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Showing 8 results for Pseudomonas Aeruginosa
Mohammadreza Nahaei , Reza Bohloli Khiavi , Mohammad Asgarzadeh, Alka Hasani , Javid Sadeghi, Mohammad Akbari Dibavar ,
Volume 7, Issue 1 (4-2007)
Abstract
Background and Objectives: Pseudomonas aeruginosa is a nosocomial pathogen that presents high antibiotic resistance.There are phenotyping and genotyping methods for epidemiologic study of Pseudomonas aeruginosa such as antibiotic resistance pattern and plasmid profile analysis. Plasmid analysis provides useful information concerning the source of the strains and number of clones present in the epidemies. Thus, this study was conducted to evaluate antibiotic and plasmid profiles of P. aeruginosa strains isolated from in-patients of the Sina Medical Centre of Tabriz to clarify epidemyological correlation among isolated strains. Methods: During 13 months, 135 strains of P. aeruginosa were isolated from different infections in hospitalized patients at Sina Medical Center of Tabriz. Antibiotic susceptibility tests were performed using disc agar diffusion test. For plasmid DNA extraction and detection of open circular bands from supercoiled ones, modified alkaline lysis procedure and two dimensional electrophoresis were used, respectively. Enzymatic digestion of plasmids was carried out by EcoRI and HincII restriction enzymes. Results: Resistance rates of strains against antibacterial agents were recorded as: Aztreonam (77%), colistin (74%), ceftazidime (69%), pipracillin (67%), ofloxacin (62%), tobramycin (56%), carbenicillin (54%), gentamicin (51%), ciprofloxacin (22%), amikacin (15%), polymixin B (13%) and imipenem (2%). Plasmid profiles of our test strains revealed that only 67 strains harbored plasmid(s). Number of isolated plasmids ranged 1-6 in each strain with molecular mass of 0.5kb-21kb. When the isolated plasmids were digested using restriction endonuclease enzymes (EcoRI and HincII), in 32% of them similar digestion profiles were obtained by EcoRI indicating a unique source for them. Conclusion : Our findings suggest high antibiotic resistance and plasmid presence in P. aeruginosa strains isolated from different infections, and there were remarkable similarities among isolated plasmids. Since our test strains had been isolated from various wards in a short period of time, the results raise the possibility of unique source for some strains or high prevalence of genetic exchange among P. aeruginosa strains.
Abbasali Imani Foolad , Zahra Rostami , Reza Shapouri,
Volume 10, Issue 3 (9-2010)
Abstract
Background and Objectives: Detection of TEM and SHV genes in ESBL producing Pseudomonas aeruginosa and their antimicrobial resistance pattern can provide useful information about the epidemiology and risk factors of associated infections. In this study we determined the antimicrobial susceptibility pattern and prevalence of ESBLs in clinical isolates of Pseudomonas aeruginosa by phenotypic and genotypic methods. Methods: In this analytic-descriptive study, 110 Pseudomonas aeruginosa strains isolated from different clinical specimens were used. The pattern of antimicrobial resistance was determined by disk diffusion (Kirby-buer) method. The ESBL production was determined by combination disk method using disks containing ceftazidim and cefotaxim alone and in combination with Clavulanic acid. SHV and TEM types of ESBL producing genes was detected by PCR. Results: In this study Co-trimoxazole and Amoxicilin with 96.4% and 92.7% and Amikacin with 17.3% showed the highest and lowest resistance against isolates respectively. According to PCR results 37.5% and 12.5% of isolate were carried SHV and TEM genes respectively and 12.5% of isolate were carried both the SHV and TEM genes. Conclusion: According to the results most of the isolates are drug resistant and among the ESBL producing strains the frequency of SHV type is higher than TEM . The isolate ceftazidim resistance was contains SHV (37.5%) and TEM gene (12.5%), that showed SHV and TEM genes play more important role in create of ceftazidim resistance than cefotaxim resistance.
