Microbiology
Zahra Yousefpour; Fateme Davarzani; Parviz Owlia
Abstract
Background & Objective: The ability of Pseudomonas aeruginosa to form biofilm has an important role in establishment of chronic phase of infections. Biofilm formation can be affected by antibiotics sub-MIC concentrations. The principal aim of the present study was to evaluate the effect of gentamicin ...
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Background & Objective: The ability of Pseudomonas aeruginosa to form biofilm has an important role in establishment of chronic phase of infections. Biofilm formation can be affected by antibiotics sub-MIC concentrations. The principal aim of the present study was to evaluate the effect of gentamicin at sub-MIC concentrations on biofilm formation in 100 Pseudomonas aeruginosa clinical isolates.Methods: Determination of minimal inhibitory concentration of gentamicin for clinical isolates was done using micro broth dilution method. The amount of biofilm formation in the treated and untreated isolates with gentamicin sub-MIC (1/2&1/4MIC) concentrations was evaluated using microtitre plate assay. pelA and pslA genes were detected in clinical isolates by PCR method.Results: 99% of clinical isolates were biofilm producer. Different changes in amountof biofilm formation were observed in the treated clinical isolates with sub-MIC concentrations of gentamicin. Two dominant changes were observed in 80% of clinical isolates. These concentrations had inhibitory effect on biofilm formation in 46.4% of isolates and caused a significant decrease in its amount. While in 31.3% of the isolates, the biofilm formation was significantly increased. The frequency of pelA and pslA genes among clinical isolates was 100%. Conclusion: gentamicin sub-MIC concentrations cause different changes on biofilm formation of Pseudomonas aeruginosa clinical isolates. Therefore, further studies are needed for discovering new treatment strategies and using sub-MIC concentrations of the antibiotic in prevention and treatment of Pseudomonas aeruginosa infections.
Microbiology
Zoheir Heshmatipour; Nasibeh Arabameri; Shima Eftekhar Ardebili; Zeinab Jafari Bidhendi
Abstract
Background & Objective: Pseudomonas aeruginosa is an opportunistic pathogen and one of the most common causes of nosocomial infections. This bacterium's antibiotic resistance to the common fluoroquinolone antibiotics, especially ciprofloxacin, is due to mutations in the gyrA and parC genes. This ...
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Background & Objective: Pseudomonas aeruginosa is an opportunistic pathogen and one of the most common causes of nosocomial infections. This bacterium's antibiotic resistance to the common fluoroquinolone antibiotics, especially ciprofloxacin, is due to mutations in the gyrA and parC genes. This study aimed to investigate the effect of the mutation in (gyrA, parC) on ciprofloxacin resistance in clinical isolates of Pseudomonas aeruginosa.Methods: A total of 140 clinical samples were collected from hospitals. The samples were identified by standard biochemical tests, and the antibiotic resistance was investigated by the disk diffusion method. DNA was extracted from 30 isolates, and PCR was performed. PCR-sequencing was carried out to assess gyrA and parC mutations in drug-resistant isolates. NCBI-Blast and MEGA7 software was used to analyze the nucleotide sequences.Results: 30 clinical isolates were 80% resistant to ciprofloxacin; meanwhile, in 21 samples, mutations were observed. 87/5% of mutations were related to gyrA (Thr83 → Ile), 79/16 % parC (Ser87 → Leu), and 4/18% (Glu91 → Lys). The antibiotic resistance to ciprofloxacin and mutations in gyrA and parC genes in resistant isolates are significantly related to each other (P<0.05). Conclusion: The mutations in the gyrA and parC genes play an essential role in resistance to ciprofloxacin in clinical isolates of Pseudomonas aeruginosa.
Microbiology
Samaneh Rouhi; Rashid Ramazanzadeh
Volume 13, Issue 3 , July 2018, , Pages 348-356
Abstract
Background and Objective: Pseudomonas aeruginosa (P. aeruginosa) causes serious nosocomial and non-nosocomial infections. blaOxacillinases (OXA)-23 and blaOXA24/40 provide resistance to carbapenem antibiotics. The aim of this study was assessment of blaOXA-23 and blaOXA-24/40 in P. aeruginosa isolated ...
