Data correction pre-processing for electronically stored blood culture results: implications on microbial spectrum and empiric antibiotic therapy.
BACKGROUND
The outcome of patients with bacteraemia is influenced by the initial selection of adequate antimicrobial therapy. The objective of our study was to clarify the influence of different crude data correction methods on a) microbial spectrum and ranking of pathogens, and b) cumulative antimicrobial susceptibility pattern of blood culture isolates obtained from patients from intensive care units (ICUs) using a computer based tool, MONI.


METHODS
Analysis of 13 ICUs over a period of 7 years yielded 1427 microorganisms from positive results. Three different data correction methods were applied. Raw data method (RDM): Data without further correction, including all positive blood culture results. Duplicate-free method (DFM): Correction of raw data for consecutive patient's results yielding same microorganism with similar antibiogram within a two-week period. Contaminant-free method (CFM): Bacteraemia caused by possible contaminants was only assumed as true bloodstream infection, if an organism of the same species was isolated from > 2 sets of blood cultures within 5 days.


RESULTS
Our study demonstrates that different approaches towards raw data correction - none (RDM), duplicate-free (DFM), and a contaminant-free method (CFM) - show different results in analysis of positive blood cultures. Regarding the spectrum of microorganisms, RDM and DFM yielded almost similar results in ranking of microorganisms, whereas using the CFM resulted in a clinically and epidemiologically more plausible spectrum.


CONCLUSIONS
For possible skin contaminants, the proportion of microorganisms in terms of number of episodes is most influenced by the CFM, followed by the DFM. However, with exception of fusidic acid for gram-positive organisms, none of the evaluated correction methods would have changed advice for empiric therapy on the selected ICUs.
Assadian
Ojan
O
Clinical Institute for Hygiene and Medical Microbiology, Medical University of Vienna, Division of Hospital Hygiene, Waehringer Guertel 18-20, A-1090 Vienna, Austria. ojan.assadian@meduniwien.ac.at
Diab-Elschahawi
Magda
M
Makristathis
Athanasios
A
Blacky
Alexander
A
Koller
Walter
W
Adlassnig
Klaus-Peter
KP
D000046:Academic Medical Centers; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D001317:Austria; D016470:Bacteremia / Q000188:drug therapy* / Q000453:epidemiology / Q000382:microbiology*; D001769:Blood / Q000382:microbiology*; D002984:Clinical Laboratory Information Systems / Q000706:statistics & numerical data*; D003428:Cross Infection / Q000188:drug therapy* / Q000382:microbiology*; D003430:Cross-Sectional Studies; D003625:Data Collection / Q000379:methods*; D006801:Humans; D007362:Intensive Care Units; D051188:Knowledge Bases; D008826:Microbial Sensitivity Tests / Q000706:statistics & numerical data*; D015203:Reproducibility of Results; D012984:Software
D000900:Anti-Bacterial Agents