Time to positivity of blood cultures causing candidemia and its relation to mortality

Early diagnosis of candidemia is of vital importance in reducing mortality and morbidity. The main objective of the study was to determine the TTP (Time to Positivity) of different species of Candida causing bloodstream infection and to see whether TTP can help differentiate Candida glabrata which is frequently fluconazole resistant from Fluconazole sensitive Candida.

TTP (Time to positivity) and AAT (Appropriate Antifungal therapy) were noted for Blood cultures becoming positive for Candida. Presence of Risk factors for candidemia like prolonged ICU stay, neutropenia, Total Parenteral Nutrition (TPN), use of steroids , broad spectrum antibiotics, use of Central Venous Catheter, Foleys catheter were also analyzed.

The most frequent isolates were Candida parapsilosis, Candida tropicalis and Candida albicans. The median TTP for all Candida isolates in our study was 34 hours. The diagnostic sensitivity of TTP for detecting C. glabrata and C. tropicalis in patients with candidemia was 88% and 85% respectively. TTP showed that there was no difference in survival between TTP <24 hrs. and > 24hrs. Initiation of antifungal therapy <24 hours and > 24hrs after onset of candidemia had no association with survival.

Longer TTP maybe predictive of C. glabrata while shorter TTP may be predictive of C. tropicalis. In our study we found that fluconazole resistant Candida causing blood stream infection is quite unlikely if the TTP of the isolate is <48hrs.