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Volume 50, Number 4, August 2017

Time-to-positivity of blood culture: An independent prognostic factor of monomicrobial Pseudomonas aeruginosa bacteremia 


Poh-Chang Tang, Ching-Chi Lee, Chia-Wen Li, Ming-Chi Li, Wen-Chien Ko, Nan-Yao Lee


 

Corresponding author:

Wen-Chien Ko, Corresponding authors. Department of Internal Medicine, National Cheng Kung University Hospital, Number 138, Sheng Li Road, 704, Tainan, Taiwan. 



 

Background and purpose: 

Pseudomonas aeruginosa bacteremia is an important cause of nosocomial infections with high morbidity and mortality. Time-to-positivity (TTP) of blood cultures is considered to be a predictor of the clinical outcome for bacteremia. The aim of the study is to investigate the relationship between TTP and clinical outcomes in patients with monomicrobial P. aeruginosa bacteremia. 



 

Methods:

From January 2013 to June 2014, a retrospective cohort study was conducted in a 1200-bed tertiary care hospital. The cases of monomicrobial P. aeruginosa bacteremia were studied