scholarly journals Postexposure factors influencing the duration of postantibiotic effect: significance of temperature, pH, cations, and oxygen tension.

1997 ◽  
Vol 41 (8) ◽  
pp. 1693-1696 ◽  
Author(s):  
K Fuursted
Keyword(s):  
Sodium Chloride ◽  
Oxygen Tension ◽  
Incubation Temperature ◽  
Penicillin G ◽  
Postantibiotic Effect ◽  
High Concentration ◽  
E Coli ◽  
Generation Times ◽  
Mueller Hinton ◽  
Incubation Temperatures

The purpose of the present study was to assess and compare the impacts of various postexposure conditions on postantibiotic effect (PAE). PAEs were induced in Staphylococcus aureus and Escherichia coli by exposing the organisms to different antibiotics (penicillin G, ampicillin, erythromycin, ciprofloxacin, and gentamicin) at 5 or 10 times the MIC in plain Mueller-Hinton broth for 1 h at 35 degrees C. Regrowth was determined by measuring the viable counts after drug removal by a 10(-3) or 10(-4) dilution procedure under various postexposure conditions (incubation temperatures at 20, 25, 30, or 35 degrees C; growth under shaken, unshaken, anaerobic conditions; pH 6.0, 7.4, or 9.0; and with sodium chloride concentrations at 0, 1, 3, or 6%). PAE increased in response to a decrease in incubation temperature from 35 to 20 degrees C, and a significant correlation between bacterial generation times and duration of PAEs (r2, 0.82 to 0.97) was demonstrated. The duration of PAE was also modified by the pH in the regrowth medium. PAE increased considerably for S. aureus at pH 6.0 and 9.0 compared to that at pH 7.4 after induction with penicillin G, and with gentamicin the PAE against S. aureus recovering at pH 6.0 also increased considerably. A high concentration of sodium chloride in the regrowth medium produced the most extensive changes in PAE except for that against E. coli induced by ampicillin. PAE increased significantly in response to increased salinity. No recovery even after overnight incubation was detected for S. aureus after preexposure to penicillin, ciprofloxacin, or gentamicin. Only minor changes in the duration of PAE were observed in relation to recovery oxygen tension. It is concluded that many postexposure factors have a profound effect on the duration of PAE.

scholarly journals Broader incubation temperature tolerances for microbial drinking water testing with enzyme substrate tests

2013 ◽  
Vol 12 (1) ◽  
pp. 113-121 ◽  
Author(s):  
Robert L. Matthews ◽  
Rosalind Tung
Keyword(s):  
Drinking Water ◽  
Incubation Temperature ◽  
Significant Loss ◽  
Testing Procedures ◽  
E Coli ◽  
Water Testing ◽  
Enzyme Substrate ◽  
Laboratory Facilities ◽  
Microbiological Testing ◽  
Incubation Temperatures

Microbiological testing is an integral part of measures to ensure safe drinking water. However, testing can be restricted in low-resource settings by the requirement for specialized laboratory facilities and testing procedures. Precisely controlled incubation temperature is one example. The effect of varied incubation temperatures on the performance of two enzyme substrate tests for the detection of Escherichia coli and total coliforms has been examined. The aim was to determine whether these tests would provide consistent and comparable enumeration over a broader temperature range than currently specified. Recovery of chlorine-injured and wild type E. coli was examined over a range of non-standard incubation temperatures in comparison to 37 °C ± 1. Colilert® and Aquatest, a new E. coli-specific detection medium, served as the two representative enzyme substrate media. Recovery of chlorine-injured E. coli in Colilert was not impaired within the range 33–39 °C; the equivalent range in Aquatest medium was 31–43 °C. Both these tests recovered E. coli without significant loss of performance over a wider range of temperatures than currently specified.

Viability and Adaptability of E. coli. and Enterococcus Group to Salt Water with High Concentration of Sodium Chloride

1982 ◽  
Vol 14 (4-5) ◽  
pp. 115-126 ◽  
Author(s):  
T Omura ◽  
M Onuma ◽  
Y Hashimoto
Keyword(s):  
Sodium Chloride ◽  
Salt Water ◽  
The Other ◽  
Type I ◽  
Citrobacter Freundii ◽  
Type Ii ◽  
High Concentration ◽  
E Coli ◽  
Rapid Extinction ◽  
Other Hand

Some experiments were carried out to examine the adaptability of E. coli. and enterococcus group to salt water with high concentration of sodium chloride after the experiments on viability in this salt water. Unlike E. coli. type I, when E.coli. type II was repeatedly exposed to salt water, the survival of E.coli. type II was changed from rapid extinction to multiplication as the experiments went on. At the same time, it was also made clear by means of the IMViC test that E.coli. type II was replaced by Citrobacter freundii as E.coli. type II adapted itself to salt water. The enterococcus group was separated into four distinct types; S. faecalis, S. faecalis var. liquefaciens, S. faecium and S. durans. The results of the experiments on viability in salt water indicated that S. faecalis var. liquefaciens possessed the greatest viability, and S. faecium the weakest. From the results of the experiments on adaptability, it was found that each type of enterococcus group had a different adaptability to salt water. In spite of the weakest viability, S. faecium could adapt itself to salt water as well as S. faecalis and S. faecalis var. liquefaciens. On the other hand, S. durans could not adapt itself to salt water at all.

