scholarly journals The lactose system inKlebsiella aerogenesV9A: 4. A comparison of thelacoperons ofKlebsiellaandEscherichia coli

1974 ◽  
Vol 24 (3) ◽  
pp. 323-331 ◽  
Author(s):  
E. C. R. Reeve ◽  
J. A. Braithwaite
Keyword(s):  
Lac Repressor ◽  
Klebsiella Aerogenes ◽  
E Coli ◽  
Esherichia Coli ◽  
Active Repressor

SUMMARYKlebsiella aerogenesV9A contains twolacoperons, one chromosomal and one borne by the Lac plasmid,FKlac. It is shown that the plasmid Lac repressor resembles that ofEsherichia coliin that it represses theE. colioperon but is inactivated by melibiose. In contrast, the chromosomal Lac repressor of V9A is unable to repress theE. colioperon or the FKlacoperon, but is converted into an active repressor of both these operons on becoming bound to melibiose. The chromosomal Lac repressor is able to repress its own operon whether or not it is bound to melibiose, but is inactivated by isopropyl-β-D-thiogalactoside. These results support the hypothesis that theKlebsiellaLac plasmid was derived from an ancestralE. colichromosome.

Viability of Edwardsiella tarda and Esherichia coli preserved with glycerol-tryptone soy broth (TSB) kept at freezing temperature

2013 ◽  
Vol 1 (2) ◽  
pp. 154
Author(s):  
Abdur Rohman ◽  
Frans Ijong ◽  
I K Suwetja
Keyword(s):  
Research And Development ◽  
Germ Plasm ◽  
Freezing Temperature ◽  
Experimental Methods ◽  
Edwardsiella Tarda ◽  
Diagnostic Tools ◽  
Glycerol Concentration ◽  
E Coli ◽  
Esherichia Coli ◽  
Escherchia Coli

Preservation of bacteria carried out in relation to the collection and preservation of germ plasm microbe is useful for research and development or for the establishment of diagnostic tools. Glycerol is a good preservation media but it is not known what doses should be used for effective preservation.  This research used two experimental  methods consisting of 2 factors and 3 treatments. This study aimed to find the best glycerol concentration that can be used to preserve Edwarsiella tarda and Escherchia coli in the -20ºC environment, to understand the viability of bacteria after being preserved and to describe the characteristics of the preserved bacteria. Treatments applied were 10%, 15% and 20%  glycerol in TSB. Viability of the bacteria was analyzed after 7, 14, 28, 35, and 42 days of preservation. Results showed that E.coli bacteria preserved in 15%  glycerol had the highest viability, i.e. 84% and preserved in 10% glycerol had the lowest viability, i.e. 80%. But for E. tarda bacteria preserved in 10% glycerol had the highest viability, i.e. 1.83% and preseved in 15% glycerol had the lowest viability, i.e. 0,55%. Preservasi bakteri dilakukan dalam kaitannya dengan koleksi dan konservasi plasma nutfah mikroba yang berguna untuk penelitian dan pengembangan atau untuk pembentukan alat diagnosa. Gliserol merupakan bahan preservasi yang baik, tetapi belum diketahui dosis yang baik dan efektif untuk preservasi bakteri Edwarsiella tarda dan Escherchia coli pada suhu -20ºC. Penelitian ini dilakukan dengan metode eksperimen yang terdiri dari 2 faktor dan 3 taraf perlakuan, masing-masing perlakuan dengan 3 kali ulangan, media preservasi yang digunakan adalah TSB dan gliserol dengan konsentrasi 10%, 15% dan 20%. Parameter yang diukur adalah viabilitas dan kecocokan/penyimpangan karakteristik biokimia. Penelitian ini dilaksanakan di Laboratorium Balai Karantina Ikan Pengendalian Mutu dan Keamanan Hasil Perikanan Manado, dari bulan September sampai dengan November 2013. Tujuan Penelitian ini adalah untuk menentukan konsentrasi gliserol dalam TSB sebagai media preservasi yang efektif dan efisien pada bakteri  Edwarsiella tarda dan Escherchia coli yang dipreservasi dengan suhu -20ºC dan disimpan selama 42  hari. Hasil penelitian menunjukkan adanya penurunan laju pertumbuhan bakteri selama preservasi. Persentase viabilitas  bakteri E. coli yang tertinggi selama preservasi diperoleh dengan penggunaan gliserol konsentrasi 15% dengan jumlah 84% dan yang terendah adalah dengan penggunaan konsentrasi 10% yakni sebesar 80%, sedangkan untuk E. tarda persentase viabilitas  bakteri yang tertinggi selama preservasi diperoleh dengan penggunaan gliserol konsentrasi 10% dengan jumlah 1,83% dan yang terendah adalah dengan penggunaan konsentrasi 15% yakni sebesar 0,55%. Berdasarkan uji statistik analisis variasi (ANAVA) didapat hasil F hitung E. tarda dan E. coli yang lebih besar  dari FTabel dengan tingkat kepercayaan 95 %.

