scholarly journals Comparison of the MICs Obtained by Gradient Concentration Strip and EUCAST Methods for Four Azole Drugs and Amphotericin B against Azole-Susceptible and -Resistant Aspergillus Section Fumigati Clinical Isolates

2019 ◽  
Vol 64 (3) ◽  
Author(s):  
S. Dellière ◽  
L. Verdurme ◽  
J. Bigot ◽  
E. Dannaoui ◽  
Y. Senghor ◽  
...  
Keyword(s):  
Amphotericin B ◽  
Sensu Stricto ◽  
Clinical Isolates ◽  
Broth Microdilution ◽  
Routine Testing ◽  
Content Type ◽  
Valuable Method ◽  
Resistant Strains ◽  
Potential Impact

ABSTRACT Reference methods used to assess the drug susceptibilities of Aspergillus fumigatus isolates consisted of EUCAST and CLSI standardized broth microdilution techniques. Considering the increasing rate and the potential impact on the clinical outcome of azole resistance in A. fumigatus, more suitable techniques for routine testing are needed. The gradient concentration strip (GCS) method has been favorably evaluated for yeast testing. The aim of this study was to compare the CGS test with EUCAST broth microdilution for amphotericin B (AMB), posaconazole (PCZ), itraconazole (ITZ), voriconazole (VRZ), and isavuconazole (ISA). A total of 121 Aspergillus section Fumigati strains were collected, including 24 A. fumigatus sensu stricto strains that were resistant to at least one azole drug. MICs were determined using GCS and EUCAST methods. Essential agreement between the 2 methods was considered when MICs fell within ±1 dilution or ±2 dilutions of the 2-fold dilution scale. Categorical agreement was defined as the percentage of strains classified in the same category (susceptible, intermediate, or resistant) with both methods. Essential agreements with ±1 dilution and ±2 dilutions were 96.7, 93.4, 90.0, 89.3, and 95% and 100, 99.2, 100, 97.5, and 100% for AMB, PCZ, ITZ, VRZ, and ISA, respectively. Categorical agreements were 94.3, 86.1, 89.3, and 88.5% for AMB, PCZ, ITZ, and VRZ, respectively. Detection of resistance was missed with the GCS for one strain (4.1%) for PCZ and for 2 strains (8.3%) for ISA. Determination of ITZ MICs using the GCS allowed the detection of 91.7% of azole-resistant strains. The GCS test appears to be a valuable method for screening azole-resistant A. fumigatus clinical isolates.

scholarly journals Increased Antifungal Drug Resistance in Clinical Isolates of Cryptococcus neoformans in Uganda

2015 ◽  
Vol 59 (12) ◽  
pp. 7197-7204 ◽  
Author(s):  
Kyle D. Smith ◽  
Beatrice Achan ◽  
Kathy Huppler Hullsiek ◽  
Tami R. McDonald ◽  
Laura H. Okagaki ◽  
...  
Keyword(s):  
Amphotericin B ◽  
Low Income ◽  
Low Cost ◽  
Drug Susceptibility ◽  
Antifungal Drug ◽  
Clinical Isolates ◽  
Hiv Care ◽  
Low Income Countries ◽  
Broth Microdilution ◽  
Content Type

ABSTRACTCryptococcal antigen screening is recommended among people living with AIDS when entering HIV care with a CD4 count of <100 cells/μl, and preemptive fluconazole monotherapy treatment is recommended for those with subclinical cryptococcal antigenemia. Yet, knowledge is limited of current antimicrobial resistance in Africa. We examined antifungal drug susceptibility in 198 clinical isolates collected from Kampala, Uganda, between 2010 and 2014 using the CLSI broth microdilution assay. In comparison with two previous studies from 1998 to 1999 that reported an MIC50of 4 μg/ml and an MIC90of 8 μg/ml prior to widespread human fluconazole and agricultural azole fungicide usage, we report an upward shift in the fluconazole MIC50to 8 μg/ml and an MIC90value of 32 μg/ml, with 31% of isolates with a fluconazole MIC of ≥16 μg/ml. We observed an amphotericin B MIC50of 0.5 μg/ml and an MIC90of 1 μg/ml, of which 99.5% of isolates (197 of 198 isolates) were still susceptible. No correlation between MIC and clinical outcome was observed in the context of amphotericin B and fluconazole combination induction therapy. We also analyzedCryptococcussusceptibility to sertraline, with an MIC50of 4 μg/ml, suggesting that sertraline is a promising oral, low-cost, available, novel medication and a possible alternative to fluconazole. Although the CLSI broth microdilution assay is ideal to standardize results, limit human bias, and increase assay capacity, such assays are often inaccessible in low-income countries. Thus, we also developed and validated an assay that could easily be implemented in a resource-limited setting, with similar susceptibility results (P= 0.52).

