Sulfated Polysaccharide Extracted from the Green Algae Codium bernabei: Physicochemical Characterization and Antioxidant, Anticoagulant and Antitumor Activity.

Codium bernabei is a green alga that grows on Chilean coasts. The composition of its structural polysaccharides is still unknown. Hence, the aim of this work is to isolate and characterize the hot water extracted polysaccharide fractions. For this purpose, the water extracts were further precipitated in alcohol (TPs) and acid media (APs), respectively. Both fractions were characterized using different physicochemical techniques such as GC-MS, GPC, FTIR, TGA, and SEM. It is confirmed that the extracted fractions are mainly made of sulfated galactan unit, with a degree of sulfation of 19.3% (TPs) and 17.4% (ATs) and a protein content of 3.5% in APs and 15.6% in TPs. Other neutral sugars such as xylose, glucose, galactose, fucose, mannose, and arabinose were found in a molar ratio (0.05:0.6:1.0:0.02:0.14:0.11) for TPs and (0.05:0.31:1.0:0.03:0.1:0.13) for ATs. The molecular weight of the polysaccharide samples was lower than 20 kDa. Both polysaccharides were thermally stable (Tonset > 190 °C) and showed antioxidant activity according to the ABTS•+ and DPPH tests, where TPs fractions had higher scavenging activity (35%) compared to the APs fractions. The PT and APTTS assays were used to measure the anticoagulant activity of the polysaccharide fractions. In general, the PT activity of the TPs and APs was not different from normal plasma values. The exception was the TPs treatment at 1000 µg mL−1 concentration. The APTTS test revealed that clotting time for both polysaccharides was prolonged regarding normal values at 1000 µg mL−1. Finally, the antitumor test in colorectal carcinoma (HTC-116) cell line, breast cancer (MCF-7) and human leukemia (HL-60) cell lines showed the cytotoxic effect of TPs and APs. Those results suggest the potential biotechnological application of sulfate galactan polysaccharides isolated from a Chilean marine resource.

Protective effect of inactivated blastoconidia in keratinocytes and human reconstituted epithelium against C. albicans infection.

Candida albicans is commensal yeast that colonizes skin and mucosa; however, it can become an opportunist pathogen by changing from blastoconidia (commensal form) into hypha (pathogenic form). Each form activates a different cytokines response in epithelial cells. Little is known about the commensal role of C. albicans in the innate immunity. This work studied whether stimulation with C. albicans blastoconidia induces protection in keratinocytes and/or in a reconstituted human epithelium (RHE) infected with C. albicans. For this, inactivated C. albicans blastoconidia was used to stimulate keratinocytes and RHE prior to infection with C. albicans. Blastoconidia induced different cytokine expression profiles; in the case of RHE it decreased interleukin (IL)-1ß and IL-10 and increased IL-8, tumor necrosis factor α (TNF-α), and interferon γ (IFN-γ). A significant increase in the expression of human ß-defensins (HBD) 2 and HBD3 was observed in blastoconidia stimulated keratinocytes and RHE, associated with impaired growth and viability of C. albicans. Additionally, blastoconidia stimulation decreased the expression of virulence factors in C. albicans that are associated with filamentation (EFG1, CPH1 and NRG1), adhesion (ALS5), and invasion (SAP2). Blastoconidia stimulated RHE was significantly less damaged by C. albicans invasion. These results show that the commensal form of C. albicans would exert a protective effect against self-infection.

Microbiological characterisation of the colonisation by Candida sp in patients with orthodontic fixed appliances and evaluation of host responses in saliva.

