The Link between Phylogeny and Virulence inEscherichia coli Extraintestinal Infection

ABSTRACT Previous studies suggesting a link between Escherichia coli phylogenetic groups and extraintestinal virulence have been hampered by the difficulty in establishing the intrinsic virulence of a bacterial strain. Indeed, unidentified virulence factors do exist, and the susceptibility of the host to infection is highly variable. To overcome these difficulties, we have developed a mouse model of extraintestinal virulence to test the virulence of the strains under normalized conditions. We then assessed the phylogenetic relationships compared to the E. coli reference (ECOR) collection, the presence of several known virulence determinants, and the lethality to mice of 82 human adult E. coli strains isolated from normal feces and during the course of extraintestinal infections. Commensal strains belong mainly to phylogenetic groups A and B1, are devoid of virulence determinants, and do not kill the mice. Strains exhibiting the same characteristics as the commensal strains can be isolated under pathogenic conditions, thus indicating the role of host-dependent factors, such as susceptibility linked to underlying disease, in the development of infection. Some strains of phylogenetic groups A, B1, and D are able to kill the mice, their virulence being most often correlated with the presence of virulence determinants. Lastly, strains of the B2 phylogenetic group represent a divergent lineage of highly virulent strains which kill the mice at high frequency and possess the highest level of virulence determinants. The observed link between virulence and phylogeny could correspond to the necessity of virulence determinants in a genetic background that is adequate for the emergence of a virulent clone, an expression of the interdependency of pathogenicity and metabolic activities in pathogenic bacteria.

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Extensive Genomic Rearrangements along with Distinct Mobilome and TALome are Associated with Extreme Pathotypes of a Rice Pathogen

Genome Biology and Evolution ◽

10.1093/gbe/evaa025 ◽

2020 ◽

Vol 12 (2) ◽

pp. 3951-3956

Author(s):

Amandeep Kaur ◽

Kanika Bansal ◽

Prabhu B Patil

Keyword(s):

Structural Changes ◽

Genome Structure ◽

Effector Proteins ◽

Virulence Determinants ◽

Transcription Activator ◽

Virulent Strains ◽

Systematic Understanding ◽

Highly Virulent ◽

Highly Evolved

Abstract Xanthomonas oryzae pv. oryzae (Xoo) is a serious pathogen of rice which displays tremendous interstrain variation. The emergence of highly-virulent strains of Xoo is a major threat to rice cultivation. Evolutionary insights into genome dynamics of highly virulent strains as compared with the less-virulent ones are crucial for understanding the molecular basis of exceptional success of Xoo as a highly evolved plant pathogen. In the present study, we report complete genome sequence of Xoo strains with extreme-virulent pathotypes (XVPs) characterized based on their reaction toward ten resistance (Xa) genes. One strain, IXO1088, can overcome resistance mediated by all the ten resistance genes while the other strain IXO704 cannot overcome any of them. Interestingly, our investigation revealed that XVPs display dramatic variation in the genome structure with numerous rearrangements/inversions. Moreover, XVPs also possess distinct transposon content and prophage elements that may provide genomic flux required for the acquisition of novel gene cassettes and structural changes in the genome. Interestingly, analysis of transcription activator-like effector proteins, which are major virulence determinants of Xanthomonas pathogen show marked variation in the transcription activator-like effector content and DNA binding domain of tal genes. Overall, the present study indicates the possible role of mobilomes and repetitive elements in major structural and sequence alterations, which may be leading to the emergence of novel and extreme pathotypes. The knowledge and resource of XVPs will be invaluable in the further systematic understanding of evolution and management of variant pathotypes of Xoo.

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Bioenhancing Effect of Cow Urine Distillate and Pepper Extract on Antibacterial Activity of Azadirachta Indica Leaves

International Journal of Pharmaceutical Sciences and Nanotechnology ◽

10.37285/ijpsn.2016.9.2.8 ◽

1970 ◽

Vol 9 (2) ◽

pp. 3212-3214

Author(s):

Pramod Dhakal ◽

Ankit a Achary ◽

Vedamurthy Joshi

Keyword(s):

