In vitro antimicrobial activity of aqueous extracts from Lentinula edodes isolates against Colletotrichum sublineolum and Xanthomonas axonopodis pv. Passiflorae

The aim of this study was to evaluate the antimicrobial activity of aqueous extracts from fruiting bodies of different isolates of Lentinula edodeson the pathogens Colletotrichum sublineolum, the causal agent of anthracnose in sorghum, and Xanthomonas axonopodispv. passiflorae, the causal agent of bacterial spot in passion fruit. Results showed that the aqueous extracts from isolates LE JAB-K and LE 95/01 significantly reduced C. sublineolumspore germination,while the isolate LE 96/22 was the only one to inhibit the pathogen mycelial growth. However, all L. edodesisolates showed inhibitory effect on C. sublineolumappressorium formation. Regarding X. axonopodispv. passiflorae, the aqueous extracts from all L. edodesisolates significantly reduced the in vitromultiplication of the bacterium. However, antimicrobial activity was lost when the extracts were autoclaved, demonstrating their thermolabile property. The aqueous extract from isolate LE 96/22 was also partially purified by anion exchange chromatography and fraction V exhibited high inhibitory activity on the in vitromycelial growth of C. sublineolum, while the multiplication of X. axonopodispv. passifloraewas inhibited by fractions IV, V and VII. Thus, L. edodesisolates were shown to produce compounds exhibiting antifungal and antibacterial activities against phytopathogens, which are mainly concentrated in fraction V.

Chemical characterization and antimicrobial activity of essential oils of salvia L. species

In this work, the essential oils of S. officinalis, S. sclarea, S. lavandulifolia and S. triloba were chemically analyzed by gas chromatography coupled to a mass spectrometry detector (GC/MSD), and their antimicrobial activity was tested against 10 microorganisms using the disk diffusion method and the Minimum Inhibitory Concentration (MIC) technique. The following major compounds were identified in the essential oils: α - and β-thujone, camphor and 1,8-cineole, except in S. sclarea, where linalool, linalyl acetate and α-terpineol were the major constituents. The antimicrobial activity showed significant differences (p < 0.05) only when obtained by the MIC method. Gram-positive microorganisms presented larger sensitivity for the essential oils. The lowest MIC was observed when Staphylococcus aureus was exposed to 2.31 mg.mL-1 of S. lavandulifolia essential oil, while the highest MIC value was obtained when Shigella flexneri was exposed to 9.25 mg.mL-1 of the same essential oil, thus demonstrating that this essential oil may be effective as a bacteriostatic agent against Gram-positive microorganisms.

Tamoxifen as a potential antileishmanial agent: efficacy in the treatment of Leishmania braziliensis and Leishmania chagasi infections

The aim of this study was to evaluate the efficacy of tamoxifen in vivo in experimental models of cutaneous (CL) and visceral leishmaniasis (VL) caused by Leishmania braziliensis and Leishmania chagasi, respectively. Drug activity was assessed against intracellular amastigotes by treating infected macrophage cultures and evaluating the number of infected cells. In vivo efficacy of tamoxifen was tested in L. braziliensis-infected BALB/c mice and in L. chagasi-infected hamsters. Treatment with 20 mg/kg/day tamoxifen was administered for 15 days by the intraperitoneal route. Efficacy was evaluated through measurements of lesion size, parasite burden at the lesion site or liver and spleen and survival rate. Tamoxifen killed L. braziliensis and L. chagasi intracellular amastigotes with 50% inhibitory concentrations (IC(50)) of 1.9 +/- 0.2 and 2.4 +/- 0.3 mu M, respectively. Treatment of L. braziliensis-infected mice with tamoxifen resulted in significant reductions in lesion size and 99% decrease in parasite burden, compared with mock-treated controls. L. chagasi-infected hamsters treated with tamoxifen showed significant reductions in liver parasite load expressed as Leishman-Donovan units and 95% to 98% reduction in spleen parasite burden. All animals treated with tamoxifen survived while 100% of the mock-treated animals had died by 11 weeks after the interruption of treatment. Tamoxifen is effective in the treatment of CL and VL in rodent models.

Antimicrobial resistance of isolated Streptococcus pneumoniae in a hospital of the Brazilian public system

Streptococcus pneumoniae is the predominant bacterial agent that affects the human population with pneumonia. This disease is an important cause of death in the elderly and the children under five years old. In this study, 29 strains of invasive S. pneumoniae were isolated from 29 patients of pneumonia, bacteremia and meningitis in the laboratory of the Municipal Hospital in Paulinia, Brazil, from May 2006 to October 2007. Patients' age ranged from 8 months old to 60 years old. These strains of S. pneumoniae were isolated from blood, pleural fluid and cerebrospinal fluid (CSF) of patients. After typing of encapsulated strains of S. pneumoniae through quellung reaction, their resistance to antimicrobial agents was gauged through Disc Diffusion Technique followed by determination of minimum inhibitory concentration (MIC). Among the 29 strains analyzed, 23 were methicillin-sensitive and six were methicillin-resistant and penicillin intermediate resistant. No strain presented full resistance to penicillin. Serotyping was performed only in two samples, which belonged to serotype 18. Our data may alert ambulatory regarding the incidence of pneumococcal strains resistant to the most common drugs due to inappropriate use of antimicrobials and also collaborate to the elaboration of pneumococcal conjugate vaccines specific to each region.

