Synthesis and Characterization of Cassava Gum Hydrogel Associated with Chlorhexidine and Evaluation of Release and Antimicrobial Activity

Hydrogels from natural sources are attracting increasing interest due to their ability to protect biologically active molecules. Starch extracted from cassava tubers is a promising material for synthesizing these hydrogels. Copolymerization of cassava gum and incorporation of chlorhexidine digluconate (CLX) into the hydrogels is confirmed by changes in the crystallographic profile, as observed through X-ray diffraction, and a shift in the 1000 cm-1 band in the Fourier-transform infrared spectroscopy spectrum. The differential scanning calorimetry reveals changes in the decomposition temperature of the synthesized hydrogels related to CLX volatility. Micrographs illustrate the material's porosity. Release tests indicate a constant linear release over 72 h, while antimicrobial activity against Staphylococcus aureus, Escherichia coli, and Candida albicans is satisfactory, with 100% effectiveness from 0.5% CLX and the formation of inhibition halos. Toxicity and biocompatibility studies show no cytotoxicity. The continuous release of chlorhexidine is promising for components of biomedical implants and applications as it can ensure antimicrobial action according to specific therapeutic needs.

Chemical composition of Piper gaudichaudianum Kunth essential oil and evaluation of its antimicrobial and modulatory effects on antibiotic resistance, antibiofilm, and cell dimorphism inhibitory activities

Essential oils extracted from many plant species have different biological activities, among which microbial activity stands out. Species of the genus Piper have antimicrobial potential against different species of bacteria and fungi. In this sense, the present study aimed to determine the chemical composition of the essential oil from the leaves of Piper gaudichaudianum (EOPG), as well as to investigate their antimicrobial activity and their modulatory effect on the Norfloxacin resistance in the Staphylococcus aureus SA1199B strain overproducer of the NorA efflux pump. Furthermore, their inhibitory activities on the biofilm formation as well as on the cellular differentiation of C. albicans were evaluated. Gas chromatography analysis identified 24 compounds, such as hydrocarbon sesquiterpenes (54.8%) and oxygenated sesquiterpenes (28.5%). To investigate the antimicrobial potential of EOPG against S. aureus, E. coli, and C. albicans, a microdilution assay was performed, and no intrinsic antimicrobial activity was observed. On the other hand, the oil potentiated the activity of Norfloxacin against the SA1199B strain, indicating that EOPG could be used in association with Norfloxacin against S. aureus strains resistant to this antibiotic. EOPG also inhibited S. aureus biofilm formation, as evidenced by the crystal violet assay. In the dimorphism assay, EOPG was able to inhibit the cell differentiation process in C. albicans. Results indicate that EOPG could be used in association with Norfloxacin in the treatment of infections caused by resistant S. aureus strains overproducing the NorA efflux pump. Furthermore, its ability to inhibit the formation of hyphae by C. albicans suggests that EOPG could also be applied in the prevention and/or treatment of fungal infections.

Inhibition of NorA efflux pump of Staphylococcus aureus by anacardic acids isolated from the cashew nutshell liquid of Anacardium occidentale L

The rising of diseases caused by multidrug-resistant bacteria has encouraged researchers to explore more antimicrobial substances, as well as chemicals capable of potentiating the action of existing ones against multidrug-resistant bacteria. Anacardium occidentale produces a fruit known as cashew nut, filled with a dark, almost black, caustic, and flammable liquid called cashew nutshell liquid (CNSL). The goal of the study was to evaluate the intrinsic antimicrobial activity of the major compounds present in CNSL, called anacardic acids (AA), as well as their possible modulatory action as an adjuvant of Norfloxacin against a Staphylococcus aureus strain overproducing the NorA efflux pump (SA1199B). Microdilution assays were performed to determine the minimum inhibitory concentration (MIC) of AA against different microbial species. Norfloxacin and Ethidium Bromide (EtBr) resistance modulation assays were performed in the presence or absence of AA against SA1199-B. AA showed antimicrobial activity against Gram-positive bacterial strains tested but no activity against Gram-negative bacteria or yeast strains. At subinhibitory concentration, AA reduced the MIC values for Norfloxacin and EtBr against the SA1199-B strain. Furthermore, AA increased the intracellular accumulation of EtBr in this NorA overproducer strain, indicating that AA are NorA inhibitors. Docking analysis showed that AA probably modulates Norfloxacin efflux by spatial impediment at the same binding site of NorA.

