Vol 2 No 1-2 (2013)

Published: 2013-06-15

Original Articles

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    Background: Acinetobacter baumannii, is an important opportunistic pathogens   responsible   for   nosocomial   infections.   The   aim   of   this experiment  was  to  determine  prevalence  of  Class  I  Integron  in  A. baumannii strains isolated from burn patients in Mottahari Hospital and the drug susceptibility pattern.Methods: There were 69 Acinetobacter isolates, 68 (98.5%) were identified as A. baumannii. Antimicrobial susceptibility of these isolates were determined by a disk diffusion method. PCR assay for detection of blaOXA-51 like gene (for identity confirmation) and intI was performed.Results:  The  most  effective  antibiotic  for  treating  A.  baumannii  was colistin, followed by tetracyclin and tobramycin. The presence of Integron class  I  was  detected  in  14.49%  of  isolates.  ESBL  and  carbapenemase production were observed in 10% and 24.6% of isolates, respectively.Conclusion: Due to the high resistance of strains lacking Integron I, the findings are although class I integrons are disseminated among clinical isolates  of  A.  baumannii,  at  present  research,  they  they  do  not  play important role in dissemination of antibiotic resistance genes in Mottahari Hospital in Tehran, Iran.
  • XML | PDF | downloads: 505 | views: 723 | pages: 12-19
    Background: In recent decades, extended spectrum beta-lactamase (ESBL) producing bacteria have increased worldwide. The most important causative agents of nosocomial infections throughout the world, Escherichia coli and Klebsiella pneumoniae as main ESBL-producing bacteria are so highly regarded. Trends  in  the  treatment  of  infections  by such  bacteria  have  led  to  a  global concern. This study was conducted to evaluate the incidence of ESBL producing E. coli and K. pneumoniae among inpatients and outpatients referred to the Imam Reza hospital unit in Mashhad during 2007-8.Methods: This study represents a descriptive cross-sectional study. All 339 samples from hospital and a special clinic of the Imam Reza hospital of Mashhad were collected and cultured in defined media. Identification by morphological and  biochemical  tests  were  performed  to  determine  the  Enterobacteriaceae genera. The secretion of ESBL was studied by the double disc diffusion method. At the end, the data were analyzed by statistical software.Results: Out of 339 isolates collected from 192 women (56.6%) and 147 men (43.4%), 26.5% of E. coli (n = 211) and 43% of K. pneumoniae (n = 128) were ESBL positive. Most of the ESBL-positive isolates were related to ICU and the least of them were related to neonatal ward.Conclusion: The present study indicates the high prevalence of ESBL producing Enterobacteriaceae family especially in inpatients. Limiting the spread of such superbugs is of utmost importance.
  • XML | PDF | downloads: 375 | views: 344 | pages: 20-26
    Background: The current study aimed to determine the effect and properties of surface-modified copper doped Cu:ZnO NPs on killing curves of bacterial pathogens.Methods:  Preparation  of  in  situ  surface-modified  copper  doped  ZnO nanoparticles (Cu:ZnO NPs) was done according to standard procedure.Assay for antimicrobial activity of Cu:ZnO NPs against bacterial pathogens was carried out based on disc diffusion method. Determination of shelf life, thermal and pH stability of antibacterial activity of Cu:ZnO NPs was done and residual activity was determined against the target cultures.Results: FTIR spectra indicate that the nanomaterials synthesized have higher peak intensity compared with reagent grade ZnO. According to the SEM image the nanoparticles synthesized have different size and heterogeneous morphology.  400  ppm  of  Cu:ZnO  NPs  gave  zones  of  inhibition  with diameters of 9.0 – 16 mm against the target cultures. Amongst the target cultures, Escherchia coli was the most sensitive to the Cu:ZnO NPs inhibition zone diameter 16 mm; whereas, 9 mm wide inhibition zone was obtained against  Staphylococcus  aureus. The  Cu:ZnO  NPs  was  fairly stable  for a period of 60 days at room temperature (RT) showing lost of only 20% and 30%     antibacterial  activity  as  tested  against  E.  coli  and  S.  aureus, respectively. The Cu:ZnO NPs was quite stable at this pH and temperature range tested against both E. coli and S. aureus.Conclusion: Surface-modified copper doped Cu:ZnO NPs have significant potential for their usefulness as antibacterial agents.
  • XML | PDF | downloads: 353 | views: 281 | pages: 27-34
    Background: The pathologies classified as urinary tract infections (UTI) can have a deleterious effect on patients who have undergone a renal transplantation.  Often recurrent UTIs will occur, leading to high morbidity, failure of the grafting process overall and even death.  The study presented here seeks to expand the knowledge of recurrent UTIs in the context of renal transplantation, what risks recurrent UTIs pose to transplant patients and evaluate possible treatments.Methods: Renal transplantations were performed on 94 patients.   For six months post-surgery the patients were evaluated for the presence of recurrent UTIs.  The criteria for determining a patient as having a UTI was given as finding   more than 103    and 105  pure colonies within one ml of urine for asymptomatic and symptomatic patients, respectively.   The criteria of recurrent UTI was defined as two or more conclusive UTIs within the first six months after the surgery or three more within a year after renal transplantation.Results: Of the 94 hospitalized patients, 29 UTIs were diagnosed (30.8%). The majority of diagnosed UTIs were in female patients (11.15, 73.3% vs.4.15, 26.7%; p-value = 0.003).   Those patients with diabetes mellitus correlated with a better chance of having a UTI (p-value = 0.019; CI = 1.2-12.2). The incidence rate of UTI was 51.7%, female predominant 73.3%. No  other  pathologies  were  shown  to  affect  the  chance  of  developing recurrent UTIs.   Typically Escherichia coli was the bacterium isolated from urine  cultures  (48.3%)  from  those  who  developed  recurrent  UTI.    The isolates tended to possess resistance to TMP / SMX and piperacillin but were susceptible to imipenem.Conclusion:   Recurrent UTIs in renal transplant patients can be mitigated with proper identification of risk factors.
