Promising activity of etomidate against mixed biofilms of fluconazole-resistant Candida albicans and methicillin-resistant Staphylococcus aureus

Introduction. Candida albicans and Staphylococcus aureus are recognized for their development of resistance and biofilm formation. New therapeutic alternatives are necessary in this context.Hypothesis. Etomidate shows potential application in catheters against mixed biofilms of fluconazole-resistant C. albicans and methicillin-resistant S. aureus (MRSA).Aim. The present study aimed to evaluate the activity of etomidate against mixed biofilms of fluconazole-resistant C. albicans and MRSA.Methodology. The action of etomidate against mature biofilms was verified through the evaluation of biomass and cell viability, and its ability to prevent biofilm formation in peripheral venous catheters was determined based on counts of colony forming units (c.f.u.) and confirmed by morphological analysis through scanning electron microscopy (SEM).Results. Etomidate generated a reduction (P<0.05) in biomass and cell viability starting from a concentration of 250 µg ml-1. In addition, it showed significant ability to prevent the formation of mixed biofilms in a peripheral venous catheter, as shown by a reduction in c.f.u. SEM revealed that treatment with etomidate caused substantial damage to the fungal cells.Conclusion. The results showed the potential of etomidate against polymicrobial biofilms of fluconazole-resistant C. albicans and MRSA.

Antimicrobial activity of hydralazine against methicillin-resistant and methicillin-susceptible Staphylococcus aureus

Background: Staphylococcus aureus is a human pathogen responsible for high mortality rates. The development of new antimicrobials is urgent. Materials & methods: The authors evaluated the activity of hydralazine along with its synergism with other drugs and action on biofilms. With regard to action mechanisms, the authors evaluated cell viability, DNA damage and molecular docking. Results: MIC and minimum bactericidal concentration values ranged from 128 to 2048 μg/ml. There was synergism with oxacillin (50%) and vancomycin (25%). Hydralazine reduced the viability of biofilms by 50%. After exposure to hydralazine 2× MIC, 58.78% of the cells were unviable, 62.07% were TUNEL positive and 27.03% presented damage in the comet assay (p < 0.05). Hydralazine showed affinity for DNA gyrase and TyrRS. Conclusion: Hydralazine is a potential antibacterial.

Antifungal activity of selective serotonin reuptake inhibitors against Cryptococcus spp. and their possible mechanism of action

Fungal infections caused by Cryptococcus spp. pose a threat to health, especially in immunocompromised individuals. The available arsenal of drugs against cryptococcosis is limited, due to their toxicity and/or lack of accessibility in low-income countries, requiring more therapeutic alternatives. Selective serotonin reuptake inhibitors (SSRIs), through drug repositioning, are a promising alternative to broaden the range of new antifungals against Cryptococcus spp. This study evaluates the antifungal activity of three SSRIs, sertraline, paroxetine, and fluoxetine, against Cryptococcus spp. strains, as well as assesses their possible mechanism of action. Seven strains of Cryptococcus spp. were used. Sensitivity to SSRIs, fluconazole, and itraconazole was evaluated using the broth microdilution assay. The interactions resulting from combinations of SSRIs and azoles were investigated using the checkerboard assay. The possible action mechanism of SSRIs against Cryptococcus spp. was evaluated through flow cytometry assays. The SSRIs exhibited in vitro antifungal activity against Cryptococcus spp. strains, with minimum inhibitory concentrations ranging from 2 to 32 μg/mL, and had synergistic and additive interactions with azoles. The mechanism of action of SSRIs against Cryptococcus spp. involved damage to the mitochondrial membrane and increasing the production of reactive oxygen species, resulting in loss of cellular viability and apoptotic cell death. Fluoxetine also was able to cause significant damage to yeast DNA. These findings demonstrate the in vitro antifungal potential of SSRIs against Cryptococcus spp. strains.

