scholarly journals Tigecycline MIC Testing by Broth Dilution Requires Use of Fresh Medium or Addition of the Biocatalytic Oxygen-Reducing Reagent Oxyrase To Standardize the Test Method

2005 ◽  
Vol 49 (9) ◽  
pp. 3903-3909 ◽  
Author(s):  
Patricia A. Bradford ◽  
Peter J. Petersen ◽  
Mairead Young ◽  
C. Hal Jones ◽  
Mark Tischler ◽  
...  
Keyword(s):  
Standardized Test ◽  
Culture Collection ◽  
Fresh Medium ◽  
Test Method ◽  
Chromatography Analysis ◽  
Mueller Hinton ◽  
Early Peak ◽  
The Media ◽  
Time Kill ◽  
Mueller Hinton Broth

ABSTRACT Tigecycline is a broad-spectrum glycylcycline antibiotic with activity against not only susceptible gram-positive and gram-negative pathogens but also strains that are resistant to many other antibiotics. In the process of determining quality control (QC) limits for the American Type Culture Collection reference strains for tigecycline, a number of inconsistencies in MICs were encountered which appeared to be related to the age of the Mueller-Hinton broth (MHB) medium used in the MIC testing. The objective of this study was to determine the cause of the discrepant MIC results between fresh and aged MHB. The MICs of tigecycline were determined in MHB that was either prepared fresh (<12 h old), prepared and stored at 4°C, stored at room temperature, stored anaerobically, or supplemented with the biocatalytic oxygen-reducing reagent Oxyrase. When tested in fresh media, tigecycline was 2 to 3 dilutions more active against the CLSI-recommended QC strains compared to aged media (MICs of 0.03 to 0.25 and 0.12 to 0.5 μg/ml, respectively). Media aged under anaerobic conditions prior to testing or supplemented with Oxyrase resulted in MICs similar to those obtained in fresh medium (MICs of 0.03 to 0.12 and 0.03 to 0.25 μg/ml, respectively). Time-kill kinetics demonstrated a >3 log10 difference in viable growth when tigecycline was tested in fresh or Oxyrase-supplemented MHB compared to aged MHB. High-pressure liquid chromatography analysis revealed the accumulation of an early peak (oxidative by-product of tigecycline) to be 3.5% in fresh media and 25.1% in aged media after 24 h and that addition of Oxyrase prevented the accumulation of this oxidized by-product. These results suggested that the activity of tigecycline was affected by the amount of dissolved oxygen in the media. The use of fresh MHB or supplementation with Oxyrase resulted in a more standardized test method for performing MIC tests with tigecycline.

scholarly journals Method for evaluating broth culture media: application to Haemophilus

1978 ◽  
Vol 8 (5) ◽  
pp. 520-524
Author(s):  
A W Brinkley ◽  
T W Huber
Keyword(s):  
Nicotinamide Adenine Dinucleotide ◽  
Research Laboratory ◽  
Culture Media ◽  
Nicotinamide Adenine ◽  
Broth Culture ◽  
Mueller Hinton ◽  
The Media ◽  
Growth Promoting ◽  
Mueller Hinton Broth

A method was devised to test the growth-promoting ability of a broth medium. The "dilute to extinction" method determines the inoculum required to develop heavy turbidity in a broth with overnight incubation. A statistical method using Poisson distribution was used to show that a single Haemophilus cell can develop heavy turbidity in an optimal broth. The dilute to extinction method was used to evaluate the shelf life of stored media, to titrate the growth factor requirements of Haemophilus, and to evaluate the use of purified hemin and nicotinamide adenine dinucleotide in a broth medium for the growth of Haemophilus. Of the media tested, the most suitable formulation was Mueller-Hinton broth supplemented with 10 microgram of hemin and 10 microgram of nicotinamide adenine dinucleotide per ml. The dilute to extinction method appears to be especially useful in the development of broth media for fastidious organisms. The method could also be used to assure the quality of other broth media which are required to support the growth of small inocula in the clinical or research laboratory.

