Objective: In this study, it was aimed to investigate in vitro activities of linezolid combined with vancomycin, teicoplanin, fusidic acid, and ciprofloxacin against Gram-positive pathogens. Material and Methods: This study was conducted at Ege University, Faculty of Pharmacy, Department of Pharmaceutical Microbiology. Clinical isolates used in this study were obtained retrospectively from the collection of Ege University Medical Faculty, Department of Microbiology and Clinical Microbiology, Bacteriology Laboratory. Minimal inhibitor concentrations (MICs) of test strains_methicillin-susceptible Staphylococcus aureus (MSSA), methicillin-resistant S. aureus (MRSA), vancomycin intermediate S. aureus (VISA), Mu50 (vancomycin intermediate S. aureus strain), methicillin-susceptible Staphylococcus epidermidis (MSSE), methicillin-resistant S. epidermidis (MRSE), vancomycin-susceptible Enterococcus faecalis (VSE) and vancomycin-resistant E. faecalis (VRE)) were determined by microdilution method. Time-kill studies were performed over 24 h using an inoculum of 5 x 106 and 1 x 107 CFU/mL. Antibiotics were tested at concentrations 1x and 4 x MIC (minimum inhibitory concentration). Results: Synergy was detected between linezolid plus teicoplanin and fusidic acid at 1 x MIC concentrations in MSSA strain. In MRSE strain, linezolid showed the same effect with fusidic acid at 1xMIC. Antagonistic effect was found linezolid plus vancomycin and teicoplanin (4 x MIC) in VSE and linezolid plus ciprofloxacin (4 x MIC) in MRSE strain. Conclusion: In this study, linezolid plus fusidic acid appeared to be the most active combination against Gram-positive pathogens.
Abstract The photoinactivation efficiency of antimicrobial photodynamic therapy (aPDT) with cationic porphyrin derivatives (CPDs) against multidrug-resistant (MDR) bacterial strain was assessed. MDR bacterial strains including Pseudomonas aeruginosa, Escherichia coli, Acinetobacter baumannii, and Klebsiella pneumoniae were used. The CPDs named PM, PE, PN, and PL were synthesized as a photosensitizer (PS). A diode laser with a wavelength of 655 nm was used as a light source. Photoinactivation efficiency of the combinations formed with different energy density (50, 100, and 150 J/cm²) and PS concentrations (ranging from 3.125 µM and 600 µM) on each bacterial strain were evaluated. Toxicity of the aPDT combinations that showed a strong photoinactivation on the bacterial strains and dark toxicity of PSs and were evaluated on fibroblasts cells. In the aPDT experiments, survival reductions of up to 5.80 log₁₀ on E. coli, 5.90 log₁₀ on P. aeruginosa, 6.11 log₁₀ on K. pneumoniae and 6.78 log₁₀ on A. baumannii were obtained. There was an increase in the photoinactivation efficiency in parallel with increasing the energy density, and the best effect seen at an energy density of 150 J/cm2. PL did not show any toxic effect on fibroblasts. However, other PSs were toxic in fibroblasts at high concentrations. In this research, which reflected the results of in vitro experiments, aPDT provided potent photoinactivation against MDR clinical isolates. The research results lead to an in vivo wound model study of aPDT with CPD infected with an MDR clinical isolate.
In this study, it was aimed to investigate the antibacterial activities of the cationic porphyrin derivatives against some multi drug resistant clinical bacterial isolates and standard strains for the development of potential antibacterial agents. In addition to the standard strains, methicillin-resistant Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa clinical isolates were studied. We synthesized eight (P1-P8) cationic porphyrin derivatives. The minimum inhibitory concentrations (MIC) of these substances were determined by micro dilution method. Ciprofloxacin was used for quality control. The study was repeated three times. All porphyrin derivatives exhibited antibacterial activity at different levels according to the studied bacteria. The strongest antibacterial activity was obtained with compounds P6, P7 and P8. These compounds were found to have MIC values of <5-156μg/ml. Because of the low MIC values, it has been concluded that these synthesized porphyrin derivatives may be high-potency agents against bacteria with high resistance profile.
TEM- and SHV-derived extended-spectrum beta-lactamases (ESBLs) producing Enterobacteriaceae have been reported from throughout the world, but there has been limited data for the molecular characterization of these enzymes in Turkey. The aim of this study was to investigate and to type the TEM- and SHV-derived ESBLs in 63 ESBL-producing clinical isolates of Enterobacteriaceae, and it included further analysis; transfer experiments, isoelectric focusing, PCR, PCR-restriction fragment length polymorphism, and DNA sequencing. According to PCR results the transconjugant strains included 52.7% TEM, 74.3% SHV, and 32.4% of both the TEM and SHV genes. Using PCR/NheI restriction analysis, 45 of the 46 ESBL detected in transconjugants were determined to be SHV-derived. DNA sequencing was performed for the identification of TEM- and SHV-derived ESBLs for 18 selected transconjugants. SHV-2, SHV-5, and SHV-12 were detected in five, seven, and five samples, respectively. This is the first description of SHV-12 in Turkey.
We investigated the linezolid susceptibility of Mycobacterium tuberculosis strains isolated from a tertiary care hospital in Izmir. A total of 67 M. tuberculosis strains (33 multidrug-resistant [MDR] and 34 non-MDR) were isolated and identified by the Tuberculosis Laboratory, Department of Microbiology and Clinical Microbiology, Faculty of Medicine, Ege University. The activity of linezolid was studied by the standard agar proportion method. For all of the strains, the MIC range was 0.06-1 mg/L, and the MIC50 and MIC90 values were 0.5 mg/L. No differences were observed between the MDR and non-MDR isolates. In general, linezolid was found to be effective for both the non-MDR and MDR M. tuberculosis strains.
We investigated the linezolid susceptibility of Mycobacterium tuberculosis strains isolated from a tertiary care hospital in Izmir. A total of 67 M. tuberculosis strains (33 multidrug-resistant [MDR] and 34 non-MDR) were isolated and identified by the Tuberculosis Laboratory, Department of Microbiology and Clinical Microbiology, Faculty of Medicine, Ege University. The activity of linezolid was studied by the standard agar proportion method. For all of the strains, the MIC range was 0.06-1 mg/L, and the MIC(50) and MIC(90) values were 0.5 mg/L. No differences were observed between the MDR and non-MDR isolates. In general, linezolid was found to be effective for both the non-MDR and MDR M. tuberculosis strains.
The present study aimed to evaluate antimicrobial activity of tigecydcline against 84 multidrug resistant (MDR) Acinetobacter spp. strains by disc diffusion and E-test methods. The results of disc diffusion test were compared according to two different interpretation ways. In addition, E-test results and the disc diffusion results that interpreted by both the methods were checked for compatibility. According to the disc diffusion test, 3 strains (3.57%) were found resistant to tigecycline when considering breakpoints suggested by Food and Drug Administration (FDA). On the other hand, none of the strains was found resistant to the evaluation criteria recommended by Jones etal. (2007). Considering E-test results of tigecycline, MIC, and MICG, values of tigecycline for Acinetobacter spp. were 0.75 and 1 mg/l, respectively. Based on FDA defined breakpoints for Enterobacteriaceae, any resistant isolate was detected. In conclusion, although there are some differences in the results, tigecycline was found quite effective on Acinetobacter spp. isolates with reference to the both disc diffusion and the E-test methods.
