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Abstract Introduction: The purpose of this study was to investigate the prevalence of multi-resistant Pseudomonas aeruginosa and Acinetobacter spp. in Patients admitted in baqiyatallah hospital in 2005. Malenals & methods: The study was conducted prospectively during a period of 12 months from March to February 2005 in Baqyiatallah hospital in Tehran, Iran. All patients who were hospitalized with no signs and symptoms of infection before the first 48 hours of hospitalization and presenting signs and symptoms of infection after 48 hours of hospitalization were included in this study. Bacterial strains were isolated from various clinical samples of patients and identified as Pseudomonas aeruginosa and Acinetobacter spp by the conventional methods. Results: The prevalence of multi-resistant Pseudomonas aeruginosa during the study current was 1.3%.The most infections were belonged to intensive care unit (ICU). Among 278 MDR isolates, 58(20.8%) and 35(12.6%) strains were belonged to Pseudomonas auroginosa and Acinetobacter spp respectively. The most MDR microorganisms were isolated from samples obtained from lower respiratory tract (53.8%) and wounds (19.3%). Conclusion: Isolation rate of MDR Pseudomonas auroginosa and Acinetobacter spp in current study was lower than those reported by other researchers however, the most prevalence of infections was observed in ICU and in patients with more than 50 year of ages. It is necessary to study the causes of nosocomial infections and development of preventative strategies in order to prevent the spread of nosocomial infections.

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Abstract Introduction: Pseudomonas aeruginosa is one of the most important pathogens commonly seen in immuno-compromised patients. Septicemia due to this organism is rare in healthy individuals. We reported a multiple trauma patient with septicemia due to Pseudomonas aeruginosa and Acinetobacter. Material & methods: The case was a male patient of 43 years old who had experienced multiple trauma. Before referring to Baqiyatallah hospital, the patient had been admitted to another hospital for treatment. The case was studied by clinical and paraclinical examinations. Findings: The patient was febrile and toxic. His traumatic lesions were purulent. He was introduced to surgery unit for debridement of traumatic lesions. Pseudomonas aeruginosa and Acinetobacter were isolated from traumatic lesions. Conclusion: It seems that nosocomial infection due to Pseudomonas aeruginosa and Acinetobacter was causative agents of septicemia in the patient during the first hospitalization. Infection surveillance and control programs play a key role in prevention of nosocomial infections in hospitals.

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Introduction: Pseudomonas aeruginosa is an opportunistic pathogen and one of the most frequent pathogens in nosocomial infections. It causes different types of infections including urinary tract infections and Bacteremiae. This bacterium has many pathogenic factors including exotoxin A, lipopolysacharide, phospholipase C, pili, elastase and alkaline protease. In this study, frequency of exotoxin A and alginate genes in clinical pseudomonas aeroginosa strains isolated from nosocomial infections were analysed. Materials & Methods: 50 Pseudomonas aeroginosa strains were isolated in clinical samples of Ilam hospitals and Milad hospital in Tehran. The isolates were identified by biochemical methods, after- wards DNAs were extracted. Next, using special primers for exotoxin A and alginate genes PCR was applied to detect the presence or non-presence of the related geres. Findings: According to PCR results, 37 isolates (74%) and 46 ones (92%) had exotoxin A and alginate respectively. Among Pseudomonas aeroginosa strains isolated from urinary tract infections including 30 isolates, exotoxin A and alginate genes were observed in 21 (70%) , and 26 (86/6%) isolates, respectively. Also, in other strains isolated from burn wound infections including 20 isolates, exotoxin A and alginate genes were detected in 16 (80%) and 20 (100%) isolates. Discussion & Conclusion: The results of our study confirm that exotoxin A and alginate genes presence is considered an important virulence factor of pseudomonas aeruginosa. The results of our study showed that alginate gene is so important in pseudomonas aeroginosa strains isolated from urinary tract infections and burn wound infections.