scholarly journals Species Identification andIn VitroAntifungal Susceptibility ofAspergillus terreusSpecies Complex Clinical Isolates from a French Multicenter Study

2018 ◽  
Vol 62 (5) ◽  
pp. e02315-17 ◽  
Author(s):  
S. Imbert ◽  
A. C. Normand ◽  
S. Ranque ◽  
J. M. Costa ◽  
J. Guitard ◽  
...  
Keyword(s):  
Amphotericin B ◽  
Antifungal Susceptibility ◽  
Sensu Stricto ◽  
Antifungal Drugs ◽  
Clinical Isolates ◽  
Clinical Samples ◽  
Azole Resistance ◽  
University Hospitals ◽  
Content Type ◽  
Interesting Alternative

ABSTRACTAspergillussectionTerreiis a species complex currently comprised of 14 cryptic species whose prevalence in clinical samples as well as antifungal susceptibility are poorly known. The aims of this study were to investigateA. Terreiclinical isolates at the species level and to perform antifungal susceptibility analyses by reference and commercial methods. Eighty-two clinicalA. Terreiisolates were collected from 8 French university hospitals. Molecular identification was performed by sequencing parts of beta-tubulin and calmodulin genes. MICs or minimum effective concentrations (MECs) were determined for 8 antifungal drugs using both EUCAST broth microdilution (BMD) methods and concentration gradient strips (CGS). Among the 79A. Terreiisolates,A. terreus stricto sensu(n= 61),A. citrinoterreus(n= 13),A. hortai(n= 3), andA. alabamensis(n= 2) were identified. All strains had MICs of ≥1 mg/liter for amphotericin B, except for two isolates (bothA. hortai) that had MICs of 0.25 mg/liter. FourA. terreusisolates were resistant to at least one azole drug, including one with pan-azole resistance, yet no mutation in theCYP51Agene was found. All strains had low MECs for the three echinocandins. The essential agreements (EAs) between BMD and CGS were >90%, except for those of amphotericin B (79.7%) and itraconazole (73.4%). Isolates belonging to theA. sectionTerreiidentified in clinical samples show wider species diversity beyond the knownA. terreus sensu stricto. Azole resistance inside the sectionTerreiis uncommon and is not related to CYP51A mutations here. Finally, CGS is an interesting alternative for routine antifungal susceptibility testing.

scholarly journals Azole and Amphotericin B MIC Values against Aspergillus fumigatus: High Agreement between Spectrophotometric and Visual Readings Using the EUCAST EDef 9.3.2 Procedure

2020 ◽  
Vol 65 (1) ◽  
pp. e01693-20 ◽  
Author(s):  
Julia Serrano-Lobo ◽  
Ana Gómez ◽  
Waldo Sánchez-Yebra ◽  
Miguel Fajardo ◽  
Belén Lorenzo ◽  
...  
Keyword(s):  
Aspergillus Fumigatus ◽  
Amphotericin B ◽  
Fungal Growth ◽  
Sensu Stricto ◽  
Resistance Rate ◽  
Wild Type ◽  
Growth Reduction ◽  
High Agreement ◽  
Content Type

