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Background: Differentiation ofmesenchymal stem cells (MSCs) to hepatocyte-like cells could be associated with development of liver function factors. The impact of differentiation-dependent changes on DNA integrity is not well understood. In this study, hepatocytes and their progenitor stem cells were treated with aflatoxin B1 (AFB1) and amplification of selected genes linked to DNA damage was examined. Methods: MSCs and CD34+ cells isolated from umbilical cord blood (UCB) were treated with AFB1 (0, 2.5, 10 and 20 µM) in selective media supporting the hepatocyte differentiation. After 24 htreatment the DNA damage (Comet assay) and amplification rates ofP53 and β-globin genes were measured using real time polymerase chain reaction (QPCR). Results:The results show that AFB1 treatments resulted in a concentration- dependent increase in the DNA damage and suppression of the specific gene amplification. The extent of DNA damage was significantly greater in hepatocytes differentiated from MSCs when compared to those obtained from CD34+ cells. The effects of AFB1 on the rate of selected gene amplification in QPCR showed that the lesions (expressed as lesions/10 kb) in P53 and β-globin genes was significantly greater in hepatocytes derived from MSCs as compared to the cells derived from CD34+ cells. Conclusions: These data together with the results of cytochrome P450 (CYP3A4) expression in the cells suggest that the non-differentiated stem cells are probably less vulnerable to genotoxic agents as compared to hepatocytes differentiated from them.

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Background:Accumulative research is in progress to clarify clinical aspects of GBV-C. The possibility of interaction between HCV and GBV-C as well as its consequence on development of liver diseases is the most important clinical aspect which encourages researchers to develop a rapid and cost effective technique for simultaneous detection of both viruses. Methods: In this study, a SYBR Green real time multiplex RT-PCR technique as a new economical and sensitive method was designed and validated for simultaneous detection of HCV/GBV-C in HCV positive plasma samples. SYBR green real time RT-PCR technique optimization was performed separately for each virus. Multiplex PCR was established next. Standard sera with known concentrations of HCV RNA and dual HCV/GBV-C positive control samples along with negative control samples were used to validate the assay. Results and Conclusions:  Fifty six non cirrhotic HCV positive plasma samples [29 of genotype 3a and 27 of genotype 1a] were collected from patients before receiving treatment. 20.6% of genotype 3a and 18.7% of genotype 1a showed HCV/GBV-C co-infection. As a result, 19.6% of 56 samples had HCV/GBV-C co-infection that was compatible with other results from all over the world. SYBR Green real time multiplex RT-PCR technique can be used to detect HCV/GBV-C co-infection in plasma samples. Furthermore, with application of this method more time and cost could be saved in clinical-research settings.

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Background and Objectives:HBV and HTLV-I are life threatening infectious agents in patients who receive blood and blood products. Although serological methods have been proved to be useful, detection of these viruses has remained a challengingissue due to the many obstacles. By the advent of Nucleic Acid Testing methods, especially in multiplex format, more precise detection is possible.The objective of this study was to develop a reliable, rapid and cost- effective method tosimultaneously detect HBV and HTLV-I. Materials and Methods: We have developed a multiplex Real time-PCR assay for simultaneous detection of HBV and HTLV-I. Primer sets were designed for highly conserved regions of genome of each virus. Using these primers and standard plasmids, we determined the limit of detection, clinical and analytical specificity and sensitivity of the assay. Monoplex and multiplex Real-time PCRs were performed. Results: Analytical sensitivity was considered to be 1000 and 100 copies/ml for HBV and HTLV-I, respectively. High concentration of one virus had no adverse effect on detection of t low concentrations of the other one. By analyzing 30 samples, clinical sensitivity of the assay was determined to be 87% and 96% for HBV and HTLV-I, respectively. Using different viral and human genome samples, the specificity of the assay was verified to be 100%. Conclusions:We have developed a reliable, rapid and cost effective method tosimultaneously detect HBV and HTLV-I.Our results indicatedthe high capability of this simple and rapid method for detecting these viruses in clinical samples.

