Natural populations of Escherichia coli and Salmonella typhimurium harbor the same classes of insertion sequences.

Abstract Despite their close phylogenetic relationship, Escherichia coli and Salmonella typhimurium were long considered as having distinct classes of transposable elements maintained by either host-related factors or very restricted gene exchange. In this study, genetically diverse collections of E. coli and S. typhimurium (subgroup I) were surveyed for the presence of several classes of insertion sequences by Southern blot analysis and the polymerase chain reaction. A majority of salmonellae contained IS1 or IS3, elements originally recovered from E. coli, while IS200, a Salmonella-specific element, was present in about 20% of the tested strains of E. coli. Based on restriction mapping, the extent of sequence divergence between copies of IS200 from E. coli and S. typhimurium is on the order of that observed in comparisons of chromosomally encoded genes from these taxa. This suggests that copies of IS200 have not been recently transferred between E. coli and S. typhimurium and that the element was present in the common ancestor to both species. IS200 is polymorphic within E. coli but homogeneous among isolates of S. typhimurium, providing evidence that these species might differ in their rates of transfer and turnover of insertion sequences.

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Structure of recombinants from conjugational crosses between Escherichia coli donor and mismatch-repair deficient Salmonella typhimurium recipients.

Genetics ◽

10.1093/genetics/136.1.17 ◽

1994 ◽

Vol 136 (1) ◽

pp. 17-26

Author(s):

I Matic ◽

M Radman ◽

C Rayssiguier

Keyword(s):

Escherichia Coli ◽

Salmonella Typhimurium ◽

Mismatch Repair ◽

Genomic Dna ◽

Sequence Divergence ◽

Physical Analysis ◽

Repair System ◽

Donor Genome ◽

E Coli ◽

Recombination Pathway

Abstract To get more insight into the control of homologous recombination between diverged DNA by the Mut proteins of the long-patch mismatch repair system, we have studied interspecies Escherichia coli/Salmonella typhimurium recombination. Knowing that the same recombination pathway (RecABCD) is responsible for intraspecies and interspecies recombination, we have now studied the structure (replacement vs. addition-type or other rearrangement-type recombinants) of 81 interspecies recombinants obtained in conjugational crosses between E. coli donor and mutL, mutS, mutH, mutU or mut+ S. typhimurium recipients. Taking advantage of high interspecies sequence divergence, a physical analysis was performed on one third of the E. coli Hfr genome, which was expected to be transferred to S. typhimurium F- recipients during 40 min before interruption of the mating. Probes specific for each species were hybridized on dot blots of genomic DNA, or on colonies, and the composition of the rrn operons was determined from purified genomic DNA. With very few exceptions, the structure of these interspecies recombinants corresponds to replacements of one continuous block of the recipient genome by the corresponding region of the donor genome.

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Niche and local geography shape the pangenome of wastewater- and livestock-associated Enterobacteriaceae

10.1101/2020.07.23.215756 ◽

2020 ◽

Author(s):

Liam P. Shaw ◽

Kevin K. Chau ◽

James Kavanagh ◽

Manal AbuOun ◽

Emma Stubberfield ◽

...

Keyword(s):

Escherichia Coli ◽

Selective Pressure ◽

Natural Populations ◽

Insertion Sequences ◽

E Coli ◽

The United Kingdom ◽

Diverse Species ◽

Complete Genomes ◽

Show Evidence

Escherichia coli and other Enterobacteriaceae are highly diverse species with ‘open’ pangenomes1,2, where genes move intra- and inter-species via horizontal gene transfer3. These species can cause clinical infections4,5 as well as persist environmentally6,7. Environmental populations have been suggested as important reservoirs of antimicrobial resistance (AMR) genes. However, as most analyses focus on clinical isolates8,9, the pangenome dynamics of natural populations remain understudied, particularly the role of plasmids. Here, we reconstructed near-complete genomes for 828 Enterobacteriaceae, including 553 Escherichia spp. and 275 non-Escherichia species with 2,293 circularised plasmids in total, collected from nineteen locations (livestock farms and wastewater treatment works in the United Kingdom) within a 30km radius at three timepoints over the course of a year. We find different dynamics for the chromosomal and plasmid-borne components of the pangenome, showing that plasmids have a higher burden of both AMR genes and insertion sequences, and AMR plasmids show evidence of being under stronger selective pressure. Focusing on E. coli, we observe that plasmid dynamics are more strongly dominated by niche and local geography, rather than phylogeny or season. Our results highlight the diversity of the AMR reservoir in these species and niches, and the importance of local strategies for controlling the emergence and spread of AMR.