OBJECTIVES: We investigated the colonisation by Candida spp in patients using orthodontic fixed appliances by characterising the isolated Candida strains and by evaluating the host oral mucosa response through the measure of human ß-defensins 3 (HBD-3) expression and Interleukin-1ß/IL-10. METHODS: Ninety patients were enrolled after signing an informed consent. Prevalence, susceptibility to fluconazole, genotyping and oral fungal burden of Candida sp. isolated were determined. Host responses were evaluated by measuring HBD-3 expression as well as IL-1ß and IL-10 in saliva. RESULTS: The colonisation rate reached 6.7% (6/90), and 5 patients were colonised with C. albicans strains and one with one with C. tropicalis. The fluconazole MIC90/susceptibility of C. albicans strains ranged 1/0.25-1 µg/mL. However, isolated strains did not present different genotype (SAB>0.9), C. albicans colonisation seems to be influenced by the duration of treatment and by level expression of HBD3 that were higher in colonised patients (not statistically different). A negative correlation between the fungal burden and IL-1ß levels was found in colonised patients but not for IL-10. CONCLUSIONS: Our study revealed that patients with orthodontic fixed appliances were mainly colonised by C. albicans, which was related to a decrease in HBD-3 expression and IL-1ß levels.

Modified Profile of Matrix Metalloproteinase 2 and 9 Production by Human Fallopian Tube Epithelial Cells After Infection In Vitro With Neisseria gonorrhoeae.

Epithelial shedding and scarring of fallopian tube mucosa are the main consequences of sexually transmitted Neisseria gonorrhoeae infection and probably involve an imbalance of host extracellular matrix components and their regulators such as matrix metalloproteinases (MMPs). In the current study, primary human fallopian tube epithelial cells were infected with N. gonorrhoeae, and MMP patterns were examined. Gonococcal infection induced a significant increase in secreted MMP-9 and an accumulation of cytoplasmic MMP-2 over time, but no significant MMP-3 or MMP-8 production was observed. Thus, MMP-9 in particular could play a role in tubal scarring in response to gonococcal infection.

Genotyping and Persistence of Candida albicans from Pregnant Women with Vulvovaginal Candidiasis.

OBJECTIVE: To study Candida albicans genotypes using RAPD and their susceptibility to fluconazole in healthy pregnant women and in vulvovaginal candidiasis (VVC) patients after topical treatment with clotrimazole. METHODS: Vaginal swabs were collected at t = 0 and t = 1 (1 month later) in pregnant women (control group, n = 33), and before (t = 0), at 1 month (t = 1) and at 2 months (t = 2) after clotrimazole treatment in pregnant women with VVC. RESULTS: Candida albicans was isolated in 30% of healthy pregnant women and 80% of patients with VVC. A high genetic heterogeneity was observed in C. albicans genotypes between individuals. In patients with VVC, topical antifungal treatment with clotrimazole was clinically effective, but only in a 62% C. albicans was eradicated. In patients in which C. albicans was not eradicated, this microorganism persisted for 1 or 2 months after the antifungal treatment. The persistent colonies were not associated with a specific genotype, but they were associated with higher MICs in comparison with colonies isolated from the control group. CONCLUSIONS: Therapy with topical clotrimazole, despite a good clinical outcome, could not eradicate completely C. albicans allowing the persistence of genotypes, with higher MICs to fluconazole. More studies with higher number of patients are needed to validate this preliminary finding.

Neurological Adverse Effects of Antipsychotics in Children and Adolescents.

OBJECTIVE: The aim of this study was to evaluate demographic, clinical, and treatment factors that may impact on neurological adverse effects in naive and quasi-naive children and adolescents treated with antipsychotics. METHODS: This was a 1-year, multicenter, observational study of a naive and quasi-naive pediatric population receiving antipsychotic treatment. Two subanalyses were run using the subsample of subjects taking the 3 most used antipsychotics and the subsample of antipsychotic-naive subjects. Total dyskinesia score (DyskinesiaS) and total Parkinson score (ParkinsonS) were calculated from the Maryland Psychiatric Research Center Involuntary Movement Scale, total UKU-Cognition score was calculated from the UKU Side Effect Rating Scale. Risk factors for tardive dyskinesias (TDs) defined after Schooler-Kaine criteria were studied using a logistic regression. RESULTS: Two hundred sixty-five subjects (mean age, 14.4 [SD, 2.9] years) with different Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition Axis I disorders were recruited. DyskinesiaS (P < 0.001) and ParkinsonS (P < 0.001) increased at 1-year follow-up. Risperidone was associated with higher increases in DyskinesiaS compared with quetiapine (P < 0.001). Higher increases in ParkinsonS were found with risperidone (P < 0.001) and olanzapine (P = 0.02) compared with quetiapine. Total UKU-Cognition Score decreased at follow-up. Findings were also significant when analyzing antipsychotic-naive subjects. Fifteen subjects (5.8%) fulfilled Schooler-Kane criteria for TD at follow-up. Younger age, history of psychotic symptoms, and higher cumulative exposure time were associated with TD at follow-up. CONCLUSIONS: Antipsychotics increased neurological adverse effects in a naive and quasi-naive pediatric population and should be carefully monitored. Risperidone presented higher scores in symptoms of dyskinesia and parkinsonism. Quetiapine was the antipsychotic with less neurological adverse effects. Younger subjects, psychosis, and treatment factors predicted an increased risk of TD.

