Mirsalehian A, Jabalameli F, Kazemi B, Alizadeh S A,
Volume 61, Issue 6 (9-2003)
Abstract
Background: Staphylococci as a micro-organism, has the most importance to cause nosocomial infections, particularly in patients with indwelling catheters or other medical devices. Unfortunately 90% of Staphylococci isolated from the nosocomial infections are resistant to methicillin, and methicillin resistance strains are also resistant to a wide range of antimicrobial drugs, therefore detecting of these strains are valuable to eradicate the infection elements. Despite guidelines published by the national committee for clinical laboratory standards (NCCLS) for testing of susceptibility to methicillin for Staphylococci, the phenotypic method for detecting methicillin resistance remains controversial. Therefore, the genetic assays have been used to detect antimicrobial susceptibility of Staphylococci to methicillin.
Materials and Methods: Resistance to methicillin is coded by mec A gene in staphylococcus, and this gen must be detected in genetic assays. In this study 155 clinical staphylococcal isolates (70 coagulase- negative staphylococcus and 85 coagulase- Positive staphylococci) were evaluated for susceptibility to methicillin by using disk diffusion method.
ResuIts&Conclusion: Methicillin resistance was shown in 62 coagulase- negative staphylococcus (72.9%) and 27 coagulas positive staphylococcus (38.6%) but 63 coagulase negative Staphylococci (74%) and 28 coagulase positive isolates with mec a gene associated resistance were detected by PCR method. The results of this test were compared to the results for mec A gene detection by PCR test as a gold standard. The sensitivity, specifity and accuracy of the disk diffusion test for coagulase-negative staphylococcus were 96.8%, 95.45% and 96.47% and for coagulase positive staphylococci were 98.43%, 95.45% and 98.32% respectively.
Aligholi M, Emaneini M, Hashemi F. B , Shasavan Sh, Jebelameli F, Kazemi B,
Volume 64, Issue 9 (9-2006)
Abstract
Background: Staphylococcus aureus (SA (is an important cause of nosocomial and community-acquired infections. The emergence of antibiotic resistance, especially in methicillin-resistant SA (MRSA) strains, has caused difficulties in treatment of such infections. The determination of antibiotic resistance patterns, particularly domestic patterns of Iran, is essential for appropriate treatment of MRSA infections and proper infection control measures in our country.
Methods: The antibiotic resistance of 338 SA isolates from various clinical specimens was determined by disk agar diffusion (DAD), minimum inhibitory concentration (MIC) and polymerase chain reaction (PCR) methods.
Results: Using the DAD method, 47% (160/338) of the SA isolates were resistant to oxacillin, and only 6% (20/338) were resistant to vancomycin. By PCR, 48% (162/338) of the isolates had the mecA gene. The MIC of oxacillin in 93% of isolates was higher than 256µg/mL. The MRSA isolates, showed a high resistant to gentamicin (40.5%), erythromycin (40%), and ciprofloxacin (38%). However, only a few of the SA isolates showed a high resistance to vancomycin (5%) or erythromycin (3.5%).
Conclusion: The results of this study can provide guidance for physicians toward a more appropriate treatment of SA infections in Iran, thereby preventing the emergence of further antibiotic resistance among SA. Our results also revealed the need for further investigations using a higher number of specimens representing a wider variety of locations to determine the antibiotic resistance patterns in our state more precisely.
Hadadi A, Moradi-Tabriz H, Mehdipour Aghabagher B, Moslehi B, Esmaielzadeh P,
Volume 69, Issue 6 (9-2011)
Abstract
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false
false
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AR-SA
MicrosoftInternetExplorer4 Background: Staphylococcus aureus infection pervasively occurs in communities and
hospitals and observing related guidelines is essential in preventing development
of antibiotic resistance in Hospitals. In this study we tried to determine the
prevalence of Methicillin and vancomycine resistant staphylococcus aureus (MRSA
& VRSA) and find the most suitable diagnostic tool and
treatment in affected patients.
Methods: This study was performed on hospitalized patients in Sina Hospital in Tehran,
Iran during 2009-2010. Eighty-five staphylococcus
aureus samples were evaluated for resistance to oxacillin and vancomycine
by both disc diffusion and E-test methods.
Results: The study population included 46 male and 39
female patients. The mean age of the participants was 51.46±19.21
years. The MRSA frequency was 50%.
67 (78.8%) patients had hospital-acquired
staphylococcus infection. The rate of hospital-acquired MRSA
was 93%. Length of hospital stay, undergoing invasive
methods, history of antibiotic use three months prior to hospitalization and its
kind were recognized as MRSA risk factors. There
were no reports of VRSA except one case of vancomycine-intermediate
S. aureus (VISA). The results of disk effusion and E-test
methods were consistent.
Conclusion: Considering
the prevalence of methicillin resistance in hospital-acquired infections, it seems
that oxacillin should not be used as the first-line option for empiric therapy
against S. aureus till
antibiogram results are available. Disc diffusion can also be reliably used
instead of the more expensive E-test.
Monireh Rahimkhani,, Zahra Rajabi,
Volume 80, Issue 7 (10-2022)
Abstract
Background: Considering the frequency of MRSA strains in hospitals and medical centers as well as in different communities, it seems necessary and important to observe the use of appropriate drugs in order to reduce antibiotic resistance and reduce the economic costs of treatment. This study aimed to investigate the antibiotic resistance pattern of MRSA isolated from blood and wound samples of patients. The study patients were hospitalized in different departments in a number of Tehran University of Medical Sciences hospitals.
Methods: In this descriptive cross-sectional study from September 2021 to February 2022, the blood and wound samples of the patients were collected and referred to laboratory. Staphylococcus aureus had identified by phenotypic and biotypic tests. MRSA isolates were screened by showing resistance to Cefoxitin by disc diffusion method and finally confirmed by examining the mecA gene by PCR. The microbial resistance pattern of MRSA was also measured by disk diffusion method and resistance to Vancomycin was confirmed by E.test.
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Results: 41 isolates from 87 Staphylococcus aureus samples were confirmed as MRSA by present the mecA gene. The mecA gene was detected in all MRSA by PCR method. The antibiotic resistance pattern showed the highest sensitivity to Vancomycin and Linezolid with 100% sensitivity and the highest resistance to three antibiotics Erythromycin, Ceftriaxone and Cloxacillin with 97.57%by disk diffusion method. The most MRSA strains were isolated from the ICU department with 13 cases and the least MRSA strains were isolated from the two NICU and pediatric departments with one case.The majority of the population infected with MRSA belonged to the age group of 40-65 years.
Conclusion: The prevalence of microbial resistance with high dispersion was obtained among MRSA strains isolated from clinical samples; which indicates a significant increase in resistant strains and requires a quick and timely diagnosis to prescribe the appropriate antibiotic.
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