Displaying publications 1 - 20 of 58 in total

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  1. Fulltext Titanium Dioxide Nanoparticle-Based Interdigitated Electrodes: A Novel Current to Voltage DNA Biosensor Recognizes E. coli O157:H7
    Nadzirah Sh, Azizah N, Hashim U, Gopinath SC, Kashif M
    PLoS One, 2015;10(10):e0139766.
    PMID: 26445455 DOI: 10.1371/journal.pone.0139766
    Nanoparticle-mediated bio-sensing promoted the development of novel sensors in the front of medical diagnosis. In the present study, we have generated and examined the potential of titanium dioxide (TiO2) crystalline nanoparticles with aluminium interdigitated electrode biosensor to specifically detect single-stranded E.coli O157:H7 DNA. The performance of this novel DNA biosensor was measured the electrical current response using a picoammeter. The sensor surface was chemically functionalized with (3-aminopropyl) triethoxysilane (APTES) to provide contact between the organic and inorganic surfaces of a single-stranded DNA probe and TiO2 nanoparticles while maintaining the sensing system's physical characteristics. The complement of the target DNA of E. coli O157:H7 to the carboxylate-probe DNA could be translated into electrical signals and confirmed by the increased conductivity in the current-to-voltage curves. The specificity experiments indicate that the biosensor can discriminate between the complementary sequences from the base-mismatched and the non-complementary sequences. After duplex formation, the complementary target sequence can be quantified over a wide range with a detection limit of 1.0 x 10(-13)M. With target DNA from the lysed E. coli O157:H7, we could attain similar sensitivity. Stability of DNA immobilized surface was calculated with the relative standard deviation (4.6%), displayed the retaining with 99% of its original response current until 6 months. This high-performance interdigitated DNA biosensor with high sensitivity, stability and non-fouling on a novel sensing platform is suitable for a wide range of biomolecular interactive analyses.
    Matched MeSH terms: Escherichia coli Infections/microbiology
  2. The influence of antibiotic resistance gene carriage on biofilm formation by two Escherichia coli strains associated with urinary tract infections
    Teh AH, Wang Y, Dykes GA
    Can J Microbiol, 2014 Feb;60(2):105-11.
    PMID: 24498987 DOI: 10.1139/cjm-2013-0633
    Urinary tract infections (UTI) caused by uropathogenic Escherichia coli are one of the most common forms of human disease. In this study, the effect of the presence of newly acquired antibiotic resistance genes on biofilm formation of UTI-associated E. coli strains was examined. Two clinical UTI-associated E. coli strains (SMC18 and SMC20) carrying different combinations of virulence genes were transformed with pGEM-T, pGEM-T::KmΔAmp, or pGEM-T::Km to construct ampicillin-resistant (Km(S)Amp(R)), kanamycin-resistant (Km(R)Amp(S)), or ampicillin- and kanamycin-resistant (Km(R)Amp(R)) strains. Transformed and wild-type strains were characterized for biofilm formation, bacterial surface hydrophobicity, auto-aggregation, morphology, and attachment to abiotic surfaces. Transformation with a plasmid carrying an ampicillin resistance gene alone decreased (p < 0.05) biofilm formation by SMC18 (8 virulence marker genes) but increased (p < 0.05) biofilm formation by SMC20 (5 virulence marker genes). On the other hand, transformation with a plasmid carrying a kanamycin resistance gene alone or both ampicillin and kanamycin resistance genes resulted in a decrease (p < 0.05) in biofilm formation by SMC18 but did not affect (p > 0.05) the biofilm formation by SMC20. Our results suggest that transformation of UTI-associated E. coli with plasmids carrying different antibiotic resistance gene(s) had a significant impact on biofilm formation and that these effects were both strain dependent and varied between different antibiotics.
    Matched MeSH terms: Escherichia coli Infections/microbiology
  3. Fulltext The higher prevalence of extended spectrum beta-lactamases among Escherichia coli ST131 in Southeast Asia is driven by expansion of a single, locally prevalent subclone
    Chen SL, Ding Y, Apisarnthanarak A, Kalimuddin S, Archuleta S, Omar SFS, et al.
    Sci Rep, 2019 09 13;9(1):13245.
