Growthanddetection offilamentous fungi in theBacT/Alert bloodculture system

Little isknownaboutthebehaviour offilamentousfungi inmostbloodculture systems,despite their increasingly recognised roleininfections ofimmunocompromised hosts. Theability oftheBacT/Alert system (Organon Teknika, Durham,NorthCarolina, USA)todetect thegrowthof19such fungi wasexamined. Elevenspecies grew andweredetected rapidly; twospecies did notgrow.Sixspecies grewslowly, andwere generally onlyrecovered withterminal subculture afterprolonged incubation. TheCO2production graphforsomeof thesefungi showedaslowbutsteady rise, insufficient tocausetheapparatus tosignalpositive. Theseresults showthatthe BacT/Alert systemmay misssomefungi, either because ofnogrowth inthemedium or undetected slowgrowth. The latter problemcouldbeovercomebyprolonged incubation andterminal subculture when fungal infection isconsidered likely. Alteration of thesignalling mechanism mightpermitearlier detection ofsome slowgrowing fungi. (J7 Clin Pathol 1995;48:670-672)