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Background and Objective: Pseudomonas aeruginosa (P. aeruginosa) causes serious nosocomial and non-nosocomial infections. blaOxacillinases (OXA)-23 and blaOXA24/40 provide resistance to carbapenem antibiotics. The aim of this study was assessment of blaOXA-23 and blaOXA-24/40 in P. aeruginosa isolated from patients with nosocomial and non-nosocomial infections. Methods: In this descriptive cross-sectional study performed in Sanandaj, Iran (Kurdistan province) in a period from December 2015 to August 2017, 146 isolates of Pseudomonas spp. were collected from patients’ specimens. Microbiological methods and polymerase chain reaction (PCR) with gyrB were applied for P. aeruginosa detection. Disk diffusion method with imipenem (IMP) (10µg) was performed for detection of resistant bacteria, and multiplex PCR of OXA-23 and OXA-24/40 were performed as well. Stata 12 with Fisher’s exact test and logistic regression were used for data analysis (P≤0.05).Results: PCR gyrB gene proved the existence of 91.78% P. aeruginosa isolates. Nosocomial infection with P. aeruginosa was observed in 41.79%. 27.61% of P. aeruginosa strains were resistant to IMP. blaOXA-23 and blaOXA24/40 were detected in 11.19% and 2.24% of the strains, respectively. 2.23% strains of P. aeruginosa showed a co-existence of blaOXA-23 and blaOXA24/40. There were no significant relationships between antibiotic resistance and presence of genes, and between IMP resistance and age, sex, city of residence, inpatient/outpatient, and specimen’s type (P≥0.05).Conclusion: Resistance to IMP and the presence of resistant genes in this study were observed in patients. More precautions should be taken in prescribing antibiotics and applying molecular techniques to detect genes, since they can cause antibiotic resistant.
Abdolmajid Ghasemian; Kobra Salimian Rizi; Hassan Rajabi Vardanjani; Farshad Nojoomi
Abstract
Background & Objective: The spread of carbapenem-resistant Pseudomonas aeruginosa is a global concern. Metallo-beta-lactamase (MBL) enzymes cause extensive drug resistance among Gram-negative bacteria. The current study aimed at determining the prevalence of MBL-producing P. aeruginosa in Iran. Methods: ...
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Background & Objective: The spread of carbapenem-resistant Pseudomonas aeruginosa is a global concern. Metallo-beta-lactamase (MBL) enzymes cause extensive drug resistance among Gram-negative bacteria. The current study aimed at determining the prevalence of MBL-producing P. aeruginosa in Iran. Methods: A total of 43 studies were found out of which 36 were adopted. Data were collected from Google, Google Scholar, Science Direct, PubMed, Scopus, Embase, and Sciverse. The terms “Pseudomonas aeruginosa”, “metallo-beta-lactamase”, “prevalence”, “carbapenems”, and “Iran” were searched. Data from the isolates not producing MBLs were excluded from the study. Data were analyzed with Graph Pad Prism 6, meta-analysis section. Results: According to the results of the current study, 36 surveys indicated that 55% of the clinically isolated P. aeruginosa in Iran were resistant to imipenem and meropenem, among which 37.72% were the MBL producers. Among genes encoding MBLs, blaVIM and blaIMP were predominant with the prevalence of 12.91%±11.01% and 12.50%±23.56%, respectively. No report of harboring blaNDM1 and blaSPM1 by P. aeruginosa was found, similar to most of the other countries in Asia. The prevalence of blaVIM and blaIMP from burn settings were 11.50%±3.5% and 24.65%±23%, respectively. Furthermore, the prevalence of these genes was not significantly different among burn and non-burn isolates (P=0.942 and P=0.597, respectively). Moreover, no relationship was observed between the MBL production and patients’ age range. Conclusion: Approximately half of P. aeruginosa isolates were carbapenem-resistant in Iran, and approximately half were the MBL producers. The blaVIM and blaIMP were the predominantMBLs among P. aeruginosa strains, while other genes were not found in P. aeruginosa. Moreover, there was no significant difference between blaVIM and blaIMPamong burn and non-burn isolates. Due to the multiple drug resistance conferred by MBLs, detection and control of their spread alongside proper therapeutic regimens in hospitals and community settings are essential to prevent infection acquisition.