Efflux Pump (QacA, QacB, and QacC) and β-Lactamase Inhibitors? An Evaluation of 1,8-Naphthyridines against Staphylococcus aureus Strains

The bacterial species Staphylococcus aureus presents a variety of resistance mechanisms, among which the expression of β-lactamases and efflux pumps stand out for providing a significant degree of resistance to clinically relevant antibiotics. The 1,8-naphthyridines are nitrogen heterocycles with a broad spectrum of biological activities and, as such, are promising research targets. However, the potential roles of these compounds on bacterial resistance management remain to be better investigated. Therefore, the present study evaluated the antibacterial activity of 1,8-naphthyridine sulfonamides, addressing their ability to act as inhibitors of β-lactamases and efflux pump (QacA/B and QacC) against the strains SA-K4414 and SA-K4100 of S. aureus. All substances were prepared at an initial concentration of 1024 μg/mL, and their minimum inhibitory concentrations (MIC) were determined by the broth microdilution method. Subsequently, their effects on β-lactamase- and efflux pump-mediated antibiotic resistance was evaluated from the reduction of the MIC of ethidium bromide (EtBr) and β-lactam antibiotics, respectively. The 1,8-naphthyridines did not present direct antibacterial activity against the strains SA-K4414 and SA-K4100 of S. aureus. On the other hand, when associated with antibiotics against both strains, the compounds reduced the MIC of EtBr and β-lactam antibiotics, suggesting that they may act by inhibiting β-lactamases and efflux pumps such as QacC and QacA/B. However, further research is required to elucidate the molecular mechanisms underlying these observed effects.

Riparin-B as a Potential Inhibitor of AdeABC Efflux System from Acinetobacter baumannii

Acinetobacter baumannii is an important opportunistic pathogen that causes serious health-related infections, especially in intensive care units. The present study aimed to investigate the antimicrobial activity of Riparin-B (Rip-B) alone and in association with norfloxacin against multidrug-resistant clinical isolates of A. baumannii. For this, the minimum inhibitory concentrations were determined by the microdilution method. For the evaluation of resistance-modulating activity, MIC values for antibiotics were determined in the presence or absence of subinhibitory concentrations of Rip-B or chlorpromazine (CPZ). The AdeABC-AdeRS efflux system genes from these isolates were detected by PCR. Docking studies were also carried out to evaluate the interaction of Riparin-B and the AdeABC-AdeRS efflux system. The study was conducted from 2017 to 2019. The results showed that Rip-B showed weak intrinsic activity against the strains tested. On the other hand, Rip-B was able to modulate norfloxacin's response against A. baumannii strains that express efflux pump-mediated resistance. Docking studies provided projections of the interaction between Rip-B and EtBr with the AdeB protein, suggesting that Rip-B acts by competitive inhibition with the drug. Results found by in vitro and in silico assays suggest that Rip-B, in combination with norfloxacin, has the potential to treat infections caused by multidrug-resistant A. baumanni with efflux pump resistance.

Seasonal variation of the composition of essential oils from Piper cernuum Vell and Piper rivinoides Kunth, ADMET study, DFT calculations, molecular docking and dynamics studies of major components as potent inhibitors of the heterodimer methyltransferase complex NSP16-NSP10 SARS COV-2 protein

