Antifungal susceptibility testing and the correlation with clinical outcome in neonatal candidemia

The objective of this article is to assess the distribution of minimal inhibition concentrations (MIC) for candidal isolates from bloodstreams in neonates and to assess the correlation of clinical outcome with antifungal susceptibility testing. Of the 62 episodes of neonatal candidemia in a Children's Hospital between January 1994 and July 1998, 38 stocked isolates from 38 infants' bloodstreams were available and underwent antifungal susceptibility test according to National Committee for Clinical Laboratory Standards M27-A document. Correlation of clinical response with in vitro results was assessed in 37 patient-episode-isolate events. No less than 90% of these isolates tested were susceptible to amphotericin B, flucytosin, and fluconazole. The ranges of amphotericin B MICs and flucytosin MICs were narrow, ranging from 0.25 to 2 μg/mL, respectively. The range of fluconazole MICs was broad, ranging from 0.25 to >64 μg/mL. Successful therapy was achieved in 18 (62%) of 29 amphotericin B-treated patient-episode-susceptible isolate (MIC ≤1 μg/mL) events and 9 (64%) of 14 fluconazole-treated patient-episode-susceptible isolate events, respectively. Most isolates from the bloodstreams of neonates with candidemia were susceptible to antifungal agents tested but a low MIC of the antifungal agent did not predict successful therapy in this study. Correlating MICs with clinical outcome in neonatal candidemia requires complex evaluation of other factors.