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Some bacteria can survive in conditions in which even extremophiles cannot survive. In this study, the conditions of contamination of mine-waste extremophiles with other bacteria was studied on the laboratory scale. At the first step, the acid-producing extremophile bacteria were isolated from mine tailings and characterized using a biochemical protocol. The extremophiles survived at the pH from 0 to 8.5 and temperature from ‒ 70 °C to 90 °C. After the complete growth and isolation of active colonies of the acidophilic bacteria in solid medium, their pollution possibility were examined in the laboratory. The characterization of contaminating microorganisms was performed through polymerase chain reaction (PCR) and 16s rRNA gene sequencing. The polluting bacteria were isolated from the acid-producing bacteria using a nutrient broth liquid medium in a sterilized condition for 1 week, which reached an anaerobic condition after a while. The significant growth of acidophilic bacteria in an anaerobic condition required the 9K medium containing Fe₂(SO₄)₃ and elemental sulphur. The results showed that the contaminating bacteria of extremophiles included Bacillus cereus (strain 1), Bacillus sp. (TS3) and Bacillus oryzaecorticis (WJB138), enduring the anaerobic conditions in a nutrient broth medium.
 

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The citrus leafminer, Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae) is a major invasive pest of citrus in Tunisia. In order to help the implementation of an efficient integrated management strategy, it was essential to assess the genetic diversity and population structure of the pest. For this purpose, random-amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) was applied, using eight oligo-nucleotide primers, to reveal genetic variability among eight populations of P. citrella, originating from the north, center and south of Tunisia. A total of 66 RAPD markers and 33 phenotypes were generated. Inter-population polymorphism was revealed, using the percentage of polymorphic markers (62.12 %), mean number of phenotypes generated per primer (4.125) and mean genetic distance (0.199). Hierarchical analysis, using the UPGMA method, indicated that the genetic variability was influenced by the regional distribution. This pattern of population clustering was supported by Principal Coordinate Analysis (PCO). Yet, a weak correlation (0.69) was revealed between genetic and geographic distances, suggesting that climatic contrariety between the north and south of Tunisia plays a major role in the differentiation of P. citrella, leading to a restriction of gene flow between populations. Results obtained in this work show clear genetic differences, which should be considered in the development of control strategies.  

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Background: Acne vulgaris is an inflammatory chronic disease of pilosebaceous unit. One of the most important factors playing a role in occurrence of acne is presence of Propionibacterium acnes. With the aim of molecular identification of the P. acnes from the acne vulgaris lesions, current research was carried out. Methods: In this study, contents within the lesions was collected from 70 patients. The presence of the P. acnes was examined by a specific PCR technique. Results: Of 70 samples, 58 samples (82.85%) were determined to be positive in terms of presence of P. acnes. No significant relationship was observed between presence of P. acnes and each one of the studied demographic factors, including gender, age, disease period, family background and treatment background. Conclusions: The adopted molecular technique has obviated the limitations associated with the culture method for identification of the bacteria. To overcome the problems with conventional culture techniques for P. acne, this PCR method is promising for better identification of this bacterium.

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Background: Erythropoietin (EPO) is a glycoprotein hormone function to regulate the production of red blood cells. Deficiency of EPO is known to cause anemia in chronically infected renal patients and they require regular blood transfusion. Availability of recombinant EPO has eliminated the need for blood transfusion and now it is extensively used for the treatment of anemia. Glycosylation of erythropoietin is essential for its secretion, stability, protein conformation and biological activity. However, maintenance of human like glycosylation pattern during manufacturing of EPO is a major challenge in biotechnology. Currently, Chinese hamster ovary (CHO) cell line is used for the commercial production of erythropoietin but this cell line does not maintain glycosylation resembling human system. With the trend to eliminate non-human constituent from biopharmaceutical products, as a preliminary approach, we have investigated the potential of human emberyo kidney cell line (HEK293) to produce recombinant EPO. Methods: Initially, the secretory signal and Kozak sequences was added before the EPO mature protein sequence using overlap extension PCR technique. PCR-amplified cDNA fragments of EPO was inserted into mammalian expression vector under the control of the cytomegalovirus (CMV) promoter and transiently expressed in CHO and HEK293 cell lines. After RT-PCR analysis, ELISA and Western blotting was performed to verify the immunochemical properties of secreted EPO. Results: Addition of secretory signal and Kozak sequence facilitated the extra-cellular secretion and enhanced the expression of EPO protein. Significant expression (P < 0.05) of EPO was observed in the medium from HEK293 cell line. Conclusions: HEK293 cell line has a great potential to produce glycosylated EPO, suggesting the use of this cell line to produce glycoproteins of the therapeutic importance resembling to the natural human system.

