Ufuk Abbasoglu

Slime production and proteinase activity of Candida species isolated from blood samples and the comparison of these activities with minimum inhibitory concentration values of antifungal agents.

Slime and proteinase activity of 54 strains consisting of 19 Candida parapsilosis and 35 C. albicans strains isolated from blood samples were investigated in this study. Ketoconazole, amphothericin B, and fluconazole susceptibility of Candida species were compared with slime production and proteinase activity of these species. For both Candida species, no correlation was detected between the slime activity and minimum inhibitory concentration (MIC) values of the three antifungal agents. For both Candida species no correlation was detected between the proteinase activity and the MIC values of amphothericin B, and fluconazole however, statistically significant difference, was determined between the proteinase activity and MIC values of ketoconazole (p = 0.007). Slime production was determined by using modified Christensen macrotube method and proteinase activity was measured by the method of Staib. Antifungal susceptibility was determined through the guidelines of National Committee for Laboratory Standards (NCCLS M27-A).

Fluconazole release from hydrogels including acrylamide-acrylic acid-itaconic acid, and their microbiological interactions

Polyacrylamide (PAAm), polyacrylic acid (PAA), poly(acrylamide-co-itaconic acid) (PAAmIA) and poly(acrylic acid-co-itaconic acid) (PAAIA) hydrogels were prepared via free-radical polymerization using ethylene glycol dimethacrylate (EGDMA) as cross-linker. The variations of swelling percentages with time and pH were determined for these hydrogels at 37°C. PAAmIA was found as the most swollen hydrogel at pH 4.0. SEM micrographs were taken to observe the morphology of the hydrogels. The less swollen hydrogel, PAAIA, displays less porosity relative to PAAmIA hydrogel. Fluconazole was entrapped into PAAmIA and PAAIA hydrogels and the release was investigated in Britton–Robinson buffer solution (BR) at pH 4.0 and 37°C. The kinetic release parameters of the hydrogels, n and k, were calculated and Fickian-type diffusion was established for PAAmIA, which releases Fluconazole faster than PAAIA hydrogel. Therapeutic range was reached in the first hour for both hydrogels. Microbiological interactions of hydrogels were also studied in vitro in vaginal medium. It is found that Fluconazole entrapped in hydrogels inhibited the growth of Candida albicans.

Synthesis and antimicrobial activity of 1,4-diaryl-2-azetidinones.

Cycloaddition of substituted 4,4-benzylidene-anilines to in situ prepared dichloroketenes in the presence of dichloroacetyl chloride and triethylamine affords a variety of 2-azetidinones. All the compounds were characterized by IR and 1H NMR. Their antimicrobial activity, against Gram(+) and Gram(-) bacteria and fungi, was tested.

Screening of quinolone antibiotic residues in chicken meat and beef sold in the markets of Ankara, Turkey

This study aimed to find the effects of quinolone antibiotics in chicken and beef used in Ankara, Turkey. Total number of 127 chicken and 104 beef meat samples were collected randomly from local markets for analysis. Extraction and determination of quinolones were made by ELISA procedure. One hundred eighteen of 231 (51.1%) examined chicken meat and beef samples were found to contain quinolone antibiotic residue. Among the chicken meat and beef samples, 58 (45.7%) of chicken meat samples and 60 (57.7%) of beef meat samples were positive for quinolones, respectively. The mean levels (±SE) of quinolones were found to be 30.81 ± 0.45 µg/kg and 6.64 ± 1.11 µg/kg in chicken and beef samples, respectively. This study indicated that some chicken and beef meat sold in Ankara contains residues of quinolone antibiotics.

Synthesis, antimicrobial activity and QSAR studies of 2,5-disubstituted benzoxazoles

In this study, a new series of 2,5-disubstituted benzoxazoles was synthesized and their structures were elucidated by elemental analysis, MASS, 1H-NMR, 13C-NMR and IR spectral data. Newly and previously synthesized 2,5-disubstituted benzoxazole derivatives were evaluated for antibacterial and antifungal activity against standard strains and their drug-resistant isolates. Microbiological results showed that the compounds presented a large spectrum of activity having MIC values of 250–7.8 µg mL−1 against the tested microorganisms. Among the newly synthesized derivatives 3–22, compound 11 was the most active against Candida krusei out of all; however, it was one dilution less potent than standard drug fluconazole. In addition, all the new and previous compounds were more active than standard drugs ampicillin trihydrate and rifampicin against Pseudomonas aeruginosa and its gentamicin-resistant isolate. The 2D-QSAR (Quantitative Structure–Activity Relationship) analysis of a set of newly and previously synthesized benzoxazoles tested for growth inhibitory activity against methicillin-resistant Staphylococcus aureus (MRSA) was also performed by using multivariable regression analysis. The activity contributions for substituent effects of these compounds were determined from the correlation equation for predictions of the lead optimization.

Antimicrobial Activities of Plants from the Apicaceae

The aim of this study was to examine the antimicrobial activities of ethanol extracts of five plants containing furanocoumarins. Antimicrobial activities of ethanol extracts of Astrodaucus orientalis (L.) Drude, Bifora radians Bieb., Conium maculatum L., Crithmum maritimum L., Daucus carota L., and standard furanocoumarins (umbelliferone, xanthotoxin, and bergapten) were tested against Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, Staphylococcus aureus, and Candida albicans using a microdilution method. The minimum inhibition dilution (MID) values of the extracts were determined. Astrodaucus orientalis showed the highest antibacterial activity.

