia Wallacei.

In vitro activity of some essential oils alone and in combination against the fish pathogen Nocardia seriolae.

Microplate resazurin assay was applied to investigate the in vitro activity of four essential oils (EOs); cinnamon (Cinnamomum zeylanicum), thyme (Thymus vulgaris), lemongrass (Cymbopogon flexuosus) and tea tree (Melaleuca alternifolia) oils against 80 clinical isolates of the fish pathogen Nocardia seriolae. The checkerboard test was then used to determine the possible synergistic effect of EOs combination against reference type strains of fish nocardiosis. All tested EOs had antibacterial activity against N. seriolae isolates. Among the tested EOs, cinnamon and thyme oils both exhibited the lowest minimum inhibitory concentrations (MICs) with 5-160 and 10-160 µg/ml, respectively. The activities of lemongrass and tea tree EOs were noted to be less effective with MICs of 20-640 and 160->5120 µg/ml, respectively. The checkerboard panel of cinnamon-thyme EOs combination against N. seriolae ATCC43993 demonstrated a synergistic effect with a fractional inhibitory concentration (FIC) index of 0.75. For N. salmonicida ATCC27463, the combination panel showed an additive effect with an FIC index of 1.0. For N. asteroides ATCC19247, the combination panel demonstrated an indifference effect with an FIC index of 1.125. These results indicate that thyme and cinnamon oils alone or the combination of them at a given ratio has a promising potent clinical significance in the treatment of fish nocardiosis. Despite the promising results given by our in vitro studies, the clinical benefits of these EOs combinations can only be determined through carefully designed in vivo experimental studies.

Impact of immune status on the clinical characteristics and treatment outcomes of nocardiosis.

Nocardiosis occurs in both immunocompromised and immunocompetent patients. We aimed to assess how its characteristics differ depending on patients' immune status. Of a total of 54 patients with culture-proven nocardiosis diagnosed over 13 years, 18 (33%) were immunocompetent. Half of immunocompetent patients had chronic lung disease and were not receiving systemic corticosteroid. There were no significant differences in clinical, radiographic, and microbiologic characteristics, and treatment outcomes according to immune status, except that pulmonary cavitation (47% vs. 8%) and coexisting infections (17% vs. 0%) were more frequent in immunocompromised hosts. Nocardia farcinica, the most commonly identified isolates at the species level (51%), was highly susceptible to trimethoprim-sulfamethoxazole (100%) and highly resistant to ceftriaxone (94%). Nocardiosis should be considered in differential diagnosis of pneumonia, brain abscess, or soft tissue infection that does not respond to conventional antibiotic therapy such as ceftriaxone, regardless of whether the patient is immunocompromised or not.

[Destruction of oil in the presence of Cu2+ and surfactants of Acinetobacter calcoaceticus IMV B-7241, Rhodococcus erythropolis IMV Ac-5017 and Nocardia vaccinii IMV B-7405].

The effect of copper cations (0.01-1.0 mM) and surface-active agents (surfactants) of Acinetobacter calcoaceticus IMV B-7241, Rhodococcus erythropolis IMV Alc-5017 and Nocardia vaccinii IMV B-7405 in the form of culture liquid on the destruction of oil in water (3.0-6.0 g/L) and soil (20 g/kg), including in the presence of Cd2+ and Pb2+ (0.01-0.5 mM), was investigated. It was shown that the degree of oil degradation in water and soil after 20 days in the presence of low concentrations of Cu2+ (0.01-0.05 mM) and culture liquid of strains IMV B-7241, IMV Ac-5017, and IMV B-7405 was 15 - 25% higher than without copper cations. The activating effect of Cu2+ on the decomposition of complex oil and Cd2+ and Pb2+ pollution was established: after treatment with surfactant of A. calcoacelicus IMV B-7241 and R. erythropolis IMV Ac-5017 destruction of oil in water and soil was 85-95%, and after removal of the copper cations decreased to 45-70%. Intensification of oil destruction in the presence of copper cations may be due to their stimulating effect on the activity of alkane hydroxylases as in surfactant-producing strains, and natural (autochthonous) oxidizing microbiota.

Multidrug-resistant Nocardia pseudobrasiliensis presenting as multiple muscle abscesses.

A 79-year-old Caucasian man presented with multiple leg abscesses due to Nocardia pseudobrasiliensis. He was on chronic steroid therapy for myasthenia gravis. We present the difficulties in diagnosis and treatment of this rare organism. N. pseudobrasiliensis is a new emerging species that was previously thought to belong to the N. brasiliensis species. The distinction between the two species is extremely important given the different antibiotic susceptibility pattern and association of N. pseudobrasiliensis with more invasive and disseminated disease.

Fluoroquinolone treatment and susceptibility of isolates from bacterial keratitis.

