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.

scholarly journals In VitroActivity of Fosfomycin against a Collection of Clinical Pseudomonas aeruginosa Isolates from 16 Spanish Hospitals: Establishing the Validity of Standard Broth Microdilution as Susceptibility Testing Method

2013 ◽  
Vol 57 (11) ◽  
pp. 5701-5703 ◽  
Author(s):  
María Díez-Aguilar ◽  
María-Isabel Morosini ◽  
Rosa del Campo ◽  
María García-Castillo ◽  
Javier Zamora ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Susceptibility Testing ◽  
Disk Diffusion ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Broth Microdilution ◽  
Content Type ◽  
Testing Method ◽  
Broth Microdilution Method ◽  
Agar Dilution

ABSTRACTThe broth microdilution method for fosfomycin andPseudomonas aeruginosawas assessed and compared with the approved agar dilution method in 206 genetically unrelatedP. aeruginosaclinical isolates. Essential agreement between the two methods was 84%, and categorical agreement was 89.3%. Additionally, Etest and disk diffusion assays were performed. Results validate broth microdilution as a reliable susceptibility testing method for fosfomycin againstP. aeruginosa. Conversely, unacceptable concordance was established between Etest and disk diffusion results with agar dilution results.

scholarly journals Comparison of methods for the determination of antimicrobial resistance in Campylobacter spp. human and the food chain isolates

2008 ◽  
Vol 52 (No. 4) ◽  
pp. 169-174
Author(s):  
M. Holasova ◽  
R. Karpiskova ◽  
S. Karpiskova ◽  
V. Babak ◽  
J. Schlegelova
Keyword(s):  
Nalidixic Acid ◽  
Antimicrobial Agents ◽  
Disk Diffusion ◽  
Diffusion Method ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Disk Diffusion Method ◽  
Microdilution Method ◽  
Study Results ◽  
Agar Dilution

With a microdilution method, using the commercial diagnostic test Sensititre Susceptibility Plates for Campylobacter MIC (Trek Diagnostic Systems, Cleveland, OH, USA), disk diffusion and agar dilution method, resistance to six antimicrobial agents were examined in a reference strain <i>Campylobacter jejuni</i> ATCC 33560 and 73 thermo-tolerant isolates of <i>Campylobacter</i> spp. For the microdilution method and all tested antimicrobial agents, our determined values of microbiological breakpoints of resistant strains were suggested as the minimum inhibitory concentration (MIC<sub>R</sub>) for ciprofloxacin &ge; 0.5, erythromycin &ge; 4, gentamicin &ge; 4, nalidixic acid &ge; 32 and tetracycline &ge; 4 &mu;g/ml. On the basis of our study results, strains resistant to clindamycin were MIC<sub>R</sub> &ge; 2 &mu;g/ml for the dilution methods and a zone diameter R ≤ 16 mm for the disk diffusion method. Comparison of the results of the resistance examination, a microdilution method and disk diffusion method with the reference agar dilution method, showed that all compared methods yielded identical results with the exception of the resistance determination in erythromycin and nalidixic acid. The errors were mostly the result of the interpretation criteria for MIC<sub>R</sub> of agar dilution method and different conditions of cultivation used. However, the compared methods, provide results comparable with the reference method having greater convenience of measurement.

scholarly journals Variation in erythromycin and clindamycin susceptibilities of Streptococcus pneumoniae by four test methods.

1997 ◽  
Vol 41 (1) ◽  
pp. 129-134 ◽  
Author(s):  
E L Fasola ◽  
S Bajaksouzian ◽  
P C Appelbaum ◽  
M R Jacobs
Keyword(s):  
Streptococcus Pneumoniae ◽  
Susceptibility Testing ◽  
Ambient Air ◽  
Test Methods ◽  
Disk Diffusion ◽  
Broth Microdilution ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Agar Dilution ◽  
Resistant Strains

