Skip to main content
  • ASM
    • Antimicrobial Agents and Chemotherapy
    • Applied and Environmental Microbiology
    • Clinical Microbiology Reviews
    • Clinical and Vaccine Immunology
    • EcoSal Plus
    • Eukaryotic Cell
    • Infection and Immunity
    • Journal of Bacteriology
    • Journal of Clinical Microbiology
    • Journal of Microbiology & Biology Education
    • Journal of Virology
    • mBio
    • Microbiology and Molecular Biology Reviews
    • Microbiology Resource Announcements
    • Microbiology Spectrum
    • Molecular and Cellular Biology
    • mSphere
    • mSystems
  • Log in
  • My alerts
  • My Cart

Main menu

  • Home
  • Articles
    • Current Issue
    • Accepted Manuscripts
    • COVID-19 Special Collection
    • Archive
    • Minireviews
  • For Authors
    • Submit a Manuscript
    • Scope
    • Editorial Policy
    • Submission, Review, & Publication Processes
    • Organization and Format
    • Errata, Author Corrections, Retractions
    • Illustrations and Tables
    • Nomenclature
    • Abbreviations and Conventions
    • Publication Fees
    • Ethics Resources and Policies
  • About the Journal
    • About JCM
    • Editor in Chief
    • Editorial Board
    • For Reviewers
    • For the Media
    • For Librarians
    • For Advertisers
    • Alerts
    • RSS
    • FAQ
  • Subscribe
    • Members
    • Institutions
  • ASM
    • Antimicrobial Agents and Chemotherapy
    • Applied and Environmental Microbiology
    • Clinical Microbiology Reviews
    • Clinical and Vaccine Immunology
    • EcoSal Plus
    • Eukaryotic Cell
    • Infection and Immunity
    • Journal of Bacteriology
    • Journal of Clinical Microbiology
    • Journal of Microbiology & Biology Education
    • Journal of Virology
    • mBio
    • Microbiology and Molecular Biology Reviews
    • Microbiology Resource Announcements
    • Microbiology Spectrum
    • Molecular and Cellular Biology
    • mSphere
    • mSystems

User menu

  • Log in
  • My alerts
  • My Cart

Search

  • Advanced search
Journal of Clinical Microbiology
publisher-logosite-logo

Advanced Search

  • Home
  • Articles
    • Current Issue
    • Accepted Manuscripts
    • COVID-19 Special Collection
    • Archive
    • Minireviews
  • For Authors
    • Submit a Manuscript
    • Scope
    • Editorial Policy
    • Submission, Review, & Publication Processes
    • Organization and Format
    • Errata, Author Corrections, Retractions
    • Illustrations and Tables
    • Nomenclature
    • Abbreviations and Conventions
    • Publication Fees
    • Ethics Resources and Policies
  • About the Journal
    • About JCM
    • Editor in Chief
    • Editorial Board
    • For Reviewers
    • For the Media
    • For Librarians
    • For Advertisers
    • Alerts
    • RSS
    • FAQ
  • Subscribe
    • Members
    • Institutions
Mycology

Antifungal Susceptibility Testing of Aspergillus spp. by Using a Composite Correlation Index (CCI)-Based Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry Method Appears To Not Offer Benefit over Traditional Broth Microdilution Testing

Melissa R. Gitman, Lisa McTaggart, Joanna Spinato, Rahgavi Poopalarajah, Erin Lister, Shahid Husain, Julianne V. Kus
David W. Warnock, Editor
Melissa R. Gitman
aMulti-Organ Transplant Unit, University Health Network, Toronto, ON, Canada
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
Lisa McTaggart
bPublic Health Ontario, Toronto, ON, Canada
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
Joanna Spinato
bPublic Health Ontario, Toronto, ON, Canada
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
Rahgavi Poopalarajah
bPublic Health Ontario, Toronto, ON, Canada
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
Erin Lister
bPublic Health Ontario, Toronto, ON, Canada
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
Shahid Husain
aMulti-Organ Transplant Unit, University Health Network, Toronto, ON, Canada
cDivision of Infectious Diseases, Department of Medicine, University of Toronto, Toronto, ON, Canada
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
Julianne V. Kus
bPublic Health Ontario, Toronto, ON, Canada
dDepartment of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
David W. Warnock
Roles: Editor
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
DOI: 10.1128/JCM.00254-17
  • Article
  • Figures & Data
  • Info & Metrics
  • PDF
Loading