Impediometric Detection of Campylobacter coli

2002 ◽  
Vol 65 (10) ◽  
pp. 1660-1662 ◽  
Author(s):  
JOHN E. MOORE ◽  
ROBERT H. MADDEN
Keyword(s):  
Yeast Extract ◽  
Brain Heart Infusion ◽  
Campylobacter Coli ◽  
Growth Substrate ◽  
Wild Type ◽  
Mueller Hinton ◽  
Impedance Technique ◽  
The Media ◽  
Charged Ions ◽  
Mueller Hinton Broth

The rapid automated bacterial impedance technique (RABIT) was examined as a method for the detection of two wild-type isolates of Campylobacter coli in broth media. Both isolates failed to produce a change in impedance that was sufficient for detection in any combination of six nonselective basal broth media, including Mueller-Hinton broth, nutrient broth no. 2, brain heart infusion broth supplemented with yeast extract (0.5% [wt/vol]), brucella broth, Campy broth supplemented with yeast extract (0.5% [wt/vol]), and Whitley impedance broth, at 37 and 42°C. Although the strains did proliferate in the media, changes in conductivity were very small (ranging from 0 to 1,000 μS) and were not significantly greater than the drift in conductance observed in the control broth medium. Additional work is therefore required to define a nonionic growth substrate that will produce charged ions upon metabolism that are detectable by RABIT.

scholarly journals Stability studies with tigecycline in bacterial growth medium and impact of stabilizing agents

2020 ◽  
Vol 40 (1) ◽  
pp. 215-218
Author(s):  
Lisa F. Amann ◽  
Emilia Ruda Vicente ◽  
Mareike Rathke ◽  
Astrid Broeker ◽  
Maria Riedner ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Bacterial Growth ◽  
Susceptibility Testing ◽  
Stability Studies ◽  
Rapid Degradation ◽  
Stabilizing Agents ◽  
Mueller Hinton ◽  
Therapeutic Decisions ◽  
Time Kill ◽  
Mueller Hinton Broth

Abstract Purpose This study aimed to examine the degradation of tigecycline in Mueller Hinton broth (ca-MHB), as knowledge about bacterial susceptibility is key for therapeutic decisions. Methods Antioxidative stabilizers were evaluated on tigecycline stability in a quantitative chromatography assay and tigecycline induced kill against Staphylococcus aureus (ATCC29213) was determined in time kill studies. Results Ascorbic acid caused rapid degradation of tigecycline and resulted in loss of antibacterial activity. Tigecycline was stabilized in aged broth by 2% pyruvate and bacterial growth, and tigecycline killing was similar to fresh broth without supplementation, but independent of age. Conclusion Our results underline the importance of using freshly prepared ca-MHB or the need for stabilizers for tigecycline susceptibility testing while using aged ca-MHB.

scholarly journals Twenty-four-hour area under the concentration-time curve/MIC ratio as a generic predictor of fluoroquinolone antimicrobial effect by using three strains of Pseudomonas aeruginosa and an in vitro pharmacodynamic model.

1996 ◽  
Vol 40 (3) ◽  
pp. 627-632 ◽  
Author(s):  
K J Madaras-Kelly ◽  
B E Ostergaard ◽  
L B Hovde ◽  
J C Rotschafer
Keyword(s):  
Antibacterial Effect ◽  
Antimicrobial Effect ◽  
Time Curve ◽  
Emax Model ◽  
Concentration Time ◽  
Mueller Hinton ◽  
Kill Curve ◽  
Time Kill ◽  
Mueller Hinton Broth

