Vol 1 No 3-4 (2012)

Original Articles

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    Background: Multi-drug resistant strains of Acinetobacter spp. have created therapeutic problems worldwide. The objective of this study was to detect integrons  in Acinetobacter  spp. isolates  from Ventilator-Associated  Pneu- monia patients using PCR method.Methods: A total 51 Bronchoalveolar lavage samples were obtained from patients in ICU and examined for Acinetobacter spp. infection by biochemical and PCR methods using blaOXA51-like primers. Antimicrobial susceptibility testing was performed using disk diffusion and MIC methods.Results: Among 51 patients with VAP (62.7% males, 35.2% females, mean age 53 year), 50 (98%) were positive, with a high prevalence of gram-nega- tive bacteria, mainly Acinetobacter spp. (70%), from which A. baumani was detected in 34 (68%) and A. lwoffii in 1 (2%) of isolates. More than 90% of isolates were resistant to imipenem,  piperacillin+tazobactam,  third genera- tion cephalosporins and gentamicin, while the most effective antibiotic was colistin (100%). The correlation coefficient between disk diffusion and MIC was 0.808 (p = 0.001). Three Acinetobacter isolates (8%) harbored integrase I gene but none of isolates contained Class II or III integrons.Conclusion: The results showed that colistin was an effective antibiotic and can be used for treatment  of patients in ICU. Due to the high number of MDR isolates lacking Integrons it can be concluded that although class I in- tegrons are important among clinical isolates of A. baumannii, they have no significant  role  in  dissemination  of  antibiotic  resistance  genes  in  Rasoul Akram  Hospital in Tehran, Iran. The presence of IntI in A. lwoffii may be related to transfer of integron to A. baumannii which can be considered as an important threat for hospitalized patients.
  • XML | PDF | downloads: 325 | views: 897 | pages: 10-16
    Background: The prevalence of Urinary Tract Infection (UTI) is really high in the world. Escherichia coli is a major agent of UTI. One of the strategies for decreasing UTI infections is vaccine development. As the attachment is a really important stage in colonization and infection, at- tachment inhibition has an applied strategy.  FimH protein is a major factor during bacterial colonization in urinary tract and could be used as a vaccine. Thus, it was considered in this research as a candidate anti- gen.Methods: The sequences of fimH and acmA genes were used for de- signing a synthetic gene. It was cloned to pET23a expression vector and transformed  to E. coli (DE3) Origami.  To confirm the expression  of recombinant  protein,  SDS-PAGE  and western  blotting  methods  were used.  Subsequently,  recombinant  protein  was  purified.  On  the  other hand, Lactobacillus reuteri was cultured and mixed with FimH / AcmA recombinant  protein. The rate of protein localization  on lactobacillus surface was assessed using ELISA method.Results: It was showed that the recombinant protein was expressed in E. coli (DE3) Origami and purified by affinity chromatography. More- over, this protein could be localized on lactobacillus surface by 5 days. Conclusion:  In current study,  a fusion recombinant  protein was pre- pared and displayed on L. reuteri surface. This strain could be used for animal  experiment  as  a  competitor  against  Uropathogenic   E.  coli (UPEC). Using manipulated probiotics strains instead of antibiotic ther- apy could decrease the antibiotic consumption  and reduce multi-drug resistant strains.
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    Background: The prevalence of antibiotic resistance among extended spectrum  β-lactamase  (ESBL)  producing  Escherichia  coli  and  Klebsiella  pneumoniae  has been increased  markedly  in recent  years. The present study was done to know the prevalence  of ESBL production among isolates of E. coli and K. pneumoniae and to study the susceptibility pattern of isolates against different antibiotics.Methods:  Extended spectrum  β-lactamase  producing  E.  coli  and  K.pneumoniae were isolated from various samples obtained from outdoor and indoor patients of the Prathima Institute of medical sciencesdisc synergy test and resistance to various antibiotics like fluoroquinolones,  cephalosporins,  aminoglycosides  and  ß-lactamase  inhi- bitor combinations and susceptibility to carbapenems were determined by Kirby-Bauer disc diffusion method.Results: A total of 94 ESBL producing isolates were obtained. Of them 60 were E. coli and 34 K. pneumoniae. They were obtained from urine, sputum, pus, wound swabs blood & tracheal aspirates. Urine (38.29%) was the main source of ESBL-producing isolates from all patients, fol lowed by sputum (34.04%).  About 37.23% of these isolates were collected from medical wards and 27.65% were collected from outdoor. All isolates were susceptible to imipenem. The resistance to cephalos porins (1-4 generations)  was almost 100%. Resistance  to Aztreonam, Ampicillin and Coamoxyclav was also 100%. A high degree of resis tance was observed to other antibiotics.Conclusion:  The highest prevalence  of resistance to ESBL in E. coli and K. pneumonia is associated with a multitude of infections in hospi talized patients with a significant longer duration of hospital stay, increased morbidity and greater hospital charges. Advanced  drug resistance surveillance and molecular characteristics of ESBL isolates is ne- cessary to guide the proper and judicious antibiotic use.
  • XML | PDF | downloads: 331 | views: 826 | pages: 25-36