Antimicrobial Properties and Cytotoxicity of an Antimicrobial Monomer for Application in Prosthodontics

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Oxacillin Resistance and Antimicrobial Susceptibility Profile of Staphylococcus saprophyticus and Other Staphylococci Isolated from Patients with Urinary Tract Infection

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Identification and antimicrobial susceptibility of Staphylococcus from home-treated peritoneal dialysis patients

Staphylococcus aureus is the main agent of infections during peritoneal dialysis (PD). The presence of S. aureus in the nasal cavity has been extensively studied and suggested as a risk factor of dialysis-related infections, whereas coagulase-negative Staphylococcus (CNS) species are frequently considered part of the normal human microbiota. The aim of this study was to identify Staphylococcus in the nasal cavity, pericatheter skin and peritoneal effluent from PD patients, as well as to evaluate the antimicrobial activity evolution in vitro. Thirty-two chronic PD patients were observed during 12 months and had nasal and pericatheter skin samples collected for culture. When peritonitis was detected, samples were also collected from the peritoneal effluent for culture. The activity of several antimicrobial drugs (penicillin G, oxacillin, cephalothin, ofloxacin, netilmicin and vancomycin) against different Staphylococcus species was measured by using the agar drug diffusion assay (Kirby-Bauer method). Staphylococcus was separated into S. aureus, S. epidermidis and other CNS species in order to determine the in vitro resistance level. S. epidermidis resistance to oxacillin progressively increased during the study period (p < 0.05). Resistance to ofloxacin was inexpressive, whereas resistance to netilmicin and vancomycin was not detected. of the oxacillin-resistant species (n = 74), 83% were S. epidermidis, 13% other CNS and 4% S. aureus (p < 0.05). Regarding multidrug resistant strains (n = 45), 82% were S. epidermidis, 13% other CNS, and 5% S. aureus (p < 0.05). This study shows the relevance of resistance to oxacillin and CNS multi-drug resistance, particularly concerning S. epidermidis, in PD patients.

Antimicrobial Bacterial Cellulose-Silver Nanoparticles Composite Membranes

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Essential oil of Lithraea molleoides (Vell.): chemical composition and antimicrobial activity

Lithraea molleoides(Vell.) (Anacardiaceae) é uma árvore encontrada no Brasil, Paraguai, Bolívia, Uruguai, Argentina e Chile. É popularmente usada na forma de extrato alcoólico, decocção e infusão para o tratamento de tosse, bronquite, artrite, doenças do sistema digestivo, como diurético, tranqüilizante, hemostático e tônico. O objetivo do presente estudo foi a extração do óleo essencial dos frutos maduros, folhas e outras partes aéreas da planta e o rendimento do mesmo; a identificação e quantificação dos principais componentes e a determinação da atividade antimicrobiana. O rendimento do óleo essencial dos frutos maduros foi de 1%, entretanto, não foi encontrado óleo essencial nas partes aéreas da planta. A análise do óleo essencial por cromatografia gasosa com espectrometria de massa, mostrou a presença de limoneno (89,89%), alfa-pineno (3,48%), beta-pineno (2,63%), alfa-terpineol (1.27%), mirceno (0,64%), sabineno (0,54%), 4-terpineol (0,28%), canfeno (0,22%) e delta-3-careno (0,13%). O óleo essencial foi ativo contra algumas bactérias Gram positivas e leveduras testadas e não apresentou atividade contra bactérias Gram negativas.

Influence of antimicrobial subinhibitory concentrations on hemolytic activity and bacteriocin-like substances in oral: Fusobacterium nucleatum

Fusobacterium nucleatum is considered for its role in colonization of initial and late microorganisms in dental plaque and for its coaggregation with other bacterial species. It is known that action of different antimicrobial substances may interfere with either virulence factors or with host-bacteria interaction. The goal of this study was to examine the influence of subinhibitory concentrations of chlorhexidine, triclosan , penicillin G and metronidazole on hemolytic activity and bacteriocin-like substance production of oral F. nucleatum. A high resistance to penicillin G was observed and 63% of the isolates were β-lactamase positive. All the tested isolates were susceptible to metronidazole. F. nucleatum isolates grown with or without antimicrobials were alpha-hemolytics. Bacteriocin-like substance production was increased in isolates grown with penicillin G. Impaired production of hemolytic or antagonic substances can suggest a role in the regulation of oral microbiota.

