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Bialvaei A.Z.,Tehran University of Medical Sciences | Rahbar M.,Iranian Reference Health Laboratory | Yousefi M.,Tabriz University of Medical Sciences | Asgharzadeh M.,Tabriz University of Medical Sciences | Kafil H.S.,Tabriz University of Medical Sciences
Journal of Antimicrobial Chemotherapy | Year: 2017

Linezolid, an oxazolidinone antimicrobial agent that acts by inhibiting protein synthesis in a unique fashion, is used in the treatment of community-acquired pneumonia, skin and soft-tissue infections and other infections caused by Gram-positive bacteria including VRE and methicillin-resistant staphylococci. Currently, linezolid resistance among these pathogens remains low, commonly <1.0%, although the prevalence of antibiotic resistance is increasing in many countries. Therefore, the development of resistance by clinical isolates should prompt increased attention of clinical laboratories to routinely perform linezolid susceptibility testing for this important agent and should be taken into account when considering its therapeutic use. Considering the importance of linezolid in the treatment of infections caused by Gram-positive bacteria, this review was undertaken to optimize the clinical use of this antibiotic. © The Author 2016.


Karami S.,Islamic Azad University at Karaj | Rahbar M.,Iranian Reference Health Laboratory | Yousefi J.V.,Islamic Azad University at Karaj
Iranian Journal of Pathology | Year: 2011

Background and Objectives: Rapid and accurate detection of methicillin resistant Staphylococcus aureus (MRSA) is an important role of clinical microbiology laboratories to avoid treatment failure. The aim of this study was to compare conventional methods against the E-test minimum inhibitory concentration (MIC) method to determine the best phenotypic method. Materials and Methods: Methicillin resistance was studied among clinical isolates of S. aureus from April to October 2009 in Milad Hospital of Tehran. These methods included E-test MIC, oxacillin screen agar, oacillin disk diffusion, cefoxitin disk diffusion, and CHROMagar- MRSA methods. Results: Out of 294 isolates of S. aureus, one hundred and six (36%) strains of MRSA were isolated from clinical specimen. Oxacillin screen agar and CHROMagar-MRSA showed both 110 MRSA isolates. The sensitivity and specificity for these two methods were 100% and 97.9%, respectively. The sensitivity and specificity of oxacillin disk diffusion method was similar to those of oxacillin screen and CHROMagar-MRSA. One hundred and eight strains of S. aureus were MRSA by cefoxitin disk diffusion method. The sensitivity and specificity of cefoxitin disk diffusion method was 100% and 98.1% respectively. All isolates including MRSA were susceptible to vancomycin. Nearly al MRSA isolates were resistant to erythromycin, clindamycin, chloramphenicol, tetracycline, ceftriaxone and ciprofloxacin. Conclusion: All phenotypic methods had high sensitivity and specificity for detection of MRSA. However, cefoxtin disk diffusion method in comparison to other methods had higher specificity.


Rastegar Lari A.,Tehran University of Medical Sciences | Azimi L.,Tehran University of Medical Sciences | Rahbar M.,Iranian Reference Health Laboratory | Fallah F.,Shahid Beheshti University of Medical Sciences | Alaghehbandan R.,Memorial University of Newfoundland
Burns | Year: 2013

Background: Resistance to antimicrobial agents such as carbapenems among enterobacteriacea has been increasing, especially in Klebsiella pneumonia that produces variety of enzymes including Klebsiella pneumoniae carbapenemase (KPC). This study is the first report of its kind investigating the resistance to carbapenems among burns patients in Iran. Method: During a 6-month period, 28 hospitalized burn patients who required to be placed on broad spectrum antibiotics were studied. Isolated species identified by routine biochemical test. Susceptibility testing for these species was performed by recommended the CLSI guidelines method. The tested antibiotics included cefotaxime, cefepime, aztreonam, imipenem, amoxicillin + clavulonic acid, gentamicin, amikacin, tobramycin, tetracycline, and trimethoprim-sulfamethoxazole, and chloramphenicol. For determination of KPC in phenotypical forms, Modified Hodge Test was utilized as per CLSI recommendation. Results: Thirty-five Klebsiella spp. were isolated from 28 hospitalized patients. Nineteen out of 35 Klebsiella isolates were resistant to imipenem and that all of them had positive KPC. Nine of imipenem resistant isolates were also resistant to all tested antibiotics. Mortality rate among patients with positive KPC was 33%. Conclusion: High rate of multi-drug resistant (MDR) strains in isolates with positive KPC is a major challenge in Iran and that it could cause an increase in both mortality and morbidity among burn patients. Thus, appropriate infection control measures and guidelines are needed to prevent such infections among burn patients. © 2012 Elsevier Ltd and ISBI.