    PMID: 31519972 DOI: 10.1038/s41598-019-49467-5
    The ST131 multilocus sequence type (MLST) of Escherichia coli is a globally successful pathogen whose dissemination is increasing rates of antibiotic resistance. Numerous global surveys have demonstrated the pervasiveness of this clone; in some regions ST131 accounts for up to 30% of all E. coli isolates. However, many regions are underrepresented in these published surveys, including Africa, South America, and Asia. We collected consecutive bloodstream E. coli isolates from three countries in Southeast Asia; ST131 was the most common MLST type. As in other studies, the C2/H30Rx clade accounted for the majority of ST131 strains. Clinical risk factors were similar to other reported studies. However, we found that nearly all of the C2 strains in this study were closely related, forming what we denote the SEA-C2 clone. The SEA-C2 clone is enriched for strains from Asia, particularly Southeast Asia and Singapore. The SEA-C2 clone accounts for all of the excess resistance and virulence of ST131 relative to non-ST131 E. coli. The SEA-C2 strains appear to be locally circulating and dominant in Southeast Asia, despite the intuition that high international connectivity and travel would enable frequent opportunities for other strains to establish themselves.
    Matched MeSH terms: Escherichia coli Infections/drug therapy; Escherichia coli Infections/genetics; Escherichia coli Infections/microbiology; Escherichia coli Infections/epidemiology*
  4. Fulltext The complete genome sequence of Escherichia coli EC958: a high quality reference sequence for the globally disseminated multidrug resistant E. coli O25b:H4-ST131 clone
    Forde BM, Ben Zakour NL, Stanton-Cook M, Phan MD, Totsika M, Peters KM, et al.
    PLoS One, 2014;9(8):e104400.
    PMID: 25126841 DOI: 10.1371/journal.pone.0104400
    Escherichia coli ST131 is now recognised as a leading contributor to urinary tract and bloodstream infections in both community and clinical settings. Here we present the complete, annotated genome of E. coli EC958, which was isolated from the urine of a patient presenting with a urinary tract infection in the Northwest region of England and represents the most well characterised ST131 strain. Sequencing was carried out using the Pacific Biosciences platform, which provided sufficient depth and read-length to produce a complete genome without the need for other technologies. The discovery of spurious contigs within the assembly that correspond to site-specific inversions in the tail fibre regions of prophages demonstrates the potential for this technology to reveal dynamic evolutionary mechanisms. E. coli EC958 belongs to the major subgroup of ST131 strains that produce the CTX-M-15 extended spectrum β-lactamase, are fluoroquinolone resistant and encode the fimH30 type 1 fimbrial adhesin. This subgroup includes the Indian strain NA114 and the North American strain JJ1886. A comparison of the genomes of EC958, JJ1886 and NA114 revealed that differences in the arrangement of genomic islands, prophages and other repetitive elements in the NA114 genome are not biologically relevant and are due to misassembly. The availability of a high quality uropathogenic E. coli ST131 genome provides a reference for understanding this multidrug resistant pathogen and will facilitate novel functional, comparative and clinical studies of the E. coli ST131 clonal lineage.
    Matched MeSH terms: Escherichia coli Infections/microbiology
  5. The bacterial causes of diarrhoea in Malaysia
    Jegathesan M, Singh RB, Kanaganayagi M, Soon LE
    Med J Malaysia, 1976 Sep;31(1):46-56.
    PMID: 799233
    Matched MeSH terms: Escherichia coli Infections/complications
  6. Fulltext T4-like coliphage ΦKAZ14 virulent to pathogenic and extended spectrum β-lactamase-producing Escherichia coli of poultry origin
    Ahmad KA, Mohanmmed AS, Abas F, Chin SC
    Virol Sin, 2015 Feb;30(1):73-5.
    PMID: 25662886 DOI: 10.1007/s12250-014-3541-8
    Matched MeSH terms: Escherichia coli Infections/microbiology*
  7. Fulltext Studies on properties of rice straw/polymer nanocomposites based on polycaprolactone and Fe₃O₄ nanoparticles and evaluation of antibacterial activity
    Khandanlou R, Ahmad MB, Shameli K, Saki E, Kalantari K
    Int J Mol Sci, 2014;15(10):18466-83.
