Showing 29 results for Escherichia Coli
Kargar, M, Kargar, M, Zareian Jahromi, M,
Volume 9, Issue 3 (9-2015)
Abstract
Abstract
Background and Objective: Escherichia coli O157:H7 is one of the most well-known pathogenic bacteria worldwide that can develop severe diseases such as hemolytic uremic syndrome (HUS). This study aimed to assess the prevalence of virulence genes of E. coli O157:H7 in patients with suspected urinary tract infections (UTIs).
Material and Methods: This cross-sectional study was conducted on 10,372 urine samples collected from patients with suspected UTI from six hospitals and clinical laboratories in Shiraz city. CT-SMAC medium, b-glucosidase activity test (MUG), specific antiserum, and the presence of O157 and H7 genes by PCR were used to confirm E. coli O157:H7 isolates. Then, stx1, stx2, eaeA, and hlyA genes were evaluated using multiplex PCR.
Results: In this study, 16 (7.8%) and 13 (6.3%) bacteria had O157 and H7 genes, respectively. Evaluation of virulence genes showed that genes eaeA (15.4%), stx1 and eaeA (15.4%), stx2 (7.7%), and stx2 and eaeA (7.7%) had the highest frequency in E. coli O157:H7.
Conclusion: Due to the severity of pathogenicity, low infectious dose of E. coli O157: H7, and its pathogenic genes, more extensive studies and genotyping of E. coli O157: H7 are required to be conducted in other areas of Iran in order to measure the frequency in UTIs and control the infections caused by E. coli O157: H7.
Keywords: Escherichia coli O157:H7; Urinary Tract Infections; Shiga Toxin 1; Shiga Toxin 2.
Zahra Khozein , Ayatollah Nasrolahi Omran , Aylar Jamali ,
Volume 9, Issue 5 (11-2015)
Abstract
Abstract
Background and Objective: the Formation of urinary infection by uropathogenic E.coli needs numerous virulence factors and biofilm formation is among these factors. Bacteria that form biofilms express phenotype traits that appear according to the bacteria type. Cellulose is an important compound on the outside of E.coli causing bacterial cell-cell reactions and connection to nonliving surfaces. Curli pili cause the reaction between cell-cell and surface-cell in biofilms and lead to bacteria aggregation. Microorganisms’ ability to form biofilm on a surface depends on the surface nature and its conditions. This study aimed at determining the production ability of cellulose polysaccharide and curli pili in UPEC strains, and its correlation with formation and intensity of biofilm.
Methods: In this study carried out to compare the ability of cellulose and pili curli production ability in 40 uropathogenic E.coli isolates ,by morphotype method in Congo Red medium (CR), each isolate was incubated at 37 oC, for 24 hours. After 24 hours, all colonies’ morphology characteristics were studied
Results: It was shown that 67.5% of strains produced cellulose and 72.5% produced curli pili. In addition, 92.6% and 89% of isolates that produce cellulose and curli, respectively, had a moderate to strong biofilm. Moreover, it was shown that there is a significant correlation between cellulose and / or curli pili production with biofilm intensity.
Conclusion: About 70% of E.coli isolates from patients' urine are able to produce cellulose or curli pili; therefore, it can be concluded that the production of these two combinations is effective in amount and intensity of biofilm formation.
Keywords: Escherichia coli; Cellulose Polysaccharide; Curli Pili; Biofilm.
Hesam Alizade , Fatemeh Fallah , Reza Ghanbarpour , Hosein Goudarzi , Hamid Sharifi , Mohammad Reza Aflatoonian ,
Volume 10, Issue 2 (3-2016)
Abstract
ABSTRACT
Background and Objective: One of the main tasks of clinical microbiology laboratories is to determine antibiotic resistance profiles in common pathogens and ensure the selection of effective antibiotics for certain infections. The aim of this study was to compare the methods of disk diffusion, broth microdilution and modified Hodge test in Escherichia coli isolates from urinary tract infection and diarrhea for susceptibility testing against beta-lactam antibiotics in Kerman, Iran.
Methods: In this study, 432 E. coli isolates were collected from diarrhea (216 isolates) and urinary tract infection samples (216 isolates). The antibiotic susceptibility testing methods of disk diffusion, broth microdilution and modified Hodge test were performed according to the Clinical and Laboratory Standards Institute guidelines.
