Are bacterial culture quantifications reliable? Comparative performance of the WASP automated inoculation instrument in the era of ISO 15189 accreditation.

Purpose: Isolating colonies and obtaining accurate colony counts from bacterial cultures are critical steps for the optimal management of infected patients. The uncertainties in the colony count results from the bacterial cultures were evaluated by verifying the performance of the WASP inoculation system according to the International Organization for Standardization (ISO) 15189 standard.

Methodology: We first (i) evaluated the cross-contamination and precision of the WASP instrument (Copan Diagnostics, Italy) and (ii) established enumeration reading grids for urine, swab, bronchopulmonary specimens (BPSs) and catheter tip cultures.