Antipsychotic use in children and adolescents: a 1-year follow-up study.

OBJECTIVE: The objective of this study was to analyze the initial treatment with antipsychotics (APs) and its changes during the first year of treatment in patients visited in specialized child and adolescent psychiatry departments. METHODS: Participants were 265 patients, aged 4 to 17 years, who attended consecutively at 4 different centers and were naive of AP or quasi-naive (less than 30 days since the beginning of AP treatment). Type of AP, dosage, and concomitant medication were registered at baseline, 1, 3, 6, and 12 months after beginning the treatment with AP. RESULTS: At baseline, the patients' mean age was 14.4 (2.9) years, and 145 (54.7%) patients were males. Antipsychotics were more prescribed in the following: schizophrenia spectrum disorders (30.2%), disruptive behavior disorders (DBDs) (18.9%), bipolar disorders (14.3%), depressive disorders (12.8%), and eating disorders (11.7%). A total of 93.2% of the patients were on an off-label indication of AP. Risperidone was the AP most prescribed in all the assessments, but differences were observed in the type of AP according to diagnosis. Thus, risperidone was significantly most prescribed in patients with DBD and olanzapine was most prescribed in patients with eating disorders. Olanzapine and quetiapine were the second-generation APs (SGAs) most prescribed after risperidone, and haloperidol was the most prescribed first-generation AP. Up to 8.3% of patients during the follow-up were on AP polypharmacy. Almost 16% patients had a change in its AP treatment during the follow-up, and the main switch was from one SGA to another. CONCLUSIONS: Second-generation APs were the APs most prescribed in our sample and approximately 93% of the patients used AP off-label. Risperidone was the most common AP used above all in patients with DBD, whereas olanzapine was most prescribed in patients with eating disorders. Antipsychotic polypharmacy and switch rates were low during the follow-up.

Chitosan microparticles loaded with yeast-derived PCV2 virus-like particles elicit antigen-specific cellular immune response in mice after oral administration.

BACKGROUND: Porcine circovirus type 2 (PCV2)-associated diseases are a major problem for the swine industry worldwide. In addition to improved management and husbandry practices, the availability of several anti-PCV2 vaccines provides an efficient immunological option for reducing the impact of these diseases. Most anti-PCV2 vaccines are marketed as injectable formulations. Although these are effective, there are problems associated with the use of injectable products, including laborious and time-consuming procedures, the induction of inflammatory responses at the injection site, and treatment-associated stress to the animals. Oral vaccines represent an improvement in antigen delivery technology; they overcome the problems associated with injection management and facilitate antigen boosting when an animals' immunity falls outside the protective window. METHODS: Chitosan microparticles were used as both a vehicle and mucosal adjuvant to deliver yeast-derived PCV2 virus-like particles (VLPs) in an attempt to develop an oral vaccine. The physical characteristics of the microparticles, including size, Zeta potential, and polydispersity, were examined along with the potential to induce PCV2-specific cellular immune responses in mice after oral delivery. RESULTS: Feeding mice with PCV2 VLP-loaded, positively-charged chitosan microparticles with an average size of 2.5 µm induced the proliferation of PCV2-specific splenic CD4+/CD8+ lymphocytes and the subsequent production of IFN-γ to levels comparable with those induced by an injectable commercial formulation. CONCLUSION: Chitosan microparticles appear to be a safe, simple system on which to base PCV2 oral vaccines. Oral chitosan-mediated antigen delivery is a novel strategy that efficiently induces anti-PCV2 cellular responses in a mouse model. Further studies in swine are warranted.