Susceptibilities of 124 strains of Streptococcus pneumoniae to erythromycin and clindamycin were determined by the National Committee for the Clinical Laboratory Standards (NCCLS) broth microdilution method, with incubation for 20 to 24 h in ambient air and with modifications of this method by incubation for up to 48 h in air and CO2. Strains were also tested by agar dilution, E-test, and disk diffusion; good correlation was obtained with these methods, with clear separation into bimodal populations of susceptible and resistant stains. The broth microdilution method, however, using incubation in air for 24 h (NCCLS method), misclassified 4 of 92 erythromycin-resistant strains (1 as susceptible and 3 as intermediate) and 25 of 58 clindamycin-resistant strains (all as susceptible). With the exception of one strain with clindamycin, susceptible and resistant strains were correctly classified by the microdilution method with incubation in CO2 for 24 h or in ambient air for 48 h. Disk diffusion, agar dilution, and E-test methods with incubation in 5% CO2 are therefore reliable methods for susceptibility testing of pneumococci against these agents. However, the NCCLS microdilution method, which specifies incubation for 20 to 24 h in ambient air, produced significant very major errors (43%) clindamycin. Modification of the microdilution method by incubation in 5% CO2 or by extension of incubation time in ambient air to 48 h corrected these errors. Disk diffusion, however, was shown to be a simple, convenient, and reliable method for susceptibility testing of pneumococci to erythromycin and clindamycin and is suggested as the method of choice for these agents.

scholarly journals Broth Microdilution and Gradient Diffusion Strips vs. Reference Agar Dilution Method: First Evaluation for Clostridiales Species Antimicrobial Susceptibility Testing

Antibiotics ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 975
Author(s):  
Florian Baquer ◽  
Asma Ali Sawan ◽  
Michel Auzou ◽  
Antoine Grillon ◽  
Benoît Jaulhac ◽  
...  
Keyword(s):  
Antimicrobial Susceptibility ◽  
Susceptibility Testing ◽  
Reference Method ◽  
Antimicrobial Susceptibility Testing ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Broth Microdilution ◽  
Multicenter Studies ◽  
Gradient Diffusion ◽  
Agar Dilution

Antimicrobial susceptibility testing of anaerobes is challenging. Because MIC determination is recommended by both CLSI and EUCAST, commercial broth microdilution and diffusion strip tests have been developed. The reliability of broth microdilution methods has not been assessed yet using the agar dilution reference method. In this work, we evaluated two broth microdilution kits (MICRONAUT-S Anaerobes® MIC and Sensititre Anaerobe MIC®) and one gradient diffusion strip method (Liofilchem®) for antimicrobial susceptibility testing of 47 Clostridiales isolates (Clostridium, Clostridioides and Hungatella species) using the agar dilution method as a reference. The evaluation focused on comparing six antimicrobial molecules available in both microdilution kits. Analytical performances were evaluated according to the Food and Drug Administration (FDA) recommendations. Essential agreements (EA) and categorical agreements (CA) varied greatly according to the molecule and the evaluated method. Vancomycin had values of essential and categorical agreements above 90% for the three methods. The CA fulfilled the FDA criteria for three major molecules in the treatment of Gram-positive anaerobic infections (metronidazole, piperacillin/tazobactam and vancomycin). The highest rate of error was observed for clindamycin. Multicenter studies are needed to further validate these results.

scholarly journals Validation of a method of broth microdilution for the determination of antibacterial activity of essential oils

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Vanegas David ◽  
Abril-Novillo Andrea ◽  
Khachatryan Aleksandr ◽  
Jerves-Andrade Lourdes ◽  
Peñaherrera Eugenia ◽  
...  
Keyword(s):  
Essential Oils ◽  
Sensitivity And Specificity ◽  
Inhibitory Concentration ◽  
Tween 80 ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Broth Microdilution ◽  
Continuous Contact ◽  
Microdilution Method ◽  
Broth Microdilution Method

Abstract Objective The aim of the present study was to adapt and optimize a broth microdilution method and compare it to the agar dilution method for the evaluation of activity of essential oils from medicinal plants against Gram-negative bacteria. Based on bibliographic research, active and not active oils were selected. The sensitivity and specificity were established as parameters for validation. The comparison between both methods was made using contingency analysis tables, based on the observed frequencies. For both methods, the minimum inhibitory concentration was determined against Escherichiacoli strains, in an essential oil concentration range between 0.03 and 0.48% (v/v). Results A stable emulsion formation was achieved with the addition of Tween 80 and constant agitation, guaranteeing the continuous contact of oil with bacteria (critical step in the microdilution method). The statistical analysis of results obtained with both methods presented a good sensitivity and specificity (100% in both cases), which let us correctly discriminate between active and non-active oils. The values obtained for the minimal inhibitory concentration were independent of the technique used. Finally, the obtained results show that the validated microtechnique allows important diminishment of time and resources for investigations dealing with essential oils or lipophilic extracts evaluation.

