فهرست مطالب

  • Volume:2 Issue: 3, 2013
  • تاریخ انتشار: 1392/09/15
  • تعداد عناوین: 8
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  • Amirhossein Mirhashemi, Abbas Bahador, Mohammad Zaman Kassaee, Ghazaleh Daryakenari, Mohammad Sadegh Ahmad Akhoundi Page 1
    Background
    Incidence of white spots due to demineralization of enamel and gingival problems is an unacceptable result of orthodontic treatment. Plaque accumulation and bacterial biofilm growth are responsible for these phenomena. The resin-based dental composites used as bonding agents in orthodontics play a major role in mentioned problems. As recent researches assert the antimicrobial effects of chitosan (CS) and zinc oxide (ZnO) nanoparticles (NPs), it seems that adding these nanoparticles to the composite can be beneficial in reducing the number and function of microorganisms. The aim of this study was to evaluate the antimicrobial effects of ZnO-NP and CS-NP-containing orthodontic composite.
    Methods
    Antibacterial effectiveness of ZnO-NPs and CS-NPs was assessed in four groups against Streptococcus mutans, Streptococcus sanguis and Lactobacillus acidophilus grown both planktonic and as a biofilm on composites. One group as the unmodified control group and three groups consisting of three different concentrations of ZnO-NPs and CS-NPs mixture: 1%, 5% and 10% (1:1 w/w). 108 CFU/ml microorganism suspensions were provided with spectrophotometer. Biofilm formation was quantified by viable counts. Disc agar diffusion (DAD) test was carried out to determine antimicrobial effects of nanoparticles by measuring the inhibition diameter on brain heart infusion agar plates. Finally,viable counts of microorganisms on days 3, 15 and 30 were collected for the antimicrobial effects of eluted components from composite discs.
    Results
    In biofilm formation test, a reduction in bacterial counts was observed with 10% nanoparticle-containing composites compared with their unmodified counterpart. In the DAD test only 10% nanoparticle-containing specimens showed statistically significant inhibition. The only noticeable datain eluted component test was on day 30 for 10% nanoparticle-containing discs, inhibiting L. acidophilus.
    Conclusion
    It seems that a mixture of ZnO-NPs and CS-NPs has induced an antibacterial activity in resin composite; especially in 10% weight concentrations which was significantly higher than other groups.
  • Neda Noori, Jalil Vandyosefi, Faeze Sabet, Sara Ashrafi, Kiarash Ghazvini Page 11
    Background
    The emergence and rapid spread of metallo-beta-lactamase (MBL) producing Acinetobacter spp. are of great concern worldwide due to limited treatment options. Epidemiologic studies of the causing genes are important for prevention.
    Methods
    In this study, 70 imipenem-resistant Acinetobacter strains were isolated from health care associated infections. These isolates were screened for detection of metallo-beta-lactamase (MBL) using inhibitor potentiated disk diffusion tests with ethylenediaminetetraacetic acid (EDTA). PCR was designed for detection of bla vim and bla imp-1 using specific primers.
    Results
    Among these 70 strains, 50 strains appeared to produce metallo-beta-lactamase. Three isolates were detected by PCR to carry metallo-beta-lactamase gene bla vim, but bla imp-1 gene was not detected.
    Conclusion
    These findings suggest that in our area other genetic elements are responsible for resistance against metallo-beta-lactams.
  • Zahra Moravvej, Yasaman Fakhar, Mahboubeh Naderi, Nasab, Emran Askari Page 17
    Background
    Health care-associated infections are an important cause of morbidity and mortality in hospitals. Reports have shown that nurses’ uniforms are sources of health care-associated infection transmission. The present study assessed the rate of bacterial contamination of healthcare worker’s white coats in two tertiary hospitals in Mashhad, Iran.
    Methods
    300 healthcare workers participated in the study from July to October 2011. Samples were obtained with a sterile swab from the outer surfaces of three sites of the white coat including the cuff, pocket mouth of the dominant hand and abdominal region. The samples were examined according to standard procedures.
