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Background and objectives: Gouda Cheese is regarded as a high quality and one of the most popular cheeses in the world. The defining characteristics of Gouda cheese are its yellow color, great aroma and taste of caramel sweetness. The cheese should be well chilled before waxing, to get better seal. The seal is very important to prevent contamination with molds and putrefactive bacteria. Cheese wax is made from paraffin with additional microcrystalline to make pliable for better seal. The aim of this study was to investigate antibacterial effects of Gouda cheese wax.
Methods: Gouda cheese wax samples were collected from four different manufacturers in Iran. The total count of coliforms, Escherichia coli, Salmonella, coagulase-positive Staphylococcus and mold and yeast on the samples was determined. The antimicrobial activities of Gouda cheese wax against E. coli, S. aureus, Saccharomyces cerevisiae, Aspergillus brazilissis and Salmonella enterica were investigated by determining minimum bactericidal concentration and minimum inhibitory concentration.
Results: The results indicated that all Gouda cheese wax samples were prepared in accordance with the national standards. In addition, the examined wax samples had no antimicrobial properties against the tested microorganisms.
Conclusions: The wax used in production of Gouda cheese in Iran has no antimicrobial properties.

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Background and objectives: Neutralized electrolyzed water (NEW) is a novel natural disinfectant. It has been suggested that application of NEW can improve the shelf life of fish. This study aimed to investigate effect of NEW incorporated in alginate coating on growth of Escherichia coli O₁₅₇: H₇ on salmon fillets over a period of 12 days.
Methods: Fish fillets were inoculated with E. coli O₁₅₇:H₇ and divided into six different treatment groups: control (no coating), distilled water, alginate, EW, EW & alginate (Samples coated with alginate solution prepared by EW), and EW+ alginate (samples immersed in EW, then coated with alginate solution). The fillets were kept at 4 °C, and the bacterial count was determined on days: 0, 2, 4, 8, and 12. Data analysis was performed using repeated ANOVA and Bonferroni post-hoctest at statistical significance of 0.05.
Results: Treatment with alginate coating and EW alone could significantly reduce E. coli O₁₅₇: H₇ count on the salmon fillets. However, maximum reduction (1.27 log CFU/g) of bacteria was achieved when using alginate coating combined with EW.
Conclusion: According to the results, the combination of alginate coating with EW can be applied as a natural antimicrobial for increasing safety of food products, especially fish, against pathogenic bacteria such as E. coli O157: H7.

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Background and objectives: Bacteriocins are generally active antimicrobial peptides effective against bacteria closely related to the producer. Escherichia coli produce two bacteriocins: colicins and microcins. Microcin J25 (Mcc J25) is an antibacterial peptide that inhibits bacterial transcription by disrupting the nucleotide-uptake channel of bacterial RNA polymerase. The objective of this study was to evaluate antimicrobial activity of MccJ25 produced by the bacteriocinogenic E. coli.
Methods: In this experimental study, 120 clinical specimens were selected from private diagnostic laboratories in Isfahan (Iran) in 2020. Antagonistic activity of isolates was tested by adopting agar plug method. Total DNA was extracted from clinical specimens and polymerase chain reaction (PCR) was performed using specific primers for amplification of the complete sequence of MccJ25 gene. Accuracy of the PCR products was confirmed by direct sequencing. Homology analysis was performed by using BLAST. Data were analyzed with Chromasv2.1.1 software.
Results: Overall, 120 E. coli strains were isolated from the clinical specimens. The antibiotic activity of Mcc J25 was mainly directed at Enterobacteriaceae, including several pathogenic E. coli strains of which 25 had positive well test samples, and about 5 (20%) of the collected clinical samples that were infected with E. coli had the MccJ25 gene.
Conclusions: Based on the results, Mcc J25 has favorable antibacterial potential, which can be further exploited as an alternative to chemical antibiotics.

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Background: Colistin is the most significant last-line antibiotic for the treatment of multidrug-resistant infections caused by Gram-negative bacteria, especially the Enterobacteriaceae family. The emergence and rapid spread of the plasmid-mediated resistance gene, mcr-1 (mobilized colistin resistance), in some isolates of Escherichia coli in recent years provoked public health concerns since it has been shown that mcr-1 with other resistance genes, such as ESBLs (extended-spectrum beta-lactamases) and carbapenemases, could be carried on a single plasmid concurrently. The excessive consumption of colistin, particularly in the livestock industry, and the transmission of these resistant bacteria from livestock to humans may potentially increase the risk of the spread of resistance in humans. Therefore, this study aimed to detect the prevalence of mcr and carbapenem resistance genes among neonatal calves in Mashhad, Razavi Khorasan Province, Iran.
Methods: In the current study, 200 fecal samples from healthy and diarrheic neonatal calves (≤35 days old) were collected in Mashhad (190 E. coli strains were isolated). Antibiotic susceptibility to ceftazidime, cefepime, cefixime, meropenem, colistin, and ciprofloxacin was examined. The double-disk diffusion method (ceftazidime + ceftazidime/clavulanic acid) was performed on Mueller-Hinton agar (MHA) media to phenotypically distinguish the ESBL producers. Afterward, the Multiplex polymerase chain reaction (PCR) method was used to detect colistin resistance genes (mcr-1, mcr-2, mcr-3, mcr-4, and mcr5), NDM-1 (New Delhi metallo-beta-lactamase 1), and OXA-48 as carbapenemases.
Results: The results of the resistance rate to antibiotics were cefepime, ceftazidime, cefixime, meropenem, and colistin. Based on the findings, 33.7% were phenotypically ESBL producers, 4.21% harbored mcr-1, and no NDM-1 or OXA-48 was detected. Among the mcr-1-positive isolates, 5 strains showed the ESBL phenotype.
Conclusion: The results highlight the need for continued monitoring of antibiotic resistance in livestock and the potential for transmission to humans. The findings also underscore the importance of responsible antibiotic use in both human and animal health to mitigate the spread of antibiotic resistance.