Results: The findings of disk diffusion method showed that resistance to cefotaxime, ceftazidime, aztreonam, cefepime and imipenem was 51.15%, 30.55%, 24.30%, 15.27% and 1.85%, respectively. In the disk diffusion test, 51.15% of the isolates were resistant to at least one antibiotic, all of which were later evaluated by the broth microdilution method. Moreover, 52.94%, 17.19%, 13.12% and 0.90% of the isolates were resistant to cefotaxime, ceftazidime, cefepime and imipenem, respectively. All of the isolates were evaluated for the production of carbapenemase enzyme by the modified Hodge test and none of the isolates were found as positive.
Conclusion: This study shows that performing carbapenem tests is very challenging, and laboratories are recommended to use secondary and independent antibiotic susceptibility tests such as modified Hodge test to confirm the carbapenem-resistant results.
Mohammad Faezi Ghasemi , Seyede Negin Dibadji,
Volume 10, Issue 5 (9-2016)
Abstract
ABSTRACT
Background and Objective: Extended-spectrum beta-lactamases (ESBL) are widely produced by Escherichia coli strains. The aim of this study was to determine frequency of blaOXA-1 and blaSHV genes in E.coli strains isolated from patients hospitalized in city of Rasht, Iran.
Methods: In this cross-sectional study, 200 samples were collected from patients. The E. coli strains were identified using morphological characteristics and biochemical tests. Antimicrobial susceptibility testing was performed. The prevalence of the blaOXA-1 and blaSHV genes in the E. coli isolated was assessed by PCR method.
Results: Overall, 160 E. coli strains were isolated. Of these, 83 (51.9%) showed ESBL activity while 71 (48.1%) did not. All positive strains were resistant to cephalothin. Moreover, 98.8% of ESBL-producing strains were resistance to amoxicillin, cefotaxime and ceftriaxone. The prevalence of the blaOXA-1 and blaSHV genes in ESBL-producing strains were 45% and 17%, respectively. In addition, 28.9% of the strains had both genes while the genes were absent in 9.6% of the strains.
Conclusion: Prevalence of the blaOXA-1gene is higher than that of the blaSHV gene. The absence of both genes in some isolates indicates the possible role of other genes in the ESBL activity.
Keywords: Prevalence, ESBLs, Escherichia coli, blaOXA-1gene, blaSHV gene.
Mohammad Arjmand , Ezatallah Ghaemi , Ailar Jamalli ,
Volume 11, Issue 1 (1-2017)
Abstract
ABSTRACT
Background and Objectives: Biofilm is a population of bacteria growing on a surface and enclosed in an exopolysaccharides matrix, which increases resistance to antimicrobial agents and immune response. Uropathogenic Escherichia coli (UPEC) are biofilm-forming bacteria and the most common cause of urinary tract infections (UTIs). This study evaluated the effect of different concentrations of glucose, NaCl, blood, serum and urine on biofilm formation and antigen 43 (Ag43) gene expression, as a main gene involved in biofilm formation.
Methods: Among E. coli isolates from patients with UTI, four extended-spectrum beta-lactamase (ESBL) and non-ESBL strains, and a standard UPEC strain were selected. Biofilm formation of the strains in brain heart infusion (BHI) broth with different concentrations of glucose, NaCl, sheep blood, serum and human urine was evaluated using microplate method and crystal violet staining. Ag43 gene expression was investigated using Real-Time polymerase chain reaction, SYBR Green dye, and specific primers.
Results: Presence of glucose at all concentrations reduced biofilm formation. Presence of 1% NaCl, 1% sheep blood, 10% bovine serum, and 5% urine significantly increased biofilm formation. Expression of Ag43 by the strains grown under 1% glucose, 1% NaCl, 1% sheep blood, 10% bovine serum and 5% urine decreased.
Conclusion: All environmental factors other than glucose may increase biofilm formation of E. coli at different concentrations. This is not affected by factors such as isolation from inpatient or outpatients and type of strains (ESBL or non-ESBL). Contrary to our expectations, Ag43 expression is independent of environmental factors and decreases even under the most suitable concentrations.
Keywords: Biofilms, Uropathogenic Escherichia coli, UTI, Antigen 43, Real-Time PCR.
Majid Komijani , Majid Bouzari , Fateh Rahimi ,
Volume 11, Issue 2 (3-2017)
Abstract
ABSTRACT
Background and Objective: Escherichia coli is one of the most common causes of hospital-acquired infections. Extended-spectrum β-lactamase (ESBL)-producing E. coli strains are resistant to third-generation cephalosporins. The three main genes involved in ESBL production are TEM, SHV and CTX-M. Detection of ESBL-producing E. coli is of importance for infection control, reduction of excessive antibiotic use and epidemiological surveillance. This study aimed to detect ESBL-producing E. coli strains isolated from wound infections using phenotypic and molecular methods.