Melanocytes and melanin represent a first line of innate immunity against Candida albicans.

Melanocytes are dendritic cells located in the skin and mucosae that synthesize melanin. Some infections induce hypo- or hyperpigmentation, which is associated with the activation of Toll-like receptors (TLRs), especially TLR4. Candida albicans is an opportunist pathogen that can switch between blastoconidia and hyphae forms; the latter is associated with invasion. Our objectives in this study were to ascertain whether C. albicans induces pigmentation in melanocytes and whether this process is dependent on TLR activation, as well as relating this with the antifungal activity of melanin as a first line of innate immunity against fungal infections. Normal human melanocytes were stimulated with C. albicans supernatants or with crude extracts of the blastoconidia or hyphae forms, and pigmentation and TLR2/TLR4 expression were measured. Expression of the melanosomal antigens Melan-A and gp100 was examined for any correlation with increased melanin levels or antifungal activity in melanocyte lysates. Melanosomal antigens were induced earlier than cell pigmentation, and hyphae induced stronger melanization than blastoconidia. Notably, when melanocytes were stimulated with crude extracts of C. albicans, the cell surface expression of TLR2/TLR4 began at 48 h post-stimulation and peaked at 72 h. At this time, blastoconidia induced both TLR2 and TLR4 expression, whereas hyphae only induced TLR4 expression. Taken together, these results suggest that melanocytes play a key role in innate immune responses against C. albicans infections by recognizing pathogenic forms of C. albicans via TLR4, resulting in increased melanin content and inhibition of infection.

[Characterization of azole resistance mechanisms in Chilean clinical isolates of Candida albicans]. / Caracterización de los mecanismos de resistencia a azoles en aislados clínicos chilenos de Candida albicans.

INTRODUCTION: The commensal yeast Candida albicans, can cause superficial or systemic candidiasis in susceptible hosts. In Chile, azole antifungals are the most widely used drugs in the treatment of candidiasis. In a previous study performed at our center, 2.1 and 1.6% of clinical isolates of C. albicans were found to be resistant to fluconazole and voriconazole, respectively. OBJECTIVE: To characterize the resistance mechanisms involved in azoles resistance in Chilean clinical isolates. METHODOLOGY: Eight resistant, nine susceptible-dose dependent (SDD) and 10 susceptible strains (n: 27) were selected according to the Clinical Laboratory Standards Institute (CLSI) M27-S3 criteria, from vaginal and urine samples. Mutations in the 408-488 region of the ERG11 gene were studied by sequencing, and the relative expression of ERG11 gene and efflux pump genes CDR1, CDR2 and MDR1, was evaluated by quantitative real-time PCR (q-PCR). RESULTS: No mutations were detected in the ERG11 gene and its overexpression was found only in 12.5% of the resistant strains (1/8). The most prevalent mechanism of resistance was the over-expression of efflux pumps (62.5%; 5/8). CONCLUSION: The study of the expression of efflux pumps by q-PCR could be a useful diagnostic tool for early detection of azole resistance in C. albicans.

[Antifungal activity of melanin in clinical isolates of Candida spp]. / Actividad antifúngica de melanina en cepas clínicas de Candida spp.

BACKGROUND: Melanocytes are cells located in epidermis and mucous membranes that synthesize melanin and cytokines. It is known that melanin has antimicrobial activity and that melanocytes are melanized in presence of microbial molecules. OBJECTIVE: To study the antifungal activity of melanin on Candida spp. METHODOLOGY: The minimum inhibitory concentration (MIC) to melanin was determined in 4 Candida ATCC strains (C. albicans SC5314, C. parapsilosis 22019, C. glabrata 2001, C. krusei 6258) and 56 clinical isolates of Candida spp. (33 C. albicans, 12 C. glabrata, 3 C. famata, 3 C. krusei, 3 C. parapsilosis, 2 C. tropicalis) using a broth microdilution method. In addition, the antifungal activity of melanocytes and mice melanoma cells was tested against C. albicans. RESULTS: Melanin inhibited the tested isolates, including the susceptible dose-dependent and fluconazole-resistant strains; MIC range and MIC50 were 0.09-50 µg/mL and 6.25 µg/mL, respectively. Pigmented cells lysates inhibited C. albicans. CONCLUSIONS: Melanin is able to inhibit clinical isolates of Candida spp. Melanization could be an important protective mechanism of melanocytes.