ABSTRACT

Aspergillus spp. cause serious invasive lung infections, and Aspergillus fumigatus is the most commonly encountered clinically significant species. Voriconazole is considered to be the drug of choice for treating A. fumigatus infections; however, rising resistance rates have been reported. We evaluated a matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS)-based method for the differentiation between wild-type and non-wild-type isolates of 20 Aspergillus spp. (including 2 isolates of Aspergillus ustus and 1 of Aspergillus calidoustus that were used as controls due their intrinsic low azole susceptibility with respect to the in vitro response to voriconazole). At 30 and 48 h of incubation, there was complete agreement between Cyp51A sequence analysis, broth microdilution, and MALDI-TOF MS classification of isolates as wild type or non-wild type. In this proof-of-concept study, we demonstrated that MALDI-TOF MS can be used to accurately detect A. fumigatus strains with reduced voriconazole susceptibility. However, rather than proving to be a rapid and simple method for antifungal susceptibility testing, this particular MS-based method showed no benefit over conventional testing methods.

INTRODUCTION

Aspergillus spp. cause serious invasive lung infections, and Aspergillus fumigatus is the most commonly encountered clinically significant species (1). Voriconazole is considered to be the drug of choice for treating A. fumigatus infections (2); however, rising resistance rates have been reported (3, 4), and antifungal susceptibility testing (AFST) remains limited to a small number of specialized laboratories. Early initiation of appropriate therapy has been shown to lead to better clinical outcomes (5). Additionally, it has been demonstrated that patients infected with resistant strains have poorer outcomes than those infected with susceptible strains (6).

Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) has been widely demonstrated to be an excellent tool for the rapid, accurate, and inexpensive identification of microorganisms (7, 8). Groups are now investigating this technology for potentially equally rapid, simple, and inexpensive antimicrobial susceptibility testing (9–12). One method that has been explored uses the composite correlation index (CCI), a statistical autocorrelation method that analyzes the relationships/similarity between spectra generated by microorganisms treated with different concentrations of drug (13). By comparing theses spectra against the spectra obtained at the null or the maximal concentration of drug, similarity of the spectra to the two extremes can be determined (14). This allows for establishment of the minimal profile change concentration (MPCC), which is the lowest drug concentration where the spectra is more similar to that of the maximum drug concentration than to that of the null drug concentration (14). The MPCC has been shown to approximate an MIC determined by broth microdilution (BMD) (14). Here, we sought to explore this method to determine if it could be used to determine voriconazole MICs for Aspergillus spp.

The objectives of this study were to (i) demonstrate whether a MALDI-TOF MS system could be used to determine MPCCs of voriconazole, which approximate MICs for Aspergillus spp., (ii) determine if these MPCCs could correctly classify A. fumigatus isolates as wild type (WT) (no acquired resistance) or non-WT (acquired resistance) with respect to voriconazole, and (iii) establish if this method had any advantages over traditional BMD.

RESULTS

BMD-based MICs, CYP51A genotype, and MALDI-TOF MS MPCC results are presented in Table 1, with A. fumigatus MICs and MPCCs interpreted as WT or non-WT using an epidemiological cutoff value (ECV) of 1 μg/ml. At 24 h incubation, all MPCC data allowed for the appropriate classification of A. fumigatus WT strains as WT. For the Cyp51A mutants, however, 2 of 4 mutant strains displaying non-WT BMD MICs were assigned WT MALDI-TOF MS MPCCs; these would be classified as very major errors (15). Slightly longer incubation times (30 and 48 h) allowed for accurate discrimination between WT and non-WT A. fumigatus strains. Barring the exceptions noted above at the 24-hour time point, the MALDI-TOF MS MPCCs for all Aspergillus strains were within ±1 dilution of the BMD MICs.

