Humberto Medeiros Barreto

Effectiveness of Lippia sidoides Cham. (Verbenaceae) essential oil in inhibiting the growth of Staphylococcus aureus strains isolated from clinical material

Staphylococcus aureus apresenta-se como um microrganismo patogenico classico sendo comumente reconhecido como agente etiologico de infeccoes comunitarias e hospitalares. Considerando o conhecimento acerca das propriedades biologicas apresentadas por Lippia sidoides Cham. (Verbenaceae), este estudo teve como objetivo avaliar a efetividade de seu oleo essencial em inibir o crescimento de cepas de S. aureus com diferentes perfis de resistencia antibiotica isoladas de material clinico. Os resultados mostraram destacavel atividade anti-S. aureus do oleo essencial de L. sidoides notada por grandes halos de inibicao do crescimento bacteriano (15-21 mm). A CIM encontrada foi de 0.4 µL/mL para todas as cepas ensaiada. A CIM apresentou destacavel efetividade de inibicao da viabilidade de S. aureus em caldo durante vinte e quatro horas de interacao caracterizando um efeito bacteriostatico. Estes resultados mostram a destacavel atividade antiestafilococica do oleo essencial de L. sidoides, bem como suportam a possibilidade de seu uso racional como agente antimicrobiano alternativo.

Phytochemical Prospection and Modulation of Antibiotic Activity In Vitro by Lippia origanoides H.B.K. in Methicillin Resistant Staphylococcus aureus

The Lippia origanoides H.B.K. ethanol extract (LOEE) and hexane (LOHEX), dichloromethane (LODCM), and ethyl acetate (LOEA) fractions were tested for their antimicrobial activity alone or in combination with antibiotics against a methicillin resistant Staphylococcus aureus (MRSA) strain. The natural products did not show antimicrobial activity against multidrug resistant strain at the clinically significant concentrations tested. However, a modulatory effect in the antibacterial activity of the neomycin and amikacin was verified when LOEE, LOHEX and LODCM were added to the growth medium at subinhibitory concentrations. A similar modulation was found when the natural products were changed for chlorpromazine, an inhibitor of bacterial efflux pumps, suggesting the involvement of resistance mediated by efflux system in the MRSA tested. The fractions LOHEX and LODCM showed a modulatory activity bigger than their majority compounds (carvacrol, thymol, and naringenin), indicating that this activity is not due to their majority compounds only, but it is probably due to a synergism between their chemical components. These results indicate that L. origanoides H.B.K. can be a source of phytochemicals able to modify the phenotype of resistance to aminoglycosides in MRSA.

Chitosan Hydrogel in combination with Nerolidol for healing wounds.

Chitosan is a natural polymer with antibacterial property, that is biodegradable, extremely abundant and non-toxic. This study aimed to develop and characterize chitosan hydrogels in combination with nerolidol, in order to optimize the antimicrobial and healing properties. The hydrogels were prepared using a reaction of the chitosan with acetic acid solution, followed by the addition of 2 or 4% of the nerolidol. Using thermogravimetry, differential scanning calorimetry and infrared spectroscopy, the incorporation of nerolidol in the hydrogel was confirmed. Direct contact tests using hydrogels and Staphylococcus aureus showed a synergistic effect in the materials, enabling total inhibition of bacterial growth. The hydrogel containing 2% nerolidol showed excellent healing effects. The beginning of re-epithelialization and reorganization of collagen was already observed on the 7th day of treatment. The material created proofed to be promising as a healing and antibacterial agent.

Knowledge, attitudes and practices regarding the Pap test among women in Northeastern Brazil.

CONTEXT AND OBJECTIVE The Papanicolaou (Pap) test has been shown to be effective in preventing cervical cancer. However, both the national and international literature shows that Pap testing has not reached the level of coverage desired. The objective of this study was to assess womens knowledge, attitudes and practices regarding the Pap test and to investigate whether there are any associations between these three factors and the womens sociodemographic characteristics. DESIGN AND SETTING Cross-sectional descriptive study conducted in Floriano, Piauí. METHODS The study was conducted among 493 women between November 2009 and December 2010. A questionnaire with precoded questions was sed, and the responses were analyzed in terms of appropriateness in relation to the Pap test. RESULTS The degrees of adequacy of knowledge, attitudes and practices regarding the Pap test were 36.7%, 67.2% and 69.6%, respectively. Among the main barriers against testing, absence of symptoms and a sense of embarrassment were the most notable. CONCLUSIONS Women who visit doctors periodically had the most appropriate practices regarding the Pap test, but their knowledge of the procedure was poor. This suggests that these women were not receiving adequate information about the benefits of periodic testing.