Optimization of lung tissue pre-treatment by bead homogenization for subsequent culturomics.

The discovery that the lung harbors a diverse microbiome, as revealed by next-generation sequencing, has significantly altered our understanding of respiratory health and disease. Despite the association between the lung microbiota and disease, the nature of their relationship remains poorly understood, and culture isolation of these microorganisms could help to determine their role in lung physiology. Current procedures for processing samples from the lower respiratory tract have been shown to affect the viability of microorganisms, so it is crucial to develop new methods to improve their survival. This study aimed to improve the isolation and characterization of lung microorganisms using a bead-beating homogenization method in a mouse model. Microsphere diameter and bead-beating time affected the survival of the microorganisms (E. coli, S. aureus and C. albicans). Using 2.3 mm diameter microspheres for 60 s of bead-beating promoted the survival of both bacteria and yeast strains. After intratracheal instillation of these microorganisms in mice, approximately 70% of the cells were recovered after the tissue homogenization. To assess the efficiency of the proposed method, the diversity of bacteria was compared between the homogenate and lung tissue samples. Ninety-one genera were detected in the lung tissue, and 63 in the homogenate. Bacterial genera detected in the homogenate represented 84% of the total abundance of the microbiota identified in the lung tissue. Taken together, these results demonstrate that the tissue homogenization process developed in this study recovered the majority of the microorganisms present in the lung. This study presents a bead-beating homogenization method for effective cultivation of lung tissue microorganisms, which may help to improve the understanding of host-microbe interactions in the lung.

[Species distribution and susceptibility pattern of Candida spp.: the importance to survey also strains isolated from the community]. / Distribución de especies y perfil de susceptibilidad de aislados de Candida spp: la importancia de vigilar también cepas de la comunidad.

BACKGROUND: The most of the surveillance studies has been conducted in hospitalized patients with invasive infections. Recently, new clinical breakpoints (CBPs) have been proposed for antifungal susceptibility testing and epidemiological cutoffs (ECVs). AIM: To evaluate species distribution and susceptibility pattern of Candida spp. obtained from in and outpatients in a period of 6 months. MATERIAL AND METHODS: The isolates (n=223) came from vaginal discharge (51.6%), lower respiratory tract (24.7%), urine (20.2%), wounds (1.8%), blood (0.9%), peritoneal fluid (0.4%) and nails (0.4%). RESULTS: The species distribution was C. albicans 84.8% (n: 189), C. glabrata 7.6% (n: 17), C. tropicalis 2.7% (n: 6), C. parapsilosis 2.2% (n: 5), C. kefyr 0.9% (n: 2) and others 1.8% (C. krusei, C. lusitanie, C. guilliermondii, C. intermedia) (n: 4). The susceptibility dose dependence (SDD) and resistance were 3.2% for fluconazole and 2.2% for voriconazole. The most of SDD and resistant strains were isolated from ambulatory patients. Also, a higher percentage of MICs over the new CBPs and ECVs were found in strains from ambulatory patients and especially in C. glabrata isolates to caspofungin. CONCLUSION: Taking into consideration that most of the invasive infections are caused by strains from the endogenous microbiota, and that there is a resistant population of Candida spp. in the community, should be important to include in surveillance studies strains isolated from ambulatory patients.

Overnutrition as a risk factor for more serious respiratory viral infections in children: A retrospective study in hospitalized patients.