Coronavirus disease (COVID-19) has the virus that causes the SARS-CoV-2 severe acute respiratory syndrome, which has reached a pandemic proportion, with thousands of deaths worldwide already registered. It has no standardized effective clinical treatment, arousing the urgent need for the discovery of bioactive compounds for the treatment of symptoms of COVID-19. In this context, the present study aimed to evaluate the influence of seasonality on the yield and chemical composition of the essential oils of Piper cernuum and Piper rivinoides as well as to evaluate the anti-SARS-CoV-2 potential of the major components of each oil by molecular docking and quantum chemical calculation (Density Functional Theory method), being possible indicate that the winter and autumn periods, the seasons of the year where it is possible to obtain the highest percentage of Piper cernuum and Piper rivinoides oils, respectively. Regarding the anti-SARS-Cov-2 potential, the present work showed that the dihydroagarofuran present in Piper cernuum, presented a strong interaction with amino acid residues from Mpro, presenting a potential similar to Remdesivir, a drug for clinical use. Regarding methyltransferase, dihydroagarofuran (Piper cernuum) and myristicin (Piper rivinoids) showed better affinity, with important interactions at the active site of the inhibitor Sinefugin, suggesting a potential inhibitory effect of the heterodimer methyltransferase complex NSP16-NSP10 SARS Cov-2. Molecular docking and molecular dynamics studies represent an initial step, being indicative for future in vitro studies of dihydroagarofuran and myristicin, as possible pharmacological tools for COVID-19.

Mechanism of the lethal effect of Riparin E against bacterial and yeast strains

Riparins are alkamides naturally found in the fruits of Aniba riparia (Nees) Mez, but currently synthetic molecules as Riparin E (Rip-E) can be obtained. Potential biological of Rip-E as schistosomicidal agent against Schistosoma mansoni worms, as well as against Staphylococcus aureus strains has already been described. However, the mechanism of action related to antimicrobial activity of Rip-E against bacterial or fungi species has not yet been reported. This study had as objective to evaluate the Rip-E antimicrobial activity against Gram-positive and Gram-negative bacteria, as well as against yeast species of clinical importance. Minimal inhibitory concentrations of the compound against bacterial and yeast strains were determined by microdilution method. To verify if a possible lethal effect caused by Rip-E were related to plasma membrane damage, microbial cells treated with Rip-E were stained with 7-aminoactinomycin D (7-AAD) and analyzed by flow cytometry. Rip-E showed a bactericide effect against Gram-positive species S. aureus and S. epidermidis, as well as, against Gram-negative species Escherichia coli and Salmonella enterica Typhimurium, but was inactive against Pseudomonas aeruginosa. Moreover, Rip-E showed activity against fungi species Candida albicans and C. tropicalis. S. aureus, E. coli and C. albicans cells treated with Rip-E were marked with 7-aminoactinomycin D (7-AAD) indicating that Rip-E can cause plasma membrane damage, acting as a potential microbicide agent for prevention or treatment of infectious diseases.

Potentiating activity of Norfloxacin by synthetic chalcones against NorA overproducing Staphylococcus aureus

Staphylococcus aureus is responsible for a series of infections occurring in both human and animal hosts. S. aureus SA1199B is a strain resistant to hydrophilic fluoroquinolone due to overproduction of the NorA efflux pump that has been used as a microbial model to evaluate if a compound act as efflux pump inhibitor. Finding substances from natural or synthetic origin able to reverse resistance mechanisms like those of efflux pumps is a challenge. The use of Chalcones and their derivatives is of great chemical and pharmacological interest, as they present a simple structure and several pharmacological activities. This study aims to evaluate the antibacterial potential of 4 synthetic chalcones, as well as to evaluate their action in the modulation of Norfloxacin resistance against the strain SA1199B strain. Microdilution assays were performed for evaluation of the antimicrobial activity. For evaluation of the modulating effect on resistance to Norfloxacin or EtBr, MIC values of these compounds were determined in the absence or presence of subinhibitory concentrations used of each chalcone. MICs values of both Norfloxacin and EtBr were significantly reduced in the presence of all tested chalcones, indicating that inhibition of the active efflux of these compounds by NorA could be a possible mechanism of action of the chalcones. These results show that the compounds studied have a high potential as a NorA inhibitor, with the best modulating effect verified for the compound 3. Pharmacokinetic and toxicity predictive studies indicated a high intestinal absorption and good volume of distribution for chalcones by oral administration, activity in the central nervous system and ease to be transported between biological membranes. Emphasizing that analogs 1 and 4 were easily metabolized by CYP3A4 enzyme, constituting a pharmacological active ingredient without toxic risk due to metabolic activation. These chalcones combined with Norfloxacin could be a promise technological strategy to be applied in the treatment of infections caused by S. aureus overproducing NorA.