Antibacterial Activity ◽

Azadirachta Indica ◽

Pathogenic Bacteria ◽

Ethanol Extract ◽

Watery Diarrhea ◽

Diffusion Method ◽

E Coli ◽

Drug Molecules ◽

Cow Urine

Bioenhancers are drug facilitator which do not show the typical drug activity but in combination to enhance the activity of other molecule in several way including increase the bioavailability of drug across the membrane, potentiating the drug molecules by conformational interaction, acting as receptor for drug molecules and making target cell more receptive to drugs and promote and increase the bioactivity or bioavailability or the uptake of drugs in combination therapy. The objective of the present study was to evaluate the antibacterial and activity of combination in Azadirachta indica extract with cow urine distillate and pepper extract against common pathogenic bacteria, a causative agent of watery diarrhea. It has been found that Indian indigenous cow urine and its distillate also possess bioenhancing ability. Bioenhancing role of cow urine distillate (CUD) and pepper extract was investigated on antibacterial activity of ethanol extract of Azadirachta indica. Antibacterial activity of ethanol extract neem alone and in combination with CUD and pepper extract were determined the ATCC strains against Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa and E-coli by cup plate diffusion method. Ethanol extract of neem has showed more effect on P. aeruginosa, E-coli than S. aureus and K. pneumonia with combination of CUD and pepper extract. CUD and pepper did not show any inhibition of test bacteria in low concentration. The antibacterial effect of combination of extract and CUD was higher than the inhibition caused by extract alone and is suggestive of the bioenhancing role of cow urine distillate and pepper. Moreover, inhibition of test bacteria was observed with less concentration of extract on combining with CUD

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Sero- and apx-typing of German Actinobacillus pleuropneumoniae field isolates from 2010 to 2019 reveals a predominance of serovar 2 with regular apx-profile

Veterinary Research ◽

10.1186/s13567-020-00890-x ◽

2021 ◽

Vol 52 (1) ◽

Author(s):

Lukas Schuwerk ◽

Doris Hoeltig ◽

Karl-Heinz Waldmann ◽

Peter Valentin-Weigand ◽

Judith Rohde

Keyword(s):

Reference Strain ◽

Actinobacillus Pleuropneumoniae ◽

Etiological Agent ◽

Toxin Gene ◽

Gene Profile ◽

Field Isolates ◽

Porcine Pleuropneumonia ◽

Virulent Strains ◽

Highly Virulent

AbstractSerotyping is the most common method to characterize field isolates of Actinobacillus (A.) pleuropneumoniae, the etiological agent of porcine pleuropneumonia. Based on serology, many farms seem to be infected and antibodies against a wide variety of serovars are detectable, but, so far it is unknown to what degree respective serovars contribute to outbreaks of clinical manifest disease. In this study, 213 German A. pleuropneumoniae field isolates retrieved for diagnostic purposes from outbreaks of porcine pleuropneumonia between 2010 and 2019 were genetically serotyped and analyzed regarding their apx-toxin gene profile using molecular methods. Serotyping revealed a prominent role of serovar 2 in clinical cases (64% of all isolates) and an increase in the detection of this serovar since 2010 in German isolates. Serovar 9/11 followed as the second most frequent serovar with about 15% of the isolates. Furthermore, very recently described serovars 16 (n = 2) and 18 (n = 8) were detected. Most isolates (93.4%) showed apx-profiles typical for the respective serovar. However, this does not hold true for isolates of serovar 18, as 75% (n = 6) of all isolates of this serovar deviated uniformly from the “typical” apx-gene profile of the reference strain 7311555. Notably, isolates from systemic lesions such as joints or meninges did not harbor the complete apxICABD operon which is considered typical for highly virulent strains. Furthermore, the extremely low occurrence (n = 1) of NAD independent (biovar II) isolates in German A. pleuropneumoniae was evident in our collection of clinical isolates.

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Phylogenetic Grouping and Virulence Potential of Extended-Spectrum-β-Lactamase-Producing Escherichia coli Strains in Cattle

Applied and Environmental Microbiology ◽

10.1128/aem.00351-12 ◽

2012 ◽

Vol 78 (13) ◽

pp. 4677-4682 ◽

Cited By ~ 38

Author(s):

Charlotte Valat ◽

Frédéric Auvray ◽

Karine Forest ◽

Véronique Métayer ◽

Emilie Gay ◽

...