Behrooozi A.,Islamic Azad University at Karaj | Rahbar M.,Iranian Reference Health Laboratory | Yousefi J.V.,Islamic Azad University at Karaj
African Journal of Microbiology Research | Year: 2010

Urinary tract infections (UTIs) are one of the most common infectious diseases diagnosed in communities and hospitalized patients. The aim of this study was to determine frequency of occurrence and antimicrobial susceptibility patterns of uropathogens in Milad hospital of Tehran, Iran. In a prospective study from March to June 2009, a total of 11308 urine sample from patients admitted in Milad hospital of Tehran were analyzed. All specimens were inoculated on routine culture media. Bacterial isolates were identified by conventional bacteriological methods. Susceptibility testing was performed by standard methods as recommended by clinical laboratory standard institute. 11308 urine samples were cultured and 1020 pathogen were isolated. Escherchia coli with 620 (60.78%) isolates was the most common causative agent of UTI followed by Klebsiella pneumoniae with 115 (11.27%) isolates. Among gram positive Cocci Enterococcus spp with 110 (10.78%) isolates and Staphylococcus aureus with 81 (7.94%) isolates were predominant organisms. Of 1020 patients, 227 (22.25%) were male and 793 (77.74%) were female. Of 1020 patients, 224 (21.96%) of patients were hospitalized and 796 (78.03%) were outpatients. Of 224 hospitalized patients, 85% of isolates of E. coli were resistant to ampicillin, while this figure was 90% for K. pneumoniae. Resistant to other antibiotics were also prevalent. Nitrofurantoin was the most effective antibiotics against E. coli and Enterococcus spp. In conclusion, our study revealed that bacterial resistance in uropathogens in our hospital continues to be a great problem and needs drug resistance surveillance periodically. © 2010 Academic Journals.


Azimi L.,Tehran University of Medical Sciences | Rastegar L.A.,Tehran University of Medical Sciences | Alaghehbandan R.,Memorial University of Newfoundland | Alinejad F.,Tehran University of Medical Sciences | And 2 more authors.
Annals of Burns and Fire Disasters | Year: 2012

To the best of our knowledge, this is the first report of Klebsiella, Acinetobacter and Pseudomonas-producing Klebsiella pneumoniae Carbapenemase (KPC) among burn infants in Iran. The objective of this study was to determine the phenotypic detection of these KPC among isolated Pseudomonas aeruginosa, Acinetobacter baumannii and Klebsiella spp. A cross-sectional study was performed (February to September 2011) at a tertiary burn hospital in Tehran, Iran. Sixty-four strains were isolated from 20 patients. Strain and genus of isolates were confirmed, antibiotic susceptibility testing was implemented, and KPC determined by Modified Hodge Test. Fifteen of 36 strains (six Pseudomonas aeruginosa, six Acinetobacter baumannii, and three Klebsiella pneumoniae) were resistant to imipenem. Ten strains of 36 Gram negative isolates were resistant to all tested antibiotics except for Colistin. Thirteen of 15 resistant imipenem strains were confirmed as KPC-producer bacteria that isolated from nine patients. Six of 36 isolated strains were extended-spectrum β-lactamase (ESBL)-producing bacteria, of which four strains were both KPC and ESBL. A high percentage of multidrug resistant (MDR) strains in our centre with positive KPC have created a major challenge in terms of mortality and morbidity. The findings of this study highlight the importance of implementing an effective infection control strategy to prevent and decrease the prevalence of KPC-producing organisms.