OBJECTIVE: To analyze the relationship between fluoroquinolone use at presentation and minimum inhibitory concentration in bacterial keratitis. METHODS: The Steroids for Corneal Ulcers Trial was a randomized, double-masked, placebo-controlled trial assessing the effect of adjunctive topical corticosteroid treatment on outcomes in bacterial keratitis. After presentation, all patients were treated with moxifloxacin hydrochloride, 0.5%. We compare antibiotic use at presentation with minimum inhibitory concentration against moxifloxacin for all isolates. Separate analyses accounted for organism species and fluoroquinolone generation. RESULTS: Topical fluoroquinolone use at presentation was reported in 92 of 480 cases (19.2%). Causative organisms in the 480 cases included Streptococcus pneumoniae (247 cases [51.5%]), Pseudomonas aeruginosa (109 cases [22.7%]), and Nocardia species (55 cases [11.5%]). Isolates from patients who reported fluoroquinolone use at presentation had a 2.01-fold-higher minimum inhibitory concentration (95% CI, 1.39-fold to 2.91-fold; P < .001). Fourth-generation fluoroquinolones were associated with a 3.48-fold-higher minimum inhibitory concentration than those isolates that were not exposed to pretreatment at enrollment (95% CI, 1.99-fold to 6.06-fold; P < .001). CONCLUSION: This study provides evidence that prior use of fluoroquinolones is associated with antibiotic resistance. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00324168.

Disseminated Nocardiosis caused by Nocardia concava with acute respiratory failure and central nervous system involvement treated with linezolid.

Nocardia concava was identified as a new species in 2005; however, the clinical manifestations of Nocardia concava infection have yet to be clarified. We herein present the case of an immunosuppressed patient who developed disseminated nocardiosis caused by N. concava with multiple abscesses in the lungs, cutis, subcutaneous tissue, skeletal muscles and kidneys accompanied by central nervous system involvement, including meningitis and ventriculitis. The patient was cured with appropriate treatment including linezolid after testing for susceptibility. Linezolid should be considered as an alternative agent for treating disseminated nocardiosis because of its effective distribution to multiple sites.

Current concepts in laboratory testing to guide antimicrobial therapy.

Antimicrobial susceptibility testing (AST) is indicated for pathogens contributing to an infectious process that warrants antimicrobial therapy if susceptibility to antimicrobials cannot be predicted reliably based on knowledge of their identity. Such tests are most frequently used when the etiologic agents are members of species capable of demonstrating resistance to commonly prescribed antibiotics. Some organisms have predictable susceptibility to antimicrobial agents (ie, Streptococcus pyogenes to penicillin), and empirical therapy for these organisms is typically used. Therefore, AST for such pathogens is seldom required or performed. In addition, AST is valuable in evaluating the activity of new and experimental compounds and investigating the epidemiology of antimicrobial resistant pathogens. Several laboratory methods are available to characterize the in vitro susceptibility of bacteria to antimicrobial agents. When the nature of the infection is unclear and the culture yields mixed growth or usual microbiota (wherein the isolates usually bear little relationship to the actual infectious process), AST is usually unnecessary and results may, in fact, be dangerously misleading. Phenotypic methods for detection of specific antimicrobial resistance mechanisms are increasingly being used to complement AST (ie, inducible clindamycin resistance among several gram-positive bacteria) and to provide clinicians with preliminary direction for antibiotic selection pending results generated from standardized AST (ie, ß-lactamase tests). In addition, molecular methods are being developed and incorporated by microbiology laboratories into resistance detection algorithms for rapid, sensitive assessment of carriage states of epidemiologically and clinically important pathogens, often directly from clinical specimens (ie, presence of vancomycin-resistant enterococci in fecal specimens).

Clinical and microbiological characteristics of infections caused by various Nocardia species in Taiwan: a multicenter study from 1998 to 2010.

This multicenter study in Taiwan investigated the clinical presentations of various Nocardia species infections based on 16S rRNA sequence analysis. Patients with nocardiosis in four large medical centers from 1998 to 2010 were included. A total of 100 preserved nonduplicate isolates causing human infection were identified as Nocardia species. Sequencing analysis of 16S rRNA confirmed that 35 of 36 N. asteroides isolates identified by conventional tests were non-asteroides Nocardia species, and that two of 50 N. brasiliensis isolates had also been initially misidentified. N. brasiliensis (50%) was the most common pathogen, followed by N. cyriacigeorgica (18%). In addition, several rare pathogens were identified, including N. asiatica, N. rhamnosiphila, N. abscessus, N. transvalensis, N. elegans, and N. carnea. Primary cutaneous infection was the most common presentation, noted in 55 (55%) patients, while pulmonary infection presented in 26 (26%) patients. The crude mortality rate was 6.7% (6/89), and was lowest for primary cutaneous infection (2.2%) and highest for disseminated disease and pulmonary infection (16.7%). In conclusion, N. brasiliensis and N. cyriacigeorgica were the most common pathogens causing nocardiosis in Taiwan. Molecular methods for identifying Nocardia to the species level are mandatory for better understanding the epidemiology and clinical characteristics of patients with nocardiosis.