View this table:
  • View inline
  • View popup
TABLE 1

Results of antifungal susceptibility testing of Aspergillus spp. to voriconazole using genotyping, BMD MIC, and MALDI-TOF MS MPCC determination

In addition, we also tested the A. fumigatus strains by an abbreviated AFST method of categorization of the isolates as WT or non-WT. This abbreviated method, or “three-point” assay (16), compares the spectra obtained at only three drug concentrations, namely, no drug, maximum drug concentration (16 μg/ml voriconazole), and the voriconazole ECV (1 μg/ml) (see Table S2A and B in the supplemental material). For this method, an isolate was determined to be resistant (non-WT) if at a concentration of 1 μg/ml voriconazole the CCI score was more similar to what is seen with no voriconazole compared to the maximal concentration. It was found that by evaluating just these three drug concentrations, A. fumigatus isolates could be correctly classified as WT or non-WT after incubation periods of 30 and 48 h (Table 2).

View this table:
  • View inline
  • View popup
TABLE 2

Results of antifungal susceptibility testing of A. fumigatus to voriconazole using genotyping, BMD MIC determination, and an abbreviated MALDI-TOF MS method

DISCUSSION

In this proof-of-concept study, we demonstrate the use of MALDI-TOF MS technology for the generation of MPCCs and approximation of BMD MICs (±1 dilution) for filamentous fungi and the accurate classification of A. fumigatus strains as WT or non-WT in their response toward voriconazole based on the ECV. The establishment of ECVs has aided clinicians in determining whether A. fumigatus isolates behave more like WT strains toward a certain drug or more like non-WT isolates with known acquired mechanisms of resistance.

Variable rates of Aspergillus azole resistance, ranging from as high as 2 to 8% in some areas (3, 4, 17) to <1% in others (18), have been reported. Variability of resistance rates likely relates to differences in testing frequency between laboratories and the relative risk of different populations acquiring resistant fungal infections (4). Additionally, prevalence data may be biased by susceptibility testing being carried out in referral centers, where the samples received are likely from patients who are failing therapy, as opposed to testing a random cross section of samples (4). The demand for susceptibility testing is rising, particularly for isolates from patients receiving antifungal therapy, underscoring the need for a rapid, inexpensive method of susceptibility profiling (4).

Voriconazole resistance is most commonly mediated via modification of the binding site of the drug. The target site, 14 α-demethylase, is encoded by the cyp51A gene (19). There are two proposed sources of selective pressure for the fixation of Cyp51A mutations mediating resistance. The first source is the selective pressure provided during prolonged drug exposure. Consequently, resistance of Aspergillus to voriconazole is most commonly identified in patients with aspergillomas requiring prolonged courses of therapy (20). Second, humans may be infected by inhaling environmental molds that have developed resistance due to the selective pressure from azole fungicides. This proposed mechanism of resistance has been seen primarily in Europe. The majority of resistant isolates identified in the Netherlands all share a mutation, L98H, coupled with a tandem repeat in the promoter region, suggesting a common source of a resistant strain (20).

While the use of MALDI-TOF MS technology allowed for accurate identification of isolates as WT or non-WT, the current methodology did not save any time compared to traditional BMD assays. While the abbreviated MALDI-TOF MS method, which requires only 3 drug concentrations, may potentially reduce the amount of work required for setup, it still requires 30 to 48 h of incubation prior to analysis to allow time for sufficient growth for accurate differentiation between WT and non-WT strains (Table 1). Consequently, results are not obtained any faster with this method than with traditional BMD or antifungal disk diffusion susceptibility testing (21, 22). In addition, the MALDI-TOF MS analysis resulted in MPCCs, which are only surrogates for the well-established and more easily clinically interpreted MICs.

Currently, for determination of phenotypic susceptibility profiling, BMD and antifungal disk diffusion testing are still the preferred methods, and for accurate identification of Cyp51A mutations, gene sequencing remains the gold standard. Future development of alternative MALDI-TOF MS protocols and/or databases that can recognize the specific molecular changes associated with resistance rather than serving as an indicator of MIC would ultimately be of greater utility in the clinical mycology laboratory.