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Introduction: Some Pseudomonas aerugin-osa strains produce Extended Spectrum Beta Lactamase which causes resistance to cephalosporins such as cefteriaxon, cefota-xim, ceftazidim and also monobactams such as azteronam. Over expression of efflux pumps including MexAB-OPRM is a factors which play an important role in resistance of Pseudomonas aeruginosa strains to antibiotics. Materials & Methods: In order to detect the mutation frequency in PA3721 gene, 50 isolates of Pseudomonas aeruginosa isola-ted from urinary tract infection in Emam Khomeini Hospital of Ilam and Milad Hospital in Tehran were studied. The isolates were confirmed by biochemical methods and the Extended Spectrum Beta Lactamase were screened by disk diffusion method. Phenotypic confirmatory test by combined disk was utilized for confirma-tion of ESBLs. In next step, ESBLs genes as well as mutation in frequency PA3721 gene in producing and non producing ESBLs Pseudomonas aeruginosa strains were identified by PCR method. Findings: In this study, 50 isolates were studied, including 18 isolates from Milad Hospital and the rest from Ilam Hospitals. In Milad Hospital, ESBLs genes for PER, PSE and VEB and in Ilam Hospitals ESBL gene for OxA-10 were detected. In Ilam samples including 32 isolates of which 17 samples produced ESBLs, all carried oxA-10 gene and 8 isolates (47/05%) were positive for mutation in PA3721 gene. Discussion & Conclusion: According to the results, Meropenem was more effective against Pseudomonas aeruginosa isolates in in vitro condition. The results also showed that nearly half of oxA-10 producing Pse-udomonas aeruginosa isolates carry nalC gene.

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Background: Pseudomonas aeruginosa is a ubiquitous organism which has emerged as a major threat in the hospital environment. Overuse of antibiotics has also significantly increased the emergence of antimicrobial multiresistant bacteria. P. aeruginosa has an innate ability to adhere to surfaces and form virulent biofilms. Bacteriophage might represent one attractive solution to this problem. In this study, P.aeruginosaphage was utilized to Biofilm prevention and removal. Methods: After isolation of phages and serial dilution microplate method of biofilm formation was examined. Furthermore, the effects on biofilm bacteria isolated phages were determined on the Pseudomonas putida, Acinetobacter baumanii and E.coli. Result: P.aeruginosa biofilm had OD: 1.688 in 492n.m. Pure phage, 10-2 and 10-3 diluted phage decreased OD to 1.587, 1.341 and 1.461,respectively.Isolated phage dramatically decline OD of Biofilm of all strains. Discussion: Phages have various affinity to attach to hosts, thereby it is supposed to phages compete for their receptors.Therefore it is supposed phages have most efficiency in optimum concentration to remove biofilm or growth inhibition. Also, funding prove phages have effect on various bacteria and they can use to remove different strains.

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ntroduction: Microbial decolorization in removing chromophores is investigated as an effective and potential method to be applied in textile industries. The type of dyes and degraders determines efficiency of the process. Biodegraders such as bacteria are environmentally biocompatible and cost effective which their application in deco-lorization is extending day to day. Pseud-omonas bacteria are known as one of the most powerful degrader bacteria that can be applied to decolorize textile wastewater. Materials & Methods: In this study, four different azo dyes including Acid Blue 113 (AB-113), Basic Red 46 (BR-46), Direct Blue 151 (DB-151), Direct Brown 2 (DB-2), and a mixture of the four dyes (Mix) were subjected to biodegradation using Pseudomonas aeruginosa (P. aeruginosa), and Pseudomonas putida (P. putida) at pH 7.2 and 30 °C condition. Findings: P. aeruginosa completely deco-lorized AB-113 in all initial dye concen-trations, BR-46 in the concentrations of 0.1 and 0.2 g/L and DB-2 in the concentrations of 0.1, 0.2 and 0.5 g/L. P. putida completely decolorized AB-113 in the concentrations of 0.1 and 0.2 g/L, DB-2 in the conce-ntrations of 0.1 and 0.2 g/L. The mixture of four dyes was also completely decolorized in the concentration of 0.1 g/L by P. putida. Decolorization processes followed first and second order kinetics with respect to dye concentration. The higher calculated rate constants of first and second order were observed in low dye concentrations. Discussion & Conclusion: Results of the study represented that various strains of Pseudomonas are differently able to degra-de azo dyes in different concentrations that can be used based on the components and concentrations of dyes.

