Fungal pigments inhibit the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis of darkly pigmented fungi

Buskirk, Amanda D.; Hettick, Justin M.; Chipinda, Itai; Law, Brandon F.; Siegel, Paul D.; Slaven, James E.; Green, Brett J.; Beezhold, Donald H.

doi:10.1016/j.ab.2010.11.025

Cited by 63 publications

(33 citation statements)

References 32 publications

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“…While the extra peaks did not affect organism identification in this study, the findings suggest that solid-medium components can affect protein spectral profiles. A study by Buskirk et al (4) found that fungal pigments suppress the desorption/ionization process. It could be reasoned that pigmented media such as MacConkey agar could have a similar effect.…”

Section: Discussionmentioning

confidence: 99%

Effects of Solid-Medium Type on Routine Identification of Bacterial Isolates by Use of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

Anderson

Buchan

Riebe³

et al. 2012

J Clin Microbiol

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Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) is a rapid method for the identification of bacteria. Factors that may alter protein profiles, including growth conditions and presence of exogenous substances, could hinder identification. Bacterial isolates identified by conventional methods were grown on various media and identified using the MALDI Biotyper (Bruker Daltonics, Billerica, MA) using a direct smear method and an acid extraction method. Specimens included 23 Pseudomonas isolates grown on blood agar, Pseudocel (CET), and MacConkey agar (MAC); 20 Staphylococcus isolates grown on blood agar, colistin-nalidixic acid agar (CNA), and mannitol salt agar (MSA); and 25 enteric isolates grown on blood agar, xylose lysine deoxycholate agar (XLD), Hektoen enteric agar (HE), salmonella-shigella agar (SS), and MAC. For Pseudomonas spp., the identification rate to genus using the direct method was 83% from blood, 78% from MAC, and 94% from CET. For Staphylococcus isolates, the identification rate to genus using the direct method was 95% from blood, 75% from CNA, and 95% from MSA. For enteric isolates, the identification rate to genus using the direct method was 100% from blood, 100% from MAC, 100% from XLD, 92% from HE, and 87% from SS. Extraction enhanced identification rates. The direct method of MALDI-TOF analysis of bacteria from selective and differential media yields identifications of varied confidence. Notably, Staphylococci spp. from CNA exhibit low identification rates. Extraction enhances identification rates and is recommended for colonies from this medium. P rompt and accurate identification of bacterial isolates is an objective of the clinical microbiology laboratory and is paramount for patient care. Conventionally this has been achieved using macro-and microscopic observation of morphology and biochemical analysis. These methods often require isolation of individual colonies from polymicrobial cultures and subculture prior to isolate identification. These steps can add significant time to identification of isolates. Molecular methods provide reliable results, though many are expensive to perform, time-consuming, and technically demanding (6). Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has recently emerged as a rapid, accurate, and cost-effective method of identification, applicable to a wide range of bacterial isolates (9,12,13,16,17,19).A major benefit of MALDI-TOF technology is the ability to obtain identifications using a single colony, eliminating the need for subculture and further incubation. To identify most isolates, a single colony can be picked from solid culture media using a swab or toothpick and smeared directly onto a polished steel target plate for identification (direct method) (1, 9, 14, 17, 18). Alternatively, isolates with formidable cell walls or those that produce excess exopolysaccharide matrix (i.e., mucoid pseudomonads) may require processing through a short (approximately 5-min) form...

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Section: Discussionmentioning

confidence: 99%

Effects of Solid-Medium Type on Routine Identification of Bacterial Isolates by Use of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

Anderson

Buchan

Riebe³

et al. 2012

J Clin Microbiol

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“…In contrast, culture media does not appear to affect performance of MALDI-TOF MS Lau et al, 2013) although some studies have reported this as being an issue (Coulibaly et al, 2011). Finally, while early studies reported poor performance of MALDI-TOF MS for the analysis of pigmented filamentous fungi such as Aspergillus niger (Hettick et al, 2008;Valentine, Wahl, Kingsley, & Wahl, 2002), a subsequent study showed that melanin (which is produced by dematiaceous moulds) suppresses protein and peptide ion signals during the acquisition of spectra (Buskirk et al, 2011). However, this phenomenon has not been observed in more recently published studies where more extensive extraction procedures were used (Lau et al, 2013;Ranque et al, 2014).…”

Section: Identification Of Filamentous Fungimentioning

confidence: 98%

MALDI-TOF Mass Spectrometry for Microorganism Identification

Bourassa

Butler-Wu

2015

Methods in Microbiology

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“…At present, the construction of appropriate spectral databases and extension of those provided by manufacturers are required [49•]. Furthermore, melanin pigment in many moulds can inhibit ionization [52]. Nonetheless, MALDI-TOF MS has good potential to replace phenotypic and even gene sequencing methods for the identification of filamentous fungi as it is accurate, inexpensive, and results are available in <2 h.…”

Section: Proteomic Approachesmentioning

confidence: 99%

The Genus Scedosporium and Pseudallescheria: Current Challenges in Laboratory Diagnosis

Ramsperger

Duan

Sorrell

et al. 2014

Curr Clin Micro Rpt

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Scedosporium and Pseudallescheria fungi are increasingly encountered fungal pathogens. Species identification is important as there are differences in epidemiology, virulence, and antifungal susceptibility that vary according to species or species groups. Histological and culture techniques are limited by low sensitivity and specificity but improved culture approaches employing selective media have improved the recovery of these fungi from clinical samples. Molecular-and proteomics-based methods are increasingly explored and used for species identification. These include multiplex polymerase chain reaction (PCR) and other PCR-based methods, oligonucleotide arrays, DNA sequencing, rolling circle amplification, and matrix-assisted laser desorption time-of-flight mass spectrometry. These techniques have been harnessed for the detection and identification of Scedosporium and Pseudallescheria species directly from clinical samples and from cultures. This review summarizes the methods currently used to enable an informed choice of detection and/or identification techniques in the clinical mycology laboratory.

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Fungal pigments inhibit the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis of darkly pigmented fungi

Cited by 63 publications

References 32 publications

Effects of Solid-Medium Type on Routine Identification of Bacterial Isolates by Use of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

Effects of Solid-Medium Type on Routine Identification of Bacterial Isolates by Use of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

MALDI-TOF Mass Spectrometry for Microorganism Identification

The Genus Scedosporium and Pseudallescheria: Current Challenges in Laboratory Diagnosis

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