    PMID: 25318051 DOI: 10.3390/ijms151018466
    Modified rice straw/Fe3O4/polycaprolactone nanocomposites (ORS/Fe3O4/ PCL-NCs) have been prepared for the first time using a solution casting method. The RS/Fe3O4-NCs were modified with octadecylamine (ODA) as an organic modifier. The prepared NCs were characterized by using X-ray powder diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FT-IR). The XRD results showed that as the intensity of the peaks decreased with the increase of ORS/Fe3O4-NCs content in comparison with PCL peaks, the Fe3O4-NPs peaks increased from 1.0 to 60.0 wt. %. The TEM and SEM results showed a good dispersion of ORS/Fe3O4-NCs in the PCL matrix and the spherical shape of the NPs. The TGA analysis indicated thermal stability of ORS/Fe3O4-NCs increased after incorporation with PCL but the thermal stability of ORS/Fe3O4/PCL-NCs decreased with the increase of ORS/Fe3O4-NCs content. Tensile strength was improved with the addition of 5.0 wt. % of ORS/Fe3O4-NCs. The antibacterial activities of the ORS/Fe3O4/PCL-NC films were examined against Gram-negative bacteria (Escherichia coli) and Gram-positive bacteria (Staphylococcus aureus) by diffusion method using nutrient agar. The results indicated that ORS/Fe3O4/PCL-NC films possessed a strong antibacterial activity with the increase in the percentage of ORS/Fe3O4-NCs in the PCL.
    Matched MeSH terms: Escherichia coli Infections/drug therapy
  8. Fulltext Shiga toxin sub-type 2a increases the efficiency of Escherichia coli O157 transmission between animals and restricts epithelial regeneration in bovine enteroids
    Fitzgerald SF, Beckett AE, Palarea-Albaladejo J, McAteer S, Shaaban S, Morgan J, et al.
    PLoS Pathog, 2019 10;15(10):e1008003.
    PMID: 31581229 DOI: 10.1371/journal.ppat.1008003
    Specific Escherichia coli isolates lysogenised with prophages that express Shiga toxin (Stx) can be a threat to human health, with cattle being an important natural reservoir. In many countries the most severe pathology is associated with enterohaemorrhagic E. coli (EHEC) serogroups that express Stx subtype 2a. In the United Kingdom, phage type (PT) 21/28 O157 strains have emerged as the predominant cause of life-threatening EHEC infections and this phage type commonly encodes both Stx2a and Stx2c toxin types. PT21/28 is also epidemiologically linked to super-shedding (>103 cfu/g of faeces) which is significant for inter-animal transmission and human infection as demonstrated using modelling studies. We demonstrate that Stx2a is the main toxin produced by stx2a+/stx2c+ PT21/28 strains induced with mitomycin C and this is associated with more rapid induction of gene expression from the Stx2a-encoding prophage compared to that from the Stx2c-encoding prophage. Bacterial supernatants containing either Stx2a and/or Stx2c were demonstrated to restrict growth of bovine gastrointestinal organoids with no restriction when toxin production was not induced or prevented by mutation. Isogenic strains that differed in their capacity to produce Stx2a were selected for experimental oral colonisation of calves to assess the significance of Stx2a for both super-shedding and transmission between animals. Restoration of Stx2a expression in a PT21/28 background significantly increased animal-to-animal transmission and the number of sentinel animals that became super-shedders. We propose that while both Stx2a and Stx2c can restrict regeneration of the epithelium, it is the relatively rapid and higher levels of Stx2a induction, compared to Stx2c, that have contributed to the successful emergence of Stx2a+ E. coli isolates in cattle in the last 40 years. We propose a model in which Stx2a enhances E. coli O157 colonisation of in-contact animals by restricting regeneration and turnover of the colonised gastrointestinal epithelium.
    Matched MeSH terms: Escherichia coli Infections/drug therapy; Escherichia coli Infections/microbiology; Escherichia coli Infections/veterinary*
  9. SHV-5 extended-spectrum beta-lactamases in clinical isolates of Escherichia coli in Malaysia
    Subramaniam G, Palasubramaniam S, Navaratnam P
    Indian J Med Microbiol, 2006 Jul;24(3):205-7.
    PMID: 16912441
    Escherichia coli isolates resistant to ceftazidime isolated in the University Malaya Medical Center (UMMC) Kuala Lumpur, Malaysia, between the years 1998 and 2000 were studied for extended-spectrum beta-lactamase (ESBL) production. All strains were analysed phenotypically and genotypically and found to be ESBL-producing organisms harbouring SHV-5 beta-lactamase. This was confirmed by PCR-SSCP and nucleotide sequencing of the blaSHV amplified gene. As there was no evidence of ESBL activity in E. coli prior to this, coupled with the fact that there was a predominance of SHV-5 beta-lactamases in Klebsiella pneumoniae isolates in UMMC, we postulate that the E. coli obtained the SHV-5 beta-lactamase genes by plasmid transfer from the ESBL-producing K. pneumoniae.