scholarly journals ISPITIVANJE UTICAJA FEROCENA I NJEGOVIH DERIVATA NA AKTIVNOST PROTEOLITIČKIH ENZIMA PRISUTNIH U LIZATU E. COLI ATCC 25922

2013 ◽  
Vol 4 (9) ◽  
Author(s):  
Mirjana Žabić ◽  
Zoran Kukrić ◽  
Ljiljana Topalić- Trivunović
Keyword(s):  
E Coli ◽  
Esherichia Coli

Sve značajnija upotreba organometalnih jedinjenja u terapeutske svrhe je potakla mnoga istraživanja u oblasti inhibicije enzima. U ovom radu je ispitivan efekat ferocena i njegovih derivata na proteolitičke enzime prisutne u lizatu Esherichia coli ATCC 25922. Utvrđeno je da ferocen najviše, skoro za 50%, smanjuje brzinu nastajanja p-nitroanilina iz N-α-benzoil-DL-arginin p-nitroanilida (BAPNA) uz pomoć enzima lizata bakterije E. coli. Dakle, za inhibiciju hidrolize BAPNA-e pomoću lizata ove bakterije i sam ferocen je bio dovoljno djelotvoran, iako je bilo za očekivati da će uvođenje poželjnih funkcionalnih grupa u molekulu ferocena poboljšati inhibiciju tripsina ostvarivanjem bolje interakcije sa enzimskim aktivnim mjestom.

scholarly journals Dissemination of the blaNDM-5 Gene via IncX3-Type Plasmid among Enterobacteriaceae in Children

mSphere ◽  
2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Dongxing Tian ◽  
Bingjie Wang ◽  
Hong Zhang ◽  
Fen Pan ◽  
Chun Wang ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Drug Resistance ◽  
Gene Transfer ◽  
Horizontal Gene Transfer ◽  
Klebsiella Pneumoniae ◽  
Pediatric Patients ◽  
Transmission Mechanism ◽  
Klebsiella Aerogenes ◽  
Content Type ◽  
E Coli