scholarly journals In Vitro Antimicrobial Susceptibility Testing of Helicobacter felis, H. bizzozeronii, and H. salomonis

2005 ◽  
Vol 49 (7) ◽  
pp. 2997-3000 ◽  
Author(s):  
K. Van den Bulck ◽  
A. Decostere ◽  
I. Gruntar ◽  
M. Baele ◽  
B. Krt ◽  
...  
Keyword(s):  
Antimicrobial Agent ◽  
Antimicrobial Agents ◽  
Susceptibility Testing ◽  
Acquired Resistance ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Helicobacter Felis ◽  
Agar Dilution

ABSTRACT The susceptibilities of Helicobacter felis (15 strains), H. bizzozeronii (7 strains), and H. salomonis (3 strains) to 10 antimicrobial agents were investigated by determination of the MIC using the agar dilution method. No consistent differences were noticed between the different Helicobacter species, which were all highly susceptible to ampicillin, clarithromycin, tetracycline, tylosin, enrofloxacin, gentamicin, and neomycin, as demonstrated by low MICs. Higher MICs were obtained for lincomycin (up to 8 μg/ml) and spectinomycin (up to 4 μg/ml). Two H. felis strains showed a MIC of 16 μg/ml for metronidazole, suggesting acquired resistance to this antimicrobial agent.

scholarly journals Examination of the minimum inhibitory concentration of amoxicillin and marbofloxacin against Streptococcus suis using standardised methods

2020 ◽  
Vol 65 (No. 9) ◽  
pp. 377-386
Author(s):  
D Sperling ◽  
H Karembe ◽  
M Zouharova ◽  
K Nedbalcova
Keyword(s):  
Inhibitory Concentration ◽  
Streptococcus Suis ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Microdilution Method ◽  
Linear Relationships ◽  
Broth Microdilution Method ◽  
Significant Difference ◽  
Agar Dilution ◽  
Good Agreement

The results of the antimicrobial susceptibility testing of clinical isolates Streptococcus suis to amoxicillin and marbofloxacin obtained by the agar dilution method and broth microdilution method with the results obtained by the commercially available E-test were compared. Comparisons between the methods based on the determination of the minimal inhibitory concentration (MIC) of the antimicrobials were assessed based on the degree and frequency of the categorical agreement (Agar dilution method as a reference system) and the percentage of the categorical agreement and error rate. A statistical evaluation was determined using the Bland-Atman method. The presented MIC values, determined for the isolates in the E-test, were slightly different from the MIC values determined by the dilution tests, mainly due to the different defined testing concentrations. For the E-test as the test system and agar-dilution method as the reference system, no error of any class was detected (very major, major and minor error) and a complete categorical agreement was obtained between the evaluated methods for amoxicillin. For amoxicillin, the regression and correlation analysis show linear relationships between the E-test and the two dilution methods with significant coefficients of determination (0.62 and 0.75). The slopes of the equality and regression lines were not significantly different. However, the E-test tends to slightly overestimate the MIC values when compared to the microdilution. The reverse is true when compared with the agar dilution. There was good agreement between the E-test and the dilution methods with a low bias (0.001 3 and −0.005 0), all the experimental data were within the computed limits of agreement. For marbofloxacin, the same trends were observed with lower coefficients of determination (0.42 and 0.73) and a less favourable agreement. The E-test constantly underestimated the MIC values when compared to the two dilution methods. No significant difference between the microdilution and agar dilution was obtained.

scholarly journals Comparative Analysis of Gradient Diffusion and Disk Diffusion with Agar Dilution for Susceptibility Testing of Elizabethkingia anophelis

Antibiotics ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 450
Author(s):  
Chien-Tung Chiu ◽  
Chung-Hsu Lai ◽  
Yi-Han Huang ◽  
Chih-Hui Yang ◽  
Jiun-Nong Lin
Keyword(s):  
Antimicrobial Agents ◽  
Susceptibility Testing ◽  
Disk Diffusion ◽  
Diffusion Method ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Disk Diffusion Method ◽  
Gradient Diffusion ◽  
Minimum Requirements ◽  
Agar Dilution