Hajia M.,Iranian Reference Health Laboratory | Rahbar M.,Iranian Reference Health Laboratory | Rahbar M.,Tehran University of Medical Sciences | Fallah F.,Shahid Beheshti University | Safadel N.,Iranian Reference Health Laboratory
Open Respiratory Medicine Journal | Year: 2012

Background: Even with high coverage of vaccination programs, Bordetella pertussis is still reported in various countries. It causes a high rate of mortality and morbidity in infants while it could be asymptomatic in adults. At the present study, we are going to evaluate the frequency of B. pertussis among received specimens. Methods: This cross-sectional study was performed on 138 children under one year who were suspected to have whooping cough from October 2008 to March in 2011. Nasopharyngeal dacron and rayon swabs and sera were used for PCR and serology respectively. Results: The mean age of the subjects was 1.9± 0.9 months. PCR was positive in 12 cases; ELISA was in agreement with PCR results except in one case that showed the specific antibody at borderline limit. Conclusion: The rate of reported positive results showed that pertussis not only is still present in the community, but the number of the asymptomatic cases who are able to transmit the disease may be considerable. © Hajia et al.; Licensee Bentham Open.


Armin S.,Shahid Beheshti University of Medical Sciences | Rouhipour A.,Shahid Beheshti University of Medical Sciences | Fallah F.,Shahid Beheshti University of Medical Sciences | Rahbar M.,Iranian Reference Health Laboratory | Ebrahimi M.,Shahid Beheshti University of Medical Sciences
Archives of Pediatric Infectious Diseases | Year: 2013

Background: Staphylococcus aureus is a major cause of serious hospital and community acquired infections, particularly in colonized individuals. Objectives: The study was carried out in a tertiary care center in Tehran, Iran to identify the frequency of hospital acquired methicillin resistant Staphylococcus aureus (HA-MRSA) colonization and its antibiotic susceptibility pattern and molecular characteristics. Patients and Methods: This point-prevalence study was performed on 631 children who were admitted for at least 48 hours in different wards of Mofid children’s hospital in Tehran, Iran. Samples from anterior nares of these children were taken with sterile swab and cultured. If Staphylococcus aureus (S. aureus) was isolated, methicillin resistance and antibiotic susceptibility pattern were diagnosed according to Center for Disease Control and Prevention (CDC) guidelines of 2011 and Clinical and Laboratory Standards Institute (CLSI), and molecular analysis were determined by minimum inhibitory concentration (MIC) and polymerase chain reaction (PCR) methods. Results: Rate of colonization with S. aureus and methicillin resistant Staphylococcus aureus (MRSA) were 3.2% and 1.1% (1.1% of total and 35% of S. aureus isolates), respectively. All MRSA isolates were susceptible to rifampin and clindamycin. Resistance to vancomycin was reported in six Staphylococcus strains. Resistance to linezolid was detected in 19/20 Staphylococcus. Molecular analysis of isolates showed that all vancomycin resistant S. aureus isolates contained Van A or Van B gene, and 15/19 linezolid resistant strain was positive for chloramphenicol-florfenicol resistant gene (cfr gene). Conclusions: The rate of MRSA colonization varies in any area, and the knowledge of acquisition risk factors and antibiotic susceptibility pattern are essential in prevention and treatment of MRSA infections. Based on our study, we suggest that clindamycin and rifampin are good choices in empiric treatment of patients suspected to have HA- MRSA infections until results of culture and antibiotic susceptibility pattern are prepared. In respect to the prevalence of linezolid resistance in this study, we suggest avoiding the use of linezolid as empiric therapy in HA-Staphylococcus infection. © 2013 Pediatric Infections Research Center and Shahid Beheshti University of Medical Sciences.