Comparison and Recovery of Escherichia coli and Thermotolerant Coliforms in Water with a Chromogenic Medium Incubated at 41 and 44.5°C

1999 ◽  
Vol 65 (8) ◽  
pp. 3746-3749 ◽  
Author(s):  
Jose L. Alonso ◽  
Adela Soriano ◽  
Oscar Carbajo ◽  
Inmaculada Amoros ◽  
Hemda Garelick
Keyword(s):  
Escherichia Coli ◽  
Membrane Filtration ◽  
Incubation Temperature ◽  
Lauryl Sulfate ◽  
Marine Waters ◽  
Sodium Pyruvate ◽  
Chromogenic Medium ◽  
E Coli ◽  
Thermotolerant Coliforms ◽  
Incubation Temperatures

ABSTRACT This study compared the performance of a commercial chromogenic medium, CHROMagarECC (CECC), and CECC supplemented with sodium pyruvate (CECCP) with the membrane filtration lauryl sulfate-based medium (mLSA) for enumeration of Escherichia coli and non-E. coli thermotolerant coliforms (KEC). To establish that we could recover the maximum KEC and E. coli population, we compared two incubation temperature regimens, 41 and 44.5°C. Statistical analysis by the Fisher test of data did not demonstrate any statistically significant differences (P = 0.05) in the enumeration of E. coli for the different media (CECC and CECCP) and incubation temperatures. Variance analysis of data performed on KEC counts showed significant differences (P = 0.01) between KEC counts at 41 and 44.5°C on both CECC and CECCP. Analysis of variance demonstrated statistically significant differences (P = 0.05) in the enumeration of total thermotolerant coliforms (TTCs) on CECC and CECCP compared with mLSA. Target colonies were confirmed to be E. coli at a rate of 91.5% and KEC of likely fecal origin at a rate of 77.4% when using CECCP incubated at 41°C. The results of this study showed that CECCP agar incubated at 41°C is efficient for the simultaneous enumeration of E. coli and KEC from river and marine waters.

Effect of temperature on activity of predators of Salmonella typhimurium and Escherichia coli in estuarine water

1980 ◽  
Vol 31 (6) ◽  
pp. 851 ◽  
Author(s):  
Cambridge J Mc ◽  
TA McMeekin
Keyword(s):  
Escherichia Coli ◽  
Incubation Temperature ◽  
Effect Of Temperature ◽  
Estuarine Water ◽  
Survival Curves ◽  
Temperature Optimum ◽  
E Coli ◽  
Similar Survival ◽  
Incubation Temperatures ◽  
Micro Organisms

The survival of S. typhimurium was compared with that of E. coli in estuarine water samples at various incubation temperatures. Both organisms exhibited similar survival curves, and their presence resulted in the growth of comparable numbers of predacious micro-organisms at all temperatures. Bacterial decline was found to be dependent on the presence of both bacterial and protozoan predators, the latter having a temperature optimum of 15-20�C and the former becoming more important as the incubation temperature increased.

Inhibition of Enteropathogenic Escherichia coli by Homofermentative Lactic Acid Bacteria in Skimmilk

1977 ◽  
Vol 40 (11) ◽  
pp. 749-753 ◽  
Author(s):  
J. F. FRANK ◽  
E. H. MARTH
Keyword(s):  
Escherichia Coli ◽  
Lactic Acid ◽  
Incubation Temperature ◽  
Starter Culture ◽  
Fermented Milk ◽  
Enteropathogenic Escherichia Coli ◽  
E Coli ◽  
Inhibition Of Growth ◽  
Generation Times ◽  
Present Generation

Behavior of enteropathogenic and nonpathogenic strains of Escherichia coli was determined when they were grown in skimmilk with and without 0.25 or 2.0% added lactic starter and incubated at 21 or 32 C for 15 h, and then after refrigeration at 7 C. With no lactics present, generation times for E. coli ranged from 28 to 35 min at 32 C and from 66 to 109 min at 21 C. At 32 C, after an initial 1- to 3-log increase in numbers and 6 to 9 h of incubation, E. coli was completely inhibited by both concentrations of starter culture. Complete inhibition of growth by E. coli occurred earlier at 32 than at 21 C, but smaller numbers of E. coli were obtained at 21 C; some strains virtually did not grow. The final pH of fermented milks ranged from 4.4 to 4.6. The longest survival time for E. coli in refrigerated fermented milk was about 17 days when milk was fermented at 32 C with 0.25% starter. A combination of lower incubation temperature (21 C) and higher starter concentration (2.0%) was most effective in controlling growth of E. coli in fermented skimmilk.