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High prevalence of qnrA and qnrB genes among fluoroquinolone-resistant Escherichia coli isolates from a tertiary hospital in Southern Nigeria

Bulletin of the National Research Centre ◽

10.1186/s42269-020-00475-w ◽

2021 ◽

Vol 45 (1) ◽

Author(s):

Chibuzor M. Nsofor ◽

Mirabeau Y. Tattfeng ◽

Chijioke A. Nsofor

Keyword(s):

Escherichia Coli ◽

Susceptibility Testing ◽

Tertiary Hospital ◽

Vaginal Swab ◽

Fluoroquinolone Resistance ◽

E Coli ◽

Diffusion Technique ◽

High Prevalence ◽

Polymerase Chain ◽

And Control

Abstract Background This study was aimed to determine the prevalence of qnr genes among fluoroquinolone-resistant Escherichia coli (FREC) isolates from Nigeria. Antimicrobial susceptibility testing was performed by disc diffusion technique. Polymerase chain reaction was used to identify Escherichia coli (E. coli) and for the detection of qnr genes. Results A total of 206 non-duplicate E. coli were isolated from 300 clinical specimens analyzed. In all, 30 (14.6%) of these isolates were FREC; the resistance to fluoroquinolones among these 30 FREC showed 80% (24), 86.7% (26), 86.7% (26), 100% (30), 86.7% (26), 93.3% (28) and 86.7% (26) were resistant to pefloxacin, ciprofloxacin, sparfloxacin, levofloxacin, nalidixic acid, ofloxacin and moxifloxacin, respectively. The distribution of FREC among the various sample sources analyzed showed that 14%, 10%, 13.3%, 16.7% and 20% of the isolates came from urine, stool, high vaginal swab, endo cervical swab and wound swab specimens, respectively. More FREC were isolated from female samples 73.3% (22) compared to male samples 26.7% (8) and were more prevalent among the age group 26–35 years (40%). Twenty eight out of the 30 (93.3%) FREC isolates possessed at least one fluoroquinolone resistance gene in the form of qnrA 10 (33.3%) and qnrB 18 (60%), respectively; qnrS was not detected among the FREC isolates analyzed and 13.5% of the isolates possessed both the qnrA and qnrB genes. Phylogenetic analysis showed that these isolates were genetically diverse. Conclusions These findings suggest a possible resistance to fluoroquinolone is of high interest for better management of patients and control of antimicrobial resistance in Nigeria.

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ATIVIDADE ANTIMICROBIANA DE MICRORGANISMOS ISOLADOS DE GRÃOS DE KEFIR

Ciência Animal Brasileira ◽

10.1590/1809-6891v19e-40548 ◽

2018 ◽

Vol 19 (0) ◽

Author(s):

Priscila Alves Dias ◽

Daiani Teixeira Silva ◽

Cláudio Dias Timm

Keyword(s):