Tajbakhsh M.,Shahid Beheshti University of Medical Sciences | Garcia Migura L.,IRTA - Institute of Agricultural-Alimentary Research and Technology | Rahbar M.,Iranian Reference Health Laboratory | Svendsen C.A.,Technical University of Denmark | And 4 more authors.
Journal of Antimicrobial Chemotherapy | Year: 2012

Objectives: In this study, we wanted to assess the level of antimicrobial resistance, the presence of genes encoding resistance to cephalosporins and plasmid-mediated quinolone resistance (PMQR), and genetic relatedness among Shigella isolates obtained from Iranian patients. Methods: A total of 44 Shigella isolates were collected from Iranian patients admitted to Milad Hospital, Tehran, Iran, during 2008-10. Of these, 37 were serotyped and characterized by MIC determination. A subset of eight suspected extended-spectrum β-lactamase (ESBL) producers (six Shigella sonnei phase II and two Shigella flexneri type 1b) were examined for the presence of genes encoding cephalosporin resistance. The presence of PMQR was assessed in one S. flexneri isolate exhibiting low-level resistance to ciprofloxacin and susceptibility to nalidixic acid. PFGE was performed on 25 S. sonnei phase II isolates. Results: Of the isolates, 25 (68%) were S. sonnei phase II, with 5 (14%) S. flexneri, 5 (14%) Shigella dysenteriae type 2, and 2 (5%) Shigella boydii type 2. Resistance to at least threeclasses of antimicrobials was detected in all species. The presence of bla CTX-M-15 and the AmpC β-lactamase producer bla CMY-2 was confirmed in five and one S. sonnei phase II isolates, respectively. One of the two S. flexneri type 1b that contained bla CTX-M-15 also harboured a qnrS1 gene. PFGE identified sevenPFGE profiles; the main cluster included 15 of the strains, suggesting low genetic diversity between isolates or the presence of an endemic clone in Iran. Conclusions: This is the first known description of ESBL-producing and AmpC β-lactamase-producing Shigella and of PMQR Shigella in Iran. The emergence of CTX-15, CMY-2 and qnrS1 genes may compromise the treatment of shigellosis. Strategies to minimize the spread of ESBL-producing and AmpC-β-lactamase-producing Shigella should be implemented. © The Author 2012. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved.


Hamidian M.,University of Tehran | Hamidian M.,University of Sydney | Tajbakhsh M.,University of Tehran | Tohidpour A.,University of Tehran | And 3 more authors.
International Journal of Antimicrobial Agents | Year: 2011

The aim of the current study was to detect mutations in the gyrA gene of quinolone-resistant Salmonella spp. isolates recovered in Tehran, Iran. Between April 2008 and September 2009, 174 Salmonella spp. were collected and assayed for quinolone resistance and detection of gyrA mutations. Isolates identified as Salmonella enterica were tested for susceptibility by the disk diffusion method. Polymerase chain reaction (PCR) amplification and sequencing of the gyrA gene segment encoding the quinolone resistance-determining region (QRDR) were performed for the nalidixic acid-resistant isolates. Amongst the 174 recovered Salmonella spp. isolates, 89 were resistant to nalidixic acid, of which 9 were resistant to enrofloxacin; 10 isolates had reduced susceptibility to nalidixic acid. None of the isolates were resistant to ciprofloxacin, but a single isolate showed reduced susceptibility. Twelve types of amino acid replacement were found in the QRDR region of GyrA, namely the previously described substitutions in positions 83 and 87 as well as five new substitutions Leu41-Pro, Arg47-Ser, Ser111-Thr, Ala118-Thr and Asp147-Gly. Double substitutions in both positions 83 and 87 were not identified. A Gly133-Glu substitution was identified in a single S. enterica serotype Typhi isolate. © 2011 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.


PubMed | Tabriz University of Medical Sciences, Tehran University of Medical Sciences and Iranian Reference Health Laboratory
Type: | Journal: The Journal of antimicrobial chemotherapy | Year: 2016

Linezolid, an oxazolidinone antimicrobial agent that acts by inhibiting protein synthesis in a unique fashion, is used in the treatment of community-acquired pneumonia, skin and soft-tissue infections and other infections caused by Gram-positive bacteria including VRE and methicillin-resistant staphylococci. Currently, linezolid resistance among these pathogens remains low, commonly <1.0%, although the prevalence of antibiotic resistance is increasing in many countries. Therefore, the development of resistance by clinical isolates should prompt increased attention of clinical laboratories to routinely perform linezolid susceptibility testing for this important agent and should be taken into account when considering its therapeutic use. Considering the importance of linezolid in the treatment of infections caused by Gram-positive bacteria, this review was undertaken to optimize the clinical use of this antibiotic.

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