In vitro activity of multiple antibiotic combinations against Nocardia: relationship with a short-term treatment strategy in heart transplant recipients with pulmonary nocardiosis.

BACKGROUND/OBJECTIVES: Pulmonary nocardiosis (PN) chiefly affects immunocompromised patients, particularly transplant recipients. Cotrimoxazole is still the mainstay of treatment, but it is associated with nephro- and myelo-toxicity, and can show unpredictable activity against Nocardia isolates. METHODS: Over a 20-year period, Nocardia isolates were identified from 12 heart transplant (HTx) recipients with PN. The in vitro activity of various antibacterials, alone or in combination, was assessed using disk-diffusion, minimal inhibitory concentration (MIC), and time-kill methodology. The in vitro results were compared with the clinical outcome of the patients. RESULTS: Seven different Nocardia strains were identified. Disk diffusion and MIC determinations showed that all isolates were susceptible to amikacin, netilmicin, and linezolid, and that moxifloxacin was the most active of the fluoroquinolones. All but 1 of the isolates were susceptible to imipenem. Time-kill studies showed that imipenem/amikacin and imipenem/moxifloxacin combinations were bactericidal for most isolates. Of 12 patients who received 3-4 weeks' intravenous (IV) treatment with amikacin or ciprofloxacin in combination with a beta-lactam, followed by 1-3 months' oral cotrimoxazole, moxifloxacin, or linezolid, 11 were cured; 1 patient died, but not related to Nocardia. CONCLUSION: Initial PN treatment in HTx recipients can be successfully carried out with bactericidal combinations such as imipenem plus amikacin or moxifloxacin, administered IV for 3-4 weeks. Within 1 month, a significant clinical and radiological improvement may be observed. In our experience, a <3 month oral regimen with cotrimoxazole, moxifloxacin, or doxycycline may then be used. This may allow a reduction of side effects and treatment-related burden, without any recurrence.

Antimicrobial activity screening of some sulfonamide derivatives on some Nocardia species and isolates.

Nocardia are aerobic, catalase-positive, Gram-positive microorganisms and typically acid-alcohol fast at some stage of the growth cycle. The genus Nocardia, a member of Mycolata group, is clinically important because it is an opportunistic pathogen. The sulfonamide derivative medicines are prefered to cure infection caused by Nocardia, such as nocardiaosis and mycetoma. Antimicrobial activities of seven sulfonamide derivatives have been investigated against some Nocardia species and isolates using the disk diffusion method on Sensitest agar medium (Oxoid). Thirty-six organisms, which consisted of 10 soil isolates selected from different clusters of Aymen study (2003), six clinical isolates provided by Ege University, Medical School, Microbiology and Clinical Microbiology Department, four reference strains, 15 type strains and a control strain of Staphylococcus aureus ATCC 43300 were tested. The strongest inhibition was observed in the cases of IV [N-(2-hydroxy-4-nitro-phenyl)-4-methyl-benzensulfonamid], V [N-(2-hydroxy-5-nitro-phenyl)-4-methyl-benzensulfonamid] and III [N-(2-Hydroxy-phenyl)-4-methyl-benzenesulfonamide] against Nocardia. Introducing a hydroxyl group into the ortho position on the ring increased the antimicrobial activity. Substitution of the electron withdrawing groups such as a nitro group increased the antimicrobial activity remarkably.

[Pulmonary nocardiosis with trimethoprime/sulphamethoxazole-resistant Nocardia paucivorans in a patient with no signs of immunosuppression]. / Pulmonale Nokardiose mit Trimethoprim/Sulfamethoxazol resistenter Nocardia paucivorans bei einem Patienten ohne Hinweise auf Immunsuppression.

This is so far the first published case report of a Nocardia paucivorans infection in an immunocompetent patient. A 54-year-old farmer was hospitalised with a history of coughing and fever for a period of five months. There was no indicator of either primary of secondary immunodeficiency in the prior medical history. A chest X-ray showed pneumonic infiltrates in the right middle und lower lobes, which progressed despite of antibiotic therapy with macrolides. A transbronchial biopsy revealed unspecific granulomatous inflammation of soft tissues. N. paucivorans - grew in cultures of sputum, bronchoalveolar lavage, and transbronchial biopsy. Oral antibiotic therapy was started with trimethoprime-sulphamethoxazole (TMP/SMX) and amoxicillin plus clavulanic acid. Susceptibility testing revealed high level resistance to TMP/SMX, which was consequently replaced by ciprofloxacin. Six months later, infiltrates had completely resolved and the patient did not report any residual clinical symptoms. The present case showed once again that nocardiosis is not limited to patients with immunodeficiencies. However, conservative combination therapy with oral antibiotics seems to be sufficiently effective for nocardiosis in the immunocompetent patient. For cases of suspected nocardiosis, a step-wise, risk-based diagnostic and therapeutic procedure is proposed.