Occurrences of Giardia cysts in beach water

1998 ◽  
Vol 38 (12) ◽  
pp. 73-76 ◽  
Author(s):  
B. S. W. Ho ◽  
T.-Y Tam
Keyword(s):  
Health Risk ◽  
Water Sample ◽  
Water Samples ◽  
High Concentration ◽  
Potential Health ◽  
Infectious Dose ◽  
Potential Health Risk ◽  
E Coli ◽  
Beach Water ◽  
Giardia Cysts

A total of 64 beach water samples with various bacteriological quality (Grades 1 to 4) were analysed for their bacteriological and parasitological contents (E coli and Giardia cysts respectively). Results indicated that Giardia cysts were detected in less than 10% of the Grade 1 beach water samples with E coli concentrations of <24/100mL. For Grades 2, 3 & 4 beach water samples, Giardia cysts were found, respectively, in 85, 50 and 64% of the samples. Except for one beach water sample which had an unusually high concentration of Giardia cysts (23 cysts/L), they were generally present at moderate concentrations (<10 cysts/L) in all other beach water samples. Despite moderate levels of Giardia cysts present in beach water of different grades, the potential health risk faced by swimmers bathing in local beach water needs to be carefully assessed as Giardia is known to have a low infectious dose.

scholarly journals Applicability and performance of EUCAST’s rapid antimicrobial susceptibility testing (RAST) on primarily sterile body fluids in blood culture bottles in laboratory routine with total lab automation

2021 ◽  
Author(s):  
Jasmin Kaur Jasuja ◽  
Stefan Zimmermann ◽  
Irene Burckhardt
Keyword(s):  
Blood Culture ◽  
Susceptibility Testing ◽  
Reference Method ◽  
Body Fluids ◽  
E Coli ◽  
Mueller Hinton ◽  
Mueller Hinton Agar ◽  
And Performance ◽  
Sterile Body Fluids ◽  
Better Than

AbstractOptimisation of microbiological diagnostics in primarily sterile body fluids is required. Our objective was to apply EUCAST’s RAST on primarily sterile body fluids in blood culture bottles with total lab automation (TLA) and to compare results to our reference method Vitek2 in order to report susceptibility results earlier. Positive blood culture bottles (BACTEC™ Aerobic/Anaerobic/PEDS) inoculated with primarily sterile body fluids were semi-automatically subcultured onto Columbia 5% SB agar, chocolate agar, MacConkey agar, Schaedler/KV agar and Mueller-Hinton agar. On latter, cefoxitin, ampicillin, vancomycin, piperacillin/tazobactam, meropenem and ciprofloxacin were added. After 6 h, subcultures and RAST were imaged and MALDI-TOF MS was performed. Zone sizes were digitally measured and interpreted following RAST breakpoints for blood cultures. MIC values were determined using Vitek2 panels. During a 1-year period, 197 Staphylococcus aureus, 91 Enterococcus spp., 38 Escherichia coli, 11 Klebsiella pneumoniae and 8 Pseudomonas aeruginosa were found. Categorical agreement between RAST and MIC was 96.5%. Comparison showed no very major errors, 2/7 (28.6%) and 1/7 (14.3%) of major errors for P. aeruginosa and meropenem and ciprofloxacin, 1/9 (11.1%) for K. pneumoniae and ciprofloxacin, 4/69 (7.0%) and 3/43 (5.8%) for Enterococcus spp. and vancomycin and ampicillin, respectively. Minor errors for P. aeruginosa and meropenem (1/8; 12.8%) and for E. coli and ciprofloxacin (2/29; 6.5%) were found. 30/550 RAST measurements were within area of technical uncertainty. RAST is applicable and performs well for primarily sterile body fluids in blood culture bottles, partially better than blood-based RAST. Official EUCAST evaluation is needed.

Phytotoxic Effect of Decaying Quackgrass (Agropyron repens) Residues

Weed Science ◽  
1979 ◽  
Vol 27 (6) ◽  
pp. 595-598 ◽  
Author(s):  
T. V. Toai ◽  
D. L. Linscott
Keyword(s):  
Incubation Temperature ◽  
Soil Surface ◽  
Water Soluble ◽  
Water Extracts ◽  
Phytotoxic Activity ◽  
Phytotoxic Effect ◽  
Effects Of Temperature ◽  
Incubation Temperatures ◽  
Toxin Formation ◽  
Agropyron Repens