BACKGROUND: The prevalence of obesity has increased dramatically in children worldwide. Obesity has been recognized as a risk factor for more serious viral respiratory infections, mainly in adults. OBJECTIVE: To study the relationship between overnutrition (obesity and overweight) and clinical severity in children hospitalized with acute respiratory infections of viral origin. METHODS: One hundred and forty-three clinical records of children between 2 and 18 years old hospitalized for acute respiratory infection at Clínica Dávila (2014-2018) were analyzed, recording the respiratory viruses detected at the time of hospitalization, weight, and height. Nutritional status was estimated using Z score or body mass index, according to age. RESULTS: Eighty-tree3 children (58%) were positive for more than one respiratory virus. The main virus detected in monoinfection was adenovirus (9.8%), followed by respiratory syncytial virus (7.7%) and parainfluenza virus (7.7%). There were no deaths. Patients with obesity presented more days of hospitalization (P = .04), oxygen therapy (P = .03) and mechanical ventilation (P < .001), as well as a higher probability of requiring mechanical ventilation (P = .001) and of ICU admission (P = .003) compared with children with normal weight. Patients with overweight presented more days of mechanical ventilation (P < .001) than patients with normal weight. No significant differences were found between the presence of viral coinfection and nutritional status. CONCLUSION: Overnutrition is associated with greater severity of viral respiratory infection in hospitalized children.

Overnutrition, Nasopharyngeal Pathogenic Bacteria and Proinflammatory Cytokines in Infants with Viral Lower Respiratory Tract Infections.

Background: Little is known about the interaction between the nasopharyngeal bacterial profile and the nutritional status in children. In this study, our main goal was to evaluate the associations between overnutrition and the presence of four potentially pathogenic bacteria in the nasopharynx of infants with viral lower respiratory tract infections (LRTI). In addition, we determined whether changes in the nasopharyngeal bacterial profile were associated with mucosal and serum proinflammatory cytokines and with clinical disease severity. Methods: We enrolled 116 children less than 2 years old hospitalized for viral LRTI during two consecutive respiratory seasons (May 2016 to August 2017); their nutritional status was assessed, and nasopharyngeal and blood samples were obtained. S. aureus, S. pneumoniae, H. influenzae, M. catarrhalis, and respiratory viruses were identified in nasopharyngeal samples by qPCR. Cytokine concentrations were measured in nasopharyngeal and blood samples. Disease severity was assessed by the length of hospitalization and oxygen therapy. Results: Nasopharyngeal pathogenic bacteria were identified in 96.6% of the enrolled children, and 80% of them tested positive for two or more bacteria. The presence and loads of M. catarrhalis was higher (p = 0.001 and p = 0.022, respectively) in children with overnutrition (n = 47) compared with those with normal weights (n = 69). In addition, the detection of >2 bacteria was more frequent in children with overnutrition compared to those with normal weight (p = 0.02). Multivariate regression models showed that the presence and loads of S. pneumoniae and M. catarrhalis were associated with higher concentrations of IL-6 in plasma and TNF-α in mucosal samples in children with overnutrition. Conclusions: The nasopharyngeal profile of young children with overnutrition was characterized by an over representation of pathogenic bacteria and proinflammatory cytokines.

Performance of Saliva Samples for COVID-19 Diagnosis by Using the AllplexTM 2019-nCoV Assay Kit.

Background: Although the nasopharyngeal swab (NPS) is the reference sampling method for the detection of SARS-Cov-2, it is not always possible to collect NPS in some patients. Saliva represents an interesting sampling method because it is less invasive and more convenient in patients with nasal or pharyngeal lesions. Objective: To compare the RT-qPCR test performances of saliva samples with nasal mid-turbinate swab (NMTS) and NPS samples in a cohort of ambulatory patients suspected of having COVID-19. Study Design: For each of the 112 enrolled patients, NPS, NMTS, and saliva samples were collected and tested for SARS-Cov-2 detection using three different target genes (RdRP, N and E genes) by RT-qPCR. Results: Among the positive samples (56/112), saliva samples showed a lower percentage of SARS-Cov-2 detection compared to NPS samples, (85.7 vs. 96.4%), while still a lower percentage was observed for NMTS samples (78.6%). In average, saliva samples showed higher Ct values for all tested target genes, compared to those from NPS and NMTS samples. Conclusions: By using the AllplexTM 2019-nCoV Assay Kit, saliva samples showed lower sensitivity for SARS CoV-2 compared to NPS samples; however, the not detected cases had lower viral burden in NPS samples (CT values >33) representing an interesting alternative sampling method in patients in which it is not possible to take a NPS sample.