Microbiology
Behrang Kazeminezhad; Arezoo Bostanmanesh Rad; Atoosa Gharib; Sara Zahedifard
Abstract
Background & objective: Beta-lactam antibiotics resistance specifically Imipenem and Meropenem, the last choices of treatment, causes fatal events in patients with P.aeruginosa infection. The aim of this study was to detect the VIM and IMP of metallo-beta-lactamase genes in 103 isolates of P. aeruginosa ...
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Background & objective: Beta-lactam antibiotics resistance specifically Imipenem and Meropenem, the last choices of treatment, causes fatal events in patients with P.aeruginosa infection. The aim of this study was to detect the VIM and IMP of metallo-beta-lactamase genes in 103 isolates of P. aeruginosa in two Iranian hospitals. Methods: In this study, we evaluated the susceptibility of P. aeruginosa to a range of β-lactam antibiotics using disk diffusion method as a standard biochemical test. Combined disk test of Imipenem (IMP) and Imipenem plus Ethylenediaminetetraacetic acid (EDTA) was performed as a phenotypic method to find metallo-beta-lactamase producing isolates.Using conventional PCR method; we evaluated VIM and IMP of metallo-beta-lactamase (MBL) genes in 103 isolates of P.aeruginosa. Results: Twenty six (25.2%) out of 103 isolates were resistant to Imipenem and 26 (25.2%) to Meropenem. Among 26 Imipenem and Meropenem-resistant strains (25.2%), 19 cases (73.0%) were MBL producing. Using PCR method, we detected the blaVIM and blaIMP genes in 6 (5.8%) and 2(1.9%) of 19 MBL producing isolates, respectively. Conclusions: Evaluation of these carbepenemases genes improve epidemiologic researches and also, can be used as a diagnostic tool for discriminating between antibiotics resistant and sensitive strains of P.aeruginosa as well as follow-up the patients after treatment.
Microbiology
Ehsan Kazemi Moghaddam; Parviz Owlia; Abolfazl Jahangiri; Iraj Rasooli; Mohammad Reza Rahbar; Marjan Aghajani
Abstract
Background & Objectives: Due to the importance of Pseudomonas aeruginosa in severe inpatient infections and high mortality, the need for an efficient vaccine against these bacteria is increasing. In this regard, the general outer membrane porin of the most problematic microorganism P. aeruginosa, ...
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Background & Objectives: Due to the importance of Pseudomonas aeruginosa in severe inpatient infections and high mortality, the need for an efficient vaccine against these bacteria is increasing. In this regard, the general outer membrane porin of the most problematic microorganism P. aeruginosa, outer membrane protein F (OprF), is a good vaccine candidate. Methods:The databank of NCBI was used to retrieve protein sequences recorded for OprF in P. aeruginosa.The current study aimed at investigating the conservation of the OprF in 150 reference sequences, clinical, and environmental strains of P. aeruginosa from different countries via bioinformatic tools.T-COFFEE and PRALINE software were used for alignment. Results: Of these, 134 strains were isolated from clinical specimens and other strains from environmental samples. Evaluation of alignment by the mentioned software clearly showed that this protein was conserved. Antigenicity and grand average of hydropathicity were favorable. Conclusion: Conservation of OprF in all pathogenic and environmental strains of P. aeruginosa indicated that it can be considered as a good immunogen; however, the protectivity of OprF should be validated experimentally.
Microbiology
Fatemeh Rezaei; Horieh Saderi; Shahram Boroumandi; Soghrat Faghihzadeh
Volume 11, Issue 1 , January 2016, , Pages 47-53
Abstract
Background: In order to select a better antibiotic choice for treatment of Pseudomonas aeruginosa infections, this study was conducted to determine the frequency of resistance to some antipseudomonal β-lactams in P. aeruginosa isolates from patients in Tehran, Iran. In addition, the relation between ...
