---

Introduction: Treatment of urinary tract infections(UTIs), as one of the most common nosocomial and community acquired infections, has remained an important medical problem. Differentiation between susceptibility patterns of nosocomial and community acquired pathogens is important epidemiologically and helps the administration of appropriate antimicrobial drugs. The goal of this study was isolation of the most common causative bacteria, in two groups of 13-35 years old women in Shahrekord city within 6 months period(April-September 2004). Also, the resistance patterns of common isolated organisms in these two groups were compared. Materials and Methods: This is an analythical-cross sectional study. 100 urine samples from women aged 13-35 years old hospitalized in different wards of Hajar and Kashani hospitals(group one) with positive urine cultures were obtained performing clean-catch midstream method. Also 100 urine samples from 13-35 years old women with positive urine culture and acute UTI symptoms from Shahrekord private laboratory (group two) were obtained. The most common causative bacteria in the two groups and the antibacterial sensitivity patterns of isolated organisms were evaluated. Data was analysed using T test. Results: Totally, the most common nosocomial UTI pathogens were E.coli, Klebsiella spp., Staphylococcus saprophyticus, Pseudomonas and Enterobacter spp. In group two, E.coli, Klebsiella spp., Enterobacter spp., Proteus, Staphylococcus saprophyticus and Citrobacter spp. were isolated predominantly. The highest bacterial resistance rate belonged to Ampicillin and Co-trimoxazole. Antibiotics useful in treatment of nosocomial UTI were Ceftizoxim, Nitrofurantoin, Nalidixic acid, Cephalothin and Gentamicin respectively. Nitrofurantoin, Nalidixic acid, Ceftazidim, Gentamicin and Cephalothin were the most effective antibiotics in community acquired UTIs. Conclusion: The emergence of pathogens with alarming rates of resistance, highlights the need for a more rationalized and restricted use of antibiotics in order to minimize the spread of resistant bacterial strains.

---

Introduction: Extracts of leaves from Camellia sinensis L contains polyphenolic components with antimicrobial activity. In this investigation biofilm inhibitory effects of black and green tea extracts were defined for five members of enterobacteriacea family including: Enteropathogenic Escherichia coli, Shigella flexneri, Proteus mirabilis, Klebsiella pneumoniae and Salmonella enterica serovar Typhimurium. Because tea is the most widely drunk beverage in Iran, therefore investigation of its effects on enterobacterial biofilm formation and colonization is very important. Materials and Methods: In this experimental study after extraction of samples with Soxhlet extractor in water/ methanol solution, further extraction took place in Ethyl acetate phase. The extracts preserved in 4oC refrigerator after sterilization by 0.44 µ filters. Well diffusion (Kirby Bauer) and broth dilution methods were used for evaluation of minimum inhibitory concentration of biofilm formation in black and green tea extracts treated cultures. Evaluation of biofilm formation was assayed by observation of colony forming unit of cultured bacteria per milliliter by sampling from Erlenmeyer flask wall scratching onto Tripticase soy agar medium and comparing the results with controls. Analysis of data was done using analysis of variance. Results: Biofilm inhibitory effects of black tea were greater than green tea. The concentration of 4.5 mg/ml of black tea and 5mg/ml of green tea had bactericidal effects against examined bacteria. On Mueller Hinton agar, Proteus mirabilis was more sensitive to black tea EPEC was more sensitive to green tea and Klebsiella pneumoniae showed more resistance to both extracts. Conclusion: Due to the fact that gastrointestinal tract is directly affected with consumed beverage, the high concentration of tea entered in lumen can reduce the number of enterobacteriaceae and can reduce their carcinogenic amine products. Thus it plays an important role in inhibition of gastrointestinal lymphoma and colon carcinoma. Also application of tea polyphenols as a food preservative can be useful.

