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A total of 200 samples of traditional ice creams were obtained randomly from the retail stores in the city of Shahr-e-kord. All the samples were analyzed for microbial contaminations according to the Iran national standard. Out of 200 samples, 100 showed mesophilic aerobic bacteria count more than 5*105 per gram of ice cream. One hundred fourteen samples showed Staphylococcus aureus count more than 102 per gram of ice cream. Ninety nine samples showed Enterobacteriacea count more than 102 per gram of ice cream. From 200 samples, 2 samples were Escherichia coli positive, and 24 samples showed Bacillus cereus count more than 103 per gram of ice cream. No Listeria monocytogenes was isolated from 200 samples.

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Background: Escherichia coli (E. coli) strains are among predominant agents causing nosocomial and community acquired infections. The majority of strains encode numerous virulence factors including fimbrial adhesions, secretory proteins and toxins, siderophores, and capsule. This study aimed to investigate the prevalence rate of virulence encoding genes and carbapenem resistance-encoding genes among imipenem-resistant E. coli isolates collected from patients hospitalized in Tehran, Iran.
Materials and Methods: In this cross-sectional study (April 2015-December 2017), 50 non-duplicated carbapenem-resistant E. coli isolates were collected from clinical specimens (stool, urine, blood, and wound) of hospitalized patients in three hospitals in Tehran, Iran. The antibiotic susceptibility profile was determined against 15 antibiotics on Mueller Hinton Agar (MHA) as per CLSI guidelines version 2016. The PCR was used to detect virulence and antibiotic resistance encoding genes.
Results: From a total of 50 carbapenem-resistant E. coli isolates, the highest resistance rate was observed to ceftazidime (100%), tetracycline (88%), amoxicillin (100%), sulfonamide (60%), and the least resistance rate was observed against amikacin (14%), gentamicin (22%), and fosfomycin (0%). The genes mediating resistance were as follows: beta-lactams OXA-48 (8%), IMP (16%), VIM (0%), NDM-1 (0%),  fosA3 (0%), quinolones (qnrA 48%), and colistin mcr-1(0%). Furthermore, the prevalence rates of of fimA, hlyA, cnf1, vat, pic, crl, and papH were 88, 36, 28, 10, 12, 54, and 88%, respectively.
Conclusion: In this study, all imipenem-resistant E. coli isolates were susceptible to fosfomycin, and all were  fosA3 negative. Among carbapenemase genes, IMP and OXA-48 type enzymes associated with higher MIC levels (8 to 32 µg.mL^-1) were detected. In this study, data suggest the role of these carbapenemases in resistance to carbapenems. Furthermore, the presence of multiple drug resistant strains encoding adhesive and secretory virulence factors is a concern for the infections treatment. 

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Aims: Many infectious diseases had traditionally been cured with herbal medicines. Antimicrobial agents are often produced synthetically to increase the food durability and quality. The purpose of this study was to determine the antimicrobial properties of the aqueous and alcoholic extracts of Allium schoenoprasum.
Materials & Methods: In this experimental study, after preparation Allium schoenoprasum samples, aqueous and alcoholic extracts were prepared and their minimum inhibitory concentration (MIC) was determined against Staphylococcus aureus, Bacillus cereus, Escherichia coli and Vibrio cholerae by micro broth dilution method. Erythromycin was used as the control.
Findings: The MIC of alcoholic and aqueous extracts of A. schoenoprasum was 16-256 and 32->256µg/ml, respectively and MBC of them were 32-256 and 64->256ug/ml, respectively. The A. schoenoprasum exhibited higher activity against S. aureus and B. cereus strains.
Conclusion: The extracts of A. schoenoprasum have antimicrobial effect on S. aureus, B. cereus, E. coli and V. cholerae strains in micro broth dilution method.

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Sugar beet molasses is a well-known, inexpensive and available carbon source for microbial cell growth. Its sugar components are used to produce energy for microbial growth and non-sugar components, especially nitrogen components, have important roles in improvement of cell growth. On the other hand, immobilization of whole cell is establishment and physical limitation of intact cells in specific space that keeps their catalytic activity and provides the possibility of reuse of the cells. This technique allows continuous and accelerated biological processes. It also improves production efficiency and quality and simplifies recycling of product. Immobilized living cells, as controlled catalysts, are able to perform one-step enzymatic reaction and continuous fermentative processes. In this research, E.coli cells were immobilized in calcium alginate hydrogels and using sugar beet molasses as carbon source, were applied for tryptophan production reaction in the presence of its precursors, serine and indole. In comparison between free biocatalysts and immobilized bacterial cells that entrapped in alginate gels, indicated that larger amounts of amino acids (about 42/9%) can produce in calcium alginate. Also the production reaction was followed up for 9 sequential cycles, and results showed that the cells could produce tryptophan amino acid under above conditions. Use of sugar beet molasses (by-product of agriculture industries) for growth of microbial cells and tryptophan production, causes decrease in production cost and more economical production of tryptophan by immobilized E. coli.

