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  Background & Objectives: E. coli is an opportunistic and pathogenic bacterium in human. It is a fecal contamination indicator of the water. The aim of this study is to investigate the efficiency of ultra violet radiation in disinfection of E. coli in aquatic environments in a batch system.

  Methods: At first, reactor was designed and made. The effects of pH, exposure time and initial inoculum were studied. Kinetic parameters were obtained by application of zero, first and second - order equations .

  Results: The result showed that removal efficiency decreased with increase of initial inoculum�and the kinetics of disinfection was described by first-order model. The result also showed that removal efficiency augmented with increasing exposure time and pH .

  Conclusion: The results of this study shows that ultra violet radiation can be used as an effective disinfection method for E. coli in aquatic environments.

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Background & objectives: Urinary tract infection (UTI) is one of the most common types of hu­man infections and Escherichia coli and Klebsiella pneumonia are the main causes of urinary tract infection among the gram negative bacteria. The prevalence of extended-spectrum β-lactamases (ESBLs) among these bacteria and hence resistant strains to β-lactam antibiotics have increased in recent decades. Several types of extended-spectrum β-lactamases, such as TEM, SHV and CTX-M have been identified, which are prominently present in the strains of E. coli and K. pneumoniae. The objective of this study was to determine the prevalence of TEM and SHV genes in E. coli and K. pneumoniae isolates of urinary tract infections by using phenotypic and molecular (PCR) tech­niques in microbiology laboratory at medical school of Tabriz Islamic Azad University.
Methods: In this cross-sectional descriptive study, 50 isolates of E. coli and 50 isolates of K. pneumoniae collected from uri­nary tract infections from out-patients in Tabriz. Antibiotic sensitivity patterns of isolates were stu­died against 14 antibiotics by disk diffusion test (Kirby Bauer) and also confirmatory tests were performed using combined antibiotic tests. Finally TEM and SHV genes were investigated using molecular methods (PCR).
Results: Twenty five isolates (25%) out of 100 bacterial isolates were identified as ESBL-producing isolates of which 13 isolates (26%) were E. coli and 12 isolates (24%) were K. pneumoniae. The TEM and SHV genes were detected in 2% and 4% of E.coli and 0% and 2% of K. pneumoniae isolates, respectively.
Conclusion: The presence of these genes among our isolates confirmed ESBL genes in these medically important bacteria leading to resistance against β-lac­tam antibiotics which are routinely used in their treatments. The low frequency of the studied genes could be because of the source of our isolates from out-patients which are not generally exposed to antibiotics

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Background & objectives: Due to the increasing resistance of bacteria to antibiotics and the presence of antibacterial compounds in plants, in this study, the effect of hydro-alcoholic and aqueous extracts of Physalis alkekengi on some pathogenic bacteria was investigated.
Methods: In this experimental study, the dried fruits of the Physalis alkekengi were purchased from a medicinal plant shop and after extraction, the antibacterial effect of the aqueous, ethanolic, and methanolic extracts of the plant against standard strains of Escherichia coli, Salmonella typhimurium, Bacillus subtilis, Staphylococcus aureus were evaluated. Antibacterial activity, Minimum Inhibitory Concentration (MIC), and Minimum Bactericidal Concentration (MBC) of the extracts were determined using serial dilution and disk diffusion methods.
Results: In the disk diffusion method, all concentrations of the methanolic extract of Physalis alkekengi had an inhibitory effect on Bacillus subtilis and Staphylococcus aureus. However, the inhibitory effect of the methanolic extract was considerably higher than the aqueous extract. The lowest inhibitory concentration of the methanolic extract was 12.5 mg/ml, and the minimum lethal concentration was 25 mg/ml. Aqueous and ethanolic extracts of the plant had the minimal effect on the standard strain of Staphylococcus aureus.
Conclusion: Aqueous, ethanolic, and methanolic extracts showed different levels of antibacterial properties in a concentration-dependent method. Therefore, the inhibitory effects against each bacterium can probably be attributed to the activity of the active ingredients of the plant, the extraction method, and the properties of the solvent used.