Several investigators have suggested that the 24-h area under the concentration-time curve (AUC)/MIC ratio (AUC/MIC24 or AUIC24) can be used to make comparisons of antimicrobial activity between fluoroquinolone antibiotics. Limited data exist regarding the generic predictive ability of AUC/MIC24 for the antimicrobial effects of fluoroquinolones. The purposes of the present investigation were to determine if the AUC/MIC24 can be used as a generic outcome predictor of fluoroquinolone antibacterial activity and to determine if a similar AUC/MIC24 breakpoint can be established for different fluoroquinolones. Using an in vitro pharmacodynamic model, 29 duplicate concentration time-kill curve experiments simulated AUC/MIC24s ranging from 52 to 508 SIT-1.h (inverse serum inhibitory titer integrated over time) with ciprofloxacin or ofloxacin against three strains of Pseudomonas aeruginosa. Each 24-h experiment was performed in cation-supplemented Mueller-Hinton broth with a starting inoculum of 10(6) CFU/ml. At timed intervals cation-supplemented Mueller-Hinton broth samples were collected for CFU and fluoroquinolone concentration determinations. Transformation of bacterial counts into the cumulative bacterial effect parameter of the 24-h area under the effect curve (AUEC24) was performed for each concentration time-kill curve. Multivariate regression analysis was used to compare pharmacodynamic predictors (AUC/MIC24, 24-h AUC, peak concentration [Cmax] to MIC ratios [Cmax:MIC], etc.) with ln AUEC24. To identify threshold breakpoint AUC/MIC24s, AUEC24s were stratified by the magnitude of AUC/MIC24 into subgroups, which were analyzed for differences in antibacterial effect. The Kruskal-Wallis test and subsequent Tukey's multiple comparison test were used to determine which AUC/MIC subgroups were significantly different. Multiple regression analysis revealed that only AUC/MIC24 (r2 = 0.65) and MIC (r2 = 0.03) were significantly correlated with antibacterial effect. At similar AUC/MIC24s, yet different MICs, Cmaxs, or elimination half-lives, the AUEC24s were similar for both fluoroquinolones. The relationship between AUC/MIC24 and ln AUEC24 was best described by a sigmoidal maximal antimicrobial effect (Emax) model (r2 = 0.72; Emax = 9.1; AUC/MIC50 = 119 SIT-1.h; S = 2.01 [S is an exponent that reflects the degree of sigmoidicity]). Ciprofloxacin-bacteria AUC/MIC24 values of < 100 SIT-1.h were significantly different (P < 0.05) from the AUC/MIC24 values of > 100 SIT-1.h. An ofloxacin AUC/MIC24 of > 100 SIT-1.h and an AUC/MIC24 of < 100 SIT-1.h exhibited a trend toward a significant difference (P > 0.05 but < 0.1). The inverse relationship between drug exposure and MIC increase postexposure was described by a sigmoidal fixed Emax model (AUC/MIC24, r2 = 0.40; AUC/MIC50 = 95 SIT-1.h; S = 1.97; Cmax:MIC, r2 = 0.41; Cmax:MIC50 = 7.3; S = 2.01). These data suggest that AUC/MIC24 may be the most descriptive measurement of fluoroquinolone antimicrobial activity against P. aeruginosa, that ofloxacin and ciprofloxacin have similar AUC/MIC24 threshold breakpoints at approximately 100 SIT-1.h, that the concentration-dependent selection of resistant organisms may parallel the threshold breakpoint of the antimicrobial effect, and that AUC/MIC24 generically describes the antibacterial effects of different fluoroquinolones.

scholarly journals In Vitro Bactericidal Activities of ABT-773 against ermB Strains of Streptococcus pneumoniae

2003 ◽  
Vol 47 (3) ◽  
pp. 1132-1134 ◽  
Author(s):  
Melinda M. Neuhauser ◽  
Jennifer L. Prause ◽  
Larry H. Danziger ◽  
Susan L. Pendland
Keyword(s):  
Streptococcus Pneumoniae ◽  
Beta Lactam ◽  
Beta Lactam Antibiotics ◽  
Mueller Hinton ◽  
Amoxicillin Clavulanate ◽  
Horse Blood ◽  
Bactericidal Activities ◽  
Time Kill ◽  
Mueller Hinton Broth

ABSTRACT The bactericidal activities of ABT-773, a new ketolide, were compared to those of cefuroxime and amoxicillin-clavulanate against 10 strains of Streptococcus pneumoniae containing the ermB gene. MICs and time-kill curves were determined in duplicate per NCCLS guidelines with cation-adjusted Mueller-Hinton broth with 3% lysed horse blood. Viable counts were done at 0, 2, 6, and 24 h. Antibiotic concentrations tested were two and eight times the MIC. ABT-773 MICs ranged from 0.008 to 1.0 μg/ml. Bactericidal activity was observed with ABT-773 at eight times the MIC against 4 of 10 strains at 24 h compared to 10 of 10 strains with the beta-lactam antibiotics.