Abbasali Imani Foolad, Maryam Hosainzadeh, Seiyed Fazlollah Mousavi ,
Volume 11, Issue 1 (4-2011)
Abstract
Background & Objectives: Pseudomonas aeruginosa is a Gram-negative and aerobic bacterium. Exotoxin A is one of the important toxins produced by the bacterium and it is the main cause of mortality. About 90% of P. aeruginosa strains produce this toxin. Biofilm is a functional consortium of microorganisms attached to the body surfaces and bacteria are embedded in extracellular polymeric substances produced by the microorganisms. This bacterium is nontoxic in the planktonic form, but as a biofilm is highly toxic. In this study, we examined the association between the presence of exo-A gene and antibiotic resistance patterns with biofilm formation in Pseudomonas aeruginosa strains. Methods: In this study 110 strains of Pseudomonas aeruginosa isolated from various infections with defined antibiotic resistance patterns were used. The PCR method was used to detect the presence or absence of Exotoxin A gene (exo-A). Ability of biofilm formation was evaluated by spectrophotometry. Association between exo-A gene and antibiotic resistance patterns with biofilms formation was analyzed statistically by Fishers and Chi-square tests. Results: exo-A gene was detected in 93 strains (84.5%). Sixty two strains were multidrug resistant and they produced broad spectrum beta-lactamase enzyme. Results showed that, exo-A positive strains had significantly higher ability to biofilm formation in comparison with exo-A negative strains (p<0.05). Also the biofilm formation was significantly higher in multidrug resistant and ESBL producing strains (p<0.05). Conclusion: The results of this study indicate that there is a significant association between exo-A gene as well as antibiotic resistance pattern and ESBl producing with biofilm formation in Pseudomonas aeruginosa. Because of importance of biofilms in the pathogenesis of this bacterium, our study could open a new window for investigation of the molecular processes involved in the formation of biofilms.
Maryam Adabi, Mahshid Talebi Taher , Leila Arbabi, Mastaneh Afshar , Sara Fathizadeh, Sara Minaeian, Niloofar Moghadam-Marageh, Ali Majidpour ,
Volume 15, Issue 1 (4-2015)
Abstract
Background & objectives: Wound infection is a predominant cause of death in burned patients who are clearly at increased risk of nosocomial infections. Pseudomonas aeruginosa is the most common cause of burn infections and is difficult to treat because of having high level of resistance to antibiotics. The aim of this study was to perform isolation, identification and determination of antibiotics resistance pattern of P. aeruginosa strains isolated from wounds of hospitalized burn patient.
Methods: Biochemical and molecular tests were used for identification of the P. aeruginosa and antibacterial susceptibility test was performed using disk diffusion (Kirby- Bauer) methods. Then, the minimum inhibitory concentration (MIC) was performed for four representatives of different groups of antibiotics.
Results: Among 94 evaluated strains of P. aeruginosa, 83 isolates (88.3%) were multi drugs resistant. Based on Kirby-Bauer method, the most resistance was seen to cefepime (89.5 %) and among the antibiotics studied to determine the MIC, the most resistance was observed to ciprofloxacin (89 %).
Conclusion: These results indicate high range of resistance to different antibiotics among strains of P. aeruginosa isolated from burn wounds of patients. So, the fast and accurate measurement and evaluation of antibiotic resistance for appropriate antibiotic therapy of burned patients is imperative.
Roqiyeh Nouri, Mohammad Ahangarzadeh Rezaee , Alka Hasani, Mohammad Aghazadeh, Mohammad Asgharzadeh, Morteza Ghojazadeh,
Volume 16, Issue 2 (7-2016)
Abstract
Background & objectives: Fluoroquinolones have important role in treatment of P. aeruginosa infections. The main mechanism of fluoroquinolones resistance in P. aeruginosa is mutations in the quinolone-resistance-determining region (QRDR) of gyrA and parC genes. The aim of this study was to investigate the role of these mutations in ciprofloxacin resistance in different clinical isolates of P. aeruginosa.
Methods: A total of 75 clinical P. aeruginosa isolates were collected from different university-affiliated hospitals in Tabriz. Minimum inhibitory concentrations (MICs) of ciprofloxacin were evaluated by Etest assay. DNA sequences of the QRDR of gyrA and parC were determined by dideoxy chain termination method.
Results: From 75 isolates, 77.33% were resistant to ciprofloxacin. No amino acid changes were detected in gyrA or parC genes of the ciprofloxacin susceptible isolates. Thr-83→Ile substitution in gyrA was observed in all ciprofloxacin resistant isolates. About 90% of them had Ser-87→Leu substitution in parC. Geometric mean MICs of ciprofloxacin were different for various clinical isolates of P. aeruginosa which had the same situation in type and location of gyrA and parC mutations. Moreover, the geometric mean MIC in isolates from urine was significantly (p<0.05) higher than isolates from tracheal aspirates.
Conclusion: Mutations in gyrA and parC genes are the major mechanisms for ciprofloxacin resistance in clinical isolates of P. aeruginosa. Moreover, the role of different effective factors in fluoroquinolone resistance can be different in various clinical isolates of P. aeruginosa.
Seyed Ali Bazghandi , Somayeh Safarirad, Mohsen Arzanlou, Hadi Peeri-Dogaheh , Hossein Ali-Mohammadi , Farzad Khademi,
Volume 20, Issue 2 (7-2020)
Abstract
Background & objectives: Bacterial antibiotic resistance is becoming a global health crisis. The aim of this descriptive, cross-sectional study was to investigate the prevalence of multidrug-resistant Pseudomonas aeruginosa strains in Ardabil.