    Results
    Overall, 1220 microorganisms belonging to 13 different genera were isolated from a total of 900 samples. All 300 white coats were contaminated by bacteria of which 282 (94%) were pathogenic. The abdominal region had significantly higher number of isolates than the pocket and sleeve (p = 0.02). The white coats of “cardiac surgery ICU” and “surgery ward” had the mean highest number of isolates. Gram-positive Bacilli (36.1%) were the most common isolates followed by Staphylococcus aureus (28%) and coagulase-negative Staphylococci (24.8%).
    Conclusion
    Health care workers’ white coats are contaminated with a variety of bacteria. In order to reduce cross contamination from white coats to patients, re-educational programs and stricter rules of laundering and changing white coats are suggested.
  • Leila Azimi, Abdolaziz Rastegar Lari, Malihe Talebi, Amirmorteza Ebrahimzadeh Namvar, Somayeh Soleymanzadeh, Moghadam Page 26
    Background
    One of the main mechanisms of resistance to carbapenems is potential of Klebsiella pneumoniae to produce K. pneumoniae Carbapenemase (KPC). KPC is an important type of carbapenemase, which can hydrolyze carbapenems and other beta-lactam antibiotics. Modified Hodge Test (MHT) and use of boronic acid as a KPC inhibitor are two types of phenotypic methods, which are used for detection of carbanemase-producing bacteria. Specificity of these two phenotypic tests for identification of KPC was assessed in this study.
    Methods
    Forty-four K. pneumoniae strains were isolated from wound infections of burn patients. All isolates were identified with specific biochemical tests. Carbapenem-resistant K. pneumoniae isolates were identified by disc diffusion method and analyzed with cut off-points of CLSI 2011 guideline. For detection of KPC-producing strains, carbapenem-resistant isolates were examined with two different phenotypic (i.e. MHT and Boronic acid) methods. Subsequently, strains with positive phenotypic methods were examined by PCR as a molecular method.
    Results
    Twenty-eight (64%) out of 44 isolates were resistant to carbapenem according to CLSI breakpoints and 16 (36%) were susceptible. MHT was positive in all of carbapenem-resistant isolates but none of them have had the synergism effect between meropenem and boronic acid. Also, all isolates were negative for presence of KPC genes on gel electrophoresis. According to results MHT has not enough specificity for detection of KPC.
  • Mohammad Reza Pourmand, Hooman Sadighian, Mahmood Naderi Page 32
    Background
    Quorum-sensing systems regulate expression of several virulence factors in Pseudomonas aeruginosa. This study investigated the relation between expression of the las quorum-sensing system and expression of mexY and ampC in 35 clinical isolates of P. aeruginosa.
    Methods
    Antibiotic susceptibility was determined by the disc diffusion method according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. Expression of genes including lasI, lasR, mexY, ampC and ampR was assessed by real time RT–PCR.
    Results
    Twenty eight isolates with elevated expression of mexY and ampC (compared to P. aeruginosa PAO1) were resistance to ceftazidime, imipenem, ciprofloxacin and amikacin. Also these isolates demonstrated increased expression of lasI and lasR. The remaining seven isolates showed intermediate resistance to ciprofloxacin and amikacin. These seven isolates with elevated ampR expression demonstrated decreased expression of mexY, ampC, lasI and lasR.
    Conclusion
    In contrast to previous study, current study demonstrated that the expression pattern of ampC was identical to the lasI expression pattern among clinical isolates. Furthermore according to previous study we expected that AmpR positively regulated ampC expression but in our study, some of the isolates with elevated ampR expression showed decreased ampC expression. The expression pattern of lasR and mexY was identical in all of the isolates. It seems there was a direct or indirect relation between expression of lasR and mexY expression in P. aeruginosa.
  • Sepide Hassanzadeh, Mohammad Reza Pourmand, Azar Hadadi, Keramat Nourijeylani, Masoud Yousefi, Rahil Mashhadi, Emran Askari Page 41
    Background
    Methicillin-Resistant Staphylococcus aureus (MRSA) is the one of most commonly isolated organisms from clinical samples which can cause life-threatening infections. The emergence and spread of antibiotic resistance makes the treatment of these infections more complicated. In this study, we aimed to determine the patterns of antibiotic resistance among MRSA isolates from Tehran, Iran.
