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مقدمه: افزایش شیوع بتا لاکتامازهای گروه CTX-M در جهان در برخی از پاتوژن‌های گرم منفی باعث نگرانی جامعه‌ی پزشکی شده است. هدف از این مطالعه، بررسی فراوانی نسبی باکتری‌های Escherichia coli تولید کننده‌ی بتا لاکتاماز وسیع‌الطیف (ESBL یا Extended-spectrum beta-lactamase)، فراوانی ژن CTX-M و الگوی مقاومت آنتی‌بیوتیکی در بیماران مبتلا به عفونت‌های ادراری ناشی از باکتری Escherichia coli در دو گروه بیمارستانی و سرپایی در شهر اصفهان در سال 1392 بود. روش‌ها: این مطالعه بر روی 120 نمونه‌ی باكتری Escherichia coli جدا شده از بیماران سرپایی و بستری مبتلا به عفونت ادراری انجام شد. جهت تعیین حساسیت آنتی‌بیوتیکی، از روش Disc diffusion استفاده شد. سویه‌های تولید کننده‌ی ESBL با استفاده از روش Combined disc تأیید شد و با روش PCR (Polymerase chain reaction) از نظر ژن CTX-M مورد بررسی قرار گرفتند. از نرم‌افزار WHONET 5.6 و آزمون Excel جهت واکاوی داده‌ها استفاده شد. یافته‌ها: از مجموع 120 سویه‌ی Escherichia coli، به ترتیب در گروه‌های سرپایی و بستری، 12 مورد (0/20 درصد) و 33 مورد (0/55 درصد) ESBL مثبت بودند. مقاومت به آمپی‌سیلین و کوتریماکسازول در گروه سرپایی به ترتیب 4/84 و 1/60 درصد و در گروه بستری 9/94 و 8/84 درصد گزارش شد. با استفاده از روش PCR، مشخص شد که 30 سویه، واجد ژن CTX-M بودند. نتیجه‌گیری: تولید ESBL در ایزوله‌های بیمارستانی، تهدید بزرگی برای مصرف آنتی‌بیوتیک‌های وسیع‌الطیف است. با توجه به حضور ژن CTX-M در درصد بالایی از این سویه‌ها، مطالعات بیشتر ملکولی و اپیدمیولوژیک در محیط‌های درمانی ضروری می‌باشد.

Background: The aim of this study was to isolate and identify KPC (Klebsiella pneumonia carbapenemase) enzyme producing strains of Enterobacteriaceae, and determine their antibiotic susceptibility pattern in three hospitals of Isfahan, Iran. This subject has not previously been investigated comprehensively. Methods: KPC detection was done by Modified Hodge Test (MHT) and their antibiotic susceptibility patterns were determined by disc diffusion method. Findings: The total of 475 strains were isolated and detected as Enterobacteriaceae during the period of 9 months (July 2012-March 2013) in three hospitals in Isfahan province, Iran. These isolates contained Escherichia coli: 285 strains (60%), Klebsiella: 128 strains (27%), Enterobacter aerogenes: 16 strains (3.4%), Enterobacter cloacae: 9 strains (1.9%), Proteus vulgaris: 12 strains (2.5%), Proteus mirabilis: 4 strains (0.84%), Citrobacter freundii: 8 strains (1.7%), Citrobacter diversus: 3 strains (0.6%), Serratia marcescens: 3 strains (0.6%), Shigella sonnei: 4 strains (0.84%), Salmonella paratyphi A: 2 strains (0.42%), and Providencia stuartii: 1 strain (0.2%). Percentage resistant to ceftazidime and cefotaxime and non-susceptibility to imipenem and meropenem for above isolates were, respectively, as follows: for Escherichia coli isolates 60, 63, 6, and 9; for Klebsiella isolates 70, 75, 55, and 58; for Klebsiella pneumoniae 100, 100, 95, and 94; and for other Enterobacteriaceae isolates 20, 17, 5, and 3. Our results showed that KPC test was positive for 2 isolates (0.7%) among Escherichia coli strains, 65 (87%) isolates among Klebsiella pneumoniae, and 1 isolate (6%) among Proteus strains . This was approved by Etest based MIC method. Conclusion: In general, our results showed that among Enterobacteriaceae isolates, Klebsiella pneumoniae isolates had higher KPC enzyme production, and most strains had multidrug resistant.