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 Aims
 Urinary tract infection (UTI) is one of the most common infections worldwide. The aim of this study was to investigate the association between ESBLs genes and quinolone resistance in Uropathogenic Escherichia coli isolated from patients with urinary tract infection .
Materials & Methods
A total of 150 E. coli isolates were collected from patients with urinary tract infection referring to Firouzgar Hospital in Tehran, Iran. Antimicrobial susceptibility of isolates were determined by disk diffusion method. Double-disk diffusion test was performed for phenotypic identification of extended-spectrum β-lactamase- (ESBL) producing isolates. PCR was used for the detection of ESBL-encoding genes in addition to quinolone (qnr) resistance genes.

Findings

 There was a high resistance rate to most of the studied antimicrobial agents. Phenotypically, 75% of the isolates produced an ESBL enzyme and were resistant to different antimicrobial classes. In overall, 83% of the isolates carried ESBL genes, especially bla_TEM and bla_CTX-M  . 75% were positive for the quinolone resistance genes including qnrA , qnrB ,qnrS and qepA. These results indicate the association between the presence of various ESBLs genes and quinolone resistance in uropathogenic E. coli.

Conclusion

Resistance patterns show the increased incidence of antibacterial resistance in E. coli. Results of the current study indicate the high prevalence of ESBL-producing isolates and quinolone resistance genes. Simultaneous presence of genes responsible for antibacterial resistance has made the treatment of UTI more challenging than ever before.

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Aims: Foodborne infections caused by bacteria, including Salmonella enteritidis, Shigella flexneri, and Escherichia coli O157:H7 are one of the most common diseases among poultry and humans. The purpose of this study was the simultaneous and rapid detection of important microorganisms found in fecal samples of poultry and poultry workers.
Materials & Methods: A total of 144 fecal samples were taken from poultry and poultry farms workers. Fecal swabs were cultured on specific media, and biochemical tests were performed for further confirmation of bacterial isolates. Moreover, genomic DNA of fecal swabs was extracted for molecular identification of S. enteritidis, E. coli O157: H7, and S. flexneri species using multiplex-PCR technique.
Findings: According to the multiplex-PCR technique results, 16.7, 13.9, and 9.5% of the poultry samples were positive for the presence of S. enteritidis, E. coli O157: H7, and S. flexneri species, respectively; whereas culture method results showed the corresponding prevalence rates of 18.1, 15.2, and 12.5% for the above species. Moreover, regarding the samples collected from the poultry farms workers, multiplex PCR showed the prevalence rates of 6.9, 12.5, and 4.2% for S. enteritidis, E. coli O157: H7 , and S. flexneri species, respectively; whereas culture method showed the corresponding prevalence rates of 8.3, 13.9, and 13.9% for the above species.
Conclusion: In the current study, the sensitivity and specificity of multiplex-PCR in detecting S. enteritidis, E. coli O157: H7, and S. flexneri species were 74 and 100% for samples taken from the poultry farms workers, and 82.2 and 100% for samples taken from the poultry, respectively, suggesting the possibility of using a designed multiplex-PCR method for rapid detection of infectious agents in poultry farms.

 