In vitro Time Kill of Trimethoprim/Sulfamethoxazole against Stenotrophomonas maltophilia versus Escherichia coli using Cation Adjusted Muller Hinton Broth and ISO-Sensitest Broth

2022 ◽  
Author(s):  
Maxwell J. Lasko ◽  
Matthew L. Gethers ◽  
Jennifer L. Tabor-Rennie ◽  
David P. Nicolau ◽  
Joseph L. Kuti
Keyword(s):  
Escherichia Coli ◽  
Stenotrophomonas Maltophilia ◽  
E Coli ◽  
Optimal Dosing ◽  
Mueller Hinton ◽  
Colony Forming Units ◽  
Time Kill ◽  
Pharmacodynamic Data ◽  
Mueller Hinton Broth

Trimethoprim/sulfamethoxazole (TMP/SMZ) is considered the treatment of choice for infections caused by Stenotrophomonas maltophilia , but limited pharmacodynamic data are available to support current susceptibility breakpoints or guide optimal dosing. Time-kill studies using a TMP/SMZ concentration of 4/40 μg/mL were conducted to compare 4 S. maltophilia with 4 Escherichia coli having the same MICs (0.25/4.75-4/76 μg/mL) in cation adjusted Mueller Hinton Broth (CAMHB) and ISO-Sensitest™ broth (ISO). With the exception of the resistant isolates (4/76 μg/mL), which resulted in regrowth approaching control, TMP/SMZ displayed significantly greater killing for E. coli compared with S. maltophilia at each MIC. Against E. coli , mean changes at 24 hour were -4.49, -1.73, -1.59, and +1.83 log 10 colony forming units (CFU) for isolates with MICs of 0.25/4.75, 1/19, 2/39, and 4/74 μg/mL, respectively. The f AUC/MIC required for stasis, 1-log 10 , and 2-log 10 CFU reductions were 40.7, 59.5, and 86.3, respectively. In contrast, TMP/SMZ displayed no stasis or CFU reductions against any S. maltophilia regardless of MIC, and no pharmacodynamic thresholds were quantifiable. Observations were consistent in both CAMHB and ISO broth. These data add increasing evidence that current TMP/SMZ susceptibility breakpoints against S. maltophilia should be reassessed.

scholarly journals Recording the Presence of Peanibacillus larvae larvae Colonies on MYPGP Substrates Using a Multi-Sensor Array Based on Solid-State Gas Sensors

Sensors ◽  
2021 ◽  
Vol 21 (14) ◽  
pp. 4917
Author(s):  
Beata Bąk ◽  
Jakub Wilk ◽  
Piotr Artiemjew ◽  
Jerzy Wilde
Keyword(s):  
Gas Sensors ◽  
Culture Media ◽  
Laboratory Diagnosis ◽  
Baseline Correction ◽  
American Foulbrood ◽  
Sensor Signal ◽  
Sodium Pyruvate ◽  
Mueller Hinton ◽  
Regeneration Phase ◽  
Mueller Hinton Broth

American foulbrood is a dangerous disease of bee broods found worldwide, caused by the Paenibacillus larvae larvae L. bacterium. In an experiment, the possibility of detecting colonies of this bacterium on MYPGP substrates (which contains yeast extract, Mueller-Hinton broth, glucose, K2HPO4, sodium pyruvate, and agar) was tested using a prototype of a multi-sensor recorder of the MCA-8 sensor signal with a matrix of six semiconductors: TGS 823, TGS 826, TGS 832, TGS 2600, TGS 2602, and TGS 2603 from Figaro. Two twin prototypes of the MCA-8 measurement device, M1 and M2, were used in the study. Each prototype was attached to two laboratory test chambers: a wooden one and a polystyrene one. For the experiment, the strain used was P. l. larvae ATCC 9545, ERIC I. On MYPGP medium, often used for laboratory diagnosis of American foulbrood, this bacterium produces small, transparent, smooth, and shiny colonies. Gas samples from over culture media of one- and two-day-old foulbrood P. l. larvae (with no colonies visible to the naked eye) and from over culture media older than 2 days (with visible bacterial colonies) were examined. In addition, the air from empty chambers was tested. The measurement time was 20 min, including a 10-min testing exposure phase and a 10-min sensor regeneration phase. The results were analyzed in two variants: without baseline correction and with baseline correction. We tested 14 classifiers and found that a prototype of a multi-sensor recorder of the MCA-8 sensor signal was capable of detecting colonies of P. l. larvae on MYPGP substrate with a 97% efficiency and could distinguish between MYPGP substrates with 1–2 days of culture, and substrates with older cultures. The efficacy of copies of the prototypes M1 and M2 was shown to differ slightly. The weighted method with Canberra metrics (Canberra.811) and kNN with Canberra and Manhattan metrics (Canberra. 1nn and manhattan.1nn) proved to be the most effective classifiers.

