Microbiology
Helia Ostad Asadolah-Malayeri; Mojdeh Hakemi-Vala; Kambiz Davari
Volume 11, Issue 4 , October 2016, , Pages 345-353
Abstract
Background: This study aimed to evaluate the role of efflux pump regulator and OXA-23 genes in imipenem resistance Acinetobacter baumannii strains isolated from hospitalized patients in Tehran, Iran. Methods: This study was conducted on 60 A. baumannii isolates collected from patients admitted to the ...
Read More
Background: This study aimed to evaluate the role of efflux pump regulator and OXA-23 genes in imipenem resistance Acinetobacter baumannii strains isolated from hospitalized patients in Tehran, Iran. Methods: This study was conducted on 60 A. baumannii isolates collected from patients admitted to the Shahid Motahari and Taleghani Hospitals in Tehran during 2013-14. Antibiotic susceptibility tests (AST) and minimal inhibitory concentration (MIC) was determined by broth micro dilution methods according to CLSI 2014 guidelines. The frequency of efflux pump adeRS and OXA-23 genes were detected by PCR and further sequencing. Results: The resistance of A. baumannii isolates to tested antibiotics was 100% to cefotaxime, ceftazidime, ceftriaxone, ciprofloxacin, cefepime, piperacillin, meropenem, co-trimoxazole and piperacillin/tazobactam, 97% to imipenem, 94% to gentamicin, 83% to amikacin, 76% to tetracycline, and 0.0% to colistin. The MIC of 58 (96.6%) strains to imipenem was highly decreased in the presence of efflux pump inhibitor (PaβN), by 4 to 64 folds. The adeR and adeS genes were detected in 36 (60%) and 59 (98.3%), respectively and the frequency of OXA-23 gene was 57 (95%) of isolates. Conclusion: Existence of adeRS and OXA-23 genes in more than 50% of A. baumannii isolates in this study shows the presumptiverole of efflux pump in simultaneous of carbapenemase production. Therefore, using new strategies are required in order to stop the vertical or horizontal exchanges mentioned genes from the resistant A. baumannii isolates to sensitive strains.
Maryam Amini; Ali Davati; Masomeh Piri
Volume 8, Issue 1 , January 2013, , Pages 21-26
Abstract
Background and Objective: Diabetes mellitus is one of the main problems in health systems in the world. Diabetic Foot infections (DFI) is one of the main complications and the most cause of non-traumatic lower limb amputation .This study aimed to determine the prevalence of bacteria involved in ...
Read More
Background and Objective: Diabetes mellitus is one of the main problems in health systems in the world. Diabetic Foot infections (DFI) is one of the main complications and the most cause of non-traumatic lower limb amputation .This study aimed to determine the prevalence of bacteria involved in DFI and their antibiotic resistance in patients with DFI diagnosis.
Patients and Methods: This descriptive-analytical and cross-sectional study was designed in 4 years period from April 2007 to March 2010 on 90 patient in Shahid Mostafa Khomeini Hospital,Tehran, Iran .For bacteriological analysis, all wound samples culture grown by standard methods bacteriology and Disk diffusion method was used for antibiogram. Patient’s clinical and epidemiologic data were collected from recorded file. The data were analyzed by using SPSS16 statistical software.
Results: 104 bacteria were isolated from 90 patients. 57.70% were gram-positive and 42.30% were gram-negative. Among gram-positive bacteria Staphylococcus aureus (60%) and enteroccoci spp.(33.3%) and among gram-negative bacteria E. coli (47.73%), Pseudomonas Aeroginosa (22.73%) and Proteus spp.(18.18%) were the most common isolates respectively. 75% of isolates were resistant to two antibiotics or more. Previous antibiotic therapy was significant risk factor for multidrug resistant (MDR) infections (P: 0.003). All gram-positive isolates were sensitive to Vancomycin. Imipenem and Amikacin had good activity against gram-negative bacteria.
Conclusion:Infection with MDR bacteria in patients with diabetic foot ulcers is high and have significant association with recent antibiotic therapy. So the proper use of antibiotics in order to prevent the creation of multi-drug resistant bacteria is recommended.