Methods: During 9 months, between July 2019 and March 2020, 50 strains of Pseudomonas aeruginosa were collected from different clinical specimens in four hospitals of Ardabil and the prevalence of MDR, XDR and PDR strains of Pseudomonas aeruginosa were evaluated. Antibiotic susceptibility testing was assessed using the disk diffusion method.
Results: In the present study, the prevalence of MDR, XDR and PDR strains of Pseudomonas aeruginosa were 52%, 40% and 14%, respectively.
Conclusion: Due to high prevalence of multidrug-resistant strains of Pseudomonas aeruginosa in Ardabil, continuous monitoring of the antibiotic resistance trend in clinical isolates in order to select the best medication is necessary.
Maryam Nazari, Hadi Ahmadi, Hamid Vaez, Farzad Khademi,
Volume 21, Issue 2 (7-2021)
Abstract
Background & objectives: Carbapenems are the main antibiotics for the treatment of infections caused by multidrug-resistant (MDR) Pseudomonas aeruginosa (P. aeruginosa). The aims of this study were to determine the prevalence of gene encoding outer membrane porin protein (OprD) in carbapenem-resistant P. aeruginosa strains as well as to assess the role of insertion sequence (IS) elements in the inactivation of OprD porin and the emergence of carbapenem resistance.
Methods: In this study, 103 clinical isolates of P. aeruginosa including 58, 42 and 23 strains resistant to imipenem, meropenem, and doripenem were used, respectively. The isolates were collected from patients referred to Ardabil hospitals. The presence of oprD gene and IS elements were investigated using polymerase chain reaction (PCR) and sequencing methods. P. aeruginosa PAO1 standard isolate was used as the positive control strain for oprD gene.
Results: The frequency of oprD gene among carbapenem-resistant P. aeruginosa strains isolated from Ardabil hospitals was 96.5%. Furthermore, IS elements were not observed in the investigated isolates.
Conclusion: Based on the results of this study, the presence of IS elements did not involve in the inactivation of outer membrane porin OprD and resistance to carbapenems among P. aeruginosa clinical strains in Ardabil. Therefore, an investigation of the role of other mutations in reducing the expression of oprD gene and increasing P. aeruginosa resistance to carbapenems is recommended.
Maryam Nazari, Nilofar Saeli, Mohsen Arzanlou, Saghar Jafari-Ramedani, Hafez Mirzanejad-Asl, Farzad Khademi, Aida Alinezhad,
Volume 24, Issue 1 (4-2024)
Abstract
Background: Antibiotic resistance represents a critical global concern within the medical community, posing significant challenges in the treatment of infections caused by drug-resistant pathogens. Over the years, broad-spectrum fluoroquinolones have been extensively used to treat infections caused by both Gram-positive and Gram-negative bacteria, including Pseudomonas aeruginosa. In this study, we decided to assess the prevalence of plasmid-mediated quinolone resistance mechanisms among clinical isolates of P. aeruginosa in Ardabil hospitals.
Methods: We analyzed a total of 200 clinical isolates of P. aeruginosa, collected between June 2019 and May 2023. The antibiotic resistance profiles of these strains against various fluoroquinolone antibiotics were determined using the disk diffusion method. Additionally, we investigated the presence of qnrA, qnrB, qnrC, qnrD, and qnrS genes through polymerase chain reaction (PCR) analysis. Furthermore, we assessed the expression levels of efflux pump genes and outer membrane porin genes using the quantitative reverse transcription PCR (qRT-PCR) in fluoroquinolone-resistant P. aeruginosa strains.
Results: Our findings revealed that 69% of P. aeruginosa strains were resistant to fluoroquinolones. The resistance rates for different fluoroquinolones were as follows: ciprofloxacin 55.5%, ofloxacin 62%, norfloxacin 53.5%, lomefloxacin 55.3%, and levofloxacin 55.5%. Notably, 78.9% of these strains exhibited multidrug resistance (MDR). Among the qnr genes, qnrB was the most prevalent (2.9%). No other qnr genes were identified. Interestingly, 75% of P. aeruginosa strains carrying the qnrB gene showed overexpression of efflux pump genes, while 100% exhibited down-regulation of the oprD gene.
Conclusion: Given the high prevalence of fluoroquinolone-resistant P. aeruginosa clinical isolates in Ardabil hospitals and the multifactorial nature of resistance, continuous monitoring of antibiotic resistance trends and understanding the underlying resistance mechanisms are crucial for selecting appropriate treatment strategies.
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