Additionnal MALT extract agar plate as isolation medium improves recovery and identification of filamentous fungi

Ref ID: 19391

Author:

A. Alanio, C. Gomart and S. Bretagne

Author address:

H^opital Saint Louis, APHP, Universit!e Paris Diderot, Paris, France

Full conference title:

6th Trends in Medical Mycology 2013

Date: 11 October 2014

Abstract:

Objectives Despite the development of several biomakers in the last
20 years such as galactomannan, glucan, and DNA detection, myco-
logical culture remains the cornerstone for the diagnosis of invasive
fungal disease (IFD). Culture is also of utmost importance for antifun-
gal susceptibility, fungal identification at the species level in the era of
the emergence of new species, and the delineation of cryptic species
with intrinsic resistance to various antifungal drugs (1). To improve
fungal culture that is known to have variable sensitivity (2), we tested
the interest of MALT extract agar plate in addition to the Sabouraud
slanted tube for filamentous fungi isolation in our routine laboratory.
Methods From January to April 2013, respiratory and deep cutane-
ous specimens were prospectively analyzed. Each specimen was cul-
tured on one chromagar BBL plate (BBL, BD) at 35°C for 4 days, one
Sabouraud Dextrose Agar slant with gentamycin chloramphenicol
(SDA, Biorad) at 30°C for 3 weeks, and one Malt extract agar plate
with gentamycin chloramphenicol (MEA, Merck) at 30°C for
2 weeks. The delay of recovery, the delay of identification, and the
number of fungal species per sample were recorded.
Results From 162 specimens with positive mold recovery (136
patients), 150 (92.6%) were low respiratory samples (sputum, bron-
chial aspiration, broncho-alveolar lavage fluids (BALF)), 5 (3.1%)
were high respiratory samples (nasopharyngeal aspirate, sinus aspi-
ration) and 7 (4.3%) were deep cutaneous biopsies (burn skin). Sev-
enty-seven (47.5%) were positive for yeasts and 203 mold isolates
were recovered (40 on BBL, 144 on MEA and 95 on SDA). In 47
(29%) specimens with identical species recovered in MEA and SDA,
the delay of microscopical identification was significantly improved in
MEA compared to SDA (p = 0.01) with a benefit of one day, whereas
the delay of recovery was not (p = 0.27). Mold recovery was signifi-
cantly improved using MEA (n = 74) compared with SDA (n = 33)
in yeast-positive specimens, (p < 0.0001) and not in yeast-positive specimens (p = 0.14). Using BBL, mold recovery was significantly less efficient compared to MEA and SDA (p < 0.0001). Aspergillus and Penicillium recovery on MEA was significantly higher on MEA (n = 73 and 57) compared to SDA (n = 65 and 15) (p = 0.0002). In addition, mixed mold recovery was observed in 14 specimens using MAE compared to 6 using SDA. Conclusion To add MAE agar plate to Chromagar BBL and Sabou- raud dextrose agar tube increases fungal recovery and speed up iden- tification. Improving the recovery of molds in BAL fluids is important for the interpretation of galactomannan detection in BALF since all septate filamentous fungi can produce galactomannan.This inexpen- sive medium can impact on diagnosis and management of IFD in increasing the number of molds detected. 1. Alastruey-Izquierdo et al. Ann. N. Y. Acad. Sci. 2012 2. Arendrup et al. Bone Marrow transplant. 2012

Abstract Number: p075

Conference Year: 2013

Link to conference website: NULL

New link: NULL

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