    Methods
    From December 2012 to April 2014, 120 clinical samples were collected. MRSA was identified by cefoxitin disc diffusion. Antimicrobial susceptibility testing was performed on MRSA isolates for eight other antibiotics by disc diffusion method according to CLSI (2013) recommendations. Also, the minimum inhibitory concentration (MIC) was determined for vancomycin by MIC test strips.
    Results
    According to disc diffusion, 60 (50%) isolates showed resistance to cefoxitin. Among these isolates, the rate of resistance to nitrofurantoin, vancomycin, teicoplanin, doxycycline, trimethoprim, erythromycin, clindamycin, and ciprofloxacin were 0%, 0%, 0%, 28.3%, 28.3%, 58.3%, 63.3%, and 70%, respectively. All isolates were susceptible to vancomycin according to disc diffusion and MIC.
    Conclusion
    Compared to other reports from Iran, our study indicated a moderate rate for MRSA. However, the rates of resistance to generally prescribed antibiotics in these isolates were high. In this situation, it is recommended to monitor the antibiotic resistance in these hospitals.
  • Zahra Ravesh Barakzai, Jahangir Arshad Khan, Shagufta Hussain Page 47
    Background
    The importance of Staphylococcus aureus as a persistent nosocomial and community acquired pathogen has become a global health concern and showed capability of evolving different mechanisms of resistance to most antimicrobial agents leading to constraints in treatment. This scenario is even a greater challenge for developing countries. The present study was carried out to establish the frequency of S. aureus in clinical specimens and trends of antibiotic sensitivity patterns.
    Methods
    Samples of pus, blood, urine, body fluids and catheter tips submitted for culture in Microbiology department between August to September 2012, from outdoor and indoor patients of Pakistan Institute of Medical Sciences Islamabad, yielding growth of S. aureus were included in the study. After identification by standard methods, Antibiotic susceptibility of all the isolates was performed by Kirby Baeur disc diffusion method on Muller Hinton agar. It was a retrospective descriptive observational study.
    Results
    Total 106 S. aureus were isolated. 63.2% of the samples were obtained from pus and the next was blood with 18.9%. 45.3% were MRSA most of them from hospitalized patients and which were 100% sensitive to vancomycin and 87.5% to chloramphenicol. To rest of the non -betalactam drugs resistance of 80% or more was present.
    Conclusion
    Staphylococcus is a common clinical isolate from patients in this region of Pakistan and significant number out of them are MRSA especially causing infections in hospitalized patients. The treatment option is limited to expensive carbapenems i.e. vancomycin.
    Keywords: MRSA, Nosocomial infection, Antibiotic Sensitivity Pattern
  • Samaneh Saed, Malektaj Yazdanpanah, Mitra Lal, Dehghani, Amir Reza Khalighi, Mahbubeh Honarmand, Parviz Afrough, Kiarash Ghazvini Page 56
    Background
    Acinetobacter spp. emerged as an opportunistic pathogen for hospital-acquired infections. Recently, increasing antibiotic resistance among Acinetobacter spp. has worsened the problem. The aim of this study was to investigate the emerging trend of infection due to Acinetobacter in Ghaem University Hospital, Mashhad during 2006-2012.
    Methods
    The demographic data and information about redisposing factors was collected. Appropriate bacteriological samples were collected and Acinetobacter spp. was isolated. Antibiotics susceptibility pattern of these isolates against different antimicrobials agents was determined.
    Results
    Results confirmed that Acinetobacter spp. cause 20.9% of nosocomial infection during this period. The trend of Acinetobacter nosocomial infection was increasing and patients with risk factors such as COPD, bronchectasia, diabetes mellitus were more prone to infection. There was significant association between these infections and invasive procedures such as catheterization, mechanical ventilation and broad-spectrum antibiotics usage.
    Conclusion
    Understanding trends in causative organisms of nosocomial infection can help us to better define our infection control policy.