Analysis of possible pathways on the mechanism of action of minocycline and doxycycline against strains of Candida spp. resistant to fluconazole

Species of the genus Candida, characterized as commensals of the human microbiota, are opportunistic pathogens capable of generating various types of infections with high associated costs. Considering the limited pharmacological arsenal and the emergence of antifungal-resistant strains, the repositioning of drugs is a strategy used to search for new therapeutic alternatives, in which minocycline and doxycycline have been evaluated as potential candidates. Thus, the objective was to evaluate the in vitro antifungal activity of two tetracyclines, minocycline and doxycycline, and their possible mechanism of action against fluconazole-resistant strains of Candida spp. The sensitivity test for antimicrobials was performed using the broth microdilution technique, and the pharmacological interaction with fluconazole was also analysed using the checkerboard method. To analyse the possible mechanisms of action, flow cytometry assays were performed. The minimum inhibitory concentration obtained was 4-427 µg ml-1 for minocycline and 128-512 µg ml-1 for doxycycline, and mostly indifferent and additive interactions with fluconazole were observed. These tetracyclines were found to promote cellular alterations that generated death by apoptosis, with concentration-dependent reactive oxygen species production and reduced cell viability. Therefore, minocycline and doxycycline present themselves as promising study molecules against Candida spp.

Antibacterial activity of menadione alone and in combination with oxacillin against methicillin-resistant Staphylococcus aureus and its impact on biofilms

Introduction. Antibiotic resistance is a major threat to public health, particularly with methicillin-resistant Staphylococcus aureus (MRSA) being a leading cause of antimicrobial resistance. To combat this problem, drug repurposing offers a promising solution for the discovery of new antibacterial agents.Hypothesis. Menadione exhibits antibacterial activity against methicillin-sensitive and methicillin-resistant S. aureus strains, both alone and in combination with oxacillin. Its primary mechanism of action involves inducing oxidative stress.Methodology. Sensitivity assays were performed using broth microdilution. The interaction between menadione, oxacillin, and antioxidants was assessed using checkerboard technique. Mechanism of action was evaluated using flow cytometry, fluorescence microscopy, and in silico analysis.Aim. The aim of this study was to evaluate the in vitro antibacterial potential of menadione against planktonic and biofilm forms of methicillin-sensitive and resistant S. aureus strains. It also examined its role as a modulator of oxacillin activity and investigated the mechanism of action involved in its activity.Results. Menadione showed antibacterial activity against planktonic cells at concentrations ranging from 2 to 32 µg ml-1, with bacteriostatic action. When combined with oxacillin, it exhibited an additive and synergistic effect against the tested strains. Menadione also demonstrated antibiofilm activity at subinhibitory concentrations and effectively combated biofilms with reduced sensitivity to oxacillin alone. Its mechanism of action involves the production of reactive oxygen species (ROS) and DNA damage. It also showed interactions with important targets, such as DNA gyrase and dehydroesqualene synthase. The presence of ascorbic acid reversed its effects.Conclusion. Menadione exhibited antibacterial and antibiofilm activity against MRSA strains, suggesting its potential as an adjunct in the treatment of S. aureus infections. The main mechanism of action involves the production of ROS, which subsequently leads to DNA damage. Additionally, the activity of menadione can be complemented by its interaction with important virulence targets.

Sertraline has in vitro activity against both mature and forming biofilms of different Candida species

Candida spp. infections are a serious health problem, especially in patients with risk factors. The acquisition of resistance, often associated with biofilm production, makes treatment more difficult due to the reduced effectiveness of available antifungals. Drug repurposing is a good alternative for the treatment of infections by Candida spp. biofilms. The present study evaluated the in vitro antibiofilm activity of sertraline in reducing the cell viability of forming and matured biofilms, in addition to elucidating whether effective concentrations are safe. Sertraline reduced biofilm cell viability by more than 80 % for all Candida species tested, acting at low and safe concentrations, both on mature biofilm and in preventing its formation, even the one with highest virulence. Its preventive mechanism seemed to be related to binding with ALS3. These data indicate that sertraline is a promising drug with anticandidal biofilm potential in safe doses. However, further studies are needed to elucidate the antibiofilm mechanism and possible application of pharmaceutical forms.

Antifungal activity of etomidate against growing biofilms of fluconazole-resistant Candida spp. strains, binding to mannoproteins and molecular docking with the ALS3 protein

This study evaluated the effect of etomidate against biofilms of Candida spp. and analysed through molecular docking the interaction of this drug with ALS3, an important protein for fungal adhesion. Three fluconazole-resistant fungi were used: Candida albicans, Candida parapsilosis and Candida tropicalis. Growing biofilms were exposed to etomidate at 31.25-500 µg ml^-1. Then, an ALS3 adhesive protein from C. albicans was analysed through a molecular mapping technique, composed of a sequence of algorithms to perform molecular mapping simulation based on classic force field theory. Etomidate showed antifungal activity against growing biofilms of resistant C. albicans, C. parapsilosis and C. tropicalis at all concentrations used in the study. The etomidate coupling analysis revealed three interactions with the residues of interest compared to hepta-threonine, which remained at the ALS3 site. In addition, etomidate decreased the expression of mannoproteins on the surface of C. albicans. These results revealed that etomidate inhibited the growth of biofilms.