Keyword(s):

Escherichia Coli ◽

Virulence Determinants ◽

Phylogenetic Groups ◽

Content Type ◽

E Coli ◽

Extended Spectrum ◽

Specific Distribution ◽

Extended Spectrum Beta Lactamases ◽

Phylogenetic Grouping ◽

Almost All

ABSTRACTIn line with recent reports of extended-spectrum beta-lactamases (ESBLs) inEscherichia coliisolates of highly virulent serotypes, such as O104:H4, we investigated the distribution of phylogroups (A, B1, B2, D) and virulence factor (VF)-encoding genes in 204 ESBL-producingE. coliisolates from diarrheic cattle. ESBL genes, VFs, and phylogroups were identified by PCR and a commercial DNA array (Alere, France). ESBL genes belonged mostly to the CTX-M-1 (65.7%) and CTX-M-9 (27.0%) groups, whereas those of the CTX-M-2 and TEM groups were much less represented (3.9% and 3.4%, respectively). One ESBL isolate wasstx1andeaepositive and belonged to a major enterohemorrhagicE. coli(EHEC) serotype (O111:H8). Two other isolates wereeaepositive butstxnegative; one of these had serotype O26:H11. ESBL isolates belonged mainly to phylogroup A (55.4%) and, to lesser extents, to phylogroups D (25.5%) and B1 (15.6%), whereas B2 strains were quasi-absent (1/204). The number of VFs was significantly higher in phylogroup B1 than in phylogroups A (P= 0.04) and D (P= 0.02). Almost all of the VFs detected were found in CTX-M-1 isolates, whereas only 64.3% and 33.3% of them were found in CTX-M-9 and CTX-M-2 isolates, respectively. These results indicated that the widespread dissemination of theblaCTX-Mgenes within theE. colipopulation from cattle still spared the subpopulation of EHEC/Shiga-toxigenicE. coli(STEC) isolates. In contrast to other reports on non-ESBL-producing isolates from domestic animals, B1 was not the main phylogroup identified. However, B1 was found to be the most virulent phylogroup, suggesting host-specific distribution of virulence determinants among phylogenetic groups.

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Detection and Quantification of Superoxide Formed within the Periplasm of Escherichia coli

Journal of Bacteriology ◽

10.1128/jb.00554-06 ◽

2006 ◽

Vol 188 (17) ◽

pp. 6326-6334 ◽

Cited By ~ 111

Author(s):

Sergei Korshunov ◽

James A. Imlay

Keyword(s):

Escherichia Coli ◽

Pathogenic Bacteria ◽

Phagocytic Cells ◽

Free Living ◽

E Coli ◽

Superoxide Formation ◽

Genes Encoding ◽

Copper Zinc ◽

Primary Substrate

ABSTRACT Many gram-negative bacteria harbor a copper/zinc-containing superoxide dismutase (CuZnSOD) in their periplasms. In pathogenic bacteria, one role of this enzyme may be to protect periplasmic biomolecules from superoxide that is released by host phagocytic cells. However, the enzyme is also present in many nonpathogens and/or free-living bacteria, including Escherichia coli. In this study we were able to detect superoxide being released into the medium from growing cultures of E. coli. Exponential-phase cells do not normally synthesize CuZnSOD, which is specifically induced in stationary phase. However, the engineered expression of CuZnSOD in growing cells eliminated superoxide release, confirming that this superoxide was formed within the periplasm. The rate of periplasmic superoxide production was surprisingly high and approximated the estimated rate of cytoplasmic superoxide formation when both were normalized to the volume of the compartment. The rate increased in proportion to oxygen concentration, suggesting that the superoxide is generated by the adventitious oxidation of an electron carrier. Mutations that eliminated menaquinone synthesis eradicated the superoxide formation, while mutations in genes encoding respiratory complexes affected it only insofar as they are likely to affect the redox state of menaquinone. We infer that the adventitious autoxidation of dihydromenaquinone in the cytoplasmic membrane releases a steady flux of superoxide into the periplasm of E. coli. This endogenous superoxide may create oxidative stress in that compartment and be a primary substrate of CuZnSOD.