ABSTRACTThe EUCAST EDef 9.3.2 procedure recommends visual readings of azole and amphotericin B MICs against Aspergillus spp. Visual determination of MICs may be challenging. In this work, we aim to obtain and compare visual and spectrophotometric MIC readings of azoles and amphotericin B against Aspergillus fumigatussensu lato isolates. A total of 847 A. fumigatussensu lato isolates (A. fumigatus sensu stricto [n = 828] and cryptic species [n = 19]) were tested against amphotericin B, itraconazole, voriconazole, posaconazole, and isavuconazole using the EUCAST EDef 9.3.2 procedure. Isolates were classified as susceptible or resistant/non-wild type according to the 2020 updated breakpoints. The area of technical uncertainty for the azoles was defined in the updated breakpoints. Visual and spectrophotometric (fungal growth reduction of >95% compared to the control, read at 540 nm) MICs were compared. Essential (±1 2-fold dilution) and categorical agreements were calculated. Overall, high essential (97.1%) and categorical (99.6%) agreements were found. We obtained 100% categorical agreements for amphotericin B, itraconazole, and posaconazole, and consequently, no errors were found. Categorical agreements were 98.7 and 99.3% for voriconazole and isavuconazole, respectively. Most of the misclassifications for voriconazole and isavuconazole were found to be associated with MIC results falling either in the area of technical uncertainty or within one 2-fold dilution above the breakpoint. The resistance rate was slightly lower when the MICs were obtained by spectrophotometric readings. However, all relevant cyp51A mutants were correctly classified as resistant. Spectrophotometric determination of azole and amphotericin B MICs against A. fumigatussensu lato isolates may be a convenient alternative to visual endpoint readings.

scholarly journals Antimicrobial Susceptibility Patterns among a Large, Nationwide Cohort of Abiotrophia and Granulicatella Clinical Isolates

2017 ◽  
Vol 55 (4) ◽  
pp. 1025-1031 ◽  
Author(s):  
Kunatum Prasidthrathsint ◽  
Mark A. Fisher
Keyword(s):  
Antimicrobial Susceptibility ◽  
Clinical Isolates ◽  
Broth Microdilution ◽  
Content Type ◽  
Geographical Regions ◽  
Susceptibility Patterns

ABSTRACTAntimicrobial susceptibility patterns from 599A. defectiva,G. adiacens, andG. elegansclinical isolates were determined by broth microdilution. We observed significant differences in susceptibility across species, particularly to penicillin and ceftriaxone, and across geographical regions.A. defectivawas the least susceptible species overall to penicillin. All isolates were susceptible to vancomycin and >90% were susceptible to levofloxacin.

scholarly journals Ceftaroline Activity against Bacterial Pathogens Frequently Isolated in U.S. Medical Centers: Results from Five Years of the AWARE Surveillance Program

2015 ◽  
Vol 59 (4) ◽  
pp. 2458-2461 ◽  
Author(s):  
Helio S. Sader ◽  
Robert K. Flamm ◽  
Jennifer M. Streit ◽  
David J. Farrell ◽  
Ronald N. Jones
Keyword(s):  
Staphylococcus Aureus ◽  
Streptococcus Pneumoniae ◽  
Bacterial Pathogens ◽  
Surveillance Program ◽  
Broth Microdilution ◽  
Methicillin Resistant ◽  
Content Type ◽  
Medical Centers ◽  
Resistant Strains

ABSTRACTA total of 84,704 isolates were collected from 191 medical centers in 2009 to 2013 and tested for susceptibility to ceftaroline and comparator agents by broth microdilution methods. Ceftaroline inhibited allStaphylococcus aureusisolates at ≤2 μg/ml and was very active against methicillin-resistant strains (MIC at which 90% of the isolates tested are inhibited [MIC90], 1 μg/ml; 97.6% susceptible). AmongStreptococcus pneumoniaeisolates, the highest ceftaroline MIC was 0.5 μg/ml, and ceftaroline activity against the most commonEnterobacteriaceaespecies (MIC50, 0.12 μg/ml; 78.9% susceptible) was similar to that of ceftriaxone (MIC50, ≤0.25 μg/ml; 86.8% susceptible).

scholarly journals The Capsular Polysaccharide of Acinetobacter baumannii Is an Obstacle for Therapeutic Passive Immunization Strategies