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Introduction: Pseudomonas aeruginosa (P.aeruginosa) is one of the opportunistic pathogens in hospital that afflicts patients with burning damages, respiratory diseases, cystic fibrosis, bacterinemia, septicemia and many of other prevalent infections. P.aer-uginosa has two types of cyclic PAPI such as PAPI-1(108 kb) and PAPI-2 (11kb). The big island, namely, PAPI-1 has an important role in virulence, evolution and development of pathogenic process of the bacteria. Many cellular contamination capa-bilities of the bacterium including chronic infections in people with cystic fibrosis are arisen from function of the gene. The aim of this study was to evaluate the frequency of PAPI-1 gene in clinical isolates of P.aeruginosa. Materials & Methods: Clinical isolates of P.aeruginosa were identified by traditional methods. After extraction of genomic DNA, the existence of PAPI-1 coding gene was confirmed by using polymerase chain reaction (PCR). Findings: Of the isolates under study, 17 samples (35.41%) contained PAPI-1gene. Among 29 samples of urinary tract origin, 9 samples (31.03%) contained PAPI-1 gene and from 19 samples of burn injuries, 8 samples (42.1%) contained PAPI-1. This big island of P.aeruginosa, namely, PAPI-1, was equally existed in burning and urinary infection samples. Discussion & Conclusion: Results of the present study indicated that the big island, PAPI-1, in PA14 strain of P.aeruginosa has a very wide role in bacterial infections. These results revealed the active presence of this big island in the development of pathogenicity and bacterial infection capa-bility by P.aeruginosa.

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Introduction: Extended-spectrum beta-lactamases (ESBLs) make some bacteria resistance to broad spectrum beta-lactam antibiotics. The aim of the present study was to evaluate the antibiotic resistance of clinical isolates of Pseudomonas aeruginosa in Mashhad and to detect CTX-M type extended-spectrum beta-lactamase among them. Materials and Methods: Clinical isolates of P. aeruginosa were collected from different samples (wound, urine, ear, lung, peritoneal fluid and other body fluids) of hospitalized patients in Mashhad in 2013. The antibiotic susceptibility was examined by disc diffusion method and Kirby-Bauer standards. The frequency of ESBL producing strains was determined via the combined disk method. After DNA extraction, the existence of blaCTX-M gene was detected by polymerase chain reaction (PCR) using specific primers. Findings: All isolates were resistance to ceftizoxime, cefoxitin and oxacillin. Resistance to ciprofloxacin, gentamicin, imipenem, piperacillin and co- trimoxazole was 45.31%, 48.44%, 45.31%, 43.75 and 98.44%, respectively. A large percentage of ESBL-producing isolates compared with ESBL-non producers were resistant to co-trimoxazole, gentamicin, and piperacillin and the difference for gentamicin was significant. Out of 64 clinical isolated bacteria, 8 (12.5%) isolates were beta- lactamase producers and none of them were positive for blaCTX-M type ESBL. Discussion and Conclusions: Results of this study showed that however resistance of clinical isolates of P. aeruginosa to beta-lactam antibiotics was high in our community, but this resistance was not related to prevalence of blaCTX-M gene among isolated strains. Antibiotic resistance among these isolates could be associated with other types of beta-lactamases.

