title: Growth dynamics of Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa as a function of time to detection in BacT/alert 3D blood culture bottles with various preincubation conditions.
abstract: BACKGROUND
  Delayed entry of blood culture bottles is inevitable when microbiological laboratories do not operate for 24 hr. There are few studies reported for prestorage of these bottles. The growth dynamics of Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa were investigated with respect to various preincubation conditions.
  
  
  METHODS
  Fifteen or 150 colony-forming units (CFU) of bacteria were inoculated into standard aerobic or anaerobic blood culture bottles. Bottles were preincubated at 25℃ or 37℃ for 0, 2, 4, 8, 12, 24, or 48 hr. The time to detection (TTD) then was monitored using the BacT/Alert 3D system (bioMerieux Inc., USA).
  
  
  RESULTS
  Significant difference in TTD was observed following preincubation for 8 hr at 25℃ vs. 4 hr at 37℃ for S. aureus, 4 hr at 25℃ vs. 4 hr at 37℃ for E. coli, 12 hr at 25℃ vs. 4 hr at 37℃ for P. aeruginosa, compared to no preincubation (P<0.005). TTD values did not vary significantly with bacterial CFU or with aerobic or anaerobic bottle type. The BacT/Alert 3D system returned false negatives following preincubation of P. aeruginosa for 48 hr at 25℃ or 24 hr at 37℃.
  
  
  CONCLUSIONS
  TTD was mainly affected by preincubation temperature and duration rather than by input CFU quantity or bottle type for the 3 experimental bacteria.
authors.affiliation: Department of Laboratory Medicine, Gyeongsang Institute of Health Sciences, Gyeongsang National University School of Medicine, Jinju, Korea.
authors.forename: Dong-Hyun
authors.initials: DH
authors.lastname: Lee
authors.forename: Eun-Ha
authors.initials: EH
authors.lastname: Koh
authors.forename: Sae-Rom
authors.initials: SR
authors.lastname: Choi
authors.forename: Sunjoo
authors.initials: S
authors.lastname: Kim
mesh_terms: D001431:Bacteriological Techniques / Q000295:instrumentation / Q000379:methods*; D003470:Culture Media; D004926:Escherichia coli / Q000254:growth & development / Q000302:isolation & purification*; D011550:Pseudomonas aeruginosa / Q000254:growth & development / Q000302:isolation & purification*; D013211:Staphylococcus aureus / Q000254:growth & development / Q000302:isolation & purification*; D013696:Temperature; D013997:Time Factors
chemical_list: D003470:Culture Media
keywords: Blood culture; Detection; Preincubation; Storage