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Background: Urinary tract infection (UTI) is one of the most prevalent bacterial diseases worldwide. Escherichia coli is a well-known etiological agent of UTI. The emergence and spread of metallo-beta-lactamase (MBL)-producing E. coli is a serious threat to public health.
This study aimed to investigate the antibiotic resistance pattern and prevalence of MBL-producing E. coli isolated from UTI.
Methods: From January 2020 to June 2021, 1200 urine specimens were collected from patients suspected of having UTI. Antibiotic susceptibility testing was carried out by the disk diffusion method. The prevalence of MBL (blaVIM, blaIMP, blaSPM, and blaNDM) genes was determined by the polymerase chain reaction (PCR) method.
Results: The highest susceptibility was observed against amikacin (96%) and gentamicin (95%). The isolates were mostly resistant against ampicillin (72%) and cephalothin (60%). All carbapenem-resistant isolates were MBL-positive. Based on the results of PCR, 75% of the isolates were blaNDM-positive.
Conclusion: Resistance to some antibiotics, such as ampicillin and cephalothin, was high, and their prescription must be restricted. The prevalence of MBL-producing isolates was not high; however, due to the high level of resistance against other antibiotics, continuous monitoring of MBL-producing isolates is highly essential.

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Background: Urinary tract infection (UTI) is one of the most common bacterial infections of all ages and sexes. Escherichia coli is reported as the most common predominant pathogen. Urinary tract infection treatment leads to abundant antibiotic application in hospitals and communities, continuously developing multidrug resistance (MDR). This study aimed to determine the sensitivity and resistance pattern to common antibiotics among E. coli isolates from patients with UTIs at Nemazee Hospital in Shiraz.
Methods: This retrospective cross-sectional survey studied 1910 positive urine samples with E. coli bacteria from patients referred to Nemazee Hospital from 2018 to 2019. Antimicrobial susceptibility testing was performed on 12 commonly used antibiotics for UTIs.
Results: A total of 1910 E. coli isolates were gathered during these 2 years. The most highlighted resistance was observed against quinolones and cephalosporins at 86.9% and 89.7%, respectively. Cephalexin (87.9%) and nalidixic acid (86.1%) have shown the lowest activity against E. coli isolates. Also, the highest susceptibility was determined for amikacin (88.3%), nitrofurantoin (76.8%), and gentamicin (70.6%). In addition, 1624 (85%) isolates were MDR.
Conclusion: In conclusion, resistance to antibiotics (such as ciprofloxacin, norfloxacin, tetracycline, cefotaxime, and nitrofurantoin) is increasing. Therefore, it is vital to follow an appropriate antimicrobial stewardship program.
 

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Background: Escherichia coli consists of a wide range of strains with huge diversity in their genome, distributed in nature and the alimentary tracts of animals and humans. This study analyzed the phylogenetic group determination and genetic diversity of E. coli strains isolated from domestic animals and human clinical samples.
Methods: Twenty E. coli isolates from domestic animals were analyzed for phylogenetic grouping. Also, 100 clinical samples and 20 animal samples were evaluated by the enterobacterial repetitive intergenic consensus–polymerase chain reaction (ERIC-PCR) technique. The results and the similarity between the strains were determined based on the Dice similarity coefficient in the SAHN program of the NTSYS-pc software.
Results: The frequency of phylogroups among animal samples were A = 5%, B1 = 65%, B2 = 20%, and D = 10%. Based on the ERIC-PCR results, the clinical strains were allocated into 19 clusters. Most strains were in the E7 cluster. Fifty percent of the E. coli isolated from animal specimens belonged to the E4 group, and the lowest number of strains was in the E3 and E5 (1 strain) groups.
Conclusion: The results confirmed the efficiency and usefulness of the ERIC-PCR tool for the identification and classification of bacteria. Also, we demonstrated the most phylogroup among animal samples.
 

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