Abstract

LAGE, Liset; PANIZO, María Mercedes; FERRARA, Giuseppe  and  REVIAKINA, Vera. Validation of the inoculum by densitometry for antifungal susceptibility testing in Fusarium species. Rev. Soc. Ven. Microbiol. [online]. 2013, vol.33, n.1, pp.46-52. ISSN 1315-2556.

The purpose of this work was to validate the preparation of the inoculum by densitometry for antifungal susceptibility testing in Fusarium species. Fifteen clinical isolates of Fusarium spp. were used to prepare the inocula by spectrophotometry and counting of colony forming units in a Neubauer chamber, according to the protocols established by the reference documents M38-A2 of the Clinical and Laboratory Standards Institute (CLSI), and E.DEF 9.1 of the European Committee on Antimicrobial Susceptibility Testing (EUCAST), respectively. Densitometry readings were determined in parallel for both procedures. A range of 0.5-0.7 McFarland units was established for inocula preparation by densitometry according to the CLSI, and a range of 0.2-0.8 McFarland units was established for the methodology described by EUCAST. This study allowed validating the preparation of the inocula for antifungal susceptibility testing in Fusarium spp., using densitometry as an alternative method for other procedures described internationally, with considerable advantages that can be implemented at clinical microbiology laboratories. The variability regarding sporulation capacity and conidia size, especially in less frequent Fusarium species, suggests the need of validating inocula per species.

Keywords : Fusarium spp; inoculum; antifungal susceptibility tests; CLSI; EUCAST; densitometry.