    Background: Pseudomonas aeruginosa is one of the most important oppor- tunistic pathogens responsible for various types of infections. Children suffer significant morbidity and mortality due to nosocomial infections. The aim of this study was to investigate the presence of Class1 integron, blaBEL, blaPER, blaKPC, blaVIM, blaIMP and blaOXAgroup-1  genes among P. aeruginosa isolates at Children's Medical Center Hospital in Iran and to determine phenotypic evi- dence of ESBL and MBL production.Methods: Antibiotic susceptibility tests were analyzed for 72 P. aeruginosa clinical isolates. Isolates were identified by using biochemical tests and con- firmed by PCR assay for oprL gene. ESBL and MBL producer isolates were identified  by phenotypic  tests (double disc synergy tests). Detection of β- lactamase genes and class-1 integron were performed by PCR method. Results: All of the isolates were susceptible to ceftazidime / clavulanate, me- ropenem, imipenem and ciprofloxacin. About 83.3% and 16.7% of isolates were  resistant  to  ceftazidime  and  amikacin  respectively.  Approximately,83.3% of isolates were considered as potential ESBL producers. None of the clinical isolates showed above β-lactamase genes. It seems that, the reason is the absence of class-1 integron in all of isolates. About 16.7% of strains were identified  as multidrug  resistant.  Fortunately,  all of the isolates were sus- ceptible to meropenem and imipenem which are effective against ESBL pro- ducing strains.Conclusion:  The absences of class-1 integron decreases the probability of acquired β-lactamase especially MBL. Thus, absolute susceptibility to carba- penems and ciprofloxacin among P. aeruginosa isolates in pediatric hospital has important implications for empirical antimicrobial therapy. It seems that these properties help to decrease mortality of nosocomial infections within children.
  • XML | PDF | downloads: 491 | views: 683 | pages: 37-43
    Background: Tuberculosis is a crucial health problem. Establishing a rapid, reliable and still inexpensive diagnostic method for tuberculosis seems to be substantial in developing countries where TB has very high incidence rate .Methods:  An Indirect  Enzyme-linked  immunosorbent  Assay (ELISA)  was established to detect serum antibodies against Mycobacterium  tuberculosis. Three kinds of antigens were used to prepare the solid phase for antibody as- say including: purified protein derivative (PPD), M. tuberculosis Bacilli, and Mycobacterium  bovis Bacillus  Calmette  Guerin  (BCG).  Sera  of two main following groups were investigated in this study: sera samples from smear- positive, culturepositive and Tuberculin Skin Test-positive TB patients and sera samples from smear-negative, culture negative and TST-negative healthy individuals.Results: Among the antigens used, BCG produced higher sensitivity and specificity in the assay. With PPD as the solid phase, higher sensitivity but low er specificity was observed in comparison with BCG. Both, low response and noise (non-specific binding) were observed with TB bacilli as the solid phase in the assay.Conclusion: Using BCG solid phase system in this method resulted in higher sensitivity in comparison to single antigen solid phase systems. In addition, we were able to circumvent  the problem of non-specific  bindings in more popular multi-antigenic solid systems such as PPD. By using this new indi- rect ELISA, a rapid, reliable and still inexpensive diagnosis of tuberculosis might be possible. Although, further investigations  are required to confirm our result.
  • XML | PDF | downloads: 444 | views: 1703 | pages: 44-52
    Background: The antimicrobial activity of silver nanoparticles has been investigated in medical fields in recent years, but there are few studies regarding its effect on oral microorganisms. The aim of the present study was to evaluate the in vitro antimicrobial and toxicity properties of nanosilver against two dental plaque microorganisms  and Human Gingival Fibroblast (HGF) cell line.Methods: Antibacterial effects of nanosilver colloidal solution were determined by minimal inhibitory concentration (MIC) and minimal bactericidal   concentration  (MBC)  using  microdilution   method.   Standard strains of Streptococcus sanguis and Actinomyces viscosus were used. For toxicity assessment, MTT and LDH  tests were performed  under  con- trolled conditions. Different concentrations of nanosilver were prepared and their toxic effects  on HGF were determined  after 24, 48 and 72 hours.Results: The MIC of nanosilver solution for S. sanguis and A. viscosus were 16 and 4 µ g/ml, respectively. The MBC of nanosilver was 64 µ g/ml for S. sanguis and 16 µ g/ml for A. viscosus. MTT results showed that after 24 hours the concentrations of ≥ 0.5 µ g/ml of nanosilver solution affected cell viability when compared with control group. After 48 and 72 hours only the concentration of  ≥ 5 µ g/ml showed significant effect on cultured cell viability. LDH release test demonstrated toxic effect only after 48, 72 hours by 20 and 50 µ g/ml of nanosilver.Conclusion: The results demonstrated that beside its antibacterial activity against S. sanguis and A. viscosus, nanosilver mediated a concentration and time dependent cytotoxicity on HGF.

Review Articles

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    Background: Staphylococcus aureus is a major human pathogen world wide. Vancomycin has been used for decades to treat multidrug resistant S. aureus. Ten years has passed since the first report of vancomycin re sistant S. aureus (VRSA). The objective of this systematic review was to determine  the total number of VRSA isolates that have been reported from Iran.Methods:  Search terms reflected “Iran”, “vancomycin” and “S. aureus” were  searched  in the ISI web  of knowledge,  PubMed,  SciVerse,  and Google scholar. Also two Persian scientific databases and 13 recent na tional congresses  were investigated.  Articles / abstracts working on S. aureus in Iran, evaluating vancomycin MIC and / or PCR of vanA/B were included in this systematic review.Results: Out of the 3484 records found in mentioned resources, 13 related studies were included in the final analysis. The result showed that at least 24 VRSA isolates which have been reported from Iran up to September 2012.Conclusion: It seems that many Iranian researchers did not follow a spe cific guideline for reporting and confirming VRSA. Establishing an Iranian reference center where studies on VRSA can be registered, evaluated and confirmed is strongly recommended.

Case Reports