In vitro antileishmanial and immunomodulatory activities of the synthetic analogue riparin E

Leishmaniases are infectious diseases caused by protozoa of the genus Leishmania, that may have different clinical manifestations. First line drugs used in the treatment of leishmaniosis are high costly, and are very aggressive requiring medical monitoring. Thus new therapeutic alternatives are needed and, in this context, natural products have been considered as a source of new antileishmania agents. Riparins are alkamides found in the unripe fruits of Aniba riparia. Several biological activities are described for this group of compounds, such as antimicrobial and antiparasitic potential. The objective of this work was to evaluate the anti-leishmania activity riparin E (Rip-E) in vitro, against promastigotes and internalized amastigotes of Leishmania amazonensis. Rip-E was able to inhibit promastigote cell growth (IC₅₀ 4.7 μg/ml) and to reduce the percentage of macrophages infected with amastigotes, reducing its infectivity (survival index) (IC₅₀ 1.3 μg/ml). The cytotoxicity against BALB/c murine macrophages was also assessed (CC₅₀ 50.6 μg/ml) and the selectivity index was 38.9. Rip-E also demonstrated immunomodulatory activity, evidenced by the increase of the phagocytic capacity and lysosomal activity. However, Rip-E did not affect directly the production of nitric oxide. These results suggest that Rip-E has antileishmania potential, by both its direct inhibitory effect and its ability to activate macrophages.

Chemical composition and potentiating action of Norfloxacin mediated by the essential oil of Piper caldense C.D.C. against Staphylococcus aureus strains overexpressing efflux pump genes

Infectious diseases caused by multidrug-resistant microorganisms has increased in the last years. Piper species have been reported as a natural source of phytochemicals that can help in combating fungal and bacterial infections. This study had as objectives characterize the chemical composition of the essential oil from Piper caldense (EOPC), evaluate its potential antimicrobial activity, and investigate the synergistic effect with Norfloxacin against multidrug-resistant S. aureus overproducing efflux pumps, as well as, verify the EOPC ability to inhibit the Candida albicans filamentation. EOPC was extracted by hydrodistillation, and the chemical constituents were identified by gas chromatography, allowing the identification of 24 compounds (91.9%) classified as hydrocarbon sesquiterpenes (49.6%) and oxygenated sesquiterpenes (39.5%). Antimicrobial tests were performed using a 96-well plate microdilution method against C. albicans ATCC 10231, Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 25923 standard strains, as well as against multidrug-resistant strains S. aureus SA1199B (overexpressing norA gene), S. aureus K2068 (overexpressing mepA gene) and S. aureus K4100 (overexpressing qacC gene). The oil showed activity against C. albicans ATCC 10231 (≥ 512 µg/mL) and was able to inhibit hyphae formation, an important mechanism of virulence of C. albicans. On the other hand, EOPC was inactive against all bacterial strains tested (≤ 1,024 µg mL). However, when combined with Norfloxacin at subinhibitory concentration EOPC reduced the Norfloxacin and Ethidium bromide MIC values against S. aureus strains SA1199B, K2068 and K4100. These results indicate that EOPC is a source of phytochemicals acting as NorA, MepA and QacC inhibitors.

Phthalic anhydride esterified chicha gum: characterization and antibacterial activity

The objective of this research was to modify chicha gum with phthalic anhydride to obtain a new biologically active material. The chemical modification of the gum structure was proven through FTIR, elemental analysis, XRD, TG, and DSC. The derived materials demonstrated excellent inhibitory effect against P. aeruginosa and K. pneumoniae species (rating 100% inhibition) and could also inhibit Escherichia coli growth. The best antimicrobial activity observed for the derivatives suggests that chicha gum hydrophobization due to the addition of phthalic groups improved the interaction of these derivatives with bacterial cell wall components. On the other hand, the derivatives increased CC₅₀ in macrophages but did not present acute toxicity or hemolytic activity, indicating that they are promising for use in prophylaxis or treatment of infections caused by Gram-negative bacteria.

