title: Determination of the optimum incubation period of continuously monitored blood cultures from patients with suspected endocarditis or fungaemia.
abstract: OBJECTIVE
  It is routine practice to prolong the incubation period of blood cultures from patients with suspected subacute bacterial endocarditis (SBE) or fungal infection. The protocol in this laboratory required 28 days incubation with weekly subcultures. Following the introduction of automated continuously monitored blood culture instruments, the duration of incubation for specimens from these categories of patients was reviewed.
  
  
  METHODS
  In a retrospective study of blood culture specimens submitted from 1 July 1994 to 31 July 1998, the time from collection to a positive signal from the BacT/Alert automated blood culture system, in patients suspected of SBE or fungal infection, was assessed.
  
  
  RESULTS
  From 355 patient episodes, 896 bottles were incubated for up to 28 days, during which time 116 bottles (40 patient episodes) signalled positive. Significant organisms from suspected endocarditis patients were isolated from 87 bottles (87%), with the time to detection ranging from 9 to 96 hours. The data collected from significant isolates obtained from clinically suspected fungaemias were extremely small, prompting a review of the total fungal isolates from all blood culture bottles incubated during the study period. Yeast isolates were obtained from 78 (0.08%) bottles with the detection time ranging from 15 to 144 hours.
  
  
  CONCLUSIONS
  The practice in this laboratory now is to incubate blood cultures for up to 7 days when the clinical notes indicate the possibility of SBE or a fungal infection.
authors: South Eastern Area Laboratory Services (SEALS), Division of Microbiology, The St George Hospital, Kogarah, NSW, Australia. varettask@sesahs.nsw.gov.au
authors: K
authors: K
authors: Varettas
authors: P C
authors: PC
authors: Taylor
authors: C
authors: C
authors: Mukerjee
mesh_terms: D001419:Bacteria / Q000254:growth & development / Q000302:isolation & purification; D001431:Bacteriological Techniques; D001769:Blood / Q000382:microbiology*; D004698:Endocarditis, Subacute Bacterial / Q000097:blood / Q000175:diagnosis* / Q000382:microbiology; D005658:Fungi / Q000254:growth & development / Q000302:isolation & purification; D006784:Hospitals, Teaching; D006801:Humans; D009172:Mycology / Q000379:methods*; D009181:Mycoses / Q000097:blood / Q000175:diagnosis* / Q000382:microbiology; D009517:New South Wales; D011933:Reagent Kits, Diagnostic; D012189:Retrospective Studies; D013997:Time Factors
chemical_list: D011933:Reagent Kits, Diagnostic