ABSTRACT The continuous emergence of novel New Delhi metallo-β-lactamase-5 (NDM-5)-producing Enterobacteriaceae isolates is receiving more and more public attention. Twenty-two NDM-5-producing strains were identified from 146 carbapenemase-producing Enterobacteriaceae (CRE) strains isolated from pediatric patients between January and March 2017, indicating that the blaNDM-5 gene has spread to children. All 22 isolates, including 16 Klebsiella pneumoniae strains, four Klebsiella aerogenes strains, and two Escherichia coli strains, showed significantly high resistance to β-lactam antibiotics (except aztreonam) but remained susceptible to tigecycline and colistin. K. pneumoniae and K. aerogenes strains were respectively defined as homologous clonal isolates by pulsed-field gel electrophoresis (PFGE). Multilocus sequence typing (MLST) results confirmed the genetic relatedness with all K. pneumoniae strains belonging to sequence type (ST) 48. Two E. coli isolates (ST617 and ST1236) were considered genetically unrelated. Twenty-two blaNDM-5 plasmids were positive for the IncX3 amplicon and showed almost identical profiles after digestion with HindIII and EcoRI. Four representative strains (K. pneumoniae K725, K. aerogenes CR33, E. coli Z214, and E. coli Z244) were selected for further study. Plasmids harboring blaNDM-5 showed strong stability in both clinical isolates and transconjugants, without apparent plasmid loss after 100 serial generations. S1-PFGE followed by Southern blot analysis demonstrated that the blaNDM-5 gene was located on an ∼46-kb plasmid. Plasmid sequences of pNDM-K725, pNDM-CR33, and pNDM-Z214 were almost identical but were slightly different from that of pNDM-Z244. Compared with pNDM-Z244, ΔISAba125 and partial copies of IS3000 were missing. The genetic backgrounds of the blaNDM-5 gene in four strains were slightly different from that of the typical pNDM_MGR194. This study comprehensively characterized the horizontal gene transfer of the blaNDM-5 gene among different Enterobacteriaceae isolates in pediatric patients, and the IncX3-type plasmid was responsible for the spread. IMPORTANCE The emergence of CRE strains resistant to multiple antibiotics is considered a substantial threat to human health. Therefore, all the efforts to provide a detailed molecular transmission mechanism of specific drug resistance can contribute positively to prevent the further spread of multidrug-resistant bacteria. Although the new superbug harboring blaNDM-5 has been reported in many countries, it was mostly identified among E. coli strains, and the gene transfer mechanism has not been fully recognized and studied. In this work, we identified 22 blaNDM-5-positive strains in different species of Enterobacteriaceae, including 16 Klebsiella pneumoniae strains, four Klebsiella aerogenes strains, and two Escherichia coli strains, which indicated the horizontal gene transfer of blaNDM-5 among Enterobacteriaceae strains in pediatric patients. Moreover, blaNDM-5 was located on a 46-kb IncX3 plasmid, which is possibly responsible for this widespread horizontal gene transfer. The different genetic contexts of the blaNDM-5 gene indicated some minor evolutions of the plasmid, based on the complete sequences of the blaNDM-5 plasmids. These findings are of great significance to understand the transmission mechanism of drug resistance genes, develop anti-infection treatment, and take effective infection control measures.

scholarly journals Some relationships between R-factor and chromosomal β-lactamase in Gram-negative bacteria

1971 ◽  
Vol 123 (4) ◽  
pp. 507-512 ◽  
Author(s):  
J. W. Dale ◽  
J. T. Smith
Keyword(s):  
Gel Electrophoresis ◽  
Klebsiella Aerogenes ◽  
Gram Negative Bacteria ◽  
Starch Gel Electrophoresis ◽  
Gram Negative ◽  
E Coli ◽  
Molecular Weights ◽  
R Factor ◽  
Starch Gel ◽  
R Factors

1. The β-lactamases specified by Klebsiella aerogenes 418 and the R-factor R-7268 have been partially purified. 2. The molecular weights of the K. aerogenes strains 418 and 373, Aerobacter cloacae 53, R-7268 and R-TEM β-lactamases were all about 20000; that of the enzymes from Escherichia coli strains 419 and 214T was about 31000. 3. These enzymes were also compared by means of their Km values for benzylpenicillin and ampicillin, and their behaviour on starch-gel electrophoresis. 4. The β-lactamases specified by the two Klebsiella strains, the Aerobacter strain, and the R-factors R-TEM and R-7268 were found to comprise a broadly similar group. However, within this group, only two enzymes seemed to be identical, namely those specified by the two R-factors. The two E. coli strains produce identical β-lactamases which are very different from the ‘Klebsiella/Aerobacter-type’ enzymes.

scholarly journals Roles of Glutamate Synthase, gltBD, and gltF in Nitrogen Metabolism of Escherichia coli and Klebsiella aerogenes

2001 ◽  
Vol 183 (22) ◽  
pp. 6607-6619 ◽  
Author(s):  
Thomas J. Goss ◽  
Ana Perez-Matos ◽  
Robert A. Bender
Keyword(s):  
Escherichia Coli ◽  
Nitrogen Metabolism ◽  
Glutamate Synthase ◽  
Nitrogen Sources ◽  
Enteric Bacteria ◽  
The Other ◽  
Klebsiella Aerogenes ◽  
E Coli ◽  
Glutamine Synthesis ◽  
Subsequent Failure