Methods: During 2013- early 2015, 86 strains were collected from three hospitals in Isfahan, Iran. Antibiotic susceptibility testing was done using ceftazidime and ceftazidime + clavulanic acid discs. Polymerase chain reaction was used for the detection of the three resistance genes.
Results: The resistance genes SHV, CTX-M and TEM were detected in 49 isolates (56.9%). In addition, 39 isolates (45%) were ESBL-producing strains. According to the results, 5 (5.8%), 14 (16.2%), 19 (22%) and 11 (12.7%) isolates contained the SHV, CTX-M, TEM and CTX-M + TEM genes, respectively. The frequency of CTX and TEM were significantly higher than that of SHV gene (P <0.05). Most of the isolated bacteria were resistant to cefazolin and sensitive to nitrofurantoin.
Conclusions: There is a difference between the frequency of ESBL-positive isolates reported in the phenotypic and genotypic methods, which could be due to the lower sensitivity of the phenotypic method and impact of environmental factors on the emergence of antibiotic resistance.
Keywords: Antibiotic resistance genes, ESBL, TEM, SHV, CTX-M, Escherichia coli.
Shahram Shahraki Zahedani , Nasrin Sayadzai,
Volume 12, Issue 2 (3-2018)
Abstract
ABSTRACT
Background and Objectives: Diarrheagenic Escherichia coli (DEC) pathotypes are important causes of diarrhea among children in developing countries. The objective of this study was to determine the frequency and antibiotic resistance pattern of DEC pathotypes in children aged less than 10 years.
Methods: This cross-sectional study was done on 300 E. coli strains isolated from diarrheic stool samples of children aged less than 10 years who were admitted to hospitals and central laboratory in Zahedan, between July and October 2016. DEC pathotypes were identified by standard biochemical testing and phenotypic testing using polyvalent antiserums. Antibiotic resistant pattern of these strains was evaluated against 11 different antibiotics by the agar disk diffusion method according to the Clinical and Laboratory Standards Institute guidelines.
Results: Of the 300 E. coli isolates, 89 (29.6%) were found positive for DEC using polyvalent antiserums. In this study, 35 cases (39.3%) reacted with antiserum 1, 21 cases (25.8%) reacted with the antiserum 2, and 31 cases (34.8%) reacted with antiserum 3. The highest rate of resistance was observed against ampicillin (94.8%), tetracycline (87.2%), and co-trimoxazole (70.5%). In addition, the lowest rate of resistance was related to imipenem (1%) and ciprofloxacin (8.9%).
Conclusion: DEC pathotypes are the important causes of diarrhea among children admitted to hospitals of Zahedan. Considering the high rate of antibiotic resistance among these pathotypes in this region, prescription of antibiotics should be based on accurate detection of these strains.
Keywords: Escherichia coli, Child, Antibiotic Resistance.
Mahsa Yazdi, Majid Bouzari, Ezzat Allah Ghaemi,
Volume 12, Issue 5 (9-2018)
Abstract
ABSTRACT
Background and objectives: Urinary tract infections (UTIs) are one of the most common infectious diseases caused by bacteria. The primary etiologic agent of UTIs is Escherichia coli. Uropathogenic E.coli (UPEC) strains have a number of specific virulence factors, which can worsen UTIs. This study was performed to detect fim, pap, sfa and afa genes among E.coli strains isolated from UTIs.
Methods: A total of 100 E. coli isolates from patients with UTI was collected between June and December 2015 from Mosavi and Sayyad Shirazi hospitals in Gorgan, Iran. All bacterial isolates were identified via standard biochemical testing and Gram straining. Presence of the genes was assessed by polymerase chain reaction.
Results: The frequency of the fim, pap, sfa and afa genes was 100%, 79%, 69% and 8%, respectively. All isolates contained at least one virulence gene. Prevalence of multiple adhesion genes was 6% for all genes and 65% for three genes (fim, pap and sfa) together. In addition, the frequency of the fim gene was significantly higher than that of the other genes (P<0.0001).
Conclusion: The results of this study indicate the high prevalence of virulence factors that can enhance pathogenicity of E. coli. Therefore, these factors could be used as diagnostic markers or vaccine targets.
Keywords: Virulence factors, Urinary tract infection, Uropathogenic Escherichia coli.