2017 ◽  
Vol 85 (12) ◽  
Author(s):  
Shun Xin Wang-Lin ◽  
Ruth Olson ◽  
Janet M. Beanan ◽  
Ulrike MacDonald ◽  
Joseph P. Balthasar ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Outer Membrane ◽  
Bactericidal Activity ◽  
Capsular Polysaccharide ◽  
Rapid Development ◽  
Outer Membrane Proteins ◽  
Passive Immunization ◽  
Clinical Isolates ◽  
Content Type ◽  
Resistant Strains

ABSTRACT Acinetobacter baumannii has become an important concern for human health due to rapid development and wide spread of antimicrobial-resistant strains and high mortality associated with the infection. Passive immunizations with antisera targeting outer membrane proteins (OMPs) have shown encouraging results in protecting mice from A. baumannii infection, but monoclonal anti-OMP antibodies have not been developed, and their potential therapeutic properties have not been explored. The goal of this report is to evaluate the antibacterial activity of monoclonal antibodies (MAbs) targeting outer membrane protein A (OmpA) of A. baumannii. Five anti-OmpA MAbs were developed using hybridoma technology and showed strong binding to strain ATCC 19606. However, low antibody binding was observed when they were tested against six clinical isolates, which included extensively drug-resistant strains. In contrast, high binding to an isogenic K1 capsule-negative mutant (AB307.30) was shown, suggesting that capsular polysaccharide mediated the inhibition of MAb binding to OmpA. Anti-OmpA MAbs increased the macrophage-mediated bactericidal activity of AB307.30 but failed to increase phagocytic killing of capsule-positive strains. Capsular polysaccharide was also protective against complement-mediated bactericidal activity in human ascites in the presence and absence of opsonization. Lastly, passive immunization with anti-OmpA MAbs did not confer protection against challenge with AB307-0294, the encapsulated parent strain of AB307.30, in a mouse sepsis infection model. These results reveal the important role of capsule polysaccharide in shielding OmpA and thereby inhibiting anti-OmpA MAb binding to clinical isolates. This property of capsule hindered the therapeutic utility of anti-OmpA MAbs, and it may apply to other conserved epitopes in A. baumannii.

scholarly journals In VitroInteractions of Antifungal Agents and Tacrolimus against Aspergillus Biofilms

2015 ◽  
Vol 59 (11) ◽  
pp. 7097-7099 ◽  
Author(s):  
Lujuan Gao ◽  
Yi Sun
Keyword(s):  
Antifungal Activity ◽  
Aspergillus Fumigatus ◽  
Amphotericin B ◽  
Aspergillus Flavus ◽  
Inhibitory Activity ◽  
Aspergillus Terreus ◽  
Antifungal Agents ◽  
Broth Microdilution ◽  
Content Type ◽  
Antagonistic Effects

ABSTRACTAspergillusbiofilms were prepared fromAspergillus fumigatus,Aspergillus flavus, andAspergillus terreusvia a 96-well plate-based method, and the combined antifungal activity of tacrolimus with azoles or amphotericin B againstAspergillusbiofilms was investigated via a broth microdilution checkerboard technique system. Our results suggest that combinations of tacrolimus with voriconazole or amphotericin B have synergistic inhibitory activity againstAspergillusbiofilms. However, combinations of tacrolimus with itraconazole or posaconazole exhibit no synergistic or antagonistic effects.

scholarly journals Polyphasic Identification and Susceptibility to Seven Antifungals of 102 Aspergillus Isolates Recovered from Immunocompromised Hosts in Greece

2011 ◽  
Vol 55 (6) ◽  
pp. 3025-3030 ◽  
Author(s):  
Michael Arabatzis ◽  
Manousos Kambouris ◽  
Miltiades Kyprianou ◽  
Aikaterini Chrysaki ◽  
Maria Foustoukou ◽  
...  
Keyword(s):  
Amphotericin B ◽  
Antifungal Susceptibility ◽  
Clinical Isolates ◽  
Content Type ◽  
Susceptibility Study ◽  
Immunocompromised Hosts