MATERIALS AND METHODS

Isolates.Twenty isolates of Aspergillus spp. were tested, 17 clinical isolates of A. fumigatus, 4 of which were previously demonstrated to be phenotypically and genotypically resistant to voriconazole (generously gifted by Susan Howard; 4), 2 clinical isolates of Aspergillus ustus, and 1 clinical isolate of Aspergillus calidoustus. A. ustus and A. calidoustus strains, which display intrinsic elevated MICs towards voriconzole, were included to challenge the assay against a broad range of voriconazole MICs. For each isolate, the MIC of voriconazole was determined using the Sensititre YeastOne microdilution panel (Thermo Fisher Scientific, Waltham, MA), which is an adaptation from the CLSI BMD reference method (21). The sequence of the cyp51A gene was verified for each non-wild-type A. fumigatus isolate using PCR and sequencing. Briefly, after DNA extraction, the promoter and full coding regions of the cyp51A gene were amplified and sequenced using primers described previously (23). The sequences were compared against the sequence of wild-type cyp51A (GenBank accession no. AF338659 ) to identify known resistance mutations.

Sample preparation.Stored isolates (−80°C) were subcultured on potato dextrose agar and incubated at 28°C until growth was sufficient (∼72 h). Samples were prepared according to previously published methods with a few modifications (16, 24). Fungal inocula were prepared by dislodging and suspending conidia in 0.01% Triton X-100 (108 conidia/ml). When necessary, suspensions were filtered through cotton wool to remove hyphal fragments. Wells of a 24-well microtiter plate were inoculated with RPMI broth, fungal suspension (final concentration, 107 conidia/ml), and voriconazole solution (drug concentration, 0.125 to 16 μg/ml) or no voriconazole (positive growth control), for a final volume of 2 ml. Samples were incubated for 24, 30, or 48 h at 37°C with gentle agitation (130 rotations/min). After incubation, the fungal material was collected and washed twice in water and once in 70% ethanol. Pellets were dried in a SpeedVac concentrator (Thermo Scientific Savant DNA120) for 10 min. Equal amounts of 70% formic acid (20 to 100 μl) and acetonitrile (20 to 100 μl) were added to each pellet in proportion to the biomass. Samples were vortexed and centrifuged again; the supernatant was used to spot on the target for analysis.

MALDI-TOF MS analysis.CCI and MPCC determinations were performed using the Bruker Microflex LT mass spectrometer system and Bruker MBT Compass Explorer software v1.4 as previously described (24). For each experimental condition, 12 to 24 spectra were acquired and used to generate the CCI scores used to compare all drug concentrations. MPCCs were determined by identifying the lowest drug concentration at which the spectra were more similar to that observed at the maximum drug concentration than that observed with no drug (see Table S1A and B in the supplemental material). For the A. fumigatus strains, a cutoff value of 1 μg/ml voriconazole was selected, based on the epidemiological cutoff value (ECV), to determine if MPCCs could be used to classify strains as WT or non-WT (25). ECVs combine phenotypic and genotypic data to establish whether an isolate responds as WT or non-WT to a drug (25). Published studies (19, 26) and the European Committee on Antimicrobial Susceptibility Testing (25) have determined the ECV for voriconazole against A. fumigatus to be 1 μg/ml; MICs of ≤1 μg/ml are interpreted as WT, whereas MICs of >1 μg/ml are considered non-WT and may have acquired mechanisms for resistance. For the 3 non-A. fumigatus strains, no interpretation criteria can be applied; they were tested only to assess how the MPCC compared to the MIC values.

ACKNOWLEDGMENTS

We thank Maria Witkowska and Nazareno Ocampo for their technical assistance with this project.

FOOTNOTES

    • Received 18 February 2017.
    • Returned for modification 13 March 2017.
    • Accepted 5 April 2017.
    • Accepted manuscript posted online 12 April 2017.
  • Supplemental material for this article may be found at https://doi.org/10.1128/JCM.00254-17 .