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Introduction: class B beta-lactamases such as IMP and VIM that read metallo-β-lactamase(MBL), due to the hydrolysis of penicillins, cephalosporins and carbapenems for the teatment of infectious diseases, major difficulties create. In study, the prevalence of MBL blaIMP and blaVIM genes in urinary isolates of Pseudomonas aeruginosa were investigated in ilam province.
Materials & methods: A total of 60 strains of P. aeruginosa Central Laboratory of ilam, were collected and were identified using biochemical methods Antibiotic susceptibility testing by the disk diffusion method(Kirby-Bauer) forantibiotics cefepiem, ceftriaxone, Aztreonam, gentamicin, amikacin, ciprofloxacin, ofloxacin, ceftazidime, piperacillin tazobactam and imipenem was performed. Then strain insensitive to ceftazidime, the method Ceftazidime - EDTA Combined disk synergy test(CDST-CAZ) Was used to detect MBL-producing strains. The PCR test strains using specific primers for blaIMP and blaVIM genes was investigated.
Findings: A total of 17 strains were resistant to ceftazidime. With method CDST all strains non-susceptible to ceftazidime, were MBL-producers. PCR and sequencing methods proved that 6 isolates were positive for blaVIM genes, whereas none were positive for blaIMP genes. All isolates that were positive for VIM gene were resistant to all antibiotics studied except piperacillin tazobactam.
 Discussion & conclusion :In this study, blaVIM dominant gene in P. aeruginosa urinary strains resistant to ceftazidime was administrative. Given the importance of MBL-producing strains in hospitals, rapid detection of these strains could be crucial step in the treatment and control of infections caused by these strains is considered.

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Introduction: Phagetherapy is the therapeutic use of bacteriophages to treat pathogenic bacterial infections as alternative to antibiotics for treatment of resistant bacteria. The aims of this study were to isolate, identify and evaluate effective bacteriophages active against antibiotic resistant strains of Pseudomonas aeruginosa.

Materials & methods: Different Pseudomonas aeruginosa strains isolated from clinical specimens during 9 months (July 2013 to March 2014) in three Isfahan hospitals (AlZahra, Omid and Shahid Beheshti hospitals) and Kirby Bauer's disc diffusion method was used for determination of resistance profiles of these isolates using different antibiotics including Amikacin, Imipenem, Meropenem, Ciprofloxacin, Ceftazidime, Cefepime, Cefotaxime, Piperacillin-tazobactam. The resistant strains to all tested antibiotics were selected for finding their specific bacteriophages from waste water and hospital sewage. Presence of phage investigated by plaque formation and after enrichment and stained of samples, TEM microscope was used for determination of phage morphology and size.

Findings: Among 81 Pseudomonas aeruginosa isolates, 38 isolates (47%) were resistant to all tested antibiotics and plaque due to phages was detected against 32 (84%) among these 38 isolates. Two phages belong to Cystoviridae and Leviviridae identified using TEM microscope.

Discussion & Conclusions: It seems that the mixture of two phages (cocktails phages) that has high bactericidal effect against resistant strains of Pseudomonas aeruginosa can be good candidates for use in phagetherapy.

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Introduction: Pseudomonas aeruginosa is a major cause of nosocomial infections. Different mechanisms of drug resistance and acquired-resistance genes from other bacteria, caused the treatment of infections of this opportunistic pathogen with serious problems. So even with the newer antibiotics, the treatment has failed. The use of medicinal plants is one way to develop antimicrobial agents. Given the widespread use of Urtica Dioica and Zataria multifloraherbs in traditional medicine and the potential effects against many infectious agents are going to eveluate the antibacterial effect of methanoland acetone extracts of Urtica Dioica and Zataria multiflora against metallo beta-lactamase producing Pseudomonas aeruginosa carring bla VIM and bla IMP genes.

Materials & methods: This study was performed from October to February year 2014 on 448 burn patients hospitalized in Shahid Motahari Hospital, Tehran. For all MBL-producing strains, antibiotic resistance by disk diffusion method were done according to CLSI guidelines.CDDT method for detection of MBL and PCR and Sequencing methods for Identification of metallo beta-lactamase gene, bla IMP and bla VIM,were used. The minimum inhibitory concentrations of antibiotics meropenem, cefepime, ceftazidime, cefotaxime, ampicillin, piperacillin/ tazobactam and ceftriaxoneand the minimum inhibitory concentration of methanol and acetone extracts of Urtica Dioica and Zataria multiflora herbs were donebased on agar dilution method.