ABSTRACT Mutants of Escherichia coli and Klebsiella aerogenes that are deficient in glutamate synthase (glutamate-oxoglutarate amidotransferase [GOGAT]) activity have difficulty growing with nitrogen sources other than ammonia. Two models have been proposed to account for this inability to grow. One model postulated an imbalance between glutamine synthesis and glutamine degradation that led to a repression of the Ntr system and the subsequent failure to activate transcription of genes required for the use of alternative nitrogen sources. The other model postulated that mutations in gltB or gltD (which encode the subunits of GOGAT) were polar on a downstream gene,gltF, which is necessary for proper activation of gene expression by the Ntr system. The data reported here show that thegltF model is incorrect for three reasons: first, a nonpolar gltB and a polar gltD mutation of K. aerogenes both show the same phenotype; second,K. aerogenes and several other enteric bacteria lack a gene homologous to gltF; and third, mutants of E. coli whose gltF gene has been deleted show no defect in nitrogen metabolism. The argument that accumulated glutamine represses the Ntr system in gltB or gltDmutants is also incorrect, because these mutants can derepress the Ntr system normally so long as sufficient glutamate is supplied. Thus, we conclude that gltB or gltD mutants grow slowly on many poor nitrogen sources because they are starved for glutamate. Much of the glutamate formed by catabolism of alternative nitrogen sources is converted to glutamine, which cannot be efficiently converted to glutamate in the absence of GOGAT activity. Finally, GOGAT-deficient E. coli cells growing with glutamine as the sole nitrogen source increase their synthesis of the other glutamate-forming enzyme, glutamate dehydrogenase, severalfold, but this is still insufficient to allow rapid growth under these conditions.

Systemic hypoxia enhances exercise-mediated bactericidal and subsequent apoptotic responses in human neutrophils

2009 ◽  
Vol 107 (4) ◽  
pp. 1213-1222 ◽  
Author(s):  
Jong-Shyan Wang ◽  
Ya-Ting Chiu
Keyword(s):  
Bactericidal Activity ◽  
Defense Mechanisms ◽  
Experimental Tests ◽  
Oxidase Inhibitor ◽  
Strenuous Exercise ◽  
Human Neutrophils ◽  
E Coli ◽  
Esherichia Coli ◽  
Diphenylene Iodonium ◽  
Oxidant Production

Phagocytosis and oxidative burst are critical host defense mechanisms in which neutrophils clear invading pathogens. Clearing phagocytic neutrophils by triggering apoptosis is an essential process for controlling inflammation. This study elucidates how various exercise bouts with/without hypoxia affected neutrophil bactericidal activity and subsequent apoptosis in humans. Fifteen sedentary males performed six distinct experimental tests in an air-conditioned normobaric hypoxia chamber: two normoxic exercises [strenuous exercise (SE; up to maximal O2consumption) and moderate exercise (ME; 50% maximal O2consumption for 30 min) while exposed to 21% O2], two hypoxic exercises (ME for 30 min while exposed to 12% and 15% O2), and two hypoxic exposures (resting for 30 min while exposed to 12% and 15% O2). The results showed that 1) plasma complement-C3a desArg/C4a desArg/C5a concentrations were increased, 2) expressions of L-selectin/lymphocyte functin-associated antigen-1/Mac-1/C5aR on neutrophils were enhanced, 3) phagocytosis of neutrophils to Esherichia coli and release of neutrophil oxidant products by E. coli were elevated, and 4) E. coli -induced phosphotidylserine exposure or caspase-3 activation of neutrophils were promoted immediately and 2 h after both 12% O2exposure at rest and with ME as well as normoxic SE. Although neither normoxic ME nor breathing 15% O2at rest influenced these complement- and neutrophil-related immune responses, ME at both 12% and 15% O2resulted in enhanced complement activation in the blood, expressions of opsonic/complement receptors on neutrophils, or the bactericidal activity and apoptosis of neutrophils. Moreover, the increased neutrophil oxidant production and apoptosis by normoxic SE and hypoxic ME were ameliorated by treating neutrophils with diphenylene iodonium (a NADPH oxidase inhibitor). Therefore, we conclude that ME at 12–15% O2enhances bactericidal capacity and facilitates the subsequent apoptosis of neutrophils.

scholarly journals Τροποποίηση της έκβασης σοβαρών gram αρνητικών λοιμώξεων μετά από οστεομυελίτιδα