---

Background: Aurein 1/2 is a 13-residue peptide with a vast antimicrobial and anticancer activity. Two- dimensional NMR spectroscopy of peptide solubilized in the 70% TFE (2, 2, 2-Trifluoroethanol) indicated an alpha-helical conformation. The mechanism of its action is not yet fully recognized. This study was designed to improve the antimicrobial activity and relationship between subsequence-activity in Aurein 1/2 and its analoges. Analogs of this peptide were designed and synthesized. Methods and Materials: The G1F3/RW and F3W analogs and retro - analog were synthesized with solide phase and purified via HPLC and lyophilized. These analogs were assayed by several methods: amino acid analysis, HPLC, and electrospray mass spectrometry. Then antimicrobial activity of the peptides was assessed by using the standard microdilution susceptibility test. Results: The data demonstrated that G1F3/RW analog had a higher activity and results of test figure of minimum inhibitory concentration for F3W analog had three levels. But the native, F3W analog and retro-analog was inactive. Conclusion: The higher activity of G1F3/RW in compare to F3W may be related to the positive charge of Arg that leading stronger interaction with the negative charges on the membrane surface. The result showed that reversed direction of aurein 1/2 significantly effects on activity of the peptide. It is also suggested inactivation of reto-analog amino acid type, position and size should be cautious for peptides designed as drug because it may be effect to control dimerization and maintenance of antimicrobial activity of the peptide.

---

Background: The major aim of this study was synthesis and assay of antimicrobial activity of peptide D28 and its new analogues derivatives as dimeric peptides. Materials and Methods: Three antimicrobial peptides known as D28, Di-D28-Lys,Di-Cys-D28 including 20, 41, 42 residues were synthesized respectively. For peptide synthesis, solid phase peptide synthesis method using blocked amino acids with flourenyl methoxy carbonyl group and for peptide purification HPLC were used. Peptides compositions were confirmed by amino acid analysis and SDS-PAGE electrophoresis. Antimicrobial tests against Staphylococcus aureus and Pseudomonas aeruginosa were performed as disk and well diffusion on plate and by adding to liquid broth culture (Broth macrodilution) in different concentrations. Results: Three required peptides (D28, Di-D28-Lys, Di-Cys-D28) successfully were synthesized. All three peptides were effective against S. aureus, but Di-Cys-D28 on the contrary to two other ones, showed no antimicrobial activity against P. aeruginosa. The inhibitory activity of Di-D28-Lys against P. aeruginosa was more than that of D28 peptide. Conclusion: Improvement of antimicrobial peptides activity through dimerization depends on the methods of dimerization and the strain of bacterium. Di-D28-Lys peptide in comparison with D28 and Di-Cys-D28 showed wide range and more antimicrobial activity. Therefore, Di-D28-Lys peptide could be a suitable antibiotic candidate for future studies.

---

Background: Brucellosis is one of the most common bacterial zoonotic infections in the world. The incidence of this infection is quite high and is endemic in several countries. According to WHO report, the prevalence of zoonotic and human brucellosis is on the rise in the Mediterranean region, the Middle East, and west Asian countries. The aim of this study was to investigate the usage of silver nanoparticles in treatment of brucellosis. Materials and Methods: In this experimental study, the activity of silver nanoparticles against Brucella meltensis 16M was determined by agar well diffusion method. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of silver nanoparticles were determined by macrodilution method. Also, the antibacterial effect of silver nanoparticles was studied in mouse model. Results: The results showed that silver nanoparticles in low concentrations can kill Brucella melitensis 16M in laboratory conditions. MIC and MBC of silver nanoparticles were 4 ppm and 6 ppm in macrodilution method, respectively. The anti-brucella effect of silver nanoparticles was also observed in mouse model. Conclusion: This study demonstrated that silver nanoparticles can be used against brucellosis.

---

Background: Due to increasing antibiotic resistance, it is important to identify the antimicrobial activity of herbs. This experimental study aimed to evaluate the antimicrobial activity of herbal extracts of common hop (Humulus lupulus) and oak (Quercus castaneifolia) against several microbial standard strains.

