NMR insights on nano silver post-surgical treatment of superficial caseous lymphadenitis in small ruminants

Activity of biogenic silver nanoparticles in planktonic and biofilm-associated Corynebacterium pseudotuberculosis

Corynebacterium pseudotuberculosis is a gram-positive bacterium and is the etiologic agent of caseous lymphadenitis (CL) in small ruminants. This disease is characterized by the development of encapsulated granulomas in visceral and superficial lymph nodes, and its clinical treatment is refractory to antibiotic therapy. An important virulence factor of the Corynebacterium genus is the ability to produce biofilm; however, little is known about the characteristics of the biofilm produced by C. pseudotuberculosis and its resistance to antimicrobials. Silver nanoparticles (AgNPs) are considered as promising antimicrobial agents, and are known to have several advantages, such as a broad-spectrum activity, low resistance induction potential, and antibiofilm activity. Therefore, we evaluate herein the activity of AgNPs in C. pseudotuberculosis, through the determination of minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), antibiofilm activity, and visualization of AgNP-treated and AgNP-untreated biofilm through scanning electron microscopy. The AgNPs were able to completely inhibit bacterial growth and inactivate C. pseudotuberculosis at concentrations ranging from 0.08 to 0.312 mg/mL. The AgNPs reduced the formation of biofilm in reference strains and clinical isolates of C. pseudotuberculosis, with interference values greater than 80% at a concentration of 4 mg/mL, controlling the change between the planktonic and biofilm-associated forms, and preventing fixation and colonization. Scanning electron microscopy images showed a significant disruptive activity of AgNP on the consolidated biofilms. The results of this study demonstrate the potential of AgNPs as an effective therapeutic agent against CL.

Biogenic silver nanoparticles' antibacterial activity and cytotoxicity on human hepatocarcinoma cells (Huh-7)

Exploring diverse synthetic pathways for nanomaterial synthesis has emerged as a promising direction. For example, silver nanoparticles (AgNPs) are synthesized using different approaches yielding nanomaterials with distinct morphological, physical and biological properties. Hence, the present study reports the biogenic synthesis of silver nanoparticles using the aqueous secretome of the fungus Fusarium oxysporum f. sp. cubense (AgNP@Fo) and orange peel extract (AgNP@OR). The physical and morphological properties of synthesized nanoparticles were similar, with AgNP@Fo measuring 56.43 ± 19.18 nm and AgNP@OR measuring 39.97 ± 19.72 nm in size. The zeta potentials for the nanoparticles were low, -26.8 ± 7.55 and -26.2 ± 2.87 mV for AgNP@Fo and AgNP@OR, respectively, demonstrating a similar negative charge. The spherical morphologies of both nanoparticles were evidenced by Scanning Transmission Electron Microscopy (STEM) and Atomic Force Microscopy (AFM). However, despite their similar physical and morphological properties, AgNPs demonstrated different bioactivities. We evaluated and compared the antimicrobial efficacy of these nanoparticles against a range of bacteria, such as Staphylococcus aureus, Enterococcus faecalis, Pseudomonas aeruginosa, and Escherichia coli. The AgNP@Fo showed Minimum Inhibitory Concentration (MIC) values ranging from 0.84 to 1.68 μg mL-1 and were around ten times more potent compared to AgNP@OR. The anticancer activities of both nanoparticles were investigated using human hepatocarcinoma cells (Huh-7), where AgNP@Fo exhibited around 20 times higher cytotoxicity than AgNP@OR with an IC50 value of 0.545 μmol L-1. Anticancer effects were demonstrated by the MTT, confirmed by the calcein-AM assay and fluorescence imaging. This study establishes solid groundwork for future exploration of molecular interactions of nanoparticles synthesized through distinct biosynthetic routes, particularly within bacterial and cancerous cell environments.

A serum NMR metabolomic analysis of the Corynebacterium pseudotuberculosis infection in goats

Caseous lymphadenitis (CLA), an infectious disease caused by Corynebacterium pseudotuberculosis in small ruminants, is highly prevalent worldwide. Economic losses have already been associated with the disease, and little is known about the host-pathogen relationship associated with the disease. The present study aimed to perform a metabolomic study of the C. pseudotuberculosis infection in goats. Serum samples were collected from a herd of 173 goats. The animals were classified as controls (not infected), asymptomatic (seropositives but without detectable CLA clinical signs), and symptomatic (seropositive animals presenting CLA lesions), according to microbiological isolation and immunodiagnosis. The serum samples were analyzed using nuclear magnetic resonance (¹H-NMR), nuclear Overhauser effect spectroscopy (NOESY), and Carr-Purcell-Meiboom-Gill (CPMG) sequences. The NMR data were analyzed using chemometrics, and principal component analysis (PCA) and partial least square discriminant analysis (PLS-DA) were performed to discover specific biomarkers responsible for discrimination between the groups. A high dissemination of the infection by C. pseudotuberculosis was observed, being 74.57% asymptomatic and 11.56% symptomatic. In the evaluation of 62 serum samples by NMR, the techniques were satisfactory in the discrimination of the groups, being also complementary and mutually confirming, demonstrating possible biomarkers for the infection by the bacterium. Twenty metabolites of interest were identified by NOESY and 29 by CPMG, such as tryptophan, polyunsaturated fatty acids, formic acid, NAD⁺, and 3-hydroxybutyrate, opening promising possibilities for the use of these results in new therapeutic, immunodiagnosis, and immunoprophylactic tools, as well as for studies of the immune response against C. pseudotuberculosis. KEY POINTS: • Sixty-two samples from healthy, CLA asymptomatic, and symptomatic goats were screened • Twenty metabolites of interest were identified by NOESY and 29 by CPMG • ¹H-NMR NOESY and CPMG were complementary and mutually confirming.