Evidence for production of a bacteriocin-like substance by Staphylococcus pseudintermedius, inhibitory to Staphylococcus aureus from foods

This study assessed the production of a bacteriocin-like substance by Staphylococcus pseudintermedius S28, and evaluates its inhibitory effect against isolates of S. aureus from foods. All indicator isolates were sensitive to the substance produced from S. pseudintermedius S28, showing growth inhibition zones ranging from 14.2 to 28.3 mm. The inhibitory substance has no effect against the producer strain. The inhibitory substance was affected by proteolytic enzymes, while glycolytic and lipolytic enzymes had no effect, suggesting that the active substance could be considered as a bacteriocin-like substance. From these results, S. pseudintermedius S28 could be an interesting producer of a bacteriocin-like substance capable of strongly inhibiting S. aureus.

Enhancement of the antibiotic activity of aminoglycosides by extracts from Anadenanthera colubrine (Vell.) Brenan var. cebil against multi-drug resistant bacteria

The aim of this work was to evaluate the antimicrobial activity of ethanol (EEAC) and hexane (HFAC) extracts from the stem bark of Anadenanthera colubrina (Vell.) Brenan var. cebil alone or in combination with aminoglycosides against multi-drug resistant (MDR) bacteria. Minimal inhibitory concentrations (MICs) of the extracts were determined by using microdilution assay. For the evaluation of extracts as modulators of antibiotic resistance, MICs of neomycin and amikacin were determined in presence or absence of each compound at sub-inhibitory concentrations. Both EEAC and HFAC did not show antimicrobial activity against MDR strains tested. However, the addition of EEAC and HFAC enhanced the activity of neomycin and amikacin against Staphylococcus aureus SA10 strain. When the natural products were replaced by chlorpromazine, the same effect was observed. Anadenanthera colubrine var. cebil may be a source of phytochemicals able to potentiate the aminoglycoside activity against MDR S. aureus by the inhibition of efflux pump.

Inhibition of the NorA efflux pump of Staphylococcus aureus by synthetic riparins

The goal of this study was to increase knowledge about the antimicrobial activity of some synthetic Riparin‐derived compounds, alone or in combination with fluoroquinolone antibiotics, against a strain of Staphylococcus aureus resistant to fluoroquinolone by way of overexpression of the NorA efflux pump.

Protective Effect of Furocoumarins Against 254-nm Ultraviolet in Staphylococcus aureus

For Staphylococcus aureus, pretreatment with furocoumarins (FCs) protect cells against killing by far ultraviolet light (FUV; approximately 254 nm). This protective effect was evident in the repair-proficient, parental strain as well as in the repair-deficient variants in the following order of efficacy: 4,5′’,8-trimethylpsoralen << 8-methoxypsoralen ≅ angelicin < 3-carbethoxypsoralen. The extent of protection was greater in the parental strain, indicating that despite the protective effect, a certain number of lethal lesions are nevertheless produced, which would be repaired with greater efficiency in such a strain than in the repair-deficient ones. This protective effect could be attribute to the inhibition of the formation of cyclobutyl pyrimidine dimers. Although the energy-transfer concept could explain the inhibition of pyrimidine dimer formation, and thus the protective effect of FC against FUV, we cannot rule out the possibility that the differences in degree of protection afforded by the FC employed here are related to a subtle and complex combination of effects.

Modified chitosan-based bioactive material for antimicrobial application: Synthesis and characterization

The search for natural antibacterial agents to treat diseases caused by resistant microorganisms has been gaining increasing attention. Chitosan has been studied in several areas due to its particular properties. The grafting of hydrophobic chains into the chitosan molecule, turning it amphiphilic, may improve its antimicrobial activity by increasing electrostatic interaction with the bacterial cell wall. The objective of this work was to enhance the antimicrobial activity of chitosan by the reaction of N-acylation with maleic anhydride. For this purpose, molar ratios of 1:2, 1:5 and 1:10 chitosan: anhydride were investigated, and the obtained derivatives were characterized by elemental analysis, FTIR, thermal analysis and XRD where it was possible to prove the chemical modification of chitosan. The modified materials presented excellent antibacterial action against Staphylococcus aureus and Escherichia coli, evidencing no activity against the protozoan Leishmania amazonensis. Cytotoxicity assays by the MTT analysis and hemolysis indicated that the derivatives did not show toxicity in mammalian cells. The proposed modified chitosan compounds showed to be promising for biomedical applications since they allied excellent antibacterial activity and absence of cytotoxicity.

Antibacterial Activity of a Chitosan Derivative Obtained in the Absence of a Solvent

A novel chitosan derivative was prepared through direct reaction of pure chitosan with acetylacetone in the absence of a solvent, and it was characterized by elemental analysis, Fourier transform infrared spectrometry (FTIR), and 13C Nuclear Magnetic Ressonance (NMR) spectroscopy. Moreover, the antibacterial properties of the new biomaterial were tested by the direct contact method against multi-drug resistant strains of Staphylococcus aureus and Escherichia coli. The results from the characterization were consistent with the modification of the chemical structure made. The new derivative showed a better antibacterial activity than raw chitosan against E. coli strains, indicating that incorporation of imine link (Schiff base) enhanced its antibacterial activity against Gram-negative bacterium. On the contrary, this chemical change did not decrease its antibacterial activity against Gram-positive bacterium.