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Background: In order to select a better antibiotic choice for treatment of Pseudomonas aeruginosa infections, this study was conducted to determine the frequency of resistance to some antipseudomonal β-lactams in P. aeruginosa isolates from patients in Tehran, Iran. In addition, the relation between presence of genes known to be responsible for resistance to β-lactams (ampC, mexC1,2,and mexC3,4 genes) and resistance phenotype among P. aeroginosa isolates was evaluated. Methods: P. aeruginosa strains were isolated and identified by routine methods and PCR for oprL gene. Disk diffusion method was employed to determine the antimicrobial susceptibility pattern according to CLSI recommendations. PCR was used to detect the resistance genes. Results: Among 100 isolates of P. aeruginosa, 82% had ampC, 86% mexC1,2and 89% mexC3,4 genes and combinations of these genes were seen in most of isolates and only 3% of isolates had none of these genes. Resistance to mezlocillin, cefepime, ceftazidime and piperacillin/ tazobactam was seen in 46%, 41%, 36% and 29% of isolates, respectively. Significant relation (P value ≤0.05 by Chi-square or Fisher Exact test) was observed between the presence of ampC gene and resistance to all the studied β-lactams in this study. No relation was observedfor mexC genes,although many ofisolates containing these two genes were phenotypically resistant. Conclusion: This study had shown for the first time, the presence of ampC and mexC genes in significant percent of clinical isolates of P. aeruginosa in Tehran, Iran, and relation between presence of ampC gene and resistance to β-lactams.
Microbiology
Horieh Saderi; Parviz Owlia
Abstract
Background: This study was done to detect multidrug resistant (MDR) and extremely drug resistant (XDR) of Pseudomonas aeruginosa among strains isolated from patients in Tehran, Iran, due to importance of these phenotypes in treatment of human infections. Methods: Eighty eightP. aeruginosa were isolated ...
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Background: This study was done to detect multidrug resistant (MDR) and extremely drug resistant (XDR) of Pseudomonas aeruginosa among strains isolated from patients in Tehran, Iran, due to importance of these phenotypes in treatment of human infections. Methods: Eighty eightP. aeruginosa were isolated from patients in Tehran, Iran, and identified by routine methods and PCR for oprL gene. Their antimicrobial susceptibility to 16 antimicrobial agents from 7 antimicrobial categories (aminoglycosides, carbapenems, cephalosporins, fluoroquinolones, penicillins/ß-lactamase inhibitors, monobactams, polymyxins) were determined by disk diffusion method, according to recommendation of Clinical and Laboratory Standards Institute. Characterization of P. aeruginosa isolates as MDR and XDR was done according to standardized international terminology presented by European Centre for Disease Prevention and Control as well as the Centers for Disease Control and Prevention in 2011. MDR was defined as acquired non-susceptibility to at least one agent in ≥3 antimicrobial categories and XDR was defined as non-susceptibility to at least one agent in ≥6 antimicrobial categories. Results: The rates of susceptibility to antimicrobials were as follows: gentamicin 27.3%, tobramycin 54.5%, amikacin 56.8%, netilmicin 36.4%, imipenem 55.7%, meropenem 55.7%, doripenem 60.2%, ceftazidime 63.6%, cefepime 56.8%, ciprofloxacin 59.1%, levofloxacin 60.2%, ticarcillin-clavulanic acid 37.5%, piperacillin-tazobactam 63.6%, aztreonam 43.2%, colistin 90.9%, polymyxin 95.5%. Altogether, 48 (54.5%) and 29 (33%) isolates were characterized as MDR and XDR, respectively. Discussion:The high frequency of antibiotic resistance in clinical isolates of P. aeruginosa in Iran makes epidemiological surveillance of susceptibility of this bacterium more essential for the best selection of empirical antibiotics.
Mohsen Mirzaee; Parviz Owlia; Mohammad Reza Mehrabi; Amir Gharib
Volume 4, Issue 4 , September 2009, , Pages 151-156
Abstract
Background and Objectives: The most common problems limiting the medical use of aminoglycosides have been the nephro- and oto-toxicities as well as the increasing bacterial resistance. Encapsulation of drugs into liposomes enhances their efficacy while reducing their toxicities. The aim of this ...