  • © Crown copyright 2017.

The government of Australia, Canada, or the UK (“the Crown”) owns the copyright interests of authors who are government employees. The Crown Copyright is not transferable.

REFERENCES

  1. 1.↵
    1. Neofytos D,
    2. Fishman JA,
    3. Horn D,
    4. Anaissie E,
    5. Chang CH,
    6. Olyaei A,
    7. Pfaller M,
    8. Steinbach WJ,
    9. Webster KM,
    10. Marr KA
    . 2010. Epidemiology and outcome of invasive fungal infections in solid organ transplant recipients. Transpl Infect Dis12:220–229. doi:10.1111/j.1399-3062.2010.00492.x.
    OpenUrlCrossRefPubMedWeb of Science
  2. 2.↵
    1. Walsh TJ,
    2. Anaissie EJ,
    3. Denning DW,
    4. Herbrecht R,
    5. Kontoyiannis DP,
    6. Marr KA,
    7. Morrison VA,
    8. Segal BH,
    9. Steinbach WJ,
    10. Stevens DA,
    11. van Burik JA,
    12. Wingard JR,
    13. Patterson TF
    , Infectious Diseases Society of America. 2008. Treatment of aspergillosis: clinical practice guidelines of the Infectious Diseases Society of America. Clin Infect Dis46:327–360. doi:10.1086/525258.
    OpenUrlCrossRefPubMedWeb of Science
  3. 3.↵
    1. Verweij PE,
    2. Mellado E,
    3. Melchers WJ
    . 2007. Multiple-triazole-resistant aspergillosis. N Engl J Med356:1481–1483. doi:10.1056/NEJMc061720.
    OpenUrlCrossRefPubMedWeb of Science
  4. 4.↵
    1. Howard SJ,
    2. Cerar D,
    3. Anderson MJ,
    4. Albarrag A,
    5. Fisher MC,
    6. Pasqualotto AC,
    7. Laverdiere M,
    8. Arendrup MC,
    9. Perlin DS,
    10. Denning DW
    . 2009. Frequency and evolution of azole resistance in Aspergillus fumigatus associated with treatment failure. Emerg Infect Dis15:1068–1076. doi:10.3201/eid1507.090043.
    OpenUrlCrossRefPubMedWeb of Science
  5. 5.↵
    1. Verweij PE,
    2. Snelders E,
    3. Kema GH,
    4. Mellado E,
    5. Melchers WJ
    . 2009. Azole resistance in Aspergillus fumigatus: a side-effect of environmental fungicide use?Lancet Infect Dis9:789–795. doi:10.1016/S1473-3099(09)70265-8.
    OpenUrlCrossRefPubMedWeb of Science
  6. 6.↵
    1. van der Linden JW,
    2. Snelders E,
    3. Kampinga GA,
    4. Rijnders BJ,
    5. Mattsson E,
    6. Debets-Ossenkopp YJ,
    7. Kuijper EJ,
    8. Van Tiel FH,
    9. Melchers WJ,
    10. Verweij PE
    . 2011. Clinical implications of azole resistance in Aspergillus fumigatus, The Netherlands, 2007–2009. Emerg Infect Dis17:1846–1854. doi:10.3201/eid1710.110226.
    OpenUrlCrossRefPubMed
  7. 7.↵
    1. Fenselau C,
    2. Demirev PA
    . 2001. Characterization of intact microorganisms by MALDI mass spectrometry. Mass Spectrom Rev20:157–171. doi:10.1002/mas.10004.
    OpenUrlCrossRefPubMedWeb of Science
  8. 8.↵
    1. De Carolis E,
    2. Posteraro B,
    3. Lass-Flörl C,
    4. Vella A,
    5. Florio AR,
    6. Torelli R,
    7. Girmenia C,
    8. Colozza C,
    9. Tortorano AM,
    10. Sanguinetti M,
    11. Fadda G
    . 2012. Species identification of Aspergillus, Fusarium and Mucorales with direct surface analysis by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Clin Microbiol Infect18:475–484. doi:10.1111/j.1469-0691.2011.03599.x.
    OpenUrlCrossRefPubMed
  9. 9.↵
    1. Saracli MA,
    2. Fothergill AW,
    3. Sutton DA,
    4. Wiederhold NP
    . 2015. Detection of triazole resistance among Candida species by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS). Med Mycol53:736–742. doi:10.1093/mmy/myv046.
