scholarly journals Broth microdilution testing of Haemophilus influenzae with haemophilus test medium versus lysed horse blood broth. Canadian Haemophilus Study Group.

1992 ◽  
Vol 30 (9) ◽  
pp. 2284-2289 ◽  
Author(s):  
S R Scriver ◽  
D E Low ◽  
A E Simor ◽  
B Toye ◽  
A McGeer ◽  
...  
Keyword(s):  
Haemophilus Influenzae ◽  
Study Group ◽  
Broth Microdilution ◽  
Test Medium ◽  
Horse Blood ◽  
Lysed Horse Blood

scholarly journals Effect of Polysorbate 80 on Oritavancin Binding to Plastic Surfaces: Implications for Susceptibility Testing

2008 ◽  
Vol 52 (5) ◽  
pp. 1597-1603 ◽  
Author(s):  
Francis F. Arhin ◽  
Ingrid Sarmiento ◽  
Adam Belley ◽  
Geoffrey A. McKay ◽  
Deborah C. Draghi ◽  
...  
Keyword(s):  
Clinical Isolates ◽  
Polysorbate 80 ◽  
Broth Microdilution ◽  
Microdilution Method ◽  
Drug Concentrations ◽  
Broth Microdilution Method ◽  
Horse Blood ◽  
Lysed Horse Blood ◽  
Susceptibility Assay

ABSTRACT Oritavancin, a semisynthetic lipoglycopeptide with activity against gram-positive bacteria, has multiple mechanisms of action, including the inhibition of cell wall synthesis and the perturbation of the membrane potential. Approved guidelines for broth microdilution MIC assays with dalbavancin, another lipoglycopeptide, require inclusion of 0.002% polysorbate 80. To investigate the potential impact of polysorbate 80 on oritavancin susceptibility assays, we quantified the recovery of [14C]oritavancin from susceptibility assay plates with and without polysorbate 80 and examined the effect of the presence of polysorbate 80 on the oritavancin MICs for 301 clinical isolates from the genera Staphylococcus, Enterococcus, and Streptococcus. In the absence of polysorbate 80, [14C]oritavancin was rapidly lost from solution in susceptibility assay test plates: 9% of the input drug was recovered in broth at 1 h when [14C]oritavancin was tested at 1 μg/ml. Furthermore, proportionately greater losses were observed at lower oritavancin concentrations, suggesting saturable binding of oritavancin to surfaces. The inclusion of 0.002% polysorbate 80 or 2% lysed horse blood permitted the recovery of 80 to 100% [14C]oritavancin at 24 h for all drug concentrations tested. Concordantly, oritavancin MIC90s for streptococcal isolates, as determined in medium containing 2% lysed horse blood, were identical with and without polysorbate 80. In stark contrast, polysorbate 80 reduced the oritavancin MIC90s by 16- to 32-fold for clinical isolates of enterococci and staphylococci, which are typically cultured without blood. The results presented here provide evidence that the MIC data for oritavancin in the current literature significantly underestimate the potency of oritavancin in vitro. Moreover, the combination of data from MIC and [14C]oritavancin recovery studies supports the revision of the oritavancin broth microdilution method to include polysorbate 80 throughout the assay.

scholarly journals Myeloperoxidase Selectively Binds and Selectively Kills Microbes

2010 ◽  
Vol 79 (1) ◽  
pp. 474-485 ◽  
Author(s):  
Robert C. Allen ◽  
Jackson T. Stephens
Keyword(s):  
Streptococcus Pyogenes ◽  
Direct Evidence ◽  
Minimal Bactericidal Concentration ◽  
Viridans Streptococci ◽  
E Coli ◽  
Horse Blood ◽  
Valid Comparison ◽  
Relationship Of ◽  
The Relationship ◽  
Lysed Horse Blood