Water and Antimicrobial Agent Permation of PU and PHEIMA Membranes in Relation to their Surface and Bulk Properties

Four types of polyurethane (PU) and two types of 2-polyhydroxyethylmethacrylate (PHEMA) membranes were prepared by convenient methods. Surface properties, water and antibacterial agent permeabilities of PU membranes were investigated. Water permeability values were determined in the region of 2000 g/m2 * 24 h. The membranes were found to have sufficient permeability toward antibacterial agents of 1% Silver Sulfadiazine and Bacitracin 10,000 UI-Neomycin sulphate 100 mg ointment.

Candida albicans and Pseudomonas aeruginosa adhesion on soft contact lenses

BackgroundIn this study it was aimed to determine the adherence of Pseudomonas and Candida to contact lens surfaces, and to determine the difference in adherence between five contact lens types. Biofilm-negative control strains were also used to emphasize the difference between biofilm-positive and biofilm-negative strains in adherence.MethodsFive different soft contact lenses were used to investigate the adherence of Pseudomonas aeruginosa and Candida albicans strains. P. aeruginosa ATCC 27853, P. aeruginosa ATCC 10145, C.albicans ATCC 10231 standard strains and C. albicans clinical isolate were included in the study. Slime formation was investigated by two methods; modified Christensen macrotube method, and a modified microtiter plate test. P. aeruginosa and C. albicans slime formation on soft contact lenses was studied in adherence and separation phases. Pseudomonas and Candida suspensions were serially diluted and inoculated to blood agar and sabouraud dextrose agar surfaces respectively. After overnight incubation, the colonies were counted. Sterile unworn contact lenses were used as negative controls, and bacterial and fungal culture suspensions were used as positive controls. The experiments were conducted in three parallel series.ResultsThe number of adherent Pseudomonas was as follows from high to low in polymacon, etafilcon A, hilafilcon, ocufilcon and lotrafilcon contact lenses respectively. However, the number of adherent yeast were determined higher in lotrafilcon and ocufilcon contact lenses, followed by hilafilcon, etafilcon A and polymacon contact lenses. Biofilm-negative Pseudomonas ATCC standard strain and Candida clinical isolate were used to confirm that the number of adherent cells were lower than the biofilm-positive ones.ConclusionsThis study demonstrates that in addition to the contact lens properties, the microorganisms themselves and their interactions with the lens material also play an important role in adherence.

In vitro susceptibility of Candida species isolated from cancer patients to some antifungal agents.

This study was undertaken to study the resistance of Candida species isolated from oropharyngeal swabs of cancer patients to ketoconazole (KET), fluconazole (FLU), amphotericin B (AmpB), and flucytosine (FCU). The most common species identified was C. albicans, followed by C. tropicalis, C. glabrata, C. famata, C. krusei, C. kefyr, and C. gulliermondii. The minimum inhibitory concentration (MIC) of the antifungal agents was evaluated by RPMI 1640 medium with microdilution method. There were no C. albicans strains resistant to KET, FLU and AmpB. All Candida isolates were found highly susceptible to AmpB (MIC AmpB < 1 microg/ml), followed by KET (MIC KET < or =8 microg/ml), FLU (MIC FLU < or =8 microg/ml) and FCU (MIC FCU < or =4 microg/ml). The main conclusion of this study is that prophylactic therapy planned according to typing and antifungal susceptibility will contribute to the prevention of invasive fungal infections in immunosuppressied oncology patients.

Caco-2 cell culture as a model for famotidine absorption.

The aim of the study was to determine penetration properties of Famotidine fro the formulations through colon adenocarcinoma (Caco)-2 cell monolayers and to compare in vitro with in vivo test results. It also aimed to determine the effect of particle size on the penetration properties of Famotidine when microsphere formulations were used. Famotidine was chosen as a model drug and Caco-2 cell culture model was used. Biodegradable Famotidine microspheres of poly(lactide-co-glycolide)(PLGA) polymer (50:50) were prepared by using multiple emulsion technique. Microspheres were coded according to their particle size and polymer[LHIV:60 μm Famotidine-PLGA(high viscosity), SHIV:6 μm Famotidine PLGA(high viscosity), LLIV:60 μm Famotidine-PLGA (low viscosity), SLIV:6 μm Famotidine-PLGA (low viscosity)]. Famotidine solution(5 mg/ml) and microsphere formulations were administered orally to mice and blood drug levels were determined and compared with the Caco-2 cell experiments. Permeability values of Famotidine through Caco-2 cells from various formulations were determined (log ksolution = 7, 274 ± 0, 010, log kSHIV = −3, 884 ± 0, 033, log kLHIV = −2, 300 ± 0, 009, log kSLIV = −4, 076 ± 0, 208, log kLLIV = 3, 525 ± 0, 045). Our results showed that H2 receptor antagonists alter the barrier properties of the Caco-2 cell monolayer by causing an increment in the tightness of the tight junctions. Therefore, amount of the H2 receptor antagonist-like drug at the site of action was found to be important as well as polymer type and particle size of microspheres for drug permeation. Permeation of the drug was lower when higher amounts of Famotidine were present at the diffusion site. A controlled release dosage form of H2 receptor antagonist-like drugs may be beneficial for long-term treatments.