Findings: Among 83 imipenem resistant P.aeruginosa strains, 48 (57.9%) isolates produced MBL. PCR and sequencing methods confirmed that these strains were blaIMP-1positive genes, whereas none were positive for bla (VIM) genes. Hospitalized burn patients with MBL-producing P.aeruginosainfection had 4/48 (8.3%) mortality rate. It was demonstrated that Urtica Dioica and Zataria multiflora extracts had a significant antibacterial effect on regular and IMP-producing P. aeruginosa strains.

Discussion & Conclusions: Prevalence of MBL-producing Pseudomonas aeruginosa strains among patients is high. Also due to high resistance of chemical drugs, the use of medicinal plants such as Urtica Dioica and Zataria multiflora can be a better alternative for treatment, which requires further studies. In this study the extracts of U.dioica and Z. multiflora had a high antibacterial effect against β-lactamase producing P. aeruginosa isolates.

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Introduction: Pseudomonas aeruginosa is a major agent of hospital infection which has a resistance intrinsic to a wide range of Antibiotics. It is resistant to beta-lactam antibiotics because of Beta-lactamase and Metalo-lactamase enzymes production. They have crucial problems in the treatment. The goal of this research is to isolate and characterize strains which are resistant to beta-lactam and Imipenem Antibiotics in clinical samples from four major hospitals in Tehran.

Methods & methods:  In this study 600 samples of Pseudomonas aeruginosa were  collected  from patients and those people  referring to Baqyiatallah hospital ,  Imam Khomeini hospital , Shahid Motahari Burns Center and Pediatrics Center during two years, In the first step Antibacterial resistance were prefer by wide range of Antibiotics (Kirby-Bauar). The MIC test was used to Ceftazidime and Imipenem by Microdiution tube and  CLSI protocol.

Findings: This research demonstrated that the highest sensitivity of bacteria is to Imipenem (92%) and Tetracycline (91.2%) The results showed that 6 % of the MIC of strains are resistant to imipenem (4μg/ml≤ MIC) and the 39/5 % of them are resistant to Ceftazidime (16μg/ml ≤ MIC), respectively.

Discussion & conclusions: These results showed that consumption of these Antibiotics should be used precisely due to the highest resistance of these bacteria to Imipenem and third generation Cephalosporin’s otherwise it can transfer to other strains Gram-Negative bacteria special.

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Introduction: Nanoparticles with the different sizes, surfaces and chemical characteristics can have different applications. Pseudomonas aeruginosa is an opportunistic bacterium that has the ability to produce pigment. The aim of this study was to investigate the effect of zinc oxide (ZnO) nanoparticles on pigment production of clinical isolates of Pseudomonas aeruginosa.

Materials & methods: In this description cross-sectional study, 15 clinical isolates of Pseudomonas aeruginosa were collected from hospitals in Mashhad. Bacteria were identified using biochemical tests and polymerase chain reaction (PCR) by specific primers of exoA gene. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of zinc oxide nanoparticles (diameter of 4-7 nm) were determined by agar dilution method. Glycerol- alanine (GA) medium containing different concentrations (0, 20, 40 and 60 mg/ml) of nanoparticles were used for investigation of the effect of ZnO nanoparticles on pigment production. The pigment was extracted by adding chloroform. 

Findings: All clinical isolates were identified by biochemical experiments as P. aeruginosa and exoA gene was detected in all bacteria. The average MIC and MBC of ZnO nanoparticles were 60 mg/ml and 70 mg/ml, respectively. All isolates were examined and compared for pyocyanin pigment production. The pigment production was significantly reduced with increasing concentrations the ZnO nanoparticles (p < 0.05).

Discussion & Conclusion: Zinc oxide nanoparticles had inhibitory effect on bacteria and pigment production. Pigment production decreased with increasing concentrations of nanoparticles. ZnO nanoparticles could be used in prevention or helping to treat P. aeruginosa infections.

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Introduction: Pseudomonas aeruginosa is one of the important bacteria for nosocomial infections; particularly in patients with immune deficiency. For the treatment of serious infections caused by these bacteria, antibiotics such as aminoglycosides many, quinolones and beta-lactams are used. However the emergence and spread of resistant nosocomial strains of resistance have been reported. Nowadays, efflux pump has been proposed as an important mechanism of resistance to antibiotics in bacteria.
 