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Root rot and vine decline caused by Monosporascus cannonballus is a major challenge for melon production world-wide. In recent years, a disease suggested to be related to this pathogen was observed 1-2 weeks prior to harvest in many melon production areas across Iran. In this study, melon plants with symptoms of chlorosis, wilting, decline and/or sudden death were collected from melon growing areas. Pieces of the roots with rot symptoms or discoloration were surface-sterilized and placed on PDA culture medium. DNA was extracted from the rest of the sterilized roots and used in polymerase chain reaction (PCR) using specific primers designed from ribosomal DNA of M. cannonballus. The pathogenicity of the fungus for 24 of its isolates was examined on a muskmelon genotype, Zard-e-Garmsar. In addition, the presence of M. cannonballus was tested on the symptomless melon plants at early growing stages as well as those inoculated with this pathogen using the specific primers. The presence of M. cannonballus was confirmed in 95 melon samples (63% of total samples tested) based on the morphological criteria of the isolated fungus and molecular techniques, where a unique band specific to this pathogen was amplified in diagnostic PCR. M. cannonballus was also detected in the roots of symptomless and inoculated melon plants as early as 2 days post-inoculation. This study demonstrated that M. cannonballus is the major causal organism for melon collapse in all sampling regions and that the pathogen is detectable in melon plants suspected of infection using molecular tools at early growth stages.  

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Asiatic citrus canker is a devastating disease resulting in drastic economic losses in citriculture worldwide. Amongst three different types of the disease, i.e. A, A* and A^w, the A* type is genetically less known. In order to comprehend the behavior of the Asiatic citrus canker A*-type strain (Xanthomonas citri subsp. citri) in the vicinity of the host cells, a targeted semi-quantitative transcript analysis approach via RT-PCR was carried out. A subset of sixteen genes, as representative of different steps involved in phytopathogencity, was analyzed on the culture medium (as uninduced) and compared with the subset isolated from the infected Mexican lime (Citrus auarntifolia L.) plants (as induced). The results showed that certain genes were up-regulated in induced condition, suggesting a putative role in bacteria-host interaction. Furthermore, the transcripts in induced condition could be classified into constitutive, early- and late-responsive genes, demonstrating their functional relevance during the host-pathogen interaction.    

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Background: Fusobacterium necrophorum as a non-spore-forming Gram-negative anaerobic bacillus is an important human and animal pathogen. It may cause severe systemic infections (Lemierre's syndrome) and some other infections. The aim of this study was to subtype Fusobacterium necrophorum by using PCR methods. Materials and Methods: Twenty five strains of Fusobacterium necrophorum subspecies funduliformis were used. Extraction of DNA and typing of the strains using REP-PCR, ERIC-PCR and BOX-PCR were done. Results: Molecular typing of Fusobacterium necrophorum using REP1-R-I and REP-2-I primers generated 2 to 5 amplicons ranging in size from 1500bp to 2000bp. GelCompar comparison of banding patterns revealed seven distinct ribotype strains from 25 strains tested of which most were 2 and 4 with 8 and 7 strains respectively. BOX-PCR subtyping generated 2 to 7 comparable amplicons ranging in size from approximately 600bp to more than 2000bp. ERIC-PCR subtyping generated 6 to 11 amplicons ranging in size from approximately 100bp to 1500bp. Conclusions: F. necrophorum strains have genomic variations that suggest they are never truly clonal in nature, or they may have undergone localized genetic variation across worldwide. This study also showed subtypes existing in Fusobacterium necrophorum species. We have demonstrated that Fusobacterium necrophorum REP-PCR types can be divided into seven, three subtypes by BOX-PCR and six subtypes by ERIC-PCR. BOX-PCR typing proved to be the most discriminatory method, yielding two-seven major bands. The sample size was too small to interpret statistically.