    Matched MeSH terms: Escherichia coli Infections/microbiology*
  10. Fulltext Risk factors and spatial distribution of extended spectrum β-lactamase-producing- Escherichia coli at retail poultry meat markets in Malaysia: a cross-sectional study
    Aliyu AB, Saleha AA, Jalila A, Zunita Z
    BMC Public Health, 2016 08 02;16:699.
    PMID: 27484086 DOI: 10.1186/s12889-016-3377-2
    BACKGROUND: The significant role of retail poultry meat as an important exposure pathway for the acquisition and transmission of extended spectrum β-lactamase-producing Escherichia coli (ESBL-EC) into the human population warrants understanding concerning those operational practices associated with dissemination of ESBL-EC in poultry meat retailing. Hence, the objective of this study was to determine the prevalence, spatial distribution and potential risk factors associated with the dissemination of ESBL-EC in poultry meat retail at wet-markets in Selangor, Malaysia.

    METHODS: Poultry meat (breast, wing, thigh, and keel) as well as the contact surfaces of weighing scales and cutting boards were sampled to detect ESBL-EC by using culture and disk combination methods and polymerase chain reaction assays. Besides, questionnaire was used to obtain data and information pertaining to those operational practices that may possibly explain the occurrence of ESBL-EC. The data were analysed using logistic regression analysis at 95 % CI.

    RESULTS: The overall prevalence of ESBL-EC was 48.8 % (95 % CI, 42 - 55 %). Among the risk factors that were explored, type of countertop, sanitation of the stall environment, source of cleaning water, and type of cutting board were found to be significantly associated with the presence of ESBL-EC.

    CONCLUSIONS: Thus, in order to prevent or reduce the presence of ESBL-EC and other contaminants at the retail-outlet, there is a need to design a process control system based on the current prevailing practices in order to reduce cross contamination, as well as to improve food safety and consumer health.

    Matched MeSH terms: Escherichia coli Infections/etiology; Escherichia coli Infections/microbiology*
  11. Resistance to extended-spectrum beta-lactams by the emergence of SHV-12 and the loss of OmpK35 in Klebsiella pneumoniae and Escherichia coli in Malaysia
    Palasubramaniam S, Muniandy S, Navaratnam P
    J Microbiol Immunol Infect, 2009 Apr;42(2):129-33.
    PMID: 19597644
    In addition to beta-lactamase production, loss of porins confers resistance to extended-spectrum beta-lactams in Klebsiella pneumoniae and Escherichia coli infection. This study describes the detection of SHV-12 extended-spectrum beta-lactamase (ESBL) subtype and the loss of OmpK35 porin in 4 strains of K. pneumoniae and E. coli.
    Matched MeSH terms: Escherichia coli Infections/microbiology
  12. Fulltext Prevalence and characterization of verotoxigenic-Escherichia coli isolates from pigs in Malaysia
    Ho WS, Tan LK, Ooi PT, Yeo CC, Thong KL
    BMC Vet Res, 2013;9:109.
    PMID: 23731465 DOI: 10.1186/1746-6148-9-109
    Postweaning diarrhea caused by pathogenic Escherichia coli, in particular verotoxigenic E. coli (VTEC), has caused significant economic losses in the pig farming industry worldwide. However, there is limited information on VTEC in Malaysia. The objective of this study was to characterize pathogenic E. coli isolated from post-weaning piglets and growers with respect to their antibiograms, carriage of extended-spectrum beta-lactamases, pathotypes, production of hemolysins and fimbrial adhesins, serotypes, and genotypes.
    Matched MeSH terms: Escherichia coli Infections/microbiology; Escherichia coli Infections/epidemiology; Escherichia coli Infections/veterinary*
  13. Prevalence and characterization of multidrug-resistant and extended-spectrum beta-lactamase-producing Escherichia coli from pediatric wards of a Malaysian hospital
    Ho WS, Balan G, Puthucheary S, Kong BH, Lim KT, Tan LK, et al.
    Microb Drug Resist, 2012 Aug;18(4):408-16.