  • XML | PDF | downloads: 196 | views: 297 | pages: 35-40
    Background: Legionella pneumophila is  a  dangerous pathogenic bacterium can cause serious infectious diseases especially in hospitalized immuno-compromised patients. This bacterium is shown to be resistant against different antibiotics. Resistance against a wide range of antibiotics is usually mediated by efflux pump in bacteria. Efflux pumps are proteinaceous transporters localized in the cytoplasmic membrane of all kinds of cells which excreted antibiotics outside the cells. However, synthesis of new anti-Legionella compounds or selection of resistant modulating agents are useful strategy to combat with L. pneumophilain the future.Methods: In this study the antibacterial activity of some benzofuranone derivatives have been investigated by disk diffusion method against L. pneumophila. Also the sensitivity of this test strain was evaluated against 19 antibiotics and the combination effect of reserpine at a sub-inhibitory concentration was further studied with these antibiotics using disk diffusion method with some modifications.Conclusion: Among the different synthetic compounds which were tested against L. pneumophila, the most antibacterial activity was observed for compounds 1j and 1m which contain hydroxyl and methoxy groups on the C-6 and C-7 positionsagainst L. pneumophila. To evaluate whether efflux pumps are active in L. pneumophila or not an efflux inhibitor (reserpine) was tested in combination of different antibiotics against this test strain. Reserpine significantly enhanced the antibacterial activities of kanamycin, nitrofurantoin, co-trimoxazole, erythromycin, ofloxacillin, gentamycin, rifampin, ciprofloxacin, nalidixic acid, minocycline, tobramycin, and amikacin against L. pneumophila which shows the resistances to these antibiotics are mediated by efflux system in this bacterium.
  • XML | PDF | downloads: 241 | views: 375 | pages: 41-53
    Background: Brevinin-2R, as 25 amino acids peptide of the skin of Rana ridibunda frog, possesses potent antimicrobial and low hemolytic activity. It has an N-terminal hydrophilic region and a C-terminal loop that is delineated by an intra-disulfide bridge. In our study, Brevinin-2R and its diastereomer as well  as its  cyclic  analogue  were  synthesized  and  characterized  in  order  to investigate its structural features and biological implications.Methods: MIC determination is based on the recommended classical method of national comittee for labratory safety standard (NCLSS) and standard by Hancock With some change on cationic peptides. In this study All bacterial strains were obtained from Industrial-Scientific Research center.Results: Both analogues showed lower antimicrobial activities compared to Brevinin-2R. In spite of Brevinin-2R peptide which shows low hemolytic activity, these analogues failed to show any hemolytic activity even at higher concentrations (up to 400 µ g/ml). Based on proteolytic stability measurements,diastereomer and cyclic analogues displayed 90% and 60% residual antimicrobial activity, respectively, while antimicrobial activity of Brevinin-2R was 20%. The CD analysis revealed that amphipathic α-helical conformation of the synthesized peptides is involved in antimicrobial effects.Conclusion: CD studies and HPLC based measurement of retention time using a reverse phase column indicated that the Brevinin-2R can form an amphipathic loop  resulting  in  an  enhanced  hydrophobicity.  The  hemolytic  activity  of Brevinin-2R and its analogues appeared to correlate with the retention time as well as the α-helicity. Accordingly, it seems that the combination of incorporating of D-amino acids into lytic peptides and their cyclization may result in developing new antimicrobial peptides with improved properties for treating infectious diseases.
  • XML | PDF | downloads: 278 | views: 357 | pages: 54-59
    Background: Acute bacterial meningitis is among serious infections of the central nervous system (CNS). The early diagnosis and empiric antibiotic treatments have led to a reduction in morbidity and mortality rates. PCR and the enzymatic digestion of 16S rDNA fragment following the PCR by universal primers led up fast and sensitive determination. The aims of the present study was to improve our previous method for rapid and specific detection of common bacteria causing acute meningitis.Methods: According to the gene encoding 16S rDNA found in all bacteria, a set of primers was designed. Then the universal PCR was performed for bacterial agents of meningitis by employing broad-range DNA extraction method. The amplicons were digested with restriction enzymes to identify bacterial species.Results:  By the  enzymatic  digestion  of  the  amplicons  of  each  standard strain, specific patterns were achieved. These specific patterns may be used for comparison in CSF examination. The analytical sensitivity of the assay was  approximately 1.5×102   CFU/ml  of  CSF  even in  samples with  high amount of proteins.Conclusion: The universal PCR coupled with enzymatic digestion can be used to detect and identify bacterial pathogens in clinical specimens rapidly and accurately. Molecular diagnostic of bacterial meningitis, though expensive and labor-intensive, but is valuable and critical in patient management.

Review Articles

  • XML | PDF | downloads: 219 | views: 267 | pages: 60-64
    Despite  impressive  advancements  in  diagnostic  and  treatment technologies,  infectious  diseases  still  cause  a  significant  amount  of mortality and morbidity throughout the world due to the unpredictable and inevitable  rise  of  new  or  previously  dormant  pathogens.  Emerging infectious disease (EID) outbreaks are mainly associated with changes in physical environment and human behavioral activities, and disproportionately affect developing countries. Syndromic surveillance, while challenged in developing countries by inadequate communication and public health infrastructure, could build on pre-existing systems to complement  existing governmental  and  non-governmental  programs  for outbreak detection and offers a promising avenue to detect EID eventsearlier in the course of an outbreak.