First description of Candida haemulonii infecting a snake Boa constrictor: Molecular, pathological and antifungal sensitivity characteristics

Candida haemulonii is an emergent infectious pathogen that affects human presenting comorbidities and/or immunodepression. Little is known about other possible hosts. For the first time, this fungus was found causing a cutaneous infection in a snake, Boa constrictor, characterized by scale opacity and several ulcerative lesions. This C. haemulonii was isolated, identified using molecular techniques and a phylogenetic study, and had its growth totally inhibited by all the drugs tested; however, no fungicide effect was seen for fluconazole and itraconazole. The B. constrictor clinical signals subsided after a treatment using a biogenic silver nanoparticle-based ointment. These findings, along with the B. constrictor presence near human habitats, warn for the necessity of wildlife health monitoring for emergent and opportunistic diseases in peri-urban environments.

Activity of Fusarium oxysporum-Based Silver Nanoparticles on Candida spp. Oral Isolates

Candida spp. resistant to commercially available antifungals are often isolated from patients with oral candidiasis, a situation that points to the need for the development of new therapies. Thus, we evaluated the activity of Fusarium oxysporum-based silver nanoparticles (AgNPs) on Candida spp. isolated from denture stomatitis lesions. Candida isolates were molecularly identified and submitted to susceptibility assays using AgNPs and commercial fungicides. The interference on biofilm formation and the mechanisms of action of AgNPs on Candida spp. were also investigated. Scanning electron microscopy was used to evaluate the morphology of AgNP-treated Candida. Candida albicans was the most frequent species isolated from denture stomatitis cases. All Candida spp. were susceptible to AgNPs at low concentrations, except Candida parapsilosis. AgNPs caused surface damage, cell disruption, and biofilm formation inhibition. The ergosterol supplementation protected C. albicans against the AgNP action. AgNPs are effective against Candida spp. and can be faced as a promising new therapeutic agent against oral candidiasis.

Metabolomics in the study of spontaneous animal diseases

Using analytical chemistry techniques such as nuclear magnetic resonance (NMR) spectroscopy and liquid or gas chromatography-mass spectrometry (LC/GC-MS), metabolomics allows detection of most endogenous and exogenous metabolites in a biological sample. Metabolomics has a wide range of applications, and has been employed in nutrition science, toxicology, environmental studies, and systems biology. Metabolomics is particularly useful in biomedical science, and has been used for diagnostic laboratory testing, identifying targets for drug development, and monitoring drug metabolism, mode of action, and toxicity. Despite its immense potential, metabolomics remains underutilized in the study of spontaneous animal diseases. Our aim was to comprehensively review the existing literature on the use of metabolomics in spontaneous veterinary diseases. Three databases were used to find journal articles that applied metabolomics in veterinary medicine. A screening process was then conducted to eliminate references that did not meet the eligibility criteria; only primary research studies investigating spontaneous animal disease were included; 38 studies met the inclusion criteria. The main techniques used were NMR and MS. All studies detected metabolite alterations in diseased animals compared with non-diseased animals. Metabolomics was mainly used to study diseases of the digestive, reproductive, and musculoskeletal systems. Inflammatory conditions made up the largest proportion of studies when articles were categorized by disease process. Following a comprehensive analysis of the literature on metabolomics in spontaneous veterinary diseases, we concluded that metabolomics, although in its early stages in veterinary research, is a promising tool regarding diagnosis, biomarker discovery, and in uncovering new insights into disease pathophysiology.

Biogenic Silver Nanoparticles as a Post-surgical Treatment for Corynebacterium pseudotuberculosis Infection in Small Ruminants

Caseous lymphadenitis (CL) is an infectious and zoonotic disease characterized by the development of granulomas in the lymph nodes and internal organs of small ruminants. The etiological agent of this disease is Corynebacterium pseudotuberculosis, a Gram-positive and facultative intracellular bacterium. The conventional treatment for CL consists of drainage and chemical cauterization of the lesions using a 10% iodine solution. However, this type of treatment is not effective, due to iodine's cytotoxic profile and low antibacterial activity. Currently, silver nanoparticles (AgNPs) can be seen as an alternative treatment for CL due to their antimicrobial activity and wound healing effects. Therefore, the present study aimed to evaluate AgNPs as a post-surgical treatment for CL. Twenty-nine goats and sheep with clinical signs of CL were selected. Surgical intervention was performed to excise the caseous lesions. To treat the lesions, an ointment formulation based on AgNP mixed with natural waxes and oils was used in the experimental group, and the conventional treatment with 10% iodine was used in the control group. Bacteria were isolated from the excised caseous material. The animals were observed for 8 weeks after the surgical treatment, and blood samples were taken weekly. The surgical wounds of sheep treated with AgNP healed faster, and the surgical wound area was smaller during the observation period; the latter effect was also observed in goats. AgNP-treated animals also had less purulent discharge and less moisture in the surgical wounds. The AgNP-treated animals had lower leukocyte counts and lower titers of anti-C. pseudotuberculosis antibodies. There was no statistically significant difference between the groups with regard to the hemogram results. The results of the susceptibility testing of C. pseudotuberculosis strains (T1, 1002, FRC41, and VD57 strains) and clinical isolates to AgNPs showed growth inhibition, even at low concentrations. It can be concluded that post-surgical treatment of CL using the AgNP-based ointment may be a promising tool in the control of CL, through faster healing, decreased wound contamination, and no apparent toxic effects.