Journal of

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Introduction: Drug resistant Staphylococci are the most important agents of nosocomial infections. In this survey, effect of different antibiotics on these bacteria and their drug resistance was investigated. Methods: The study included 500 strains of Staphylococci. Minimum Inhibitory Concentrations of all antibiotics was determined by the broth macro dilution technique and standard methods from the National Committee for Clinical Laboratory Standards. Result : Oxacillin resistance of S. aureus was 14.2% and that of coagulase-negative staphylococci was 53.4%. The activity of different antibiotics is presented in detail. Conclusion: Surveillance of strains resistant to methicillin is necessary.

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Introduction: Organic antibacterial materials have been used as insecticides and bactericides for many years. Unfortunately, high temperatures in manufacturing process reduce their antibacterial properties. However, inorganic materials of antibacterial agents have excellent bacterial resistance and thermal stability. Over the past few decades, inorganic nanoparticles whose structures exhibit significantly novel and improved physical, chemical and biological properties and functionality due to their nano-scale size have elicited much interest. methods:The aim of this study was to investigate the antibacterial properties of one kind of nano-specimen (TiO2 nanoparticle) against Escherichia coli and Streptococcus aureus. Our study was research perusal. In the first study, the optical density of E. coli and S. aureus cultures were observed in the presence of 0.01%, 0.75% and 1.5% of TiO2. In the second study, 6.3 log CFU/ml of E. coli and S. areus were separately exposed to 1.5% TiO2 at 37 ºC in water. In third study, we studied thew growth of E.coli in solid medium with and without nanoparticles. Results: The presence of 0.01% TiO2 nanoparticles didn’t have a statistically significant effect, but in the presence of 0.75% and 1.5% nanoparticles, the bacterial colonies decreased significantly. In the control group, bacterial cells survival was nearly 13 days, while complete cell death of E. coli was seen when 1.5% TiO2 was applied for 24 hours. The same experiment for S. aureu, showed that complete cell death occured when the bacterial culture was exposed to 1.5% TiO2 for 16 hours.. It was shown that presence of 1.5% TiO2 in the solid medium suppressed the growth of E. coli 5.6 times more (p < 0.001). Discussion: Our findings showed antibacterial effects of TiO2 nanoparticles against both bacteria, but S. areus bacteria were more sensitive to nanoparticles as compared to E. coli bacteria

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Introduction: Staphylococcus aureus is an important human pathogen which can cause a broad spectrum of diseases including minor skin disease to more severe and aggressive infections. Therefore, this study intended to assess the frequency of methicillin-resistance among clinical isolates of S.aureus by phenotypic and PCR methods in Yazd, Iran. Methods: In this descriptive-cross sectional study, a total of 114 S. aureus isolates were collected from Different specimens of patients admitted to shahid sadoughi hospital in Yazd, Iran. Antimicrobial susceptibility testing was determined by disk diffusion method (Kirby-Bauer) and minimum inhibitory concentration of oxacillin (MIC) was performed by E.test method. Moreover, PCR method was performed in order to detect mecA gene using specific primers. Results: Susceptibility testing by disk diffusion method showed that 43 samples (37/7%) and 49 samples(42/1%) were resistant to oxacillin and cefoxitin respectively. MIC results demonstrated that 47(42/1%) samples were resistant to oxacillin. Moreover, 54 samples(47/4%) were found to carry mecA gene using PCR. Highest resistances to antibiotics belonged to ampicillin(99/1 %), penicillin(98/2%), tetracycline(55/3%), erythromycin(37/7%), clindamycin(32/5%), ciprofloxacin (32/5%), ofloxacin (31/6%), gentamicin (26/3%), respectively. Conclusion: The study findings revealed that the multi-drug resistance (MDR) is prevalent among S.aureus isolates. Furthermore, cefoxitin disks were more useful than oxacillin disks to determine methicillin-resistance by disk diffusion method. However mecA gene was also detected in some samples susceptible to disk diffusion method. PCR technique was proved to be the best method to rapidly identify MRSA.

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Introduction: S. aureus, the second most common cause of nosocomial infections, is regarded as an important factor in the severe infections of the community. Methicillin-resistant strains of this bacterium involve a major pathogen which can cause disease and mortality in Iran and the world. Its treatment seems to be difficult due to the prevalence of resistance to most commonly-used antibiotics. In fact, methicillin -resistant strains need to be identified precisely and rapidly. Therefore, this study intended to assess the resistance to methicillin via the disk diffusion method and PCR for mecA gene. Methods: This study was conducted on 100 strains of Staphylococcus aureus collected from clinical various samples of Moheb and Milad hospitals in Tehran. Sensitivity to antibiotics was determined by the disk diffusion method and gene resistance (mecA) was examined by PCR method. Moreover, specific primers were explored and the results were compared. Results: The prevalence of methicillin-resistant strains by the disk diffusion method was 50% (n=50), whereas 74% (n=74) were determined to have mecA gene via PCR analysis. Out of these 100 samples, 61 samples belonged to Moheb hospital, among which 47.54% (n=29) were observed to be methicillin-resistant by disk diffusion method and 60.65% (n=37) via PCR method. Other 39 samples were obtained from Milad Hospital, of which 84/53% (n=21) demonstrated resistance to methicillin via disk diffusion and 87/94% (n=37) via PCR method. Conclusions: The study findings revealed that due to high prevalence of methicillin resistance, a quick and detailed identification method of MRSA is required. Since disk diffusion method proposes relatively high false-negative results and is observed to have a time-consuming nature, PCR can be taken in to consideration as the best method in order to identify methicillin-resistant strains.

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Introduction: Resistance to penicillin among Staphylococcus aureus species is very widespread. One of the most important resistance mechanisms toward penicillin in S. aureus is blaZ production. Detection of beta lactamase production is possible using different methods like disk diffusion, iodometric, acidometric and molecular (PCR) methods. The aim of this study was to detection of beta lactamase production among S. aureus isolated from human dental plaque using iodometric and molecular methods. Descriptive statistics were done using ANOVA test and the statistical package, SPSS, Version 15.0.
Methods: In this cross sectional study, 40 samples of human dental plaques was collected through forceps. Identification and isolation of S. aureus from samples was carried out using cultural methods, biochemical and molecular tests. Then, antibiotic resistance patterns of studied Staphylococci were determined using Kirby-Bauer method. Also, betalactamase production among the bacteria was evaluated using different iodometric and molecular methods.
Results: 30% (12) of studied samples contained Staphylococcus aureus. All Staphylococcus aureus strains had beta lactamase production ability using filter paper iodometric method. Also, all spesies had blaZ gene, which detected by polymerase chain reaction test. The results of
Conclusions: The result of this study showed that molecular (PCR) and iodometric (filter paper) methods were more accurate in detection of penicillin resistant S. aureus.
 

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Introduction: Despite advances in the recognition of new risk factors, prevention, diagnosis and treatment, cancer is still remains as a global health problem. Several numbers of studies have recently provided evidence that because of having pro apoptotic effects, biotoxins such as bacterial toxins, could be used as potential antitumor agents. Staphylococcus aureus, as a major human pathogen, has various toxins, such as enterotoxin superfamily that causes apoptosis during infection. Therefore, it seems that there is a good research field for the use of this toxin in the control and treatment of malignancies.