Materials & methods: In this cross-sectional study, 60 clinical isolates of P.aeruginosa were collected from fecal samples from laboratories in Kerman province. All isolates were approved with the phenotype and biochemical tests. The disk diffusion method was performed according to CLSI (Clinical and Laboratory Standards Institute). Multiplex-PCR tests were performed for detection of efflux pumps genes (mexA, mexB, mexR) using specific primers.
 
Findings: All the 60 fecal isolates of P..aeruginosa were confirmed by biochemical tests. The greatest sensitivity was observed for ceftizoxime 55(91.7%), imipenem, 54(90%), meropenem, 48(80%) and ciprofloxacin 40(66.7%). The greatest resistance were determined to antibiotics cefepime 36(60%) and ciprofloxacin 19(31.7%). The highest frequency was observed of Mex B gene in 59(98.3%) of the isolates.
 
Discussion & conclusions: Rapid diagnosis of Pseudomonas aeruginosa in clinical samples is more than important for initiation of treatment. In general, the use of multiplex polymerase chain reaction for detection of antibiotic-resistant P. aeruginosa is very important in clinical samples of patients.
 

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Introduction: Antibiotic resistance crisis has always been a serious problem for human health and many hospitalized patients are affected worldwide. Pseudomonas aeruginosa is a gram-negative pathogen and one of the most common causes of nosocomial infections. The main mechanism of resistance to beta-lactam antibiotics is the presence of metallo-beta-lactamase (MBL) enzymes. Most of the MBL genes are found in plasmids. The aim of this study was to evaluate the frequency of MBL-producing P. aeruginosa isolates caused by VIM-all and VIM 2, 3, 9, 11and16 genes.
 
Materials & Methods: Antimicrobial susceptibility of 127 clinical isolates of P. aeruginosa was determined using the standard Kirby-Bauer disk diffusion method according to Clinical and Laboratory Standard Institute (CLSI). Combined-disk test was used for phenotypic determination of MBLs-producing isolates. After DNA extraction, VIM-all and in specific, VIM 2, 3, 9, 11 and 16 genes were amplified using PCR method.
 
Findings: A total Of 127 clinical isolates of P. aeruginosa, 62 isolates (49%) were resistant to imipenem and 31 isolates (24.5%) showed phenotypic evidences of MBL production. Moreover, among imipenem resistant strains VIM-all genes were found in 12.5% of cases, but the VIM 2-3-9-11 and 16 genes were not detected in samples.
 
Discussion & Conclusions: The results obtained in this study suggest that in P. aeruginosa, the highest antibiotic resistance observed was to cefazolin (98%) followed by nalidixic acid (91%) and the least resistance were to ciprofloxacin (31%). One of the reasons for this trend is the growth of antibiotic-resistant bacteria and the known mechanisms of bacterial resistance.

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Introduction: This descriptive cross-sectional study examined the association between the presence of four non-Helicobacter-pylori bacterial species (e.g., Staphylococcus aureus, Lactobacillus acidophilus, Pseudomonas aeruginosa, and Streptococcus sanguis) and dyspepsia.
Material & Methods: This study included a total of 100 antral biopsy samples isolated from dyspeptic (n=50) or non-dyspeptic (healthy control) (n=50) patients referred to Mehrad and Labafinejad Hospitals, Tehran, Iran, in 2018. Following that, the presence of Staphylococcus aureus, Lactobacillus acidophilus, Pseudomonas aeruginosa, and Streptococcus sanguis was investigated by PCR and using their respective primers, including nuc, PA431CF, iga, and 16s rRNA.
Ethics  Code (IR.MODARES.REC.1397.241) .
Findings: In this study, a total of 50 antral biopsies were isolated from patients with dyspepsia, and 50 antral biopsy specimens were isolated from individuals without dyspepsia during endoscopy. The mean age of the subjects was 48 years (age range: 16-80 years); moreover, the highest age group belonged to the group of 26-46 (24%) years, and the lowest age belonged to the group of 16-26 years (0.06%). The age ranges used in this study had a relatively good population distribution. According to the results of the PCR test, the prevalence rates of Staphylococcus aureus, Lactobacillus acidophilus, Pseudomonas aeruginosa, and Streptococcus sanguis in dyspeptic patients (n=50) were 23 (46%), 3 (6%), 42 (84%), and 0 (0 %), respectively. Moreover, the corresponding prevalence values were 19 (38%), 10 (20%), 45 (90%), and 2 (4%) among the non-dyspeptic control individuals. The presence of these bacteria showed no statistically significant association with the incidence of dyspepsia (P˃0.05).
Discussion & Conclusion: Bacterial species living in this area can be highly diverse, and therefore, in addition to other epigenetic involved factors, the studying of other factors, such as environment, nutrition, lifestyle, and the host's genetic, will increase our understanding of the pathogenesis of this complex disorder