Intracranial Nocardia recurrence during fluorinated quinolones therapy.

Nocardia infection is a well-recognized complication in renal transplant recipients and other immunocompromised hosts. It is mostly a primary pulmonary infection, which can disseminate to other organs in half of the cases. Nocardiosis is a life-threatening infection. Therefore, an efficient long-lasting treatment must be rapidly administered. We report 1 case of disseminated nocardiosis with pulmonary involvement, brain lesions, and bone lesions in a renal transplant patient, who was treated with stereotactic aspiration in association with high dose of trimethoprim/sulfamethoxazole (TMP/SMX) and imipenem, changed, after 3 weeks to moxifloxacin. First, clinical manifestations decreased after surgical drainage and combination therapy with the 2 antimicrobial agents, but later the patient developed a recurrence of brain lesions during treatment with quinolones. Consequently, the patient was again treated with TMP/SMX and imipenem, after which the patient recovered. It is surprising that moxifloxacin was efficient in vitro and the antimicrobial concentration in the central nervous system was high, yet the nocardial abscess recurred under this therapy.

Nocardiosis in a teaching hospital in the Central Anatolia region of Turkey: treatment and outcome.

Predisposing factors, antimicrobial susceptibility patterns, treatment and outcome were analysed for nine consecutive patients with nocardiosis. Predisposing factors were identified in six (67%) of the nine patients. Clinical syndromes of nocardial infection were pulmonary infection (three patients), cerebral infection (five patients) and disseminated infection (one patient). The predominant (60%) species was Nocardia farcinica rather than the Nocardia asteroides complex. Treatment was started empirically, modified according to the antimicrobial susceptibility pattern, and then continued for 6-12 months. Overall mortality was 33%, with death being caused by the Nocardia infection in two cases.

In vitro and in vivo activities of antimicrobials against Nocardia brasiliensis.

In Mexico mycetomas are mostly produced by Nocardia brasiliensis, which can be isolated from about 86% of cases. In the present work, we determined the sensitivities of 30 N. brasiliensis strains isolated from patients with mycetoma to several groups of antimicrobials. As a first screening step we carried out disk diffusion assays with 44 antimicrobials, including aminoglycosides, cephalosporins, penicillins, quinolones, macrolides, and some others. In these assays we observed that some antimicrobials have an effect on more than 66% of the strains: linezolid, amikacin, gentamicin, isepamicin, netilmicin, tobramycin, minocycline, amoxicillin-clavulanic acid, piperacillin-tazobactam, nitroxolin, and spiramycin. Drug activity was confirmed quantitatively by the broth microdilution method. Amoxicillin-clavulanic acid, linezolid, and amikacin, which have been used to treat patients, were tested in an experimental model of mycetoma in BALB/c mice in order to validate the in vitro results. Linezolid showed the highest activity in vivo, followed by the combination amoxicillin-clavulanic acid and amikacin.

Application of sucrose-gradient centrifugation for selective isolation of Nocardia spp. from soil.

AIMS: To devise and evaluate a method for selective isolation of the less abundant actinomycetes, Nocardia spp. in soil. METHODS AND RESULTS: This newly developed method is based on differentiating Nocardia from other actinomycete taxa by centrifugation. A water suspension of air-dried soil is centrifuged through a gradient consisting of 10, 20, 30, 40 and 50% sucrose at 240 x g for 30 min. The 20% sucrose layer, which is enriched with Nocardia spp., is then diluted and plated on humic acid-vitamin agar supplemented with antibacterial agents. The proposed method consistently achieved selective isolation of Nocardia spp. in all 14 soil samples tested, which accounted for 5-89% of the total microbial population recovered. Tentative taxonomic characterization based on a restriction fragment length polymorphism (RFLP) analysis of the 16S ribosomal DNA suggested that many of the soil isolates could belong to N. asteroides, N. salmonicida or N. uniformis. CONCLUSIONS: Differential centrifugation can successfully and efficiently isolate soil Nocardia populations that are suppressed by conventional dilution plating approaches. SIGNIFICANCE AND IMPACT OF THE STUDY: The development and application of new methodologies with which to isolate less-explored actinomycete taxa is important for improving our knowledge about their taxonomy, ecology and industrial applications.