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Aims: The aim of this study was to investigate chemical composition, antioxidant potential, and antimicrobial activity of cardamom essential oil against Staphylococcus aureus, Escherichia coli, and Saccharomyces cerevisiae species.
Materials & Methods: The chemical compositions of cardamom essential oil were identified by Gas Chromatography-Mass Spectrometry (GC-MS) device. Cardamom essential oil antioxidant activity was measured by 2, 2-diphenyl-1-picrylhydrazyl (DPPH) assay, and its total phenolic compounds (TPC) were measured by Folin–Ciocalteu reagent. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of cardamom essential oil were determined using the serial-dilution method.
Findings: According to the GC-MS analysis results, 17 compounds were totally identified in cardamom essential oil, among which the most important compounds were 1, 8-cineole (36.74%) and α-terpinyl acetate (33.07%). MICs obtained for S. aureus, E. coli, and S. cerevisiae were 12.50, 25.00, and 1.56 mg/mL, respectively. Also, MBC obtained for both S. aureus and E. coli was 25 mg/mL, while MBC for S. cerevisiae was 3.36 mg/mL. Antioxidant activity measurement results showed that increasing the amount of cardamom essential oil reduced the amount of color and absorbance of DPPH solution to 517 nm. The results also showed that the amount of TPC in cardamom essential oil was 214.35 mg gallic acid per 100 g of dry material.
Conclusion: Cardamom essential oil used in this study showed antibacterial and anti-yeast activities against S. aureus, E. coli, and S. cerevisiae species. Antimicrobial effects of cardamom essential oil were predictable due to the presence of antimicrobial components in this oil.

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Aims: Numerous microbial agents have been identified as the causative agents of UTIs, such as Escherichia coli. The spread of antibiotic resistance is increasing among strains causing UTIs. The present study aimed to investigate the prevalence of etiological agents of UTIs and their antibiotic resistance patterns and to determine related risk factors and treatment outcomes of antibiotic resistance in Razi teaching hospital, Guilan, North of Iran.
Material & Methods: This retrospective cross-sectional study was performed from April 2017 to September 2018. All patients with clinical symptoms of UTI were included. The patients’ complete medical records were assessed. Moreover, bacterial isolation and identification were performed by conventional bacteriological and standard biochemical tests. Antibiotic susceptibility testing was performed using the disk diffusion method based on the CLSI recommendation.
Findings: Gram-negative bacilli were identified as the most common causative agents of UTIs in all cases (140, 100%), of which E. coli had the highest isolation rate with 76 cases (54.3%), followed by Klebsiella spp. with 23 cases (16.4%).  Antibacterial susceptibility tests revealed that 64.3% of the isolates were resistant to three antibiotics of different classes (MDR phenotype).
Conclusion: In conclusion, Gram-negative bacilli were the most common causative agents of UTIs, and E. coli had the highest isolation rate (54.3%). Regarding the high prevalence of antibiotic resistance and MDR phenotype, paying attention to drug resistance patterns of pathogens and proper and correct administration of antibiotics as well as proper and timely monitoring of treatment, could help physicians decrease the patients’ mortality rate.

 

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Background: Urinary tract infections are considered as a major health concern. Escherichia coli is the most common cause of urinary tract infections. The presence of qnr plasmid genes in bacteria is the main cause of resistance to quinolones. The aim of this study was to investigate the antibiotic resistance pattern and prevalence of qnrB gene in E. coli strains isolated from patients with urinary tract infections.
Materials & Methods: In this cross-sectional study, samples were taken from patients with urinary tract infections, referred to Kermanshah hospitals during the spring of 2017. E. coli strains were identified by biochemical tests. Then antibiotic susceptibility testing was performed for the isolates by the disc diffusion method. Following that, qnrB resistance gene was detected by PCR; finally, data were analyzed by SPSS software Ver. 23.
Findings: In this study, 105 E. coli strains were isolated from urine specimens. The strains resistance rate to nalidixic acid, ciprofloxacin, and ofloxacin antibiotics was 62.85, 38.09, and 33.33%, respectively. PCR results showed that 67 strains (63.8%) had qnrB gene, and 38 strains (36.19%) lacked this gene. Logistic regression analysis showed that there was a significant relationship between the presence of qnrB gene and nalidixic resistance.
Conclusion: The results of this study show that the frequency of qnrB gene among the E. coli strains isolated from urinary tract infections is fairly high in Kermanshah. Therefore, it is necessary to do further investigates using molecular techniques and to take serious preventive measures.