2020 ◽  
Author(s):  
Σταύρος Γούμενος
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
E Coli ◽  
Esherichia Coli

Σκοπός: Η αυξημένη επίπτωση της οστεομυελίτιδας σε ευπαθείς ομάδες, όπως οι πολυτραυματίες και οι ηλικιωμένοι μετά από επεμβάσεις αρθροπλαστικής, δημιουργεί το ερώτημα ποιά μπορεί να είναι η απόκρισή των ασθενών αυτών σε επαναλοίμωξη από μικροοργανισμούς υψηλής παθογονικότητας, όπως τα νοσοκομειακά στελέχη. Ζώα και μέθοδοι: Κόνικλοι Νέας Ζηλανδίας υποβλήθηκαν σε δύο χειρουργικές επεμβάσεις μέσα σε χρονικό διάστημα 3 εβδομάδων: εικονική οστεομυελίτιδα και εικονική πυελονεφρίτιδα (ομάδα S), εικονική οστεομυελίτιδα και πυελονεφρίτιδα από Escherichia coli (ομάδα P), οστεομυελίτιδα από Staphylococcus aureus και πυελονεφρίτιδα από Esherichia coli με ή χωρίς αντισταφυλοκοκκική θεραπεία (ομάδες OP και ODP). Η επιβίωση των ζώων μελετήθηκε καθημερινά για 14 ημέρες. Δείγματα περιφερικού αίματος συλλέχθηκαν προς απομόνωση και καλλιέργεια των μονοπυρήνων κυττάρων του περιφερικού αίματος (PBMCs). Την 14η ημέρα τα ζώα θυσιάστηκαν και ελήφθησαν ιστκά τεμάχια προς μέτρηση της δραστικότητας της μυελοϋπεροξειδάσης ουδετεροφίλων (MPO) και της βακτηριακής ανάπτυξης στους ιστούς. Στα ζώα της ομάδας ODP χορηγήθηκε άπαξ νταλμπαβανσίνη προ της πρόκλησης πυελονεφρίτιδας. Επιπλέον PBMCs από υγιή ζώα επωάστηκαν in vitro με οστικό ομογενοποίημα με ή χωρίς την παρουσία Staphylococcus aureus και οι παραγόμενες κυτταροκίνες μετρήθηκαν. Αποτελέσματα: Η θνητότητα των ζώων των ομάδων (S, P, OP) μετά την πρόκληση πυελονεφρίτιδας ήταν 0%, 50% και 8.3% αντιστοίχως. Η παραγωγή TNFα από τα διεγερμένα PBMCs ήταν σημαντικά μειωμένη στην ομάδα OP στις 48 ώρες μετά πυελονεφρίτιδας. Το ιστικό βακτηριακό φορτίο του E. coli ήταν παρόμοιο στις ομάδες P και OP. Η δραστικότητα της MPO της ομάδας OP ήταν μειωμένη. Ο παραγόμενος TNFα ήταν ακόμα πιο μειωμένος στα ζώα της ομάδας ODP, ενώ η δραστικότητα της MPO ήταν αυξημένη. Η παραγωγή TNFα μειωνόταν όταν PBMCs απομονωμένα από υγιή ζώα και επωασμένα με οστικό ομογενοποίημα, S. aureus (HKSA) ή και τα δύο διεγείρονταν μετέπειτα με E. coli (HKEC). Ακόμα περισσότερο μειωνόταν δε υπό την παρουσία αναστολέων των TLR υποδοχέων anti-TLR4 και anti-TLR9. Συμπέρασμα: H σταφυλοκοκκική οστεομυελίτιδα τροποποιεί την έμφυτη ανοσιακή απόκριση του ξενιστή παρέχοντάς του πλεονέκτημα επιβίωσης μετά από θανατηφόρο λοίμωξη του ουροποιητικού από E. Coli. Ο πιθανός μηχανισμός φαίνεται να είναι η ενίσχυση της ανοσίας μέσω ρύθμισης των υποδοχέων TLR.

scholarly journals Adaptation of Esherichia coli to Antiobiotic Cycling via Single Nucleotide Polymorphisms