Escherichia Coli ◽

Staphylococcus Aureus ◽

Listeria Monocytogenes ◽

Salmonella Typhimurium ◽

Salmonella Enterica ◽

Escherichia Coli O157 ◽

E Coli

Resumo Kefir é o produto da fermentação do leite pelos grãos de kefir. Esses grãos contêm uma mistura simbiótica de bactérias e leveduras imersas em uma matriz composta de polissacarídeos e proteínas. Muitos benefícios à saúde humana têm sido atribuídos ao kefir, incluindo atividade antimicrobiana contra bactérias Gram positivas e Gram negativas. A atividade antimicrobiana de 60 microrganismos isolados de grãos de kefir, frente à Escherichia coli O157:H7, Salmonella enterica subsp. enterica sorotipos Typhimurium e Enteritidis, Staphylococcus aureus e Listeria monocytogenes, foi estudada através do teste do antagonismo. A ação antimicrobiana dos sobrenadantes das bactérias ácido-lácticas que apresentaram atividade no teste do antagonismo foi testada. O experimento foi repetido usando sobrenadantes com pH neutralizado. Salmonella Typhimurium e Enteritidis sobreviveram por 24 horas no kefir em fermentação. E. coli O157:H7, S. aureus e L. monocytogenes foram recuperados até 72 horas após o início da fermentação. Todos os isolados apresentaram atividade antimicrobiana contra pelo menos um dos patógenos usados no teste do antagonismo. Sobrenadantes de 25 isolados apresentaram atividade inibitória e três mantiveram essa atividade com pH neutralizado. As bactérias patogênicas estudadas sobreviveram por tempo superior àquele normalmente utilizado para a fermentação do kefir artesanal, o que caracteriza perigo em potencial para o consumidor quando a matéria-prima não apresentar segurança sanitária. Lactobacillus isolados de grãos de kefir apresentam atividade antimicrobiana contra cepas de E. coli O157:H7, Salmonella sorotipos Typhimurium e Enteritidis, S. aureus e L. monocytogenes além daquela exercida pela diminuição do pH.

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On-column Refolding of an Insoluble His6-tagged Recombinant EC-SOD Overexpressed in Escherichia coli

Acta Biochimica et Biophysica Sinica ◽

10.1111/j.1745-7270.2005.00035.x ◽

2005 ◽

Vol 37 (4) ◽

pp. 265-269 ◽

Cited By ~ 11

Author(s):

Xi-Qiang Zhu ◽

Su-Xia Li ◽

Hua-Jun He ◽

Qin-Sheng Yuan

Keyword(s):

Escherichia Coli ◽

Inclusion Bodies ◽

Mass Ratio ◽

Chain Reaction ◽

Expression Plasmid ◽

Protein Subunits ◽

E Coli ◽

Metal Affinity ◽

Polymerase Chain ◽

Escherichia Coli Expression

Abstract The EC-SOD cDNA was cloned by polymerase chain reaction (PCR) and inserted into the Escherichia coli expression plasmid pET-28a(+) and transformed into E. coli BL21(DE3). The corresponding protein that was overexpressed as a recombinant His6-tagged EC-SOD was present in the form of inactive inclusion bodies. This structure was first solubilized under denaturant conditions (8.0 M urea). Then, after a capture step using immobilized metal affinity chromatography (IMAC), a gradual refolding of the protein was performed on-column using a linear urea gradient from 8.0 M to 1.5 M in the presence of glutathione (GSH) and oxidized glutathione (GSSG). The mass ratio of GSH to GSSG was 4:1. The purified enzyme was active, showing that at least part of the protein was properly refolded. The protein was made concentrated by ultrafiltration, and then isolated using Sephacryl S-200 HR. There were two protein peaks in the A280 profile. Based on the results of electrophoresis, we concluded that the two fractions were formed by protein subunits of the same mass, and in the fraction where the molecular weight was higher, the dimer was formed through the disulfide bond between subunits. Activities were detected in the two fractions, but the activity of the dimer was much higher than that of the single monomer. The special activities of the two fractions were found to be 3475 U/mg protein and 510 U/mg protein, respectively.

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Antimicrobial Effects of Novel H2O2-Ag+ Complex on Membrane Damage to Staphylococcus aureus,Escherichia coli and Salmonella typhimurium

Journal of Food Protection ◽

10.4315/jfp-21-087 ◽

2021 ◽

Author(s):

Bing Han ◽

Xiaoyu Han ◽

Mengmeng Ren ◽

Yilin You ◽

Jicheng Zhan ◽

...

Keyword(s):