    PMID: 22394084 DOI: 10.1089/mdr.2011.0222
    The emergence of Escherichia coli resistant to extended-spectrum cephalosporins (ESCs) is of concern as ESC is often used to treat infections by Gram-negative bacteria. One-hundred and ten E. coli strains isolated in 2009-2010 from children warded in a Malaysian tertiary hospital were analyzed for their antibiograms, carriage of extended-spectrum beta-lactamase (ESBL) and AmpC genes, possible inclusion of the beta-lactamase genes on an integron platform, and their genetic relatedness. All E. coli strains were sensitive to carbapenems. About 46% of strains were multidrug resistant (MDR; i.e., resistant to ≥3 antibiotic classes) and almost half (45%) were nonsusceptible to ESCs. Among the MDR strains, high resistance rates were observed for ampicillin (98%), tetracycline (75%), and trimethoprim/sulfamethoxazole (73%). Out of 110 strains, bla(TEM-1) (49.1%), bla(CTX-M) (11.8%), and bla(CMY-2) (6.4%) were detected. Twenty-one strains were ESBL producers. CTX-M-15 was the predominant CTX-M variant found and this is the first report of a CTX-M-27-producing E. coli strain from Malaysia. Majority (3.1%) of the strains harbored class 1 integron-encoded integrases with a predominance of aadA and dfr genes within the integron variable region. No gene cassette encoding ESBL genes was found and integrons were not significantly associated with ESBL or non-ESBL producers. Possible clonal expansion was observed for few CTX-M-15-positive strains but the O25-ST131 E. coli clone known to harbor CTX-M-15 was not detected while CMY-2-positive strains were genetically diverse.
    Matched MeSH terms: Escherichia coli Infections/drug therapy; Escherichia coli Infections/microbiology*; Escherichia coli Infections/epidemiology
  14. Fulltext Population dynamics of an Escherichia coli ST131 lineage during recurrent urinary tract infection
    Forde BM, Roberts LW, Phan MD, Peters KM, Fleming BA, Russell CW, et al.
    Nat Commun, 2019 08 13;10(1):3643.
    PMID: 31409795 DOI: 10.1038/s41467-019-11571-5
    Recurrent urinary tract infections (rUTIs) are extremely common, with ~ 25% of all women experiencing a recurrence within 1 year of their original infection. Escherichia coli ST131 is a globally dominant multidrug resistant clone associated with high rates of rUTI. Here, we show the dynamics of an ST131 population over a 5-year period from one elderly woman with rUTI since the 1970s. Using whole genome sequencing, we identify an indigenous clonal lineage (P1A) linked to rUTI and persistence in the fecal flora, providing compelling evidence of an intestinal reservoir of rUTI. We also show that the P1A lineage possesses substantial plasmid diversity, resulting in the coexistence of antibiotic resistant and sensitive intestinal isolates despite frequent treatment. Our longitudinal study provides a unique comprehensive genomic analysis of a clonal lineage within a single individual and suggests a population-wide resistance mechanism enabling rapid adaptation to fluctuating antibiotic exposure.
    Matched MeSH terms: Escherichia coli Infections/microbiology*
  15. Fulltext Polymerase chain reaction-restriction fragment length polymorphism method for differentiation of uropathogenic specific protein gene types
    Lai YM, Zaw MT, Shamsudin SB, Lin Z
    J Microbiol Immunol Infect, 2016 Aug;49(4):591-4.
    PMID: 26212311 DOI: 10.1016/j.jmii.2015.06.002
    The putative pathogenicity island (PAI) containing the uropathogenic specific protein (usp) gene and three small open reading frames (orfU1, orfU2, and orfU3) encoding 98, 97, and 96 amino acid proteins is widely distributed among uropathogenic Escherichia coli (UPEC) strains. This PAI was designated as PAIusp. Sequencing analysis of PAIusp has revealed that the usp gene can be divided into two types - uspI and uspII - based on sequence variation at the 3' terminal region and the number and position of orfUs differ from strain to strain. Based on usp gene types and orfU sequential patterns, PAIusp can be divided into four subtypes. Subtyping of PAIusp is a useful method to characterize UPEC strains. In this study, we developed a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method to differentiate usp gene types. This method could correctly identify the usp gene type in usp-positive UPEC strains in our laboratory.