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Background and Objectives: The most common problems limiting the medical use of aminoglycosides have been the nephro- and oto-toxicities as well as the increasing bacterial resistance. Encapsulation of drugs into liposomes enhances their efficacy while reducing their toxicities. The aim of this study was to evaluate the antimicrobial activity of free and liposomal amikacin. Material and Methods: Encapsulated amikacin into liposome was prepared by sonication. The drug contained in the liposome was measured by HPLC after lysis of vesicles by 0.2% Triton X-100. The amikacin kinetic released from liposomes in the presence of normal human pooled plasma was also evaluated. The MICs of this drug for Pseudomonas. aeruginosa (ATCC 27853), Escherichia. coli (ATCC 25922), Streptococcus. faecalis (ATCC 29212) and Staphylococcus. aureuse (ATCC 29213) were determined and compared to those of the respective free drug using a broth dilution method. Results: In the presence of plasma, liposomal retention of amikacin was 80.25 ± 0.55% (P ≤ 0.05) after 1 h of incubation and then remained nearly constant over a 24 h period of the study. The encapsulation efficiency of liposomal preparation was 24.36% ± 0.14 (P ≤ 0.05) of the initial amount of the drug in solution. The MICs of liposomal amikacin against all bacterial strains tested were lower than MICs of free amikacin. Conclusion: The amikacin appears a promising approach in the management of bacterial infections and should be further evaluated in vivo experiments.
Parviz Owlia; Horieh Saderi; Zohreh Karimi; Seyed Mohammad Bagher Akhavi Rad; Mohammad Ali Bahar
Volume 3, Issue 1 , January 2008, , Pages 20-25
Abstract
Background and Objective: Metallo-beta-lactamase (MBL)-mediated resistance is an emerging threat in hospital isolates of Pseudomonas aeruginosa. There is not enough information from Iran regarding the prevalence and the screening methods for such enzymes. The present study was undertaken to detect ...
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Background and Objective: Metallo-beta-lactamase (MBL)-mediated resistance is an emerging threat in hospital isolates of Pseudomonas aeruginosa. There is not enough information from Iran regarding the prevalence and the screening methods for such enzymes. The present study was undertaken to detect Metallo betalactamase in strains of P. aeruginosa isolated from burned patientusingphenotypic method. Materials and Methods: For this purpose, 128 consecutive P. aeruginosa isolates obtained from hospitalized patients were subjected to susceptibility testing to antipseudomonal drugs by disc diffusion and minimal inhibitory concentration (MIC) for ceftazidime was determined. The production of MBL was detected by the zone size enhancement with EDTA impregnated ceftazidime disc. Results: It was found out that 94 (73.44%) of the isolates were resistant to ceftazidime. These isolates screened as ESBLs producing strains and introduced for detection of MBL production. Out of the 94 P. aeruginosa that were resistant to ceftazidime, 50 (53.2%) isolates were MBL positive. This result indicated that 39.06% of all isolates were MBL positive. Conclusion: MBL-mediated ceftazidime resistance in P. aeruginosa is a cause for concern in the therapy of critically ill patients. The MBL producing P. aeruginosa isolates were more resistant to various antimicrobial agents. This result suggests that MBL producing isolates in hospitals may cause serious infections that illustrated when these strains were responsible for a nosocomial outbreak.
Sara Jam; Duman Sabzevari; Arezoo Aghakhani; Ali Eslamifar; Mohammad Banifazl; Amitis Ramezani
Volume 2, Issue 4 , September 2007, , Pages 144-148
Abstract
Background and Objective: Pseudomonas aeruginosa has become a frequent cause of nosocomial infections, particularly in intensive care units (ICUs). Many reports have documented high rates of resistance in this species to commonly-used broad-spectrum antibiotics. The aim of this study was to assess the ...
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Background and Objective: Pseudomonas aeruginosa has become a frequent cause of nosocomial infections, particularly in intensive care units (ICUs). Many reports have documented high rates of resistance in this species to commonly-used broad-spectrum antibiotics. The aim of this study was to assess the in vitro activity of some antibiotics against Pseudomonas aeruginosa strains to determine the susceptibility patterns of isolates to different antibiotics. Materials and Methods: A total of 233 Pseudomonas aeruginosa isolates obtained from various clinical specimens of hospitalized children in Ali-Asghar hospital of Tehran (Iran) were considered for susceptibility test. These strains were tested against 12 different antibiotics by a disk diffusion method. Of these isolates, 33.9% were from trachea, 31.8% from urine, 6.9% from eye, 5.2% from blood, 5.1% from ear, 1.3% from cerebrospinal fluid, 1.2% from stool, and 14.6% from other sites. In addition, 48.5% of P. aeruginosa strains were isolated from patients in ICUs. Results: The most active antimicrobials were amikacin and other active compounds were gentamicin, ceftazidime, and ciprofloxacin respectively. Isolates from ICUs were more resistant to amikacin and gentamicin as compared to those from non-ICU wards (p<0.05). Isolates from trachea were more resistant to amikacin, gentamicin, ciprofloxacin and ceftazidime than those from other sites (p<0.05). Conclusion: Our study showed that amikacin was the most active agent against P. aeruginosa followed by gentamycin, ceftazidime, and ciprofloxacin. According to our in vitro study results, active antibiotic susceptibility testing and surveillance should be continued in order to curtail the problem of antibiotic resistance.