    OpenUrlCrossRefPubMed
  10. 10.↵
    1. Lange C,
    2. Schubert S,
    3. Jung J,
    4. Kostrzewa M,
    5. Sparbier K
    . 2014. Quantitative matrix-assisted laser desorption ionization–time of flight mass spectrometry for rapid resistance detection. J Clin Microbiol52:4155–4162. doi:10.1128/JCM.01872-14.
    OpenUrlAbstract/FREE Full Text
  11. 11.↵
    1. Sparbier K,
    2. Schubert S,
    3. Weller U,
    4. Boogen C,
    5. Kostrzewa M
    . 2012. Matrix-assisted laser desorption ionization–time of flight mass spectrometry-based functional assay for rapid detection of resistance against β-lactam antibiotics. J Clin Microbiol50:927–937. doi:10.1128/JCM.05737-11.
    OpenUrlAbstract/FREE Full Text
  12. 12.↵
    1. Wattal C,
    2. Oberoi JK
    . 2016. Microbial identification and automated antibiotic susceptibility testing directly from positive blood cultures using MALDI-TOF MS and VITEK 2. Eur J Clin Microbiol Infect Dis35:75–82. doi:10.1007/s10096-015-2510-y.
    OpenUrlCrossRef
  13. 13.↵
    1. Arnold RJ,
    2. Reilly JP
    . 1998. Fingerprint matching of E. coli strains with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry of whole cells using a modified correlation approach. Rapid Commun Mass Spectrom12:630–636. doi:10.1002/(SICI)1097-0231(19980529)12:10<630::AID-RCM206>3.0.CO;2-0.
    OpenUrlCrossRefPubMedWeb of Science
  14. 14.↵
    1. Marinach C,
    2. Alanio A,
    3. Palous M,
    4. Kwasek S,
    5. Fekkar A,
    6. Brossas JY,
    7. Brun S,
    8. Snounou G,
    9. Hennequin C,
    10. Sanglard D,
    11. Datry A,
    12. Golmard JL,
    13. Mazier D
    . 2009. MALDI-TOF MS-based drug susceptibility testing of pathogens: the example of Candida albicans and fluconazole. Proteomics9:4627–4631. doi:10.1002/pmic.200900152.
    OpenUrlCrossRefPubMedWeb of Science
  15. 15.↵
    1. Elder BL,
    2. Hansen SA,
    3. Kellogg JA,
    4. Marsik FJ,
    5. Zabransky RJ
    . 1997. Verification and validation of procedures in the clinical microbiology laboratory. Cumitech 31. ASM Press, Washington, DC.
  16. 16.↵
    1. Vella A,
    2. De Carolis E,
    3. Vaccaro L,
    4. Posteraro P,
    5. Perlin DS,
    6. Kostrzewa M,
    7. Posteraro B,
    8. Sanguinetti M
    . 2013. Rapid antifungal susceptibility testing by matrix-assisted laser desorption ionization–time of flight mass spectrometry analysis. J Clin Microbiol51:2964–2969. doi:10.1128/JCM.00903-13.
    OpenUrlAbstract/FREE Full Text
  17. 17.↵
    1. Pfaller MA,
    2. Messer SA,
    3. Boyken L,
    4. Rice C,
    5. Tendolkar S,
    6. Hollis RJ,
    7. Diekema DJ
    . 2008. In vitro survey of triazole cross-resistance among more than 700 clinical isolates of Aspergillus species. J Clin Microbiol46:2568–2572. doi:10.1128/JCM.00535-08.
    OpenUrlAbstract/FREE Full Text
  18. 18.↵
    1. Pham CD,
    2. Reiss E,
    3. Hagen F,
    4. Meis JF,
    5. Lockhart SR
    . 2014. Passive surveillance for azole-resistant Aspergillus fumigatus, United States, 2011–2013. Emerg Infect Dis20(9):1498–1503. doi:10.3201/eid2009.140142.
    OpenUrlCrossRefPubMed
  19. 19.↵
    1. Pfaller MA,
    2. Diekema DJ,
    3. Ghannoum MA,
    4. Rex JH,
    5. Alexander BD,
    6. Andes D,
    7. Brown SD,
    8. Chaturvedi V,
    9. Espinel-Ingroff A,
    10. Fowler CL,