Polymorphisms in key bone modulator cytokines genes influence bisphosphonates therapy in postmenopausal women

Osteoporosis is a multifactorial and debilitating disease resulting from decreased bone mineral density (BMD) and loss of tissue microarchitecture. Ineffective therapies may lead to bone fractures and subsequent death. Single nucleotide polymorphisms (SNPs) in key immune regulator genes have been associated with therapeutic response to bisphosphonates, which are the first therapeutic line of choice for osteoporosis. However, cytokine pathways and their relation with therapeutic adhesion remain to be fully elucidated. Aimed at better understanding these processes, we investigated the response to bisphosphonate therapy in postmenopausal women and four SNPs in key proinflammatory cytokines genes: IL23R +2284 (C>A) (rs10889677), IL17A +672 (G>A) (rs7747909), IL12B +1188 (T>G) (rs3212227) and INF-γ -1616 (G>A) (rs2069705). A total of 69 patients treated with bisphosphonate were followed for a period of 1 up to 4 years, genotyped and compared according to their changes in bone mineral density (BMD) and level of biochemical markers during their treatment. The INF-γ -1616 G/G associated with increased BMD values in femoral neck (GG/AA, p = 0.016) and decreased BMD values in total hip (GG/GA, p = 0.019; GG/AA, p = 0.011). In relation to biochemical markers, INF-γ -1616 SNP associated with increased alkaline phosphatase (GG/AA; p < 0.0001) and parathyroid hormone levels (AA/GA; p = 0.017). Vitamin D values changes were related to IL17A +672 (GG/GA, p = 0.034) and to IL12B +1188 (TT/TG, p = 0.046) SNPs. Besides, significant differences in changes of calcium levels correlated with IL23R +2284 (CC/CA, p = 0.016) genotypes. Altogether, we suggest that these polymorphisms may play an important role for therapeutic decisions in osteoporosis treatment.

Influence of neurosteroids on the development of rapid tolerance to ethanol in mice

Our recent study demonstrated that neurosteroids might either facilitate or block chronic tolerance to the incoordinating effects of ethanol. The present study investigated the effects of neurosteroids on the development of rapid tolerance to ethanol-induced motor impairment using the N-methyl-D-aspartate (NMDA) receptor antagonist dizocilpine [(+)-MK-801] or the gamma-aminobutyric acid (GABA) type A (GABA(A)) receptor agonist muscimol. Male Swiss mice were pretreated with pregnenolone sulfate (0.03 to 0.15 mg/kg) or dehydroepiandrosterone sulfate (0.05 to 0.20 mg/kg) before administration of ethanol (1.9 or 2.25 g/kg) and tested with the rota-rod apparatus. Twenty-four hours later, all animals were re-tested with the rota-rod after receiving the same dose of ethanol. Pretreatment with pregnenolone sulfate or with dehydroepiandrosterone sulfate significantly facilitated the acquisition of tolerance. However, the administration of (+)-MK-801 reversed the stimulatory action of pregnenolone sulfate but did not affect the actions of dehydroepiandrosterone sulfate on ethanol tolerance. Pretreatment with pregnenolone sulfate or dehydroepiandrosterone sulfate prevented the inhibitory action of muscimol on tolerance development. Taken together, our results suggest that neurosteroids may stimulate the development of rapid tolerance to ethanol and that GABA(A) and NMDA receptor systems may be involved in these actions.

[Appendicitis in the premature newborn]

OBJECTIVE: To present a case of acute appendicitis in a premature infant. METHODS: Retrospective review of the literature using Medline and Lilacs databases, as well as the necropsy report. CLINICAL REPORT: A white male preterm infant born at 34 weeks of gestation weighing 1,750g to a primiparous mother. The Apgar score was 4 and 8 at 1st and 5th minutes, respectively. The physical exam was normal until the 9th day of life when the child developed clinical features suggestive of acute abdomen, possibly due to necrotizing enterocolitis with perforation. He was submitted to exploratory laparotomy, which leaded to the diagnostic of acute appendicitis. CONCLUSION: Acute appendicitis must be discarded on the differential diagnostic when there is a suspicion of necrotizing enterocolitis with perforation, and risk factors are not present.