Mohammad Habibi Juybari , Hamidreza Pordeli , Saeid Mikaeili ,
Volume 13, Issue 3 (5-2019)
Abstract
ABSTRACT
Background and Objectives: Schiff base ligands are prepared via the condensation reaction of 1, 10- dimethyl–phenantroline aldehyde derivative with some nitrogen donor ligands, such as benzene ring that have different functional groups (-OH, -SH, -OCH3,-CH2OH, -Br) in acetonitrile. Recent studies suggest that Schiff bases might have antibacterial activity. Therefore, we aimed to synthesize new Schiff base complexes and evaluate their antibacterial activity against a number of Gram-positive and Gram-negative bacteria.
Methods: Schiff base ligands and their complexes were characterized by mass spectrometry, infrared spectroscopy and nuclear magnetic resonance spectroscopy. The in vitro antibacterial activity of the Schiff base ligands and metal ions against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa was evaluated by determining minimum inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) using the broth dilution method.
Results: All synthesized Schiff bases exhibited favorable antibacterial activity against the tested microorganism, but the antibacterial effect of compounds 3OH and 3SH was more significant than that of other compounds.
Conclusion: Compound 3EOH has favorable antibacterial activity against the tested bacteria.
Keywords: Schiff bases, antibacterial effect, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa.
Hamidreza Ebrahimnezhad, Leila Barzegar, Davoud Esmaeili,
Volume 14, Issue 1 (1-2020)
Abstract
ABSTRACT
Background and Objectives: Probiotics are live microorganisms that function through various mechanisms and affect the alteration of the commensal microbiota against pathogens. Nowadays, given the problems associated with antibiotics use, probiotic strains offer a novel and appropriate alternative for the treatment of diseases such as diarrhea. The aim of this study was to investigate the antibacterial synergism of Lactobacillus spp., Bifidobacterium spp. and Escherichia coli strain Nissle 1917 (ECN) on the clinical sample of diarrheagenic E.coli and Campylobacter jejuni.
Methods: A paper disk-diffusion technique was used to evaluate the antibacterial activity. Sterile 6 mm paper disks were saturated with probiotic suspensions made by settling probiotic medications into distilled water. Three kinds of disk were prepared. One disk was prepared for Lactobacillus spp. and Bifidobacterium spp., another for ECN, and the third was made by combined probiotics. Clinical samples of diarrheagenic E.coli and Campylobacter jejuni were cultivated on Muller Hinton agars, and disks were placed on the inoculated Muller Hinton agars. All plates were incubated under microaerophilic and appropriate conditions.
Results: The zone of inhibition (ZOI) of the bacterial growth was measured. All pathogenic microorganisms showed sensitivity to the probiotic disks. The combined disks had better effects against pathogens compared with single disks.
Conclusion: A considerable synergistic effect was observed in the results of combined probiotics; therefore, combined strains can be more efficient against intestinal pathogens in comparison with single probiotics.
Keywords: Probiotic, Lactobacillus, Bifidobacterium, Escherichia coli Nissle, Diarrhea, Campylobacter jejun.i.
Ezzat Allah Ghaemi, Fahimeh Azadi, Naeme Javid, Hanieh Bagheri,
Volume 14, Issue 4 (7-2020)
Abstract
Background and objectives: Drug resistance in Staphylococcus aureus and Escherichia coli, as severe pathogenic bacteria, has become a health challenge. However, nanoparticles have been introduced as effective candidates for their eradication. In this study, we investigated presence of genes involved in conferring resistance to silver nanoparticles in S. aureus and E. coli isolates and evaluated its association with minimal inhibitory concentration (MIC) of the nanoparticles against these isolates.
Methods: The MIC of silver nanoparticles against 121 clinical isolates of E. coli and 183 S. aureus isolates was assessed by broth microdilution assay. Presence and expression of the silver resistance genes (silE, silR/S) in the isolates were investigated by PCR and real-time PCR, respectively.
Results: The silE gene was found in three (1.6%) S. aureus and four (3%) E. coli isolates. MIC of silver nanoparticles against S. aureus isolates with the silE gene was 1, 2 and 8 µg/ml. Moreover, the MIC of the nanoparticles against silE-positive E. coli isolates was 16 μg/ml in three cases and 8 μg/ml in one case. None of the S. aureus isolates contained the silR/S gene, but presence of both silE and silR/S was confirmed in two E. coli isolates. Real-time PCR showed no sil expression in the isolates containing the resistance genes.
Conclusion: The frequency of the silver resistance genes among S. aureus and E. coli isolates is very low. There is no relationship between presence of the resistance genes and the MIC value of silver nanoparticles.