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Background: Urinary tract infections (UTIs) cause a wide range of infections in individuals; they are common nosocomial infections that have recently become difficult to treat because of the increased emergence of multidrug-resistant bacteria. The present study aimed to determine and compare the minimum inhibitory concentration of gentamicin alone and in combination with cetirizine against Escherichia coli strains isolated from hospitalized patients with UTI.
Materials & Methods: This study was performed on 76 E. coli strains isolated from a total of 103 samples of patients admitted to three hospitals in Gonbad-e Kavus. Kirby Bauer disk diffusion and broth microdilution tests were used to determine antibiotic susceptibility and the minimum inhibitory concentration (MIC) of gentamicin alone and in combination with cetirizine according to CLSI M100-S25 (2015) criteria.
Findings: Evaluation of the minimum inhibitory concentration of gentamicin-cetirizine combination against E. coli isolates showed that none were able to grow at a concentration of 8 µg/mL. The concentration of gentamicin in combination with cetirizine, inhibiting 90% of E. coli isolates (MIC90), was 4 μg/mL, which was 16 times lower than that of gentamicin alone (MIC90= 64 μg/mL) (p=.02).    
Conclusion: Gentamicin in combination with cetirizine was found to be more potent in inhibiting E. coli isolates than gentamicin alone. Therefore, the results of this study could provide a clear perspective for dealing with drug-resistant pathogens.

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Backgrounds: This study aimed to analyse hybrid Entroaggregative/Uropathogenic Escherichia coli (EAEC/UPEC) isolates. To do so, the antibiotic resistance pattern and virulence genes were investigated in E. coli strains isolated from clinical specimens of patients hospitalized in Isfahan, Iran.
Materials & Methods: Disc diffusion method was used to determine the antibiotic susceptibility pattern of EAEC/UPEC isolates. Also, virulence determinants of these isolates were determinated by singleplex and multiplex PCR.
Findings: Overall, a total of 148 E. coli isolates were collected, of which 12 (8.1%) isolates were hybrid EAEC/UPEC strains, then antibiotic susceptibility examination was operated on these strains. The higest antibiotic resistance rate was related to ofloxacin (42%), followed by trimethoprim-sulfamethoxazole (41%), ceftriaxone and cefepime (33%), and cefoxitin (17%). All the isolates showed susceptibility to fosfomycin.
Conclusion: According to the current study, since resistance to fluoroquinolones has increased in hybrid strains, monitoring the drug susceptibility of hybrid strains seems critical in Iran. Fosfomycin is considered to be the drug of choise for infections caused by multidrug-resistant (MDR) Gram-positive and Gram-negative bacteria. Fortunately, 100% of the strains were sensitive to fosfomycin.

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Backgrounds:  Escherichia coli (E. coli) is one of the most abundant bacteria in human and animal infections. Many virulence genes in E. coli intensify its infectivity. This study explored the presence of two pathogenic genes, including fimH and bfpA, in E. coli strains isolated from pregnant women.
Materials & Methods: From autumn 2016 to spring 2017, a total of 100 E. coli isolates were collected from clinical samples (116) of pregnant women. The strains were identified using biochemical tests (catalase, Simmons citrate, indole, mobility, H₂S, MR, VP, TSI, and urease). The presence of pathogenic genes in these isolates was examined using colony PCR method. Finally, the relationship between the gene and the site of infection was analyzed in SPSS-23 software. 
Findings: PCR results indicated that out of 100 E. coli samples, 15 were bfpA positive (15%), and 64 were fimH positive (64%). A significant relationship was found between the presence of bfpA gene and samples taken from urine (p<.001), blood (p=.049), and stool (p<.001). 
Conclusion: None of the urinary strains harbored the bfpA gene, while the strains isolated from stool had a significant relationship with the presence of bfpA gene (OR = 18.667), which confirms that this gene is of great importance for EPEC (enteropathogenic E. coli). There was also a significant relationship between blood-isolated strains and the presence of bfpA gene. A significant relationship was also found between the fimH gene and strains isolated from urine samples (OR=36.733), while no relationship was observed between the presence of fimH gene and blood-isolated strains.
 

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Backgrounds: Uropathogenic Escherichia coli is one of the most important etiological agents of UTI. The aim of this study was to investigate the antibacterial effects of zinc oxide nanoparticles (ZnONPs) on aminoglycoside-resistant E. coli isolates from patients with UTI.
Materials & Methods: After identifying E. coli strains in 100 out of 250 urine samples, antibiotic susceptibility was evaluated against six antibiotic classes (with emphasis on aminoglycosides) by disk diffusion method according to CLSI-2020 guidelines. The presence of aac (6')-Ie-aph (2'') gene in isolates was investigated by PCR. Antibacterial properties and minimum inhibitory concentration (MIC) of zinc oxide nanoparticles were evaluated by agar well diffusion and broth microdilution assays, respectively.
Findings: Among 100 E. coli isolates, the highest and lowest antibiotic resistance rates were observed against tetracycline (70%) and ofloxacin (10%), respectively. Of 30 gentamicin-resistant E. coli isolates, 17 (56.5%) isolates harbored the aac (6')-Ie-aph (2'') gene. In agar well diffusion assay, 22 (74%) gentamicin-resistant isolates were eliminated by zinc oxide nanoparticles at a concentration of 150 mg/L, while ZnONPs at 300 mg/L could eliminate all gentamicin-resistant isolates. Furthermore, ZnONPs could inhibit all bacteria at a concentration of 200 μg/mL (MIC₉₀ ≥ 100).
Conclusion: Spread of the aac(6')-Ie-aph(2'') gene could increase gentamicin resistance among E. coli strains causing UTI. Given the favorable antibacterial effects of zinc oxide nanoparticles in vitro, the clinical application of these nanoparticles in the treatment of UTIs caused by multidrug-resistant E. coli could be investigated in future studies.
 