Escherichia Coli ◽

Hydrogen Peroxide ◽

Staphylococcus Aureus ◽

Salmonella Typhimurium ◽

Membrane Damage ◽

Bactericidal Effect ◽

E Coli ◽

Bacterial Cell Membrane ◽

Time Kill ◽

Environmental Disinfection

Diseases caused by harmful microorganisms pose a serious threat to human health. Safe and environment-friendly disinfectants are, therefore, essential in preventing and controlling such pathogens. This study aimed to investigate the antimicrobial activity and mechanism of a novel hydrogen peroxide and silver (H 2 O 2 -Ag + ) complex (HSC) in combatting Staphylococcus aureus ATCC 29213, Escherichia coli O157:H7 NCTC 12900 and Salmonella typhimurium SL 1344. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values against S. aureus were found to be 0.014 % H 2 O 2 -3.125 mg/L Ag + , while 0.028 % H 2 O 2 -6.25 mg/L Ag + for both E. coli and S. typhimurium . Results of the growth curve assay and time-kill trial suggest that the HSC could inhibit the growth of the tested bacteria, as 99.9 % of viable cells were killed following treatment at the 1 MIC for 3 h. Compared with Oxytech D10 disinfectant (0.25 % H 2 O 2 -5 mg/L Ag + ), the HSC exhibited better antibacterial efficacy at a lower concentration (0.045 % H 2 O 2 -10 mg/L Ag + ). The mechanism of antibacterial action of HSC was found including the disruption of the bacterial cell membrane, followed by entry into the bacteria cell to reduce intracellular adenosine triphosphate (ATP) concentration, and inhibit the activity of antioxidases, superoxide dismutase (SOD) and catalase (CAT). The enhanced bactericidal effect of hydrogen peroxide combined with silver indicates a potential for its application in environmental disinfection, particularly in the food industry.

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In Vitro Inhibition of the Growth of Salmonella typhimurium and Escherichia coli 0157:H7 by Bacteria Isolated from the Cecal Contents of Adult Chickens

Journal of Food Protection ◽

10.4315/0362-028x-54.7.496 ◽

1991 ◽

Vol 54 (7) ◽

pp. 496-501 ◽

Cited By ~ 18

Author(s):

ARTHUR HINTON ◽

GEORGE E. SPATES ◽

DONALD E. CORRIER ◽

MICHAEL E. HUME ◽

JOHN R. DELOACH ◽

...

Keyword(s):

Escherichia Coli ◽

Lactic Acid ◽

Salmonella Typhimurium ◽

Mixed Cultures ◽

Enterococcus Durans ◽

E Coli ◽

Pure Cultures ◽

In Vitro Inhibition ◽

Lactic Acids

A Veillonella species and Enterococcus durans were isolated from the cecal contents of adult broilers. Mixed cultures of Veillonella and E. durans inhibited the growth of Salmonella typhimurium and Escherichia coli 0157:H7 on media containing 2.5% lactose (w/v). The growth of S. typhimurium or E. coli 0157:H7 was not inhibited by mixed cultures containing Veillonella and E. durans on media containing only 0.25% lactose or by pure cultures of Veillonella or E. durans on media containing either 0.25% or 2.5% lactose. The mixed cultures of Veillonella and E. durans produced significantly (P<0.05) more acetic, propionic, and lactic acids in media containing 2.5% lactose than in media containing 0.25% lactose. The inhibition of the enteropathogens was related to the production of lactic acid from lactose by the E. durans and the production of acetic and propionic acids from lactic acid by the Veillonella.

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Occurrence of toxigenic Escherichia coli in raw milk cheese in Brazil

Arquivo Brasileiro de Medicina Veterinária e Zootecnia ◽

10.1590/s0102-09352007000200035 ◽

2007 ◽

Vol 59 (2) ◽

pp. 508-512 ◽

Cited By ~ 27

Author(s):

B.R. Paneto ◽

R.P. Schocken-Iturrino ◽

C. Macedo ◽

E. Santo ◽

J.M. Marin

Keyword(s):

Escherichia Coli ◽

Polymerase Chain Reaction ◽

Antimicrobial Agents ◽

Raw Milk ◽

Diffusion Method ◽

Chain Reaction ◽

Disk Diffusion Method ◽

E Coli ◽

Polymerase Chain ◽

Raw Milk Cheese

The occurrence of toxigenic Escherichia coli in raw milk cheese was surveyed in Middle Western Brazil. Fifty samples of cheese from different supermarkets were analyzed for E.coli. The isolates were serotyped and screened for the presence of verotoxigenic E. coli (VTEC) and enterotoxigenic E. coli (ETEC) by Polymerase Chain Reaction (PCR). The susceptibility to thirteen antimicrobial agents was evaluated by the disk diffusion method. E.coli were recovered from 48 (96.0%) of the samples. The serogroups identified were O125 (6.0%), O111 (4.0%), O55 (2.0%) and O119 (2.0%). Three (6.0%) and 1(2.0%) of the E.coli isolates were VTEC and ETEC, respectively. Most frequent resistance was observed to the following antimicrobials: cephalothin (60.0%), nalidixic acid (40.0%), doxycyclin (33.0%), tetracycline (31.0%) and ampicillin (29.0%).