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Introduction: Pseudomonas aeruginosa is one of the most important infectious agents in humans, which is difficult to control in hospitals due to its resistance to various antibiotics. Efflux pump systems play an important role in the drug resistance of this bacterium to a variety of antibiotics. This study aimed to determine the antimicrobial synergistic effect of silver nanoparticles and the antibiotic streptomycin on the MexX gene expression.
Material & Methods: In this cross-sectional descriptive study, 49 samples were collected from 11 medical diagnostic laboratories in Mashhad from 1398 to 1399. After the treatment of multidrug-resistant bacteria with inhibitors, the microdilution method and Real Time-PCR technique were used to determine the effective dilution of silver nanoparticles and probiotics on the expression of the MexX gene of the bacterium.
(Ethic code: IR.IAU.MSHD.REC.1400.018)
Findings: All 49 collected samples of Pseudomonas aeruginosa were identified. All strains had the MexX gene, and all were resistant to more than two antibiotics. The minimum inhibitory concentration (MIC) results and expression of the MexX gene showed that the MIC in the agar dilution method for silver nanoparticles was up to 500 μg/ml. Evaluation of the synergistic effect of silver nanoparticles with streptomycin antibiotic showed that plates containing streptomycin antibiotic disk with silver nanoparticles with the dilution of 250 μg/ml caused a growth inhibition zone according to the CLSI standard. Silver nanoparticles with streptomycin synergy had a greater effect in inhibiting bacterial growth, and this effect was greater than that of silver nanoparticles (P>0.05).
Discussion & Conclusion: Silver and streptomycin have inhibitory and antibacterial activity to reduce the function of the MexXY-OprM efflux pump in Pseudomonas aeruginosa (P>0.05).
 

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Introduction: In this study, the antimicrobial activity of biologically synthesized zinc (Zn) and copper (Cu) nanoparticles was investigated on gram-positive and gram-negative bacteria, pathogens, and resistant and common nosocomial infections.
Material & Methods: Intially, zinc oxide and copper nanoparticles were synthesized using Xanthomonas campestris and Pseudomonas stutzeri bacteria, respectively. To investigate the effect of different concentrations of nanoparticles on bacteria using the macrodilution method, concentrations of 0.01, 0.1, 0.5, 1, and 1.5% of Zn and Cu nanoparticles (culture medium + nanoparticles) were prepared and were added to the respective bacteria at a concentration of 105 cell/ml. Containers containing treated media (bacteria + nanoparticles) and control media were placed in a shaker incubator. Afterward, the optical density (OD) of treatment and positive control and negative control media were determined.
(Ethic code: IR.ILAM.REC.1401.008)
Findings: The results of statistical analysis showed that Zn and Cu nanoparticles, at a concentration of 0.5%, were able to remove almost all (100%) Klebsiella pneumoniae, Acinetobacter baumannii, Staphylococcus aureus bacteria and were bacteriostatic at the concentration of 0.1%.
Discussion & Conclusion: The results obtained from the determination of antibacterial properties of nanoparticles showed a direct relationship between the concentration of nanoparticles and the percentage of bacterial removal.
 

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