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Backgrounds: Uropathogenic Escherichia coli is a Gram-negative bacillus that is the most common cause of urinary tract infection. E. coli has the ability to produce biofilm as an important virulence factor. Due to the lack of sufficient information about ESBL resistance genes in this geographical area, this study aimed to investigate the prevalence of ESBLs in E. coli isolates to increase our knowledge about the role of these genes and biofilm formation in inducing resistance.
Materials & Methods: 139 E. coli strains were isolated from urine samples. Antibiotic susceptibility testing was performed for the isolates by disk diffusion method. ESBL production was confirmed using double-disk synergy test. Molecular detection of ESBL genes was performed using PCR. Biofilm formation assay was performed by microtiter plate method.
Findings: The most effective antibiotic against this bacterium was nitrofurantoin. Multidrug resistance was observed in 119 (85.6%) isolates. ESBL phenotype was detected in 93 (66.9%) isolates. The PCR test results showed that bla_CTX, bla_VEB, and bla_TEM were positive in 45 (32.4%), 87 (62.6%), and 10 (7.2%) isolates, respectively. The biofilm formation assay results revealed that 65 (46.8%), 58 (41.7%), 10 (7.2%), and six (4.3%) isolates were non-, weak, moderate, and strong biofilm producers, respectively.
Conclusions: The high prevalence of ESBL genes is a public health concern in this region because they could be transmitted to other susceptible bacteria and induce resistance. This study showed that biofilm production could increase antibiotic resistance.
 

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Backgrounds: The aim of this study was to evaluate genotypes and phenotypes of antibiotic resistance in Escherichia coli (E. coli) strains isolated from poultry farms in Isfahan province, Iran.
Materials & Methods: In this study, 50 E. coli strains isolated from pericarditis and perihepatitis lesions of broilers in Isfahan (central Iran) were selected. After microbiological and biochemical tests and confirmation of bacterial colonies, the colonies were purified. The pure colonies were cultured on Müeller-Hinton culture medium and then subjected to antibiotic susceptibility testing. In the next step, DNA was extracted from the purified bacteria, and the qnrA and sul1 genes were amplified with specific primers.
Findings: The results showed that 85% of E. coli isolates were resistant to at least two antibiotics, and 6% of E. coli strains were resistant to all 13 antibiotics used in this study. E. coli isolates showed the highest resistance to enrofloxacin (70%) and the lowest resistance to gentamicin (6%). Examination of resistance genes showed that about 54% of enrofloxacin-resistant E. coli strains contained the qnrA gene, and 48% of sulfonamide-resistant E. coli strains contained the sul1 gene.
Conclusion: In this study, some resistant strains lacked the resistance genes studied, indicating the importance of other resistance genes in inducing resistance against sulfonamides and fluoroquinolones. Also, the lack of resistance in some strains harboring qnrA and sul1 genes indicates the importance of gene expression in mediating resistance, and that the presence of resistance genes alone is not sufficient to induce antibiotic resistance in E. coli strains.

 

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Backgrounds: This study was done to evaluate the distribution of virulence-associated genes and antibiotic resistance in avian colibacillosis-causing Escherichia coli (E. coli) isolates.
Materials & Methods: In this study, 122 E. coli strains isolated from colibacillosis-suspected chickens in commercial broiler poultry farms (Guilan province, Iran) were examined for the presence of 12 virulence genes (hlyF, iroN, iss, iutA, ompT, astA, tra, sfa-foc, papC, fimH, cvi/cva, and Tia) using polymerase chain reaction (PCR). Antimicrobial susceptibility assessment was performed for the isolates using disc diffusion method against 19 antibiotics.
Findings: The fimH, iut, tra, iss, iroN, hly, and ompT genes were detected as the most prevalent genes among colibacillosis-causing isolates (more than 70%), while sfa-foc (S fimbriae and F1C fimbriae subunits) had the lowest frequency among colibacillosis-causing E. coli isolates (3.28%).
Conclusion: Virulence-associated genes were frequently detected in avian pathogenic E. coli strains. These findings could help better understand the pathogenicity potential of E. coli in poultry. Preventative measures are necessary to reduce food and environmental contamination with avian E. coli strains.