In vitro evaluation of the antimicrobial activity of a castor oil-based irrigant

The antimicrobial activity of irrigating solutions - Endoquil (castor oil detergent), 2% chlorhexidine gluconate solution, and 0.5% NaOCI solution - was evaluated against Gram-positive cocci (Micrococcus luteus, Staphylococcus aureus, Enterococcus faecalis, Staphylococcus epidermidis, Streptococcus mutans, and Streptococcus sobrinus), Gramnegative rods (Escherichia coli and Pseudomonas aeruginosa), and the yeast Candida albicans. Activity was evaluated using the two-layer agar diffusion technique. The base layer was obtained by pouring 10.0 ml of Muller Hinton Medium or 10.0 ml of Brain Heart Infusion agar in a Petri dish. After solidification a 5.0 ml seed layer of Muller Hinton Medium or Brain Heart Infusion agar with inoculum (106/ml) was added. Absorbent paper disks (6.0 mm in diameter) immersed in the solutions were placed at equidistant points. Plates were maintained at room temperature for 2 h for prediffusion of the solutions and incubated at 37°C for 24 h. The candle jar system was used for the Brain Heart Infusion agar plates. All tests were performed in duplicate. After incubation the medium was optimized with 0.05 g% triphenyltetrazolium chlorate gel and inhibition halos were measured. All bacterial strains were inhibited by 2.0% chlorhexidine gluconate. Endoquil was effective against Grampositive microorganisms, and 0.5% NaOCI was effective only against S. aureus. Copyright © 2001 by The American Association of Endodontists.

Conformation and lytic activity of eumenine mastoparan: A new antimicrobial peptide from wasp venom

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Propolis: anti-Staphylococcus aureus activity and synergism with antimicrobial drugs

Propolis is a natural resinous substance collected by bees from tree exudates and secretions. Its antimicrobial activity has been investigated and inhibitory action on Staphylococcus aureus growth was evaluated The in vitro synergism between ethanolic extract of propolis (EEP) and antimicrobial drugs by two susceptibility tests (Kirby and Bauer and E-Test) on 25 S. aureus strains was evaluated Petri dishes with sub-inhibitory concentrations of EEP were incubated with 13 drugs using Kirby and Bauer method and synergism between EEP and five drugs [choramphenicol (CLO), gentamicin (GEN), netilmicin (NET), tetracycline (TET), and vancomycin (VAN)] was observed. Nine drugs were assayed by the E-test method and five of them exhibited a synergism [CLO, GEN, NET, TET, and clindamycin (CLI)]. The results demonstrated the synergism between EEP and antimicrobial drugs, especially those agents that interfere on bacterial protein synthesis.

2,3,4,6-Tetra-O-(3-nitropropanoyl)-O-β-D-glucopyranoside, a new antimicrobial from the roots of Heteropteris aphrodisiaca

A new 2,3,4,6-tetra-O-(3-nitropropanoyl)-O-β-D-glucopyranoside anomer was isolated from the roots of Heteropteris aphrodisiaca and characterized by spectroscopic methods. Activity against Staphylococcus aureus, Bacillus subtilis, Candida albicans, C. parapsilosis, C. krusei, and C. tropicalis was demonstrated.

Antimicrobial endodontic compounds do not modulate alkylation-induced genotoxicity and oxidative stress in vitro

Objective: To investigate if formocresol, paramonochlorophenol, or calcium hydroxide modulate the genotoxic effects induced by the oxidatively damaging agent hydrogen peroxide (H 2O 2) or the alkylating agent methyl methanesulfonate (MMS) in vitro by using single cell gel (comet) assay. Study design: Chinese hamster ovary (CHO) cells in culture were exposed directly to formocresol, paramonochlorophenol, or calcium hydroxide (adjusted to 100 μg/mL) for 1 hour at 37°C. Subsequently the cultures were incubated with increasing concentrations (0-10 μmol/L) of MMS in phosphate-buffered solution (PBS) for 15 minutes at 37°C or of H 2O 2 at increasing concentrations (0-100 μmol/L) in distilled water for 5 minutes on ice. The negative control cells were treated with PBS for 1 hour at 37°C. The parameter from the comet assay (tail moment) was assessed by the Kruskal-Wallis nonparametric test followed by a post hoc analysis (Dunn test). Results: Clear concentration-related effects were observed for the genotoxin-exposed CHO cells. Increase of MMS-induced DNA damage was not significantly altered by the presence of the compounds tested. Similarly, no significant changes were observed when hydrogen peroxide was used with the endodontic compounds evaluated. Conclusion: Formocresol, paramonochlorophenol, and calcium hydroxide are not able to modulate alkylation-induced genotoxicity or oxidative DNA damage as depicted by the single cell gel (comet) assay. © 2006 Mosby, Inc. All rights reserved.