Parviz Owlia; Zakaria Bameri; Mohsen Chitsaz
Volume 5, Issue 3 , June 2010, , Pages 137-142
Abstract
Background and Objective: Organisms producing CTX-M β-lactamases are emerging as a source of resistance to oxyiminocefalosporins such as ceftriaxone and ceftazidime. However, the laboratory detection of these strains is not well defined. In this study, phenotypic assay for screening of extended-spectrum ...
Read More
Background and Objective: Organisms producing CTX-M β-lactamases are emerging as a source of resistance to oxyiminocefalosporins such as ceftriaxone and ceftazidime. However, the laboratory detection of these strains is not well defined. In this study, phenotypic assay for screening of extended-spectrum β-lactamases producing strains and molecular assay for the identification of CTX-M β-lactamases genes was developed and used to investigate the prevalence of these enzymes among clinical isolates of Klebsiella pneumoniae in three general hospitals of Tehran, Iran. Materials and Methods: Phenotypic detection was used for screening of isolates by agar dilution method. A decrease of ≥3 doubling dilution in an MIC for either ceftriaxone or ceftazidime tested in combination with 4 mg/l clavulanic acid (prepared from Glasco Smith company) versus its MIC when tested alone, confirmed an ESBL-producing organism. The PCR assay consisted of four primer sets. Results: In initial screening test, 117 (69%) from 168 clinical isolates were positive and 51 isolates (31%) were negative. From the positive isolates, 96 isolates were positive in phenotypic confirmatory test. Using molecular assay, 117 strains potentially producing extended-spectrum-β-lactamases were examined for the presence of CTX-M enzymes: 88 strains (75.2%) were positive for blactx-m group І genes, 1 strain (0.85%) was positive for blactx-m group ІІІ genes , and 2 strains (1.7%) were positive for blactx-m group ІV. Conclusion: The prevalence of extended-spectrum β-lactamases (ESBLs) are increasing significantly in hospitals of Tehran. In other side, we found that the CTX-M І group had the most prevalence than other CTX-M groups.
Mohammad Rahbar; Hadi Mehragan; Negar Haji Ali Akbari
Volume 5, Issue 2 , March 2010, , Pages 90-96
Abstract
Background and Objectives: Non-fementer gram-negative bacilli (NFGB) are ubiquitous pathogen that has emerged as a major cause of health care associated infections. The aim of this study was to determine the prevalence and antimicrobial susceptibility of NFGB in an Iranian hospital. ...
Read More
Background and Objectives: Non-fementer gram-negative bacilli (NFGB) are ubiquitous pathogen that has emerged as a major cause of health care associated infections. The aim of this study was to determine the prevalence and antimicrobial susceptibility of NFGB in an Iranian hospital. Materials and Methods: FromJuly 2005 to November 2006 a total of 257 strains of NFGB including 109 (42.41%) strains of Pseudomonas aeruoginosa, 88 (34.24%) strains of Acinetobacter baumannii, 48 (18.67%) stains of Stenotrophomonas maltophilia and 12 (4.66%) strains of Burkholderia cepacia were isolated from clinical specimens taken from patients hospitalized in an Iranian 1000–bed tertiary care hospital[d1] . Conventional bacteriological methods were used for identification and susceptibility testing of NFGB. Susceptibility testing was performed by method as recommended by Clinical Laboratory Standard Institute (CLSI). Data were analyzed using SPSS 11.5 for Windows (SPSS Inc., Chicago, IL) Results: A total of 257 non-duplicating of NFGB strains were isolated from 234 hospitalized patients. The most effective antibiotic against P. aeruginosa and A. baumannii was imipenem followed by tobramycin. Fluoroquinolones had moderate activity against P. aerugunosa. Most isolates of A.baumannii were multi-drug resistant. Susceptibility of S. maltophila to ticarcillin- clavuanic, ofloxacin and ceftazidim was 96%, 94% and 81%, respectively. Thirty three percent of this bacterium isolates were resistant to co-trimoxazole. Conclusion: In our study, imipenem was the most effective antibiotic against P. aeruginosa and A. baummannii isolates. Previous history use of antibiotics, longer duration of hospital stay and mechanical ventilation were the major risk factors for resistance acquisition in NFGB especially in P. aeruginosa and A. baumannii.