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Bacterial Quorum Sensing During Infection

Annual Review of Microbiology ◽

10.1146/annurev-micro-032020-093845 ◽

2020 ◽

Vol 74 (1) ◽

pp. 201-219 ◽

Cited By ~ 2

Author(s):

Sheyda Azimi ◽

Alexander D. Klementiev ◽

Marvin Whiteley ◽

Stephen P. Diggle

Keyword(s):

Quorum Sensing ◽

Bacterial Infections ◽

Pathogenic Bacteria ◽

Human Infection ◽

Future Research ◽

Virulence Determinants ◽

Plant Laboratory ◽

Bacterial Quorum Sensing ◽

Bacterial Quorum

Bacteria are highly interactive and possess an extraordinary repertoire of intercellular communication and social behaviors, including quorum sensing (QS). QS has been studied in detail at the molecular level, so mechanistic details are well understood in many species and are often involved in virulence. The use of different animal host models has demonstrated QS-dependent control of virulence determinants and virulence in several human pathogenic bacteria. QS also controls virulence in several plant pathogenic species. Despite the role QS plays in virulence during animal and plant laboratory-engineered infections, QS mutants are frequently isolated from natural infections, demonstrating that the function of QS during infection and its role in pathogenesis remain poorly understood and are fruitful areas for future research. We discuss the role of QS during infection in various organisms and highlight approaches to better understand QS during human infection. This is an important consideration in an era of growing antimicrobial resistance, when we are looking for new ways to target bacterial infections.

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Role of Exopolysaccharides in the Survival and Pathogenesis of the Fire Blight Bacterium, Erwinia amylovora

10.32747/1994.7568788.bard ◽

1994 ◽

Author(s):

David Gutnick ◽

David L. Coplin

Keyword(s):

Escherichia Coli ◽

Pathogenic Bacteria ◽

Erwinia Amylovora ◽

Extracellular Polysaccharide ◽

Gene Clusters ◽

Site Directed Mutagenesis ◽

E Coli ◽

Erwinia Stewartii ◽

Stewart's Wilt

Fireblight, a disease of apples and pears, is caused by Erwinia amylovora. Mutants of E. amylovora that do not produce the extreacellular polysaccharide (EPS), amylovoran, are avirulent. A similar EPS, stewartan, is produced by E. stewartii, which caused Stewart's wilt of corn, and which has also been implicated in the virulence of this strain. Both stewartan and amylovoran are type 1 capsular polysaccharides, typified by the colanic acid slime produced by Escherichia coli. Extracellular polysaccharide slime and capsules are important for the virulence of bacterial pathogens of plants and animals and to enhance their survival and dissemination outside of the host. The goals of this project were to examine the importance of polysaccharide structure on the pathogenicity and survival properties of three pathogenic bacteria: Erwinia amylovora, Erwinia stewartii and Escherichia coli. The project was a collaboration between the laboratories of Dr. Gutnick (PI, E. coli genetics and biochemistry), Dr. Coplin (co-PI, E. stewartii genetics) and Dr. Geider (unfunded collaborator, E. amylovora genetics and EPS analysis). Structural analysis of the EPSs, sequence analysis of the biosynthetic gene clusters and site-directed mutagenesis of individual cps and ams genes revealed that the three gene clusters shared common features for polysaccharide polymerization, translocation, and precursor synthesis as well as in the modes of transcriptional regulation. Early EPS production resulted in decreased virulence, indicating that EPS, although required for pathogenicity, is anot always advantageous and pathogens must regulate its production carefully.

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Role of Histone-Like Proteins H-NS and StpA in Expression of Virulence Determinants of Uropathogenic Escherichia coli

Journal of Bacteriology ◽

10.1128/jb.01956-05 ◽

2006 ◽

Vol 188 (15) ◽

pp. 5428-5438 ◽

Cited By ~ 78

Author(s):

Claudia M. Müller ◽

Ulrich Dobrindt ◽

Gábor Nagy ◽

Levente Emödy ◽

Bernt Eric Uhlin ◽

...

Keyword(s):

Gene Expression ◽

Escherichia Coli ◽

Gene Expression Pattern ◽

Direct Interaction ◽

Virulence Determinants ◽

Dna Arrays ◽

Infectious Dose ◽

E Coli ◽

Huge Impact

ABSTRACT The histone-like protein H-NS is a global regulator in Escherichia coli that has been intensively studied in nonpathogenic strains. However, no comprehensive study on the role of H-NS and its paralogue, StpA, in gene expression in pathogenic E. coli has been carried out so far. Here, we monitored the global effects of H-NS and StpA in a uropathogenic E. coli isolate by using DNA arrays. Expression profiling revealed that more than 500 genes were affected by an hns mutation, whereas no effect of StpA alone was observed. An hns stpA double mutant showed a distinct gene expression pattern that differed in large part from that of the hns single mutant. This suggests a direct interaction between the two paralogues and the existence of distinct regulons of H-NS and an H-NS/StpA heteromeric complex. hns mutation resulted in increased expression of alpha-hemolysin, fimbriae, and iron uptake systems as well as genes involved in stress adaptation. Furthermore, several other putative virulence genes were found to be part of the H-NS regulon. Although the lack of H-NS, either alone or in combination with StpA, has a huge impact on gene expression in pathogenic E. coli strains, its effect on virulence is ambiguous. At a high infection dose, hns mutants trigger more sudden lethality due to their increased acute toxicity in murine urinary tract infection and sepsis models. At a lower infectious dose, however, mutants lacking H-NS are attenuated through their impaired growth rate, which can only partially be compensated for by the higher expression of numerous virulence factors.