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Background: Adhesion and biofilm formation are two important steps in Candida pathogenesis. The aim of the current study was to investigate the presence of bcr1 gene in Candida albicans (C. albicans) isolates from women with vaginal candidiasis and its impact on biofilm formation. Methods: We used 50 clinical isolates which confirmed C. albicans by PCR-RFLP. Then total RNA was extracted from C. albicans isolates by glass bead and lysis buffer, and cDNA was synthesized using reverse transcriptase enzyme. RT-PCR (Reverse Transcriptase PCR) was used to evaluate the expression of bcr1 gene. Biofilm formation was evaluated in 96-well microplate and then tetrazolium reduction was assayed. All data were analyzed using t-test by SPSS software. Results: Fifty clinical isolates out of 150 were confirmed as C. albicans by using PCR-RFLP method. All the isolates were resistant to fluconazole, 47/50(94%) isolates had bcr1 gene by using PCR, and 45(95.7%) out of 47 isolates, showed BCR1 expression by the RT-PCR. Isolates which harbored bcr1 gene was succeed to form a dense biofilm on microplate. Comparison of the results of the tetrazolium reduction assay on the two isolates that had BCR1expression and two isolates that had no BCR1 expression showed significant differences (p=0.014). Conclusion: According to our result, all of the isolates that had bcr1 gene expression according to RT-PCR, were also resistant to fluconazole in disk diffusion test and additionally, their adherence was higher compared to the control group. These results indicate that there is a positive relation between expression of bcr1 gene and biofilm formation.

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Background:  Aeromonas spp. can cause diarrhea and various infections in humans. Access to rapid techniques with a high sensitivity and specificity is strongly needed for the identification of Aeromonas species. The aim of this study was to evaluate two different methods including API 20E bacterial identification tests and the molecular detection using PCR primers specific for 16s-rRNA and 23S-rRNA genes sequences for identification of Aeromonas spp. in stool samples from patients with diarrhea. Materials and Methods: One hundred stool samples from diarrheal patients were collected. All isolates were subjected toAPI 20 E strip tests and PCR using specific primers for identification of Aeromonas spp. Results: The API 20E analysis identified 2 (2.2%) isolates as Aeromonas spp. Molecular identification by aero-23S-rRNA gene confirmed the same 2 isolates as identified by the API 20E strips. Conclusion: Both API 20E system and PCR method using Aero 23S-rRNA primer were found to be accurate in identification of Aeromonas spp. isolates with highconfidence.

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Background: In this study, we investigated the prevalence of Staphylococcus aureus agr groups to detect the predominant type according to the source of isolation and assessed the possible relationship between agr groups, types of infection and susceptible or resistance to methicillin. Materials and Methods: DNA of 194 S. aureus isolates were extracted by lysozyme-phenol chloroform method that included 85clinical samples, 58 samples were isolated from nose of health care workers and 51 were obtained from food products in Gorgan, North of Iran. PCR-based assays were used for the identification of agr specificity group and mecA gene. Results: The majority of isolates belonged to agr group I (43.3%), followed by agr group III (28.87%), agr group II (22.68%), agr group IV (5.15%) and 40.7% of strains were MRSA. In our study, the majority of S. aureus isolates recovered from health care workers and food products were agr group I and isolates recovered from patients were agr group III, these differences were statistically significant (P-value <0.05). There was no statistical difference between the agr groups, infection type and susceptibility or resistance to methicillin. However, agr group III was the predominant group in MRSA strains. Conclusion: Theagr group I was predominant among isolates of health care workers and food products specimens in Gorgan, North of Iran, while agr group III was predominant in MRSA strains and the isolates from patients. Investigation of the possible role of agr group III in S.aureus infections in the further studies is recommended.

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Background: Salmonella typhimurium is one of the most important species of Salmonella that is intracellular parasite and attacks host mucus membrane. These bacteria can cause gastroenteritis, and their main transmission route is water, poultry, meat, egg, and raw food. The aim of this study was to detect three virulence genes associated with S. typhimurium named invA, STM4497, and fliC183 genes by Multiplex PCR method.
Materials and Methods: 183 samples of poultry were collected from food products in Zanjan (Iran) and cultured in BPW (Buffered Peptone Water) for 18 hr and at 37°C, and in RVS broth (Rappaport Vassiliadis Soya) for 6 hr at 41.5°C. After amplification of genomic DNA by Multiplex PCR method, occurrence of pathogen contamination was checked and compared with standard strain.
Results: From the total of 183 collected samples, 52(28.4%) samples were positive for S. typhimurium. The frequency of STM4497, fliC183, and invA genes were 49 (27%), 3 (2%), and 53 (29%), respectively.
Conclusion: Simultaneous detection of invA, STM4497, and fliC183 genes were recognized as a key for detection of S. typhimurium by Multiplex PCR method. 