Modified chicha gum by acetylation for antimicrobial and antiparasitic applications: Characterization and biological properties

It was developed a material to act as an antimicrobial and antiparasitic agent through a modification reaction in the gum structure extracted from the plant Sterculia striata. This material was characterized, the oxidant activity was evaluated and the antimicrobial activity against Candida albicans, Escherichia coli, Pseudomonas aeruginosa, Salmonella Typhimurium and Klebsiella pneumoniae was investigated, in addition to the effect against Leishmania amazonensis, testing its acute toxicity and its cytotoxicity in human cells. Characterization techniques proved the success of chemical modification. The modification led to an increase in antioxidant activity, with excellent antibacterial activity, reaching almost 100% inhibition for P. aeruginosa and S. Typhimurium, and inhibitory effect above 70% against L. amazonensis, with an affinity far superior to the parasite than macrophages. The derivative showed no acute toxicity, it was non-hemolytic, increased cell viability in macrophages and fibroblasts, and stimulated cell proliferation of keratinocytes, thus being a strong candidate to be used as an antimicrobial and antiparasitic agent in biomedical applications.

Antibacterial and cytotoxic properties from esterified Sterculia gum

Sterculia gums, as karaya and chicha gum, are complex branched and polydisperse heteropolysaccharides which can have their applications extended by improving their characteristics through chemical modifications. The objective of this work was to increase the antimicrobial activity of karaya and chicha gum through chemical modification with maleic anhydride. The incorporation of anhydride in the gum structure was confirmed by the characterization techniques. The derived biopolymers were synthesized and characterized by FTIR, X-ray diffraction, Thermogravimetric analysis and elemental analysis. Antimicrobial activity was evaluated against the Staphylococcus aureus strain (ATCC 25923). Mammalian cytotoxicity assays were also performed by MTT and hemolysis tests. The derivatives showed excellent antibacterial action inhibiting almost 100% of bacterial growth and did not present significant cytotoxicity in mammalian cells. The results showed that the derivatives are promising for biomedical applications aiming the control of infectious diseases caused by S. aureus.

Chalcones Isolated from Arrabidaea brachypoda Flowers as Inhibitors of NorA and MepA Multidrug Efflux Pumps of Staphylococcus aureus

Bacterial resistance to antibiotics has become a public health issue around the world. The present study aimed to evaluate the antibacterial activity of chalcones isolated from flowers of Arrabidaea brachypoda, and their potential as efflux pump inhibitors of Staphylococcus aureus efflux pumps. Microdilution assays were performed with natural products from A. brachypoda. Chalcones 1, 3, 4, and 5 did not show intrinsic antimicrobial activity against all S. aureus strains tested, but they were able to potentiate the Norfloxacin action against the SA1199-B (norA) strain, with a better modulating action for the 4 trimethoxylated chalcone. All chalcones were also able to potentiate the action of EtBr against SA1199-B strain, suggesting a potential NorA inhibition. Moreover, chalcone 4 was able to interfere in the activity of MepA, and interfered weakly in the QacA/B activity. Molecular docking analyzes showed that tested chalcones are capable of binding in the hydrophobic cavity of NorA and MepA, in the same Norfloxacin binding site, indicating that chalcone 4 compete with the antibiotic for the same NorA and MepA binding sites. Association of chalcone 4 with Norfloxacin could be an alternative against multidrug resistant S. aureus over-productive of NorA or MepA.