Elizabethkingia anophelis has recently emerged as a cause of life-threatening infections. This study compared the results of antimicrobial susceptibility testing (AST) conducted for E. anophelis through different methods. E. anophelis isolates collected between January 2005 and June 2019 were examined for their susceptibility to 14 antimicrobial agents by using disk diffusion, gradient diffusion (Etest; (bioMérieux S.A., Marcy l’Etoile, France), and agar dilution methods. The agar dilution method was the reference assay. According to the agar dilution method, the isolates exhibited the highest susceptibility to minocycline (100%), doxycycline (97.6%), rifampin (95.2%), and levofloxacin (78.6%). A very major error rate of >1.5% was observed for nine antibiotics tested using the disk diffusion method. The overall categorical agreement rate between the disk diffusion and agar dilution methods was 74.8%, and ceftazidime, minocycline, levofloxacin, and rifampin met the minimum requirements for discrepancy and agreement rates. The Etest method tended to produce lower log2 minimum inhibitory concentrations for the antibiotics, except for trimethoprim–sulfamethoxazole and rifampin; the method resulted in very major errors for nine antibiotics. The overall essential and categorical agreement rates between the Etest and agar dilution methods were 67.3% and 76.1%, respectively. The Etest method demonstrated acceptable discrepancy and agreement rates for ceftazidime, minocycline, doxycycline, levofloxacin, and rifampin. AST results obtained through the disk diffusion and Etest methods for multiple antibiotics differed significantly from those obtained using the agar dilution method. These two assays should not be a routine alternative for AST for E. anophelis.

scholarly journals Problems Related to Determination of MICs of Oximino-Type Expanded-Spectrum Cephems for Proteus vulgaris

2000 ◽  
Vol 38 (2) ◽  
pp. 677-681
Author(s):  
Akira Ohno ◽  
Yoshikazu Ishii ◽  
Ling Ma ◽  
Keizo Yamaguchi
Keyword(s):  
Dilution Method ◽  
Agar Dilution Method ◽  
Proteus Vulgaris ◽  
In Vitro Susceptibility ◽  
Microdilution Method ◽  
Defective Mutant ◽  
Broth Microdilution Method ◽  
Agar Dilution ◽  
Isogenic Mutants

During in vitro susceptibility testing of clinical isolates ofProteus vulgaris, we noted that the MICs of several expanded-spectrum cephems were much higher in the broth microdilution method than in the agar dilution method (termed the MIC gap phenomenon). Here we investigated the mechanism of the MIC gap phenomenon. Cephems with the MIC gap phenomenon were of the oximino type, such as cefotaxime, cefteram, and cefpodoxime, which serve as good substrates for inducible class A β-lactamase (CumA) enzymes produced by P. vulgaris; this finding suggests a relationship between the MIC gap phenomenon and CumA. Since peptidoglycan recycling shares a system common to that inducing CumA, we analyzed the mechanism of the MIC gap phenomenon using P. vulgaris B317 and isogenic mutants with mutations in the peptidoglycan recycling and β-lactamase induction systems. The MIC gap phenomenon was observed in the parent strain B317 but not in B317G (cumG-defective mutant; defective peptidoglycan recycling) and B317R (cumR-defective mutant; defective CumA transcriptional regulator). No β-lactamase activity was detected in B317G and B317R. β-Lactamase activity and the MIC gap phenomenon were restored in B317G/pMD301 (strain transcomplemented by a clonedcumG gene) and B317R/pMD501 (strain transcomplemented by a cloned cumR gene). MICs determined by the agar dilution method increased when lower agar concentrations were used. Our results indicated that the mechanism of the MIC gap phenomenon is related to peptidoglycan recycling and CumA induction systems. However, it remains unclear how β-lactamase induction of P. vulgaris is suppressed on agar plates.

scholarly journals In Vitro Activities of Gemifloxacin versus Five Quinolones and Two Macrolides against 271 Spanish Isolates of Legionella pneumophila: Influence of Charcoal on Susceptibility Test Results

2000 ◽  
Vol 44 (8) ◽  
pp. 2176-2178 ◽  
Author(s):  
M. T. García ◽  
C. Pelaz ◽  
M. J. Giménez ◽  
L. Aguilar
Keyword(s):  
Legionella Pneumophila ◽  
Free Drug ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Test Results ◽  
Progressive Decrease ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Agar Dilution

ABSTRACT The MICs at which 90% of isolates are inhibited for gemifloxacin, trovafloxacin, and grepafloxacin were low (≤0.01 μg/ml) for 271Legionella isolates when they were determined by the broth microdilution method but increased (≥6 dilutions) when they were determined by the agar dilution method. This was due to the charcoal in the agar dilution medium, as shown by the progressive decrease in the MICs when the charcoal concentrations decreased. As free drug is the active fraction, charcoal binding should be considered.

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