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Background: The importance of this research was to determine the prevalence of efflux pump genes among Acinetobacter baumannii isolates from hospitalized patients in Imam Reza hospital in Tabriz, Iran.
Materials and Methods: This descriptive study was conducted in the Imam Reza hospital, Tabriz, IR Iran during June 2013 to March 2014. Twenty-six strains were isolated from female patients (42.6%) and thirty-five from male patients (57.4%). Clinical specimens were cultured for isolation of the microbial agents of A. baumannii. The isolated bacteria were identified using biochemical tests. Disk diffusion susceptibility test was used to determine the antimicrobial susceptibility, and E-test methods were also used. The prevalence of efflux pump genes was detected by PCR and sequencing methods.
Results: The resistance of A. baumannii isolates against tested antibiotics was analyzed as follows: 51 (84%) to trimethoprim-sulfamethoxazole, 59 (98%) to ceftazidime, 60 (99%) to ciprofloxacin, 29 (48%) to amikacin, 46 (77%) to gentamicin, 30 (50%) to tobramicin, , 60 (99%) to imipenem,, 60 (99%) to meropenem,, 60 (99%) to ceftriaxon,, 60 (99%) to cefepime,, 60 (99%) to ofloxacin, 6 (11%) to colistin. By using E-test, 45 (73.3%) to imipenem, 57 (93.3%) to ciprofloxacin, 23 (38%) to amikacin were also analyzed. The prevalence of adeA, adeB, adeC, and abeMgenes was 54 (88.5%), 61 (100%), 57 (93.9%), and 60 (98.3%), respectively.
Conclusion: The result of this study showed high incidence of AdeABC efflux pump in MDR A. baumannii isolates and the growing number of nosocomial infections associated with XDR A. baumannii complex, leading to difficulties in antibiotic therapy.

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Background: Infections caused by Pseudomonas aeruginosa or Acinetobacter baumannii are of greatest concern for hospitalized patients, particularly those in intensive care units (ICUs). The aims of this study were to investigate the prevalence of integrons and biofilm formation among P. aeruginosa and A. baumannii isolates collected from ICU and non-ICU inpatients.
Materials and Methods: A total of 90 P. aeruginosa and 90 A. baumannii isolates were recovered from patients admitted into diverse units of Shahid Mohammadi hospital in Bandar Abbas from January to December 2014. Bacterial identification was carried out by phenotypic methods and PCR. Antibiotic susceptibility was measured by disk diffusion assay. The presence of Class 1, 2, and 3 integrons were evaluated by multiplex-PCR. Biofilm quantification was done by microtiter method.
Results: The highest number of isolates (48%) were recovered from ICU patients. 81% of P. aeruginosa isolateswere sensitive to piperacillin/tazobactam and ticarcillin, while 60% were resistant to third generation of cephalosporins. In case of A. baumannii, all the isolates were sensitive to colistin, but 98% were resistant to other antibiotics (p≤0.05). Susceptibility to ceftazidime, ticarcillin, imipenem, and piperacillin/tazobactam were higher among isolates obtained from non-ICU patients. Class 1 integron was detected in 13.3% of the P. aeruginosa and 40% of the A. baumannii isolates, while Class 2 integron was harbored by 7 and 6.6% of the isolates, respectively. Furthermore, 23% of the A. baumannii and 12% of the P. aeruginosa isolates showed strong biofilm activity.
Conclusion: Class 1 integron-positive isolates were resistant to three classes of antibiotics and predominantly observed in specimens collected from ICU patients showing strong biofilm.

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Background: Group B streptococcus (GBS) is the major cause of serious life threatening infections in neonates, pregnant women, and other adults with underlying diseases. Capsular polysaccharide typing is a significant way for epidemiological studies of GBS, the pathogenesis, and other studies associated with GBS infections including surveillance programs and vaccine development in future. Molecular serotyping (MS) methods offer more accurate and reliable typing of bacteria. The aim of current study was to differentiate genotypes of clinical GBS isolates based on PCR assay to acquire information about the distribution of GBS types in Hamadan, Iran.
Materials and Methods: A total of 62 clinical GBS strains including vaginal swabs, urine cultures, and blood culture isolates were examined for genotyping using multiplex PCR assay.
Results:Among the 62 GBS isolates examined, all capsular types, except VI, VII, and VIII, were found. Type III was the predominant type with 35 isolates (56.5%), followed by Type V with 11 isolates (17.7%), Type II with 7 isolates (11.3%), Type Ia with 5 isolates (8.1%), and Types Ib and IV with similar prevalence of 2 isolates (3.2%) for each type.
Conclusion: The results of the current study demonstrated that Type III is the predominant type in Hamadan, followed by Types V, II, Ia, Ib, and IV, respectively. Using MS method leads to accurate, sensitive, specific, and fast typing of GBS isolates. The advantages of MS method allow it to analyze various populations and to examine invasive and colonizing isolates in extensive epidemiological studies and surveillance activities. In fact, MS will facilitate the proper formulation of candidate GBS vaccines.