Effect of epipregnanolone and pregnenolone sulfate on chronic tolerance to ethanol

The aim of the present study was to investigate the influence of neurosteroids on the development of tolerance to ethanol. Male Swiss mice were injected daily with the positive allosteric modulator of the gamma amino butyric acid-A (GABA(A)) receptor epipregnanolone (5beta-pregnan-3beta-ol-20-one; 0.15 mg/kg i.p.) or pregnenolone sulfate (5-pregnen-3beta-ol-20-one sulfate sodium; 0.08 mg/kg i.p.) - considered a negative allosteric modulator of this receptor and/or positive allosteric modulator of the N-methyl-D-aspartate (NMDA) receptor - 30 min before ethanol (2.5 g/kg i.p.). They were tested on the rota-rod apparatus, under continuous acceleration (1rpm/s), at 30, 60 and 90 min after ethanol injections for 5 days. The results showed that tolerance to the motor incoordinating effect of ethanol occurred on the fifth day of treatment when this effect was blocked by pretreatment with epipregnanolone. On the other hand, ethanol tolerance was enhanced by pretreatment with pregnenolone sulfate from the second to the fifth days of treatment. Taken together, our results suggest that neurosteroids can either stimulate or block the development of chronic tolerance to ethanol. Moreover, since neurosteroids can interact with GABA(A) or NMDA receptor systems, our results suggest the involvement of these systems in the actions of neurosteroids upon ethanol tolerance.

Cellulose acetate as solid phase in ELISA for plague

Antigen from Yersinia pestis was adsorbed on cellulose acetate discs (0.5 cm of diameter) which were obtained from dialysis membrane by using a paper punch. ELISA for human plague diagnosis was carried out employing this matrix and was capable to detect amount of 1.3 microg of antigen, 3,200 times diluted positive serum using human anti-IgG conjugate diluted 1:4,000. No relevant antigen lixiviation from the cellulose acetate was observed even after washing the discs 15 times. The discs were impregnated by the coloured products from the ELISA development allowing its use in dot-ELISA. Furthermore, cellulose acetate showed a better performance than the conventional PVC plates.

[Effect of malnutrition and chronic use of nicotine during pregnancy on lung phospholipid concentration in neonate rats]

OBJECTIVE: The aim of the present study was to determine whether lung phospholipid concentration is affected in neonate rats "Wistar EPM-1" following a continuous 21-day gestational exposure to nicotine. METHODS: Eighty rats "Wistar EPM-1" were randomly divided in four control (diet free and water "ad libitum") groups (10 rats each): 1 - Control, 2 - Physiologic Solution (infused with 0.15ml of NaCl 0.9%), 3 - Nicotine 1 (infused with 900 micro g/kg/day of nicotine bitartrate 95%), and 4 - Nicotine 2 (infused with 2.700 micro g/kg/day of nicotine bitartrate 95%), and four undernourished (diet 13g/day and water ad libitum) groups (10 rats each), that received the same kind of treatment as the control groups. The infusion of nicotine was subcutaneous. The offspring were divided in eight groups according to their origin. RESULTS: A significant high lung phospholipid concentration was observed in the non-undernourished nicotized group which was injected with a high dose of nicotine. In the other groups, there was no alteration in that concentration. CONCLUSION: We conclude that gestational exposure to nicotine increases lung phospholipid concentration in neonate rats, and that the nutritional state also influences this lung phospholipid concentration.

[Tissue weight and histologic alterations in pregnant rats submitted to malnutrition and chronic nicotine distress, and in their neonates]

The effects of a gestational exposure of 80 rats Wistar EPM-1 to nicotine and undernutrition was examined. The weight and histological alterations on the liver and lungs was evaluated on the rats and their offspring. A significantly lower weight gain, including liver and lung weight, was observed in nicotine exposed groups. There was no alteration of the placental weight. Decidual necrosis and hepatic congestion was frequent in the rats. Lung emphysema was found in the neonates.