year 2, Issue 2 (Summer 2008)
Iran J Med Microbiol 2008, 2(2): 35-41 |
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Raei F, Eftekhar F. Studying the presence of blaZ gene and β-lactamase production in clinical isolates of Staphylococcus epidermidis. Iran J Med Microbiol 2008; 2 (2) :35-41
URL: http://ijmm.ir/article-1-118-en.html
URL: http://ijmm.ir/article-1-118-en.html
1- Department of Microbiology , Faculty of Biological Sciences, Shahid Beheshti University, GC
2- Department of Microbiology , Faculty of Biological Sciences, Shahid Beheshti University, GC , f_eftekhar@cc.sbu.ac.ir
2- Department of Microbiology , Faculty of Biological Sciences, Shahid Beheshti University, GC , f_eftekhar@cc.sbu.ac.ir
Abstract: (20621 Views)
Background and Objectives: Staphylococcus epidermidis is the most important member of coagulase
negative staphylococci. This organism has been reported as the third cause of nosocomial infections in the
last decade and one of the most important causes of bacterimia. New generation β-lactam antibiotics are
commonly used to cure these infections. Overproduction of β-lactamases not only results in bacterial
resistance against β-lactams, but also causes false methicillin resistance in some strains lacking methicillin
resistance gene. The aims of this study was to determine the susceptibility of clinical isolates of
Staphylococcus epidermidi s to some β-lactam antibiotics, to screen the isolates for β-lactamase production
and detect the presence of the β-lactamase gene (blaZ).
Materials and Methods: Sixty-nine clinical isolates of coagulase negative staphylococci were collected from three hospitals in Tehran. Susceptibility to 8 β–lactam antibiotics was determined using disc diffusion. β-lactamase production was screened by the iodometric colony test and presence of the blaZ gene was detected using specific primers and PCR.
Results: The antibiotic sensitivity results showed that 54 isolates (98.1%) were resistant to penicillin, 50 isolates (90.9%) to methicillin, 29 isolates (52.7%) to ceftriaxon, 27 isolates (49.09%) to ceftizoxime, 20 isolates (36.3%) to cefotaxim, 19 isolates (34.5%) toamoxicillin, 17 isolates (30.9%) to cefazolin and 13 isolates (23.6%) to cefalexin. The iodometric assay showed that all the isolates were β-lactamase producers and the PCR results confirmed the presence ofblaZgene in all isolates
Conclusion: Overall, 24-53 % of the clinical isolates of S. epidermidis were resistant to the third generation β-lactam antibioticas by disc diffusion. On the other hand,iodometric colony tests showed that all isolates produced β-lactamase and the presence of the blaZ gene was confirmed in all by PCR. The results obtained in this study suggest that despite the presence of the β-lactamase gene, enzyme expression is variable in different isolates and disc susceptibility test alone isnot often suitable for determining the course of antibiotic therapy.
Materials and Methods: Sixty-nine clinical isolates of coagulase negative staphylococci were collected from three hospitals in Tehran. Susceptibility to 8 β–lactam antibiotics was determined using disc diffusion. β-lactamase production was screened by the iodometric colony test and presence of the blaZ gene was detected using specific primers and PCR.
Results: The antibiotic sensitivity results showed that 54 isolates (98.1%) were resistant to penicillin, 50 isolates (90.9%) to methicillin, 29 isolates (52.7%) to ceftriaxon, 27 isolates (49.09%) to ceftizoxime, 20 isolates (36.3%) to cefotaxim, 19 isolates (34.5%) toamoxicillin, 17 isolates (30.9%) to cefazolin and 13 isolates (23.6%) to cefalexin. The iodometric assay showed that all the isolates were β-lactamase producers and the PCR results confirmed the presence ofblaZgene in all isolates
Conclusion: Overall, 24-53 % of the clinical isolates of S. epidermidis were resistant to the third generation β-lactam antibioticas by disc diffusion. On the other hand,iodometric colony tests showed that all isolates produced β-lactamase and the presence of the blaZ gene was confirmed in all by PCR. The results obtained in this study suggest that despite the presence of the β-lactamase gene, enzyme expression is variable in different isolates and disc susceptibility test alone isnot often suitable for determining the course of antibiotic therapy.
Type of Study: Original Research Article |
Subject:
Molecular Microbiology
Received: 2013/11/15 | Accepted: 2013/11/15 | ePublished: 2013/11/15
Received: 2013/11/15 | Accepted: 2013/11/15 | ePublished: 2013/11/15
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