Genotyping of Escherichia coli isolated from human and water samples using ERIC-PCR method in Hamadan city

Background and Aim: Rapid and precise typing of E.coli is a prerequisite for epidemiological surveillance and controlling of infection caused by this bacterium. The present study was conducted to determine the molecular diversity of E.coli strains isolated from human and swimming pools samples using Enterobacterial Repetitive Intergenic Consensus (ERIC) method. Materials and Methods: This was descriptive-analytic study was conducted, from 2014 to 2016. The target population in this study were 45 isolates of E.coli (25 isolates from human, 20 isolates from swimming pools sample), all of which were confirmed by biochemical and molecular methods. They were then classified using the ERIC-PCR technique. Results: Generally, in ERIC-PCR product electrophoresis, 3-7 different bands were observed in the range of 100 to 1500 bp. A total of 21 ERIC-PCR profiles were found among all of the studied isolates, that included 12 profiles among human isolates and 10 profiles among swimming pools isolates, and there was one similar profile between them. Based on the results of the dendrogram, 2 main clusters and 7 categories (A to G) were observed. Conclusion: All isolates were typed using ERIC-PCR and high genetic diversity was observed among the isolates. On the other hand, the presence of common profiles among both sources indicates the possible rotation of these isolates between human-water-humans

Chlorhexidine effect on bacterial biofilms isoleated from nosocomial infections

Introduction: Biofilms are population of bacteria cells that cause irreversible binding to the surfaces by producing extracellular polymers. Biofilm formation in bacteria causes resistance to antimicrobial agents and can lead to severe problems in this ground. Materials and methods: The purpose of this study was to evaluate biofilm formation in some isolates of Pseudomonas aeruginosa (13 case), Staphylococcus aureus (13 case), Enterobacter (13 case) and Acinetobacter (13 case) which were collected from human infections of Alzahra hospital in Isfahan. Also the minimum inhibitory concentration of chlorhexidine and its impact on the growth of planktonic and biofilm formation for these isolates were determined. Statistical analysis and graphing have been carried out by using SPSS software (version 20) and Excel. Results: All isolates (52 isolates) have produced biofilm. The mean of MIC of chlorehexidine antiseptic for the p.aeruginosa, S.aureus, Enterobacter and Acinetobacter were 0/001, 0/00013, 0/001, 0/0003 g/ml respectively. Planktonic bacterial growth inhibition from p.aeruginosa and Enterobacter in 1/4 MIC and 1/8 MIC respectively was seen in 40 and 60 % cases. Acinetobacter and Staphylobacter aureus, have been controlled in 40 % of cases in 1/4 MIC and 60 % of cases in 1/8 MIC. Biofilm has not been produced in any of MIC and 2MIC dilution, and the power of biofilm formation had been increased significantly by reducing concentration of chlorhexidine dilution. Discussion and conclusion: The results indicate that the use of chlorhexidine in appropriate concentrations (MIC) can prevent bacterial growth and biofilm formation in different species causing hospital infections, but doses of chlorhexidine that are less than the MIC can stimulate biofilm formation