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Introduction: Growth hormone is a non-glycosylated polypeptide strand of the pituitary glands of all vertebrates that has a wide range of biological activities and considering the importance of this hormone and its importance and diverse therapeutic applications in medicine, its recombinant production can be of great importance. In recent decades, protein engineering and genetic engineering have resulted in a high level of expression and production of this protein in a variety of hosts, including Escherichia coli bacteria using new techniques and methodes, hormone purification and assay are carried out easily. Therefore, the aim of this review was to investigate the production of recombinant human growth hormone (rhGH) and future challenges.
Conclusion: One of the problems of the expression and purification of the human growth hormone may involve that maybe noted the production of inclusion bodies in the expression of recombinant proteins in the cell cytoplasm, the contamination caused by host proteins, low protein recovery from these inclusion bodies, low protein secretion into the Periplasmic space, high cost of production, especially in Purification stage and so on. Due to the lack of need for glycosylated hormone and high efficiency and simplicity of work, bacterial systems, especially Escherichia coli, are the most economical and effective systems for the expression of heterologous proteins. The hormone purification stage is usually the most costly process. Therefore, an optimal design for achieving the highest target protein recovery with the elimination of all contamination from the final product and reducing the purification step is required.

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Background: Pathogenic Escherichia coli (E. coli) is usually known as the principal agent of hospital-acquired infections, particularly those related to urinary tract infections (UTIs). The purpose of tThis study aimedwas to determine ESBL (extended-spectrum B-lactamase) production and quinolone resistance (qnr) genes in cytotoxic necrotizing factor 1 (CNF-1)- producing E. coli isolatesd from UTIs in Iraq.
Materials & Methods: A total of 996 E. coli isolates were obtained from UTIs infections in two general hospitals in Hillah, Babylon, Iraq (during 2014-2022), and 100 uropathogenic E. coli (UPEC) were cnf-1 gene carriers. ESBL production was evaluated using the double-disk synergy -test. The qnr genes were detected using polymerase chain reaction (PCR).
Findings: Nalidixic acid and chloramphenicol resistance wasincluded 70% and 30%, respectively. ESBL production was observed among 46% of cnf-1 -carriers isolates. The qnrA, qnrB, and qnrS genes were detected in 18%, 21%, and 11% of the isolates, respectively. ESBL-producing isolates mainly carried the qnrB gene and showedhad the highest resistance levels to quinolones. Major risk factors of pathogenic E. coli isolation included older age (68%, p= 0.031), previous hospitalization (76%, p= 0.021), and urinary catheter (83%, p= 0.018).
Conclusion: Although the prevalenceexistence of the cnf-1 gene was not high among UPEC isolates, its prevalencerate was high among quinolone-resistant and ESBL-producing isolates. The cContinuous investigation of virulence and resistance genes is essential tfor monitoring and controlling the infections and facilitate their control. ItMore investigation is necessary to determine the virulence  traits factors and resistance genes among UPEC in Iraq and to take in timely measures action to hinder the spread of resistance genes from spreading to other nosocomial isolates.
 

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    Abstract In this study a number of 100 hamburger samples which were produced industerially from different batches were collected randomly from suprermarkets in Mashhad city, during the autumn months of 2006. For isolation of the bacteria, samples were, firstly enriched in modified trypticase soy broth containing novobiocin, followed by plating on sorbitol Mac Cankey agar supplemented with cifixime and potassium tellurite. Consequently the suspected non sorbitol fermenting (NSF) colonies were confirmed by biochemical tests as Escherichia coli and then employed for multiplex-PCR assay, using primers specific for O157 and H7 antigens gene. The m-PCR assay employed in this study may be a possible  alternative to immunological assays which detects somatic and flagellar antigens. In this study, 9 NSF Escherichia coli colonies were isolated, and in multiplex-PCR assay two samples (4%) were confirmed as Escherichia coli O157:H7.

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