Mojtaba Mohammadzadeh Vazifeh , Seyed Masoud Hosseini, Ali Mohammadi, Mahdi Jahanfar , Hadi Maleki ,
Volume 15, Issue 2 (3-2021)
Abstract
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.
Romina Saei Hamedani , Saeid Khanzadi, Mohammad Hashemi, Mohammad Azizzadeh,
Volume 16, Issue 1 (1-2022)
Abstract
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.
Saman Shalibeik, Fereshte Ghandehari, Ali-Mohammad Ahadi, Ali-Asghar Rastegari, Mojgan Ghiasian,
Volume 16, Issue 3 (5-2022)
Abstract
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.
Arvin Shajeie, Mehrnaz Rad, Mahdi Askari, Kamran Sharifi, Gholamreza Hashemi Tabar,
Volume 17, Issue 5 (9-2023)
Abstract
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.
Fatemeh Rashedi, Zahra Yazdanpour, Farzad Khademi, Hamid Vaez,
Volume 17, Issue 6 (11-2023)
Abstract
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.
Abolfazl Shirdel Abdolmaleki, Abolfazl Rafati Zomorodi, Mohammad Motamedifar, Yalda Malekzadegan,
Volume 18, Issue 1 (1-2024)
Abstract
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.
Aliehsan Karshenas, Ramak Yahya Raiat, Taghi Zahraiee Salehi, Babak Asghari, Maryam Adabi,
Volume 18, Issue 2 (3-2024)
Abstract
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.
Kirandeep Kaur,
Volume 18, Issue 3 (5-2024)
Abstract
Escherichia coli is a Gram-negative, rod-shaped bacterium, responsible for 90% of all community-acquired infections and 50% of hospital-acquired infections, with opportunistic infections found in intensive care unit (ICU) patients. The β-lactam antibiotics, which inhibit cell wall synthesis, are known for their high efficacy and broad-spectrum activity. They also have low toxicity and provide long-term effects, making them widely used drugs against Gram-negative bacteria. Bacteria develop resistance to β-lactams primarily through the expression of hydrolytic enzymes, called β-lactamases, which are divided into serine β-lactamases (Classes A, C, and D) and metallo-β-lactamases (Class B), based on their molecular mechanism. This study aimed to clarify the mechanism of action of β-lactams against Gram-negative bacilli and to emphasize the multidrug resistance of cephalosporins and carbapenems to E. coli.
Zahra Askari, Zeynab Mirzapour, Tooba Shafighi, Reyhaneh Ghorbanpour,
Volume 19, Issue 1 (1-2025)
Abstract
Background: Urinary tract infections (UTIs) caused by uropathogenic Escherichia coli (UPEC) represent a significant global health concern. Virulence factors (VFs) expressed by UPEC strains play a crucial role in promoting bacterial pathogenicity within the urinary tract. Effective treatment of these infections is frequently complicated by the high prevalence of antimicrobial resistance exhibited by Escherichia coli. The objective of this study was to investigate the VFs and antibiotic susceptibility profiles of UPEC strains isolated in the northern region of Iran.
Methods: One hundred and five urine specimens were collected from female patients diagnosed with UTIs in Rasht, located in the north of Iran. These samples underwent culturing on both Eosin Methylene Blue (EMB) agar and MacConkey agar. Following a 24-hour incubation period at 37°C, pure bacterial isolates were identified through Gram staining and a battery of standard biochemical assays. The prevalence of six VF genes - papC, sfa/foc, fimH, afa, ibeA, and neuC - within UPEC strains was determined utilizing polymerase chain reaction (PCR) and subsequently confirmed via direct sequencing. Antibiotic susceptibility testing (AST) was conducted using the disk diffusion method, adhering to the guidelines established by the Clinical and Laboratory Standards Institute (CLSI M02).
Results: The study identified 65.71% of the isolates as Escherichia coli. Among the virulence genes examined, fimH exhibited the highest prevalence (100%), while afa was the least frequent (1.44%). Antibiotic resistance analysis revealed the highest rate against Cefazolin (66.66%) and the lowest against Gentamicin (24.63%). Notably, the prevalence of multi-drug resistance (MDR) was determined to be 73.91%.
Conclusion: This study underscored the significance of localized surveillance of UPEC isolates. This emphasis stems from the pathogen's considerable capacity for genetic mutation, coupled with the influence of environmental variables and individual patient characteristics. Understanding these dynamic factors at a local level is crucial for formulating the most effective strategies to combat UTIs.