2017 ◽  
Vol 14 (1) ◽  
Author(s):  
Samuel Hager ◽  
Ellen Jensen ◽  
Timothy Johnson ◽  
David Mitchell
Keyword(s):  
Escherichia Coli ◽  
Minimum Inhibitory Concentration ◽  
Nalidixic Acid ◽  
Inhibitory Concentration ◽  
Acid Resistance ◽  
Penicillin G ◽  
Single Nucleotide ◽  
E Coli ◽  
Esherichia Coli ◽  
Nalidixic Acid Resistance

Bacteria are quick to adapt and evolve, especially under the effects of selective pressures from chemical antibiotics. In addition, bacteria may develop resistance to antibiotics from multiple classes simultaneously, making their eradication from the human body particularly challenging. This study aims to demonstrate that bacterial multiple-drug resistance can be developed and retained in a laboratory setting. Escherichia coli B was grown in tryptic soy broth in the presence of a small, increasing concentration of streptomycin. This exposure resulted in a strain of E. coli, which had an increased minimum inhibitory concentration (MIC) towards streptomycin, or “resistance.” This resistant strain was then grown in like manner in nalidixic acid and then penicillin G. The result was a strain that became resistant to streptomycin and nalidixic acid, and increasingly resistant to nalidixic acid after penicillin G exposure. Additionally, the bacteria retained resistance to streptomycin and nalidixic acid even after exposure to those chemicals ceased. Genome sequencing and comparison to E. coli B reference strain REL606 revealed the emergence of point mutations with each exposure to an antibiotic. Of particular interest is a mutation associated with the appearance of nalidixic acid resistance. Base pair 4,553,488 was changed from adenine to guanine, resulting in a change from aspartate to glycine in the protein helicase. Previous studies have not indicated mutations to this locus as nalidixic acid resistance conferring. Thus, this mutation may be a novel mutation conferring E. coli B nalidixic acid resistance. Since the region of the mutated helicase is functionally undefined, a mechanism is not apparent. Further research needs to be done to confirm this hypothesis and illuminate a mechanism. KEYWORDS: Bacteria; Escherichia coli; Evolution; Antibiotic Resistance; Nalidixic Acid; Streptomycin; Point Mutation; Single-nucleotide Polymorphism; Helicase; Minimum Inhibitory Concentration

scholarly journals Assessment of Biosecurity Measures and Distribution of Daily Live Bird ‎Markets in Four North-Western States of Nigeria ‎

2021 ◽  
Vol 18 (3) ◽  
pp. 8-18
Author(s):  
S. A. Hassan ◽  
B. V. Maikai ◽  
J. Kabir ◽  
M. B. Aliyu
Keyword(s):  
Spatial Distribution ◽  
Disease Spread ◽  
Human Settlements ◽  
E Coli ◽  
Live Bird Markets ◽  
Esherichia Coli ◽  
Biosecurity Practices ◽  
Different Sources ◽  
North Western ◽  
Live Bird

Maintenance of strict biosecurity measures is essential in preventing disease spread from Live Bird Markets (LBMs) which serve as a major intermingling area for poultry from different sources. This study assessed the Biosecurity measures and spatial distribution of daily Live Bird Markets of four North-western States in Nigeria. Closed ended questionnaires were administered in 35 daily LBMs in Kaduna, Kano, Katsina and Zamfara states and identification of disinfectants used in the LBMs were noted. Swab samples of birds’ cages in the LBMs were taken for E. coli isolation. The live bird managers and marketers were all male (100%) across all the four states. Only 6(17%) out of the 35 LBMs had high biosecurity level, 69% had a moderate biosecurity level and 5(14%) were graded as low. Of the 400 Live bird marketers administered questionnaires, only 71 (18%) employ good biosecurity practices and 305(76%) were graded as fair and remaining 24(6%) as poor. Majority of the LBMs were located within human settlements without any form of barrier. There were seven main types of disinfectants identified across the all LBMs. Esherichia coli was isolated from 1(17%) LBM among the 6(17%) LBMs that were identified to have and use disinfectant. From the remaining 29(83%) LBMs, E.coli was isolated from only 5(17%) despite lacking in use of disinfectant by these LBMs. Live bird marketers should be educated on the need to adhere to biosecurity measures and practices.

Sign in / Sign up

Export Citation Format

Share Document