ABSTRACTIn this study, the first such study in Greece, we used polyphasic identification combined with antifungal susceptibility study to analyzeAspergillusclinical isolates comprising 102 common and rare members of sections Fumigati, Flavi, Terrei, Nidulantes, Nigri, Circumdati, Versicolores, and Usti. High amphotericin B MICs (>2 μg/ml) were found for 17.6% of strains. Itraconazole, posaconazole, and voriconazole MICs of >4 μg/ml were shown in 1%, 5%, and 0% of the isolates, respectively. Anidulafungin, micafungin, and caspofungin minimum effective concentrations (MECs) of ≥2 μg/ml were correspondingly recorded for 4%, 9%, and 33%, respectively, of the strains.

scholarly journals Multiplecyp51A-Based Mechanisms Identified in Azole-Resistant Isolates of Aspergillus fumigatus from China

2015 ◽  
Vol 59 (7) ◽  
pp. 4321-4325 ◽  
Author(s):  
Musang Liu ◽  
Rong Zeng ◽  
Lili Zhang ◽  
Dongmei Li ◽  
Guixia Lv ◽  
...  
Keyword(s):  
Aspergillus Fumigatus ◽  
Clinical Isolates ◽  
Resistant Isolate ◽  
Azole Resistance ◽  
Content Type ◽  
Resistant Strains

ABSTRACTSeventy-twoA. fumigatusclinical isolates from China were investigated for azole resistance based on mutations ofcyp51A. We identified four azole-resistant strains, among which we found three strains highly resistant to itraconazole, two of which exhibit the TR34/L98H/S297T/F495I mutation, while one carries only the TR34/L98H mutation. To our knowledge, the latter has not been found previously in China. The fourth multiazole-resistant isolate (with only moderate itraconazole resistance) carries a new G432A mutation.

scholarly journals Comparison of the Sensititre YeastOne and CLSI M38-A2 Microdilution Methods in Determining the Activity of Amphotericin B, Itraconazole, Voriconazole, and Posaconazole against Aspergillus Species

2018 ◽  
Vol 56 (10) ◽  
Author(s):  
Hsuan-Chen Wang ◽  
Ming-I Hsieh ◽  
Pui-Ching Choi ◽  
Chi-Jung Wu
Keyword(s):  
Aspergillus Fumigatus ◽  
Amphotericin B ◽  
Antifungal Agents ◽  
Susceptibility Testing ◽  
Geometric Mean ◽  
Antifungal Susceptibility ◽  
Reference Method ◽  
Aspergillus Species ◽  
Broth Microdilution ◽  
Content Type

ABSTRACT This study compared the YeastOne and reference CLSI M38-A2 broth microdilution methods for antifungal susceptibility testing of Aspergillus species. The MICs of antifungal agents were determined for 100 Aspergillus isolates, including 54 Aspergillus fumigatus (24 TR34/L98H isolates), 23 A. flavus, 13 A. terreus, and 10 A. niger isolates. The overall agreement (within 2 2-fold dilutions) between the two methods was 100%, 95%, 92%, and 90% for voriconazole, posaconazole, itraconazole, and amphotericin B, respectively. The voriconazole geometric mean (GM) MICs were nearly identical for all isolates using both methods, whereas the itraconazole and posaconazole GM MICs obtained using the YeastOne method were approximately 1 dilution lower than those obtained using the reference method. In contrast, the amphotericin B GM MIC obtained using the YeastOne method was 3.3-fold higher than that observed using the reference method. For the 24 A. fumigatus TR34/L98H isolates assayed, the categorical agreement (classified according to the CLSI epidemiological cutoff values) was 100%, 87.5%, and 83.3% for itraconazole, voriconazole, and posaconazole, respectively. For four A. niger isolates, the itraconazole MICs were >8 μg/ml using the M38-A2 method due to trailing growth, whereas the corresponding itraconazole MICs obtained using the YeastOne method were all ≤0.25 μg/ml without trailing growth. These data suggest that the YeastOne method can be used as an alternative for azole susceptibility testing of Aspergillus species and for detecting the A. fumigatus TR34/L98H isolates but that this method fails to detect A. niger isolates exhibiting trailing growth with itraconazole. Additionally, for isolates with azole MICs that approach or that are at susceptibility breakpoints or with high amphotericin B MICs detected using the YeastOne method, further MIC confirmation using the reference CLSI method is needed.

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