Materials and Methods: The alcoholic and aqueous extracts of H. lupulus and Q. castaneifolia were extracted. The inhibitory effects of herbal extracts were evaluated against the microbial standard strains (Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans) by both agar diffusion and macrobroth dilution methods. In the agar diffusion method, concentrations of extracts were 125, 250, 500 and 1000 mg/ml. In order to determine the MIC, serial dilutions were prepared with a range from 1 to 512 mg/ml.

Results: Alcoholic extract of both hop and oak showed higher inhibitory effect against microbial standard strains, compared to the aqueous extract. Staphylococcus aureus ATCC 29213 and Candida albicans ATCC 76615 showed higher susceptibility to both alcoholic and aqueous extracts compared to Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853. Statistically significant difference was found on the MIC of alcoholic and aqueous extracts (p<0.05).

Conclusion: This study revealed the considerable inhibitory effects of herbal hop and oak extracts on the various microorganisms, including bacteria and fungi. Although more research is needed in this field, they can be used as new antimicrobials in medicine.

---

Abstract

Background: Prevalence extension of antibiotic resistant bacteria has raised concerns about control of infections especially nosocomial infections. Many attempts have been done to replace antibiotics or limit their use. The use of antimicrobial agents produced by bacteria as antibiotic replacement has been promising in recent years. The goal of this study was to isolate Bacillus strains and evaluate their antimicrobial activity against some standard pathogens and clinical antibiotic resistant strains.

Materials and Methods: In the present study, Bacillus strains were isolated from various resources and identified by 16S rDNA PCR method. Then, the phylogenetic tree of the isolates was constructed and antimicrobial activity of the isolates was investigated against some standard pathogens and clinical antibiotic resistant strains using spotting and well diffusion methods.

Results: Eight Bacillus strains were isolated from 15 different samples. Based on the molecular identification, the isolates were identified as B.pumilus, B.coagulans, B.licheniformis, B.endophitycus and B.amiloliquefaciens. The results showed that isolates have antimicrobial activity against meticilin-resistant Staphylococcus aureus, vancomycin resistant enterococci, Klebsiella, Acinetobacter, Salmonella, Shigella, Listeria, Streptococcus and Escherichia coli.

Conclusion: In this study, isolated Bacillus strains produced antimicrobial agents against pathogens and antibiotic resistant strains and inhibited their growth.

---

---

---

Background and Aim: One of the new technologies in this century is nanotechnology. Nanotechnology is a vast and promising research platform that has opened up a wide range of opportunities in various fields including pharmacy, medicine, electronics and agriculture. One of the applied nanoparticles in the field of nanobiotechnology is silver nanoparticles. One of the most important features of these nanoparticles is the creation of programmed cell death (Apoptosis). This property has created its antiseptic properties against bacteria, fungi, viruses and nematodes. Nanoparticles have better performance against microorganisms due to their high surface-to-volume ratio and higher contact surface. Meanwhile, silver nanoparticles have shown unparalleled antimicrobial activity against a wide range of microorganisms and have recently attracted the attention of many researchers.
Methods & Materials: In this study, a review of all databases, including ISI Web of Science, Scopus, ISC, PubMed, Google Scholar Learners, Noor, related articles were examined.
Ethical Considerations Ethical principles have been observed in writing the article.
Results: The antimicrobial effect of silver nanoparticles depends on the concentration, shape and diameter of the nanoparticles as well as the time of effect and the type of microorganism. The molecular mechanism of these nanoparticles has been through oxidative stress. The mechanism of inhibitory action of silver ions on microorganisms is the loss of DNA replication ability, inactivation of the expression of ribosomal subunit proteins and other bacterial cell proteins and enzymes necessary for ATP production. The effect of silver ions is primarily on the function of membrane-bound enzymes such as key enzymes in the respiratory chain. Thus, similar cellular mechanisms can cause cell death effects in prokaryotes, fungi, and eukaryotes.
Conclusion: The results showed that variables such as type of microorganism, contact time, concentration, shape and diameter of silver nanoparticles had a significant effect on inhibiting microbial growth.

---