Species distribution, biofilm production, and antifungal susceptibility of Candida bloodstream isolates at a university hospital

Ref ID: 17758

Author:

J. Pongracz*, K. Kristóf

Author address:

(Budapest, HU)

Full conference title:

22nd European Congress of Clinical Microbiology and Infectious Diseases

Abstract:

Objectives: The aim of our study was to determine the incidence of
candidaemia at our hospital with data on species distribution, biofilm
production and in vitro antifungal susceptibility (planctonic and sessile)
of the isolates.
Methods: All Candida bloodstream isolates were obtained at
Semmelweis University in 2010-2011. The isolates were identified
by their carbohydrate assimilation profile (API 20 C AUX) and
morphology on malt agar. Biofilms were formed in 96-well
polystyrene microtiter plates, in RPMI 1640 medium substituted
with glutamate and MOPS, incubated at 37C on a rocker. Following
72 hours of incubation, biofilms were washed three times with sterile
saline, and biofilm mass was quantified by measuring the
fluorometric emission of calcofluor-white stain added to the
biofilms. Planctonic MIC (pMIC) values for fluconazole and
anidulafungin were determined using the Eucast standard broth
dilution method. For determination of sessile MIC (sMIC) values for
fluconazole and anidulafungin, 72 hour biofilms were washed, and
reincubated for 48 hours in serial dilutions of the antifungal agents.
SMIC50 (defined as the antifungal concentration that results in 50%
growth inhibition compared to the control well with no antifungal
agent) was determined by Alamar blue assay.
Results: Candida species were isolated from the bloodstream in 40
cases over a 2-year time period (3% of all bloodstream isolates).
Candida albicans was the predominant species (52.5%), followed by C.
parapsilosis (17.5%), C. glabrata (12.5%), C. tropicalis (10%), C.
krusei (2.5%), C. lusitaniae (1%) and C. kefyr (1%). High biofilm
producers were found among the C. albicans (33%), C. tropicalis
(75%), and C. parapsilosis (33%) isolates. Fluconazole sMIC values
were significantly elevated compared to pMIC for every high biofilm
producer isolate, while anidulafungin remained active against the
biofilms.
Conclusion: Thirty percent of all Candida bloodstream isolates were
high biofilm producers. While all the high biofilm producers were
susceptible to fluconazole in vitro by the EUCAST standard
susceptibility testing method, fluconazole had no effect on mature
biofilms. Anidulafungin was active against planctonic cells and biofilms
as well.

Abstract Number: NULL

Conference Year: 2012

Link to conference website: NULL

New link: NULL

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