Parviz Owlia; Effat Souri; Qurban Behzadian-Nejad
Volume 2, Issue 3 , June 2007, , Pages 104-108
Abstract
Background and Objective: The opportunistic pathogen Pseudomonas aeruginosa secrets a capsule-like polysaccharide called alginate which is important for evasion of host defenses, especially in patients with suppressed immunity. Method of alginate determination has an important role in the study of microbial ...
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Background and Objective: The opportunistic pathogen Pseudomonas aeruginosa secrets a capsule-like polysaccharide called alginate which is important for evasion of host defenses, especially in patients with suppressed immunity. Method of alginate determination has an important role in the study of microbial alginate. In this study, a novel method for alginate determination by highperformance liquid chromatography (HPLC) was introduced. Materials and Methods: Standard alginate was used for construction of standard curve and standard mucoid and non-mucoid strains of Pseudomonas aeruginosa were used as positive and negative samples respectively. The method of Toyoda was modified for determination of microbial alginate. HPLC determination was performed using a Resolve C18 column (3.9 × 150 mm, Waters, Milford, MA) and acetonitrile-water-butyl acetate (55: 42: 3) as the mobile phase at a flow rate of 0.6 ml/min and detection at 565 nm. Results: The obtained data indicated that minimal detectable concentration of alginate by this method is 20 μg/ml. The method was linear over the range of 1-1000 μg/ml of alginate. The retention time was about 10 min. Conclusion: The proposed method was used for determination of alginate in standard mucoid and non-mucoid strains of Pseudomonas aeruginosa. The results of this study showed that the proposed method is a simple and valid method for bacterial alginate assay.
Parviz Owlia; Horieh Saderi; Sadegh Mansouri; Sirus Salemi; Hossein Ameli
Volume 1, Issue 2 , April 2006, , Pages 61-64
Abstract
Background and Objectives: Infection is the most common problem following burn injury. Selection and dissemination of intrinsic and acquired resistance mechanisms increase the probability of burn wound colonization by resistant species including Pseudomonas aeruginosa. Multi-drug resistant Pseudomonas ...
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Background and Objectives: Infection is the most common problem following burn injury. Selection and dissemination of intrinsic and acquired resistance mechanisms increase the probability of burn wound colonization by resistant species including Pseudomonas aeruginosa. Multi-drug resistant Pseudomonas aeruginosa has frequently been reported as the cause of nosocomial outbreaks of infection in burn wards or as colonizers of the wound of burned patients. Therefore, this research study was conducted to compare the activity of various antibiotics and disinfectants against clinically important strains of P. aeruginosa. Materials and Methods: One hundred strains of P. aeruginosa were obtained as clinical isolates from burn wound infections. The antimicrobial activity of antibiotics was tested by disk diffusion method of Kirby-Baur. For disinfectants, 30 μl of each of them was placed on sterile blank disk and studied by disk diffusion method. Results: The frequency of resistant strains to kanamycin, tobramycin, amikacin, cefotaxime, carbenicillin, ceftazidime, ceftizoxime, cefixim, ciprofloxacin, cefazolin, cephalexine, and ceftriaxone was 100, 93, 95, 81, 84, 95, 94, 100, 99, 100, 100, and 92 respectively. The averaged diameter of inhibition zone for chlorhexidine (0.2%), povidione iodine (10%), cetrimide-C (3.5%), dekosept, hypochlorite (10%), micro 10+ (2%), deconex 53+ (2%), and ethanol (70%) was 14.4 ± 1.9 mm, 10.6 ± 1.3 mm, 9.1 ± 2.6 mm, 8.6 ± 2.2 mm, 26.9 ± 5.2 mm, 6.58 ± 1.5 mm, 8.3 ± 2.2 mm, and 6 ± 0.0 mm respectively.