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Introduction: The aim of this study was to investigate the prevalence of pneumococcal infections, to determine penicillin and ceftriaxone susceptibility pattern among Streprococcus pneumoniae and to evaluate the risk factors of acquisition of pneumococcal infections in patients of Sari hospitals.
Materials and Methods: In this prospective study during one year (2002-2003), all patients admitted with pneumococcal infections in teaching and non-teaching hospitals were included. Diagnosis of pneumococcal infection was performed based on positive microbiological and appropriate clinical and standard laboratory findings. MICs of penicillin and ceftriaxone were determined by Agar dilution method and interpreted by NCCLS methodology. For statistically analysis Chi-square and Fisher's exact tests were used and P<0.05 was defined statistically significant.
Results: Seventy five episodes of pneumococcal infections among 32 pediatric patients and 43 adults were identified. The pattern of Streprococcus pneumoniae infections were similar between children and adults, and the most common infections were pneumonia (65.3%) and bacteremia (24%). The rate of penicillin and ceftriaxone nonsusceptible Streprococcus pneumoniae isolated from pediatric patients was higher than that in adult patients (93.8% versus 53.4%, P<0.01). This finding was correlated to prior penicillin use that was more common in children (37.5%) than in adults (7%). P=0,001. The susceptibility pattern of Streprococcus pneumoniae to penicillin and ceftriaxone isolated form pediatric patients and adults was different (6.2% from children, 46.6% in adults, P=0.0009). Eighty four percent of adults and 6.2% of pediatric patients had major underlying diseases (P<0.0001). This findings explain why adult patients tended to run higher mortality (30.2%) than children (6.8%).
Conclusion: This survey emphasis on vaccination of young children and elderly with major underlying diseases to prevent pneumococcal infections.

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Abstract Background: Misconceptions of mental models are phenomena that are variance with accepted scientific models. Purpose of this study was to investigate the prevalence of misconception about half life and concentration of insulin hormone in students of Arak university of medical sciences. Materials and Methods: In this descriptive study 153 undergraduates in medicine and nursing – midwifery faculties of Arak university of medical sciences in 2009, were asked to answer to two questions about half life and concentration of insulin hormone. Results: The prevalence of misconception about half life of insulin hormone in medical, nursing and midwifery students were 75%, 80% and 85%, respectively, and prevalence of misconception about insulin concentration in blood were 31%, 26% and 20%, respectively. Conclusion: Misconceptions about insulin half life and concentration exist in high percent of students and it is necessary to correct the teaching pattern.

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Background: This study aimed to examine the antibacterial effect of Polyamidoamine-G4 dendrimer on Escherichia coli, Enterobacter cloacae, Bacillus subtilis and Staphylococcus aureus.

Materials and Methods: In this experimental study, the antibacterial effects of Polyamidoamine-G4 dendrimer were studied by disc diffusion and micro-dilution method. Different concentrations of Polyamidoamine-G4 inoculated onto blank disks and were placed in Mueller-Hinton agar media. Zone of inhibition was investigated by bacterial inoculation according to the McFarland standard 0.5. Minimum inhibitory concentration and minimum bactericidal concentration of Polyamidoamine-G4 dendrimer were determined by micro-dilution method in nutrient broth culture.

Results: Zone of inhibition in concentration 500 &mug/ml of Polyamidoamine-G4 dendrimers for Escherichia coli, Enterobacter cloacae, Bacillus subtilis and Staphylococcus aureus were 14, 0, 35 and 29mm, respectively. Concerning the Zone of inhibition in gram negative bacteria with gram positive ones was p<0.05 and had significant difference. The minimum inhibitory concentration of Polyamidoamine-G4 dendrimer for Escherichia coli, Bacillus subtilis and Staphylococcus aureus were 1250, 2.5, and 1 &mug/ml, respectively. The minimum bactericidal concentration of Polyamidoamine-G4 dendrimer belonged to Escherichia coli, Bacillus subtilis and Staphylococcus aureus were 2500, 5 and 5 &mug/ml, respectively. Polyamidoamine-G4 dendrimer had not bacteriostatic and bactericidal effects on Enterobacter cloacae.

Conclusion: According to the results, Polyamidoamine-G4 dendrimer can eliminate Escherichia coli, Staphylococcus aureus and Bacillus subtilis effectively. It is suggested in the rest of this study that the probable toxicity of nanostructured compounds examined in drinking water and, economic studies is done for synthesis and their applications in case of prevention of using.