Antimicrobial activity and inhibition of the NorA efflux pump of Staphylococcus aureus by extract and isolated compounds from Arrabidaea brachypoda

Arrabidaea brachypoda is a native shrub of the Brazilian Cerrado widely used in the folk medicine for treatment of renal diseases and articular pains. This study aimed to, first, evaluate the antimicrobial activity of both extracts and isolated molecules Brachydins BR-A and BR-B obtained from the flowers of A. brachypoda against Staphylococcus aureus, Escherchia coli and Candida albicans species. A second objective was to investigate if these natural products were able to potentiate the Norfloxacin activity against the strain Staphylococcus aureus SA1199-B that overexpress the norA gene encoding the NorA efflux pump. Extracts and isolated compounds were analyzed by HPLC-PDA and LC-ESI-MS respectively. Minimal inhibitory concentrations of Norfloxacin or Ethidium Bromide (EtBr) were determined in the presence or absence of ethanolic extract, dichloromethane fraction, as well as BR-A or BR-B by microdilution method. Only BR-B showed activity against Candida albicans. Addition of ethanolic extract, dichloromethane fraction or BR-B to the growth media at sub-inhibitory concentrations enhanced the activity of both Norfloxacin and EtBr against S. aureus SA1199-B, indicating that these natural products and its isolated compound BR-B were able to modulate the fluoroquinolone-resistance possibly by inhibition of NorA. Moreover, BR-B inhibited the EtBr efflux in the SA1199-B strain confirming that it is a NorA inhibitor. Isolated BR-B was able to inhibit an important mechanism of multidrug-resistance very prevalent in S. aureus strains, thus its use in combination with Norfloxacin could be considered as an alternative for the treatment of infections caused by S. aureus strains overexpressing norA.

Antimicrobial activity of Mimosa caesalpiniifolia Benth and its interaction with antibiotics against Staphylococcus aureus strains overexpressing efflux pump genes

This study aimed to evaluate the antimicrobial activity of the dichloromethane fraction (DCMF) from the stem bark of Mimosa caesalpiniifolia and its effect on the activity of conventional antibiotics against Staphylococcus aureus strains overexpressing specific efflux pump genes. DCMF showed activity against S. aureus, Staphylococcus epidermidis and Candida albicans. Addition of DCMF at subinhibitory concentrations to the growth media enhanced the activity of norfloxacin, ciprofloxacin and ethidium bromide against S. aureus strains overexpressing norA suggesting the presence of efflux pump inhibitors in its composition. Similar results were verified for tetracycline against S. aureus overexpressing tetK, as well as, for ethidium bromide against S. aureus overexpressing qacC. These results indicate that M. caesalpiniifolia is a source of molecules able to modulate the fluoroquinolone- and tetracycline-resistance in S. aureus probably by inhibition of NorA, TetK and QacC respectively. SIGNIFICANCE AND IMPACT OF THE STUDY: Drug resistance is a common problem in patients with infectious diseases. Dichloromethane fraction from the stem bark of Mimosa caesalpiniifolia showed antimicrobial activity against Gram-positive bacterium Staphylococcus aureus and against Candida albicans, but did not show activity against Gram-negative specie Escherichia coli. Moreover, this fraction was able to potentiate the action of norfloxacin, ciprofloxacin and tetracycline against S. aureus strains overexpressing different efflux pump genes. Thus, Mimosa caesalpiniifolia is a source of efflux pump inhibitors which could be used in combination with fluoroquinolones or tetracycline in the treatment of infectious diseases caused by S. aureus strains overexpressing efflux pump genes.

Modulation of the resistance to norfloxacin in Staphylococcus aureus by Bauhinia forficata link

Microdilution assays were performed in order to evaluate the antimicrobial activity of the ethanoic extract from the leaves of Bauhinia forficate (EEBF) against different microorganisms. The extract did not present inner antimicrobial activities against the tested strains. However, EEBF was able to modulate the norfloxacin-resistance against Staphylococcus aureus SA1199-B that overproduce the NorA efflux pump, once sub-inhibitory concentrations of EEBF reduced the minimal inhibitory concentratio of the norfloxacin in 87.5%. This modulatory effect was also found when the antibiotic was replaced by ethidium bromide, suggesting that EEBF acts probably by inhibition of NorA, allowing the antibiotic accumulation intracellularly, and making the line more sensitive. These results point out the EEBF potential as a source of NorA inhibitors that could be used in combination with norfloxacin for treatment of infections caused by multidrug-resistant S. aureus.