    11. Johnson EM,
    12. Knapp CC,
    13. Motyl MR,
    14. Ostrosky-Zeichner L,
    15. Sheehan DJ,
    16. Walsh TJ
    , Clinical and Laboratory Standards Institute Antifungal Testing Subcommittee. 2009. Wild-type MIC distribution and epidemiological cutoff values for Aspergillus fumigatus and three triazoles as determined by the Clinical and Laboratory Standards Institute broth microdilution methods. J Clin Microbiol47:3142–3146. doi:10.1128/JCM.00940-09.
    OpenUrlAbstract/FREE Full Text
  20. 20.↵
    1. Vermeulen E,
    2. Lagrou K,
    3. Verweij PE
    . 2013. Azole resistance in Aspergillus fumigatus: a growing public health concern. Curr Opin Infect Dis26:493–500. doi:10.1097/QCO.0000000000000005.
    OpenUrlCrossRefPubMed
  21. 21.↵
    Clinical and Laboratory Standards Institute. 2008. Reference method for broth dilution antifungal susceptibility testing of filamentous fungi; approved standard—2nd ed. CLSI M38-A2. Clinical and Laboratory Standards Institute, Wayne, PA.
  22. 22.↵
    Clinical and Laboratory Standards Institute. 2010. Reference method for antifungal disk diffusion susceptibility testing of non-dermatophyte filamentous fungi; approved guideline. CLSI M51-A. Clinical and Laboratory Standards Institute, Wayne, PA.
  23. 23.↵
    1. Mortensen KL,
    2. Jensen RH,
    3. Johansen HK,
    4. Skov M,
    5. Pressler T,
    6. Howard SJ,
    7. Leatherbarrow H,
    8. Mellado E,
    9. Arendrup MC
    . 2011. Aspergillus species and other molds in respiratory samples from patients with cystic fibrosis: a laboratory-based study with focus on Aspergillus fumigatus azole resistance. J Clin Microbiol49:2243–2251. doi:10.1128/JCM.00213-11.
    OpenUrlAbstract/FREE Full Text
  24. 24.↵
    1. De Carolis E,
    2. Vella A,
    3. Florio AR,
    4. Posteraro P,
    5. Perlin DS,
    6. Sanguinetti M,
    7. Posteraro B
    . 2012. Use of matrix-assisted laser desorption ionization–time of flight mass spectrometry for caspofungin susceptibility testing of Candida and Aspergillus species. J Clin Microbiol50:2479–2483. doi:10.1128/JCM.00224-12.
    OpenUrlAbstract/FREE Full Text
  25. 25.↵
    European Committee on Antimicrobial Susceptibility Testing. 2014. Antifungal agents: breakpoint tables for interpretation of MICs, version 7.0, valid from 2014-08-12. http://www.eucast.org/fileadmin/src/media/PDFs/EUCAST_files/AFST/Antifungal_breakpoints_v_7.0.pdf .
  26. 26.↵
    1. Espinel-Ingroff A,
    2. Diekema DJ,
    3. Fothergill A,
    4. Johnson E,
    5. Pelaez T,
    6. Pfaller MA,
    7. Rinaldi MG,
    8. Canton E,
    9. Turnidge J
    . 2010. Wild-type MIC distributions and epidemiological cutoff values for the triazoles and six Aspergillus spp. for the CLSI broth microdilution method (M38-A2 document). J Clin Microbiol48:3251–3257. doi:10.1128/JCM.00536-10.
    OpenUrlAbstract/FREE Full Text
PreviousNext
Back to top
Download PDF
Citation Tools
Antifungal Susceptibility Testing of Aspergillus spp. by Using a Composite Correlation Index (CCI)-Based Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry Method Appears To Not Offer Benefit over Traditional Broth Microdilution Testing
Melissa R. Gitman, Lisa McTaggart, Joanna Spinato, Rahgavi Poopalarajah, Erin Lister, Shahid Husain, Julianne V. Kus
Journal of Clinical Microbiology Jun 2017, 55 (7) 2030-2034; DOI: 10.1128/JCM.00254-17