scholarly journals Laboratory Test to Evaluate the Resistance of Cementitious Materials to Biodeterioration in Sewer Network Conditions

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 686
Author(s):  
Amr Aboulela ◽  
Matthieu Peyre Lavigne ◽  
Amaury Buvignier ◽  
Marlène Fourré ◽  
Maud Schiettekatte ◽  
...  
Keyword(s):  
Calcium Aluminate ◽  
Standardized Test ◽  
Performance Indicator ◽  
Cementitious Materials ◽  
Test Method ◽  
Sustainable Construction ◽  
Public Health Issue ◽  
Sulfur Source ◽  
Test Protocol ◽  
Wide Range

The biodeterioration of cementitious materials in sewer networks has become a major economic, ecological, and public health issue. Establishing a suitable standardized test is essential if sustainable construction materials are to be developed and qualified for sewerage environments. Since purely chemical tests are proven to not be representative of the actual deterioration phenomena in real sewer conditions, a biological test–named the Biogenic Acid Concrete (BAC) test–was developed at the University of Toulouse to reproduce the biological reactions involved in the process of concrete biodeterioration in sewers. The test consists in trickling a solution containing a safe reduced sulfur source onto the surface of cementitious substrates previously covered with a high diversity microbial consortium. In these conditions, a sulfur-oxidizing metabolism naturally develops in the biofilm and leads to the production of biogenic sulfuric acid on the surface of the material. The representativeness of the test in terms of deterioration mechanisms has been validated in previous studies. A wide range of cementitious materials have been exposed to the biodeterioration test during half a decade. On the basis of this large database and the expertise gained, the purpose of this paper is (i) to propose a simple and robust performance criterion for the test (standardized leached calcium as a function of sulfate produced by the biofilm), and (ii) to demonstrate the repeatability, reproducibility, and discriminability of the test method. In only a 3-month period, the test was able to highlight the differences in the performances of common cement-based materials (CEM I, CEM III, and CEM V) and special calcium aluminate cement (CAC) binders with different nature of aggregates (natural silica and synthetic calcium aluminate). The proposed performance indicator (relative standardized leached calcium) allowed the materials to be classified according to their resistance to biogenic acid attack in sewer conditions. The repeatability of the test was confirmed using three different specimens of the same material within the same experiment and the reproducibility of the results was demonstrated by standardizing the results using a reference material from 5 different test campaigns. Furthermore, developing post-testing processing and calculation methods constituted a first step toward a standardized test protocol.

scholarly journals In Vitro Activities of Daptomycin against 2,789 Clinical Isolates from 11 North American Medical Centers

2001 ◽  
Vol 45 (6) ◽  
pp. 1919-1922 ◽  
Author(s):  
Arthur L. Barry ◽  
Peter C. Fuchs ◽  
Steven D. Brown
Keyword(s):  
Clinical Isolates ◽  
In Vitro Activity ◽  
Broth Microdilution ◽  
In Vitro Susceptibility ◽  
Medical Centers ◽  
Mueller Hinton ◽  
Calcium Cations ◽  
Important Exception ◽  
Mueller Hinton Broth

ABSTRACT The in vitro activity of daptomycin is affected by the concentration of calcium cations in the test medium. Mueller-Hinton broth is currently adjusted to contain 10 to 12.5 mg of magnesium per liter and 20 to 25 mg of calcium per liter, but for testing of daptomycin, greater concentrations of calcium (50 mg/liter) are recommended to better resemble the normal concentration of ionized calcium in human serum. Two levels of calcium were used for broth microdilution tests of 2,789 recent clinical isolates of gram-positive bacterial pathogens. MICs of daptomycin were two- to fourfold lower when the broth contained additional calcium. For most species, however, the percentages of strains that were inhibited by 2.0 μg of daptomycin per ml were essentially identical with the two broth media. Enterococci were the important exception; i.e., 92% were inhibited when tested in calcium-supplemented broth but only 35% were inhibited by 2.0 μg/ml without the additional calcium. This type of information should be considered when selecting criteria for defining in vitro susceptibility to daptomycin.

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