ABSTRACTMyeloperoxidase (MPO) is reported to selectively bind to bacteria. The present study provides direct evidence of MPO binding selectivity and tests the relationship of selective binding to selective killing. The microbicidal effectiveness of H2O2and of OCl−was compared to that of MPO plus H2O2. Synergistic microbicidal action was investigated by combiningStreptococcus sanguinis, a H2O2-producing microbe showing low MPO binding, with high-MPO-bindingEscherichia coli,Staphylococcus aureus, orPseudomonas aeruginosawithout exogenous H2O2, with and without MPO, and with and without erythrocytes (red blood cells [RBCs]). Selectivity of MPO microbicidal action was conventionally measured as the MPO MIC and minimal bactericidal concentration (MBC) for 82 bacteria includingE. coli,P. aeruginosa,S. aureus,Enterococcus faecalis,Streptococcus pyogenes,Streptococcus agalactiae, and viridans streptococci. Both H2O2and OCl−destroyed RBCs at submicrobicidal concentrations. Nanomolar concentrations of MPO increased H2O2microbicidal action 1,000-fold. Streptococci plus MPO produced potent synergistic microbicidal action against all microbes tested, and RBCs caused only a small decrease in potency without erythrocyte damage. MPO directly killed H2O2-producingS. pyogenesbut was ineffective against non-H2O2-producingE. faecalis. The MPO MICs and MBCs forE. coli,P. aeruginosa, andS. aureuswere significantly lower than those forE. faecalis.The streptococcal studies showed much higher MIC/MBC results, but such testing required lysed horse blood-supplemented medium, thus preventing valid comparison of these results to those for the other microbes.E. faecalisMPO binding is reportedly weak compared to binding ofE. coli,P. aeruginosa, andS. aureusbut strong compared to binding of streptococci. Selective MPO binding results in selective killing.

scholarly journals Day care characteristics associated with Haemophilus influenzae disease. Haemophilus influenzae Study Group.

1990 ◽  
Vol 80 (12) ◽  
pp. 1455-1458 ◽  
Author(s):  
J D Wenger ◽  
L H Harrison ◽  
A Hightower ◽  
C V Broome
Keyword(s):  
Haemophilus Influenzae ◽  
Day Care ◽  
Study Group

scholarly journals Activities of Trovafloxacin, Gatifloxacin, Clinafloxacin, Sparfloxacin, Levofloxacin, and Ciprofloxacin against Penicillin-Resistant Streptococcus pneumoniae in an In Vitro Infection Model

2000 ◽  
Vol 44 (3) ◽  
pp. 598-601 ◽  
Author(s):  
Ellie Hershberger ◽  
Michael J. Rybak
Keyword(s):  
Streptococcus Pneumoniae ◽  
Fibrin Clot ◽  
Infection Model ◽  
Significant Activity ◽  
Time Curve ◽  
Horse Blood ◽  
Bactericidal Activities ◽  
Lysed Horse Blood ◽  
Fibrin Clots

ABSTRACT We adapted an in vitro pharmacodynamic model of infection to incorporate infected fibrin clots. The bactericidal activities of various fluoroquinolones against two strains of penicillin-resistantStreptococcus pneumoniae were studied over a 48-h period. Bacteria were prepared in Muller-Hinton broth by using colonies from a 24-h tryptic soy agar plus 5% sheep blood plate and were added to a mixture of cryoprecipitate (80%) and thrombin (10%) to achieve approximately 106 CFU of organism per fibrin clot. The fibrin clots were suspended into the models and removed, in triplicate, at various time points over 48 h. Control models were also conducted to characterize the growth of S. pneumoniae in the growth medium without antibiotic. Trovafloxacin, gatifloxacin, clinafloxacin, sparfloxacin, levofloxacin, and ciprofloxacin were administered to simulate their pharmacokinetic profiles in humans. Fibrin clot samples were also plated onto antibiotic-containing tryptic soy agar plus 5% lysed horse blood to detect resistance. The newer fluoroquinolones demonstrated better activity than ciprofloxacin against both isolates. In conclusion, the newer quinolones demonstrated significant activity against penicillin-resistant S. pneumoniae, with standard dosing resulting in area under the concentration-time curve/MIC ratios and peak concentration/MIC ratios that resulted in 99.9% killing against these isolates.

scholarly journals Comparison of Broth Microdilution Method UsingHaemophilus Test Medium and Agar Dilution Method for Susceptibility Testing of Eikenella corrodens

1998 ◽  
Vol 36 (8) ◽  
pp. 2386-2388 ◽  
Author(s):  
Luis Alcalá ◽  
Fernando García-Garrote ◽  
Emilia Cercenado ◽  
Teresa Peláez ◽  
Gema Ramos ◽  
...  
Keyword(s):  
Antimicrobial Agents ◽  
Susceptibility Testing ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Broth Microdilution ◽  
Test Medium ◽  
Eikenella Corrodens ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Agar Dilution

Susceptibility testing of Eikenella corrodens is usually performed by a Mueller-Hinton sheep blood agar dilution (AD) method. However, this method is impractical for testing only a few strains. We compared AD with the broth microdilution method usingHaemophilus test medium (HTM) in order to determine the susceptibility of 36 clinical isolates of E. corrodens to eight antimicrobial agents. MICs obtained by the HTM method yielded 95.5 and 84% agreement (within 2 and 1 log2 dilutions, respectively) with those obtained by AD. The HTM method with incubation in CO2 for 48 h was highly reproducible and constitutes an easy alternative for antimicrobial susceptibility testing of E. corrodens.

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