    Matched MeSH terms: Escherichia coli Infections/microbiology
  16. Fulltext Neonatal bartter syndrome
    Wong AC, Chan LG
    Med J Malaysia, 2014 Oct;69(5):229-30.
    PMID: 25638238 MyJurnal
    We report a case of neonatal Bartter syndrome in a 31 weeks premature baby girl with antenatal unexplained polyhydramnios requiring amnioreduction. She presented with early onset E. coli septicaemia and severe dehydration leading to pre-renal renal impairment which obscure the typical biochemical changes of hypokalaemic hypochloraemic metabolic alkalosis.
    Matched MeSH terms: Escherichia coli Infections
  17. Mucosal and systemic responses of immunogenic vaccines candidates against enteric Escherichia coli infections in ruminants: A review
    Lawan A, Jesse FFA, Idris UH, Odhah MN, Arsalan M, Muhammad NA, et al.
    Microb Pathog, 2018 Apr;117:175-183.
    PMID: 29471137 DOI: 10.1016/j.micpath.2018.02.039
    Innumerable Escherichia coli of animal origin are identified, which are of economic significance, likewise, cattle, sheep and goats are the carrier of enterohaemorrhagic E. coli, which are less pathogenic, and can spread to people by way of direct contact and through the contamination of foodstuff or portable drinking water, causing serious illness. The immunization of ruminants has been carried out for ages and is largely acknowledged as the most economical and maintainable process of monitoring E. coli infection in ruminants. Yet, only a limited number of E. coli vaccines are obtainable. Mucosal surfaces are the most important ingress for E. coli and thus mucosal immune responses function as the primary means of fortification. Largely contemporary vaccination processes are done by parenteral administration and merely limited number of E. coli vaccines are inoculated via mucosal itinerary, due to its decreased efficacy. Nevertheless, aiming at maximal mucosal partitions to stimulate defensive immunity at both mucosal compartments and systemic site epitomises a prodigious task. Enormous determinations are involved in order to improve on novel mucosal E. coli vaccines candidate by choosing apposite antigens with potent immunogenicity, manipulating novel mucosal itineraries of inoculation and choosing immune-inducing adjuvants. The target of E. coli mucosal vaccines is to stimulate a comprehensive, effective and defensive immunity by specifically counteracting the antibodies at mucosal linings and by the stimulation of cellular immunity. Furthermore, effective E. coli mucosal vaccine would make vaccination measures stress-free and appropriate for large number of inoculation. On account of contemporary advancement in proteomics, metagenomics, metabolomics and transcriptomics research, a comprehensive appraisal of the immeasurable genes and proteins that were divulged by a bacterium is now in easy reach. Moreover, there exist marvellous prospects in this bourgeoning technologies in comprehending the host bacteria affiliation. Accordingly, the flourishing knowledge could massively guarantee to the progression of immunogenic vaccines against E. coli infections in both humans and animals. This review highlight and expounds on the current prominence of mucosal and systemic immunogenic vaccines for the prevention of E. coli infections in ruminants.
    Matched MeSH terms: Escherichia coli Infections/immunology*; Escherichia coli Infections/microbiology; Escherichia coli Infections/prevention & control*; Escherichia coli Infections/veterinary*
  18. Fulltext Molecular analysis of asymptomatic bacteriuria Escherichia coli strain VR50 reveals adaptation to the urinary tract by gene acquisition
    Beatson SA, Ben Zakour NL, Totsika M, Forde BM, Watts RE, Mabbett AN, et al.
    Infect Immun, 2015 May;83(5):1749-64.
    PMID: 25667270 DOI: 10.1128/IAI.02810-14
    Urinary tract infections (UTIs) are among the most common infectious diseases of humans, with Escherichia coli responsible for >80% of all cases. One extreme of UTI is asymptomatic bacteriuria (ABU), which occurs as an asymptomatic carrier state that resembles commensalism. To understand the evolution and molecular mechanisms that underpin ABU, the genome of the ABU E. coli strain VR50 was sequenced. Analysis of the complete genome indicated that it most resembles E. coli K-12, with the addition of a 94-kb genomic island (GI-VR50-pheV), eight prophages, and multiple plasmids. GI-VR50-pheV has a mosaic structure and contains genes encoding a number of UTI-associated virulence factors, namely, Afa (afimbrial adhesin), two autotransporter proteins (Ag43 and Sat), and aerobactin. We demonstrated that the presence of this island in VR50 confers its ability to colonize the murine bladder, as a VR50 mutant with GI-VR50-pheV deleted was attenuated in a mouse model of UTI in vivo. We established that Afa is the island-encoded factor responsible for this phenotype using two independent deletion (Afa operon and AfaE adhesin) mutants. E. coli VR50afa and VR50afaE displayed significantly decreased ability to adhere to human bladder epithelial cells. In the mouse model of UTI, VR50afa and VR50afaE displayed reduced bladder colonization compared to wild-type VR50, similar to the colonization level of the GI-VR50-pheV mutant. Our study suggests that E. coli VR50 is a commensal-like strain that has acquired fitness factors that facilitate colonization of the human bladder.