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Ciprofloxacin-Resistant Gram-Negative Bacilli in the Fecal Microflora of Children

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00548-06 ◽

2006 ◽

Vol 50 (10) ◽

pp. 3325-3329 ◽

Cited By ~ 22

Author(s):

Xuan Qin ◽

Yasmin Razia ◽

James R. Johnson ◽

Jennifer R. Stapp ◽

Daniel R. Boster ◽

...

Keyword(s):

Pathogenic Bacteria ◽

Antimicrobial Agents ◽

Enterobacter Aerogenes ◽

Fecal Excretion ◽

Achromobacter Xylosoxidans ◽

Resistant Bacteria ◽

Phylogenetic Groups ◽

Gram Negative ◽

E Coli ◽

Public Health Challenges

ABSTRACT The extent to which antibiotic-resistant bacteria are excreted by humans who have not been exposed to antibiotics is not known. Children, who rarely receive fluoroquinolones, provide opportunities to assess the frequency of fecal excretion by fluoroquinolone-naïve hosts of fluoroquinolone-resistant gram-negative bacilli. Fresh nondiarrheal stools from children were processed by screening them on agar containing ciprofloxacin to recover ciprofloxacin-resistant gram-negative bacilli. Resistant isolates were identified, and ciprofloxacin MICs were determined. Resistant Escherichia coli isolates were also analyzed for urovirulence-associated loci. Thirteen (2.9%) of 455 stools yielded ciprofloxacin-resistant E. coli (seven children), Stenotrophomonas maltophilia (four children), and Achromobacter xylosoxidans and Enterobacter aerogenes (one child each). Neither the subjects themselves nor members of their households used fluoroquinolones in the 4 weeks preceding collection. Six of the seven resistant E. coli isolates belonged to phylogenetic groups B2 and D, in which extraintestinal pathogenic E. coli bacteria are frequently found. All resistant E. coli isolates contained at least three putative E. coli virulence loci. Most ciprofloxacin-resistant bacteria were resistant to additional antibiotics. Potentially pathogenic bacteria that are resistant to therapeutically important antimicrobial agents are excreted by some humans, despite these persons' lack of exposure to the particular drugs. The sources of these resistant organisms are unknown. This underrecognized reservoir of drug-resistant potential pathogens poses public health challenges.

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Bacterial Adherence in Mastitis Caused by Escherichia coli

Veterinary Pathology ◽

10.1177/030098587701400608 ◽

1977 ◽

Vol 14 (6) ◽

pp. 618-628 ◽

Cited By ~ 17

Author(s):

J. C. Anderson ◽

M. R. Burrows ◽

A. J. Bramley

Keyword(s):

Escherichia Coli ◽

Mammary Gland ◽

Resistant Strain ◽

Clinical Mastitis ◽

Bacterial Adherence ◽

Bovine Mammary Gland ◽

E Coli ◽

Mild Disease ◽

Highly Virulent

The possible role of bacterial adherence in the pathogenesis of experimental mastitis in the mouse was examined with four strains of Escherichia coli. Two of these strains had a known adhesion antigen (K88) and two did not. The K88 antigen did not play a significant role in the virulence or infectivity of E. coli either in the murine or bovine mammary gland. Two E. coli strains, W1 (K88+) and J2 (K88−) were virulent in the mouse but did not adhere to epithelial cells. Both these strains produced clinical mastitis in the cow. A third strain, D282 (K88−), produced mild disease in the mouse but was avirulent in the cow. The fourth strain, 233/1D (K88+), was avirulent in both the mouse and the cow. Strains D282 and 233/1D were killed rapidly by bovine serum whilst J2 and W1 were more resistant. All strains were more sensitive than the control resistant strain E. coli P4, which is known to be highly virulent for the lactating udder.

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