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Background: Campylobacter jejuni and Campylobacter coli are identified as the major causes of acute gastroenteritis in humans. Because of the fastidious nature of Campylobacters, many clinical laboratories fail to routinely culture them. The detection of Campylobacter spp. using molecular-based techniques can be useful for diagnostic and epidemiological applications. This study aimed to developa multiplex PCR assay for the simultaneous detection of C. jejuni and C. coli strains from clinical specimens
Materials and Methods: During a 19-month period, stool samples were collected from 980 children admitted to a hospital in Tehran, Iran and then examined. The samples were cultured on both Brucella agar and Modified Charcoal-Cefoperazone-Deoxycholate agar (mCCDA) media at 42°C for 48 h. To confirm suspected bacteria, Gram staining and other biochemical tests were carried out. Finally, after extracting DNA from pure cultures using the boiling method, the multiplex PCR assay was performed.
Results: The multiplex PCR assay showed that Campylobacter spp. can be detected using 400 bp target product of cadF. It can also accurately distinguish between C. jejuni and C. coli species with different bands of 735 bp and 500 bp using hipO and asp genes, respectively
Conclusions: Results showed that the multiplex PCR assay can replace the biochemical assays for differentiating between C. jejuni and C. coli strains in a single-step PCR test.

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Background: Campylobacter species are the main food-borne pathogens which could cause gastroenteritis in humans. Contaminated chicken products have been documented as the primary sources of Campylobacter transmission to human. This study was done to test raw chicken meat products retailed in local markets in Tehran, Iran for the presence of Campylobacter coli and Campylobacter jejuni species.
Materials and methods: A total of 70 raw chicken meat samples were collected during a three-month study. All the Campylobacter species were identified by biochemical and species-specific polymerase chain reaction (PCR). These isolates were investigated further to examine their potential virulence factors.
Results: Campylobacter spp. were detected in 56% of the isolates and identified as C. coli. The results indicated that all of the isolates were positive for cadF, cdtA, iam genes. On the other hand, none of the isolates were positive for flaA and pladA virulence genes.
Conclusion: Overall, the results showed that Campylobacter species were common contaminants in chicken meat, which should be screened for the presence of virulence determinants and for their involvement in food-borne diseases.
 

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Background: Aspergillosis is an opportunistic infection caused by Aspergillus spp in immunocompromised patients. The role of HSP90 in Aspergillus drug resistance is still unknown. The aim of this study was to evaluate the correlation between the presence of HSP90 gene and polyene resistance in Aspergillus spp using PCR.
Materials and Methods: In this study, 32 Aspergillus strains were used, which were isolated from patients susceptible to aspergillosis through Bronchoalveolar lavage (BAL) and identified by conventional methods. The isolates were cultured on Sabouraud dextrose agar (SDA). Susceptibility testing against amphotericin B was conducted according CLSI standards (M38-A). Also, the presence of HSP90 gene was evaluated using PCR.
Results: Of 32 Aspergillus strains used in this study, 16 (50%) isolates were identified as A. Flavus, 12 (37.5%) isolates as A. fumigatus, and 4 (12.5%) isolates as A. terreus. Among these species, 19 (59.37%) isolates were sensitive to amphotericin B whereas 13 (40.62%) were resistant. Moreover, there was a significant difference  between the presence of HSP90 gene and resistance to amphotericin B in Aspergillus species.

Conclusions: The presence of HSP90 gene provides evidence that shows this gene may play important role in resistance to amphotericin B in Aspergillus isolates. Although numerous regulatory genes are involved in resistance mechanisms, they remaines to be more clarified