Citation Manager Formats

  • BibTeX
  • Bookends
  • EasyBib
  • EndNote (tagged)
  • EndNote 8 (xml)
  • Medlars
  • Mendeley
  • Papers
  • RefWorks Tagged
  • Ref Manager
  • RIS
  • Zotero
Print

Alerts
Sign In to Email Alerts with your Email Address
Email

Thank you for sharing this Journal of Clinical Microbiology article.

NOTE: We request your email address only to inform the recipient that it was you who recommended this article, and that it is not junk mail. We do not retain these email addresses.

Enter multiple addresses on separate lines or separate them with commas.
Antifungal Susceptibility Testing of Aspergillus spp. by Using a Composite Correlation Index (CCI)-Based Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry Method Appears To Not Offer Benefit over Traditional Broth Microdilution…
(Your Name) has forwarded a page to you from Journal of Clinical Microbiology
(Your Name) thought you would be interested in this article in Journal of Clinical Microbiology.
CAPTCHA
This question is for testing whether or not you are a human visitor and to prevent automated spam submissions.
Share
Antifungal Susceptibility Testing of Aspergillus spp. by Using a Composite Correlation Index (CCI)-Based Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry Method Appears To Not Offer Benefit over Traditional Broth Microdilution Testing
Melissa R. Gitman, Lisa McTaggart, Joanna Spinato, Rahgavi Poopalarajah, Erin Lister, Shahid Husain, Julianne V. Kus
Journal of Clinical Microbiology Jun 2017, 55 (7) 2030-2034; DOI: 10.1128/JCM.00254-17
del.icio.us logo Digg logo Reddit logo Twitter logo CiteULike logo Facebook logo Google logo Mendeley logo
  • Top
  • Article
    • ABSTRACT
    • INTRODUCTION
    • RESULTS
    • DISCUSSION
    • MATERIALS AND METHODS
    • ACKNOWLEDGMENTS
    • FOOTNOTES
    • REFERENCES
  • Figures & Data
  • Info & Metrics
  • PDF

KEYWORDS

antifungal agents
Aspergillus
Microbial Sensitivity Tests
Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
voriconazole
Aspergillus
voriconazole resistance
MALDI-TOF MS
antifungal susceptibility testing
composite correlation index
voriconazole

Related Articles

Cited By...

About

  • About JCM
  • Editor in Chief
  • Board of Editors
  • Editor Conflicts of Interest
  • For Reviewers
  • For the Media
  • For Librarians
  • For Advertisers
  • Alerts
  • RSS
  • FAQ
  • Permissions
  • Journal Announcements

Authors

  • ASM Author Center
  • Submit a Manuscript
  • Article Types
  • Resources for Clinical Microbiologists
  • Ethics
  • Contact Us

Follow #JClinMicro

@ASMicrobiology

       

ASM Journals

ASM journals are the most prominent publications in the field, delivering up-to-date and authoritative coverage of both basic and clinical microbiology.

About ASM | Contact Us | Press Room

 

ASM is a member of

Scientific Society Publisher Alliance

 

American Society for Microbiology
1752 N St. NW
Washington, DC 20036
Phone: (202) 737-3600

 

Copyright © 2021 American Society for Microbiology | Privacy Policy | Website feedback

Print ISSN: 0095-1137; Online ISSN: 1098-660X