Smartphone screen testing, a novel pre-diagnostic method to identify SARS-CoV-2 infectious individuals.

The COVID-19 pandemic will likely take years to control globally, and constant epidemic surveillance will be required to limit the spread of SARS-CoV-2, especially considering the emergence of new variants that could hamper the effect of vaccination efforts. We developed a simple and robust - Phone Screen Testing (PoST) - method to detect SARS-CoV-2-positive individuals by RT-PCR testing of smartphone screen swab samples. We show that 81.3-100% of individuals with high-viral-load SARS-CoV-2 nasopharyngeal-positive samples also test positive for PoST, suggesting this method is effective in identifying COVID-19 contagious individuals. Furthermore, we successfully identified polymorphisms associated with SARS-CoV-2 Alpha, Beta, and Gamma variants, in SARS-CoV-2-positive PoST samples. Overall, we report that PoST is a new non-invasive, cost-effective, and easy-to-implement smartphone-based smart alternative for SARS-CoV-2 testing, which could help to contain COVID-19 outbreaks and identification of variants of concern in the years to come.

Antifungal activity of low molecular weight chitosan against clinical isolates of Candida spp.

Chitosan is a natural polymer derived from chitin, a structural component of fungi, insects and shrimp, which exerts antimicrobial effects against bacteria and fungi. The aim of this study was to investigate the in vitro antifungal activity of low molecular weight chitosan (LMWC), and the potential synergy between chitosan and a currently used antifungal drug, fluconazole. The in vitro minimal inhibitory concentrations (MICs) of chitosan and fluconazole against 105 clinical Candida isolates were measured by the broth microdilution method. LMWC exhibited a significant antifungal activity, inhibiting over 89.9% of the clinical isolates examined (68.6% of which was completely inhibited). The species included several fluconazole-resistant strains and less susceptible species such as C. glabrata, which was inhibited at a concentration of 4.8 mg/l LMWC. Although some strains were susceptible at pH 7.0, a greater antifungal activity of LMWC was observed at pH 4.0. There was no evidence of a synergistic effect of the combination of LMWC and fluconazole at pH 7.0. This is the first report in which the antifungal activity of LMWC was investigated with clinical Candida strains. The use of LMWC as an antifungal compound opens new therapeutic perspectives, as the low toxicity of LMWC in humans supports its use in new applications in an environment of pH 4.0-4.5, such as a topical agent for vulvovaginal candidiasis.

Chilean crab (Aegla cholchol) as a new source of chitin and chitosan with antifungal properties against Candida spp.

In the present work, the chemical composition of the Chilean freshwater crab Aegla cholchol exoskeleton was studied for the first time. α-Chitin was isolated from three main body parts (pincers, legs, carapace), and its content ranged from 9.0-10.4% (w/w). Moreover, chitosan was extracted by alkaline treatment at different temperature and time regimes. Aegla cholchol exoskeleton, chitin and chitosans were characterized by FTIR, TGA, and SEM. Chemical structure of chitin and chitosan was confirmed by NMR spectroscopy. Chitosan molecular weight determinations were carried out by GPC. The obtained chitosan samples had a degree of N-acetylation (DA) between 4 and 15% and molecular weight (Mw) in the range of 65-201 kDa. The antifungal activity of the chitosan samples and the chitooligomer were tested toward twenty isolated clinical strains of Candida yeast. Chitosan with lower DA (4%) and higher molecular weight showed the lowest minimum inhibitory concentration (MIC) values, which was evidenced by the highest antifungal activity toward Candida albicans, Candida tropicalis, Candida glabrata, and Candida parapsilosis. Results suggest that Aegla cholchol is an excellent natural source for production of bioactive materials with potential applications in the health system, to prevent infections associated with Candida strains.