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Multiplex Polymerase Chain Reaction Assay for Identification of Enterotoxigenic Escherichia Coli Strains

Journal of Veterinary Diagnostic Investigation ◽

10.1177/104063870101300405 ◽

2001 ◽

Vol 13 (4) ◽

pp. 308-311 ◽

Cited By ~ 22

Author(s):

Jacek Osek

Keyword(s):

Escherichia Coli ◽

Polymerase Chain Reaction ◽

Multiplex Polymerase Chain Reaction ◽

Direct Determination ◽

Enteric Bacteria ◽

Enterotoxigenic Escherichia Coli ◽

Chain Reaction ◽

Gram Negative ◽

E Coli ◽

Polymerase Chain

A multiplex polymerase chain reaction (PCR) system was developed for identification of enterotoxigenic Escherichia coli (ETEC) strains and to differentiate them from other gram negative enteric bacteria. This test simultaneously amplifies heat-labile (LTI) and heat-stable (STI and STII) toxin sequences and the E. coli-specific universal stress protein ( uspA). The specificity of the method was validated by single PCR tests performed with the reference E. coli and non- E. coli strains and with bacteria isolated from pig feces. The multiplex PCR allowed the rapid and specific identification of enterotoxin-positive E. coli and may be used as a method for direct determination of ETEC and to differentiate them from other E. coli and gram-negative enteric isolates.

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A PCR-Based Method of Detection and Differentiation of K88+ Adhesive Escherichia Coli

Journal of Veterinary Diagnostic Investigation ◽

10.1177/104063879600800410 ◽

1996 ◽

Vol 8 (4) ◽

pp. 460-463 ◽

Cited By ~ 14

Author(s):

Mark A. Franklin ◽

David H. Francis ◽

Diane Baker ◽

Alan G. Mathew

Keyword(s):

Escherichia Coli ◽

Enzyme Linked Immunosorbent Assay ◽

Antigenic Variant ◽

Variable Regions ◽

E Coli ◽

Clinical Assay ◽

Pcr Product ◽

Structural Subunit ◽

Pcr Products ◽

Polymerase Chain

The objective of this study was to develop a polymerase chain reaction (PCR)-based method to detect and differentiate among Escherichia coli strains containing genes for the expression of 3 antigenic variants of the fimbrial adhesin K88 (K88ab, K88ac, and K88ad). Five primers were designed that allowed detection of K88+ E. coli, regardless of antigenic variant, and the separate detection of the ab, ac, and ad variants. Primers AM005 and AM006 are 21 base pair (bp) oligomers that correspond to a region of the K88 operon that is common to all 3 antigenic variants. Primers MF007, MF008, and MF009 are 24-bp oligomers that matched variable regions specific to ab, ac, and ad, respectively. Using primers AM005 and AM006, a PCR product was obtained that corresponds to a 764-bp region within the large structural subunit of the K88 operon common to all 3 antigenic variants. Primer AM005 used with MF007, MF008, or MF009 produced PCR products approximately 500-bp in length from within the large structural subunit of the K88 operon of the 3 respective antigenic variants. Fragments were identified by rates of migration on a 1% agarose gel relative to each other as well as to BstEII-digested lambda fragments. This PCR-based method was comparable to the enzyme-linked immunosorbent assay and western blot test in the ability to differentiate between the antigenic variants. K88+ E. coli were differentiated from among laboratory strains and detected in ileal samples taken from cannulated pigs challenged with a known K88+ variant. K88+ E. coli were also detected from fecal swabs taken from newly weaned pigs, thus confirming that this PCR-based test could provide a convenient clinical assay for the detection of K88+ E. coli. Detection and differentiation of K88+ E. coli using general and specific primers was successful. PCR methods of detection should permit identification of K88+ antigenic variants regardless of the level of expression of the antigen.

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