We studied the effects of temperature (5, 10, 20, and 30 C) on the phytotoxic activity of decaying quackgrass [Agropyron repens (L.) Beauv.] leaves and rhizomes that were incubated in soils for 0, 1, 2, 4, and 6 weeks. Alfalfa (Medicago sativa L.) seeds were grown for 96 h in water, water extracts of control soils, and water extracts of soil with quackgrass rhizomes or leaves. Dried quackgrass rhizomes and leaves contained water-soluble toxins that inhibited alfalfa seedling development and growth. There was a strong interaction between incubation time and temperature on the development of additional toxins by decomposing quackgrass. High incubation temperature (30 C) accelerated toxin formation and ultimate decay. Intermediate temperature (20 C) delayed toxin formation and decay. Low incubation temperatures (5 C and 10 C) prevented formation of additional toxin. In all extracts of quackgrass and soil that had been incubated for 6 weeks, normal alfalfa seedling number equaled that in water. However, seedling growth varied with incubation temperatures.Treatment of quackgrass with glyphosate [N-(phosphonomethyl) glycine] in the greenhouse did not influence the toxicity of decaying quackgrass leaves. The highest toxic effect was noted after 1 week of decay on the soil surface.

scholarly journals Efficacy of compressed sodium chloride (CSC) against E. coli and Candida auris in minutes and methods improvement for testing

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Lan N. Truong ◽  
Brayden D. Whitlock
Keyword(s):  
Sodium Chloride ◽  
Improved Method ◽  
Candida Auris ◽  
Antimicrobial Surfaces ◽  
E Coli ◽  
Route Of Transmission ◽  
The World ◽  
Short Time ◽  
First Time ◽  
Time Point

AbstractControlling infections has become one of the biggest problems in the world, whether measured in lives lost or money spent. This is worsening as pathogens continue becoming resistant to therapeutics. Antimicrobial surfaces are one strategy being investigated in an attempt to decrease the spread of infections through the most common route of transmission: surfaces, including hands. Regulators have chosen two hours as the time point at which efficacy should be measured. The objectives of this study were to characterize the new antimicrobial surface compressed sodium chloride (CSC) so that its action may be understood at timepoints more relevant to real-time infection control, under two minutes; to develop a sensitive method to test efficacy at short time points; and to investigate antifungal properties for the first time. E. coli and Candida auris are added to surfaces, and the surfaces are monitored by contact plate, or by washing into collection vats. An improved method of testing antimicrobial efficacy is reported. Antimicrobial CSC achieves at least 99.9% reduction of E. coli in the first two minutes of contact, and at least 99% reduction of C. auris in one minute.

scholarly journals In Escherichia coli Ammonia Inhibits Cytochrome bo3 But Activates Cytochrome bd-I

Antioxidants ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 13
Author(s):  
Elena Forte ◽  
Sergey A. Siletsky ◽  
Vitaliy B. Borisov
Keyword(s):  
Escherichia Coli ◽  
Molecular Mechanisms ◽  
Dissociation Constants ◽  
Reductase Activity ◽  
Ammonia Concentration ◽  
High Concentration ◽  
E Coli ◽  
Cytochrome Bd ◽  
Cytochrome Bo3 ◽  
Oxygen Reductase

Interaction of two redox enzymes of Escherichia coli, cytochrome bo3 and cytochrome bd-I, with ammonium sulfate/ammonia at pH 7.0 and 8.3 was studied using high-resolution respirometry and absorption spectroscopy. At pH 7.0, the oxygen reductase activity of none of the enzymes is affected by the ligand. At pH 8.3, cytochrome bo3 is inhibited by the ligand, with 40% maximum inhibition at 100 mM (NH4)2SO4. In contrast, the activity of cytochrome bd-I at pH 8.3 increases with increasing the ligand concentration, the largest increase (140%) is observed at 100 mM (NH4)2SO4. In both cases, the effector molecule is apparently not NH4+ but NH3. The ligand induces changes in absorption spectra of both oxidized cytochromes at pH 8.3. The magnitude of these changes increases as ammonia concentration is increased, yielding apparent dissociation constants Kdapp of 24.3 ± 2.7 mM (NH4)2SO4 (4.9 ± 0.5 mM NH3) for the Soret region in cytochrome bo3, and 35.9 ± 7.1 and 24.6 ± 12.4 mM (NH4)2SO4 (7.2 ± 1.4 and 4.9 ± 2.5 mM NH3) for the Soret and visible regions, respectively, in cytochrome bd-I. Consistently, addition of (NH4)2SO4 to cells of the E. coli mutant containing cytochrome bd-I as the only terminal oxidase at pH 8.3 accelerates the O2 consumption rate, the highest one (140%) being at 27 mM (NH4)2SO4. We discuss possible molecular mechanisms and physiological significance of modulation of the enzymatic activities by ammonia present at high concentration in the intestines, a niche occupied by E. coli.

Sign in / Sign up

Export Citation Format

Share Document