High rates of methicillin-resistant Staphylococcus aureus colonisation in a Brazilian Intensive Care Unit

OBJECTIVE

To evaluate the colonisation rate of Staphylococcus aureus in the oropharynx and the insertion site of central venous catheters in intensive care unit patients.

DESIGN

Cross-sectional study.

SETTING

Brazilian intensive care unit.

MEASUREMENTS

Samples were collected from October to December 2015 from the oropharyngeal cavity and central venous catheter insertion site of 110 patients. Samples that presented growth of Staphylococcus aureus were isolated and their sensitivity profiles were tested for several antimicrobials.

FINDINGS

The study participants (110) were mostly females older than 60 years (53.6%). The mean length of hospitalisation was 15.5 days (±31.3). A total of 188 biological samples were collected: 110 collected from the oropharynx and 78 from the central venous catheter insertion site. A 35% (n = 38/110) S. aureus colonisation rate of the patients was observed in at least one collection site. In the oropharynx alone, a 31% rate (n = 34/110) was found, and a 12.8% rate (n = 10/78) at central venous catheter insertion sites only. MRSA colonisation in the oropharynx or at the central venous catheter occurred in 29 (26.4%) patients and vancomycin resistant Staphylococcus aureus was present in 24 (22.4%) of the patients studied. Patients hospitalised for seven days or more were 4.8 times more likely to be colonised compared to patients hospitalised less than seven days (95% CI = 1.2-28.5).

CONCLUSION

The oropharynx and the central venous catheter are important reservoirs of this bacterium that in critical conditions may become pathogenic. The data showed a high degree of resistance of the bacterial populations isolated to different drugs, which may hinder the control of these organisms.

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

AIM

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.

METHODS AND RESULTS

Microdilution tests showed that Riparins A and B did not show any significant antibacterial activity against Staph. aureus strains. On the other hand, the intrinsic antibacterial activity increased with increasing lipophilicity of the compounds, in the following order: Riparin-D (MIC 256 μg ml^-1 ; Log P 2·95) < Riparin-C (MIC 102 μg ml^-1 ; Log P 3·22) < Riparin-E (MIC 16 μg ml^-1 ; Log P 3·57). The addition of all riparins to growth media at subinhibitory concentrations caused an increase in the antibacterial activity of antibiotics against the NorA-overexpressing test strain. Riparin-B, which has two methoxyl groups at the phenethyl moiety, showed the best modulatory effect.

CONCLUSIONS

Riparin-E is a good anti-staphylococci agent, while Riparin-B functions as a NorA efflux pump inhibitor.

SIGNIFICANCE AND IMPACT OF THE STUDY

Our data suggest the possibility of using Riparin-B in combination with norfloxacin or ciprofloxacin for therapy of infections caused by multi-drug resistant Staph. aureus.

Inhibition of the NorA multi-drug transporter by oxygenated monoterpenes

The aim of this study was to investigate intrinsic antimicrobial activity of three monoterpenes nerol, dimethyl octanol and estragole, against bacteria and yeast strains, as well as, investigate if these compounds are able to inhibit the NorA efflux pump related to fluoroquinolone resistance in Staphylococcus aureus. Minimal inhibitory concentrations (MICs) of the monoterpenes against Staphylococcus aureus, Escherichia coli and Candida albicans strains were determined by micro-dilution assay. MICs of the norfloxacin against a S. aureus strain overexpressing the NorA protein were determined in the absence or in the presence of the monoterpenes at subinhibitory concentrations, aiming to verify the ability of this compounds act as efflux pump inhibitors. The monoterpenes were inactive against S. aureus however the nerol was active against E. coli and C. albicans. The addition of the compounds to growth media at sub-inhibitory concentrations enhanced the activity of norfloxacin against S. aureus SA1199-B. This result shows that bioactives tested, especially the nerol, are able to inhibit NorA efflux pump indicating a potential use as adjuvants of norfloxacin for therapy of infections caused by multi-drug resistant S. aureus strains.

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 women's knowledge, attitudes and practices regarding the Pap test and to investigate whether there are any associations between these three factors and the women's 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.