Background: Furthermore application of bacteriocins as alternates for antibiotics, they are fermented as food preservation currently. The aim of this study was isolation and purification of ultraviolet-resistant bacteriocins from enterococci strains active against Listeria monocytogenes. Methods: Different strains of enterococci bacteria were isolated and identified from various clinical specimens and bacteriocin production were evaluated against strains of Listeria monocytogenes. An isolate of enterococcus bacteria that produce significant bacteriocin against all studied strains of Listeria monocytogenes was identified based on its phenotypical and biochemical properties as well as its 16SrRNA gene sequencing. In the next stage, this bacteriocin was purified and the effects of proteolytic enzymes, pH, temperature and ultraviolet radiation (UV) on its activity were tested and its molecular weight was determined by SDS-PAGE (Sodium dodecyl sulfate polyacrylamide gel electrophoresis) method. Findings: 17 strains of enterococci were isolated and five isolates exhibited an inhibitory effect against Listeria monocytogenes strains and among them, one enterococcus had inhibitory effect against all four strains of Listeria monocytogenes. This enterococcus was identified as Enterococcus faecium strain DSH20 (access number: JX567733.1). Using proteolytic enzymes led to the loss of antimicrobial activity; so, protein nature of it was confirmed. Bacteriocin production was resistant to UV, high temperature and pH changes. The molecular weight of the bacteriocin was at approximately 35 kilodaltons. Conclusion: Biochemical properties of this bacteriocin, such as thermal stability, resistance to UV radiation and pH, were significant. These properties present it as an alternative of antimicrobial agents against Listeria monocytogenes and preserving of fermented foods.

Background: Patients under hemodialysis are exposed to remarkable volume of water. As dialysis water is in direct contact with patients’ blood, absence of regular disinfection of pipes will facilitate the transfer of the endotoxins produced by bacteria in water to the patient's body. Thus, regular control of dialysis system and water disinfectant equipment is compulsory. This study aimed at comparing relative frequency of positive culture for microorganisms in piped water before and after filtration, culture of water after passing from pipes, and culture of dialysis fluid before entering the dialysis filter in hemodialysis section of Alzahra Medical Center (Isfahan, Iran). Methods: During 2010 and 2012, an interventional study was performed in Alzahra Hospital. Samples were taken from piped water before and after filtration and from dialysis fluid before passing from membrane. The obtained samples were cultured in tryptic soy agar (TSA) and the isolated bacteria were then evaluated. Interventions included the disinfection of pipes used for transmission of water and replacement of pipes in hemodialysis section. Findings: Purified water was studied before and after passing the pipes. Dialysis fluid was also assessed before and after the intervention. Bacteria had grown in eight out of 14 samples (57%) before the intervention. In fact, five samples developed Escherichia coli, three had pseudomonas, and one had candida. However, after the intervention, only one out of 14 samples was found to have bacteria (alcaligenes) after filtration and before entering dialysis water pipes. Conclusion: According to the results of this study, the probability of bacterial growth is very high in filtration system of dialysis water. Regular disinfection and microbial sampling and culture are hence crucial. Keywords: Hemodialysis, Dialysis fluid, Microbial contamination

Background: The present study was conducted to evaluate the relative frequency of Clostridium difficile (C. difficile) in patients at a university hospital, Isfahan, Iran. Methods: This descriptive, analytic study was conducted on 162 patients hospitalized in various wards of Alzahra Hospital (an 800-bed teaching hospital) of Isfahan during October 2009 to March 2010. Fecal samples of patients who suffered from diarrhea after receiving antibiotics were collected. Microbial analysis was performed to determine the existence of C. difficile. C. difficile toxins (A and B) were detected by ELISA method. The obtained data was statistically analyzed using chi-square test in SPSS at a significance level of P < 0.05. Findings: C. difficile toxins were detected in 36 (22.2%) patients. The frequency of toxins occurrence was significantly higher in men (P ≤ 0.005). In addition, a large number of individuals infected by C. difficile toxins were children under 4 years of age. Ceftriaxone caused many cases of diarrhea in our studied population. Conclusion: In general, based on our results, wrong prescription and antibiotics abuse can cause infection with C. difficile in patients receiving antibiotics. Therefore, the physicians must pay more attention to the recovery of patients with antibiotics.

BACKGROUND: Extravagant use of vancomycin as first line treatment of infections caused by this organism, has led to production of vancomycin resistant staphylococci and enterococci, as an important health problem. The goal of this study was determining sensitivity of S.aureus isolated from clinical specimens outside hospital using E-Test in order to find suitable primary therapeutic method and to reduce vancomycin use. METHODS: This cross-sectional study was performed in 2006 among 60 samples of community- acquired S.aureus Minimal Inhibitory Concentration (MIC) for various antibiotics against organisms was determined by E-test method. Qualitative control was performed by staphylococcus ATCC29213 and statistical analysis was done by SPSS ver 13 and WHONET- 5 softwares. FINDINGS: Overall, 60 patients (including 10 women and 50 men) were included in the study. The specimen studied were 47% from blood, 30% from skin ulcer, 11.7% from evacuated abscess and 8.3% from synovial fluid. Sensitivity percentage of organisms based on break point used in CLSI M7A6 (Clinical & Laboratory Standard Institute) for various antibiotics was 88.6% for Co-Amoxiclav, 81.8% for Amikacin, 79.3% for Gentamicin, 82.1% for Cephalothin, 75% for Ciprofloxacin, 75% for Clindamycin, 76.7% for Oxacillin, 90.5% for Rifampin and 77.8% for Vancomycin. Highest resistance was noted against Oxacillin (p