    Matched MeSH terms: Escherichia coli Infections/microbiology*
  19. Membrane-lytic actions of sulphonated methyl ester surfactants and implications to bactericidal effect and cytotoxicity
    Pan F, Li Z, Gong H, Petkov JT, Lu JR
    J Colloid Interface Sci, 2018 Dec 01;531:18-27.
    PMID: 30015167 DOI: 10.1016/j.jcis.2018.07.031
    Surfactants are multifunctional molecules widely used in personal care and healthcare formulations to cleanse, help disperse active ingredients (e.g., forming emulsions) and stabilise products. With increasing demands on improving biosafety, there is now mounting pressure to understand how different surfactants elicit toxicities at molecular and cellular levels. This work reports the membrane-lytic behaviour of a group of sulphonated methyl ester (SME) surfactants together with representative conventional surfactants. All surfactants displayed the clear rise of lysis of the model lipid bilayer membranes around their CMCs, but the two ionic surfactants SDS and C12TAB even caused measurable lysis below their CMCs, with membrane-lytic actions increasing with monomer concentration. Furthermore, whilst ionic and nonionic surfactants could achieve full membrane lysis once above their CMCs, this ability was weak from the SME surfactants and decreased with increasing the acyl chain length. In contrast to the conventional anionic surfactants such as SDS and SLES, the protein solubilizing capability of the SME surfactants was also low. On the other hand, MTT assays against 3T3 fibroblast cells and human chondrocyte cells revealed high toxicity from SDS and C12TAB against the other surfactants studied, but the difference between SME and the rest of conventional surfactants was small. Similar behaviour was also observed in their bactericidal effect against E. coli and S. aureus. The trend is broadly consistent with their membrane-lytic behaviour, indicating little selectivity in their cytotoxicity and bactericidal action. These results thus reveal different toxicities implicated from different surfactant head groups. Increase in acyl chain length as observed from SME surfactants could help improve surfactant biocompatibility.
    Matched MeSH terms: Escherichia coli Infections/drug therapy
  20. Fulltext Loop-mediated isothermal amplification assay for detection of generic and verocytotoxin-producing Escherichia coli among indigenous individuals in Malaysia
    Teh CS, Chua KH, Lim YA, Lee SC, Thong KL
    ScientificWorldJournal, 2014;2014:457839.
    PMID: 24967435 DOI: 10.1155/2014/457839
    We have successfully developed a Loop-mediated isothermal amplification (LAMP) assay that could specifically detect generic Escherichia coli (E. coli). This assay was tested on 85 bacterial strains and successfully identified 54 E. coli strains (average threshold time, Tt = 21.26). The sensitivity of this assay was evaluated on serial dilutions of bacterial cultures and spiked faeces. The assay could detect 10(2) CFU/mL for bacterial culture with Tt = 33.30 while the detection limit for spiked faeces was 10(3) CFU/mL (Tt = 31.12). We have also detected 46 generic E. coli from 50 faecal samples obtained from indigenous individuals with 16% of the positive samples being verocytotoxin-producing E. coli (VTEC) positive. VT1/VT2 allele was present in one faecal sample while the ratio of VT1 to VT2 was 6 : 1. Overall, our study had demonstrated high risk of VTEC infection among the indigenous community and most of the asymptomatic infection occurred among those aged below 15 years. The role of asymptomatic human carriers as a source of dissemination should not be underestimated. Large scale screening of the VTEC infection among indigenous populations and the potential contamination sources will be possible and easy with the aid of this newly developed rapid and simple LAMP assay.
    Matched MeSH terms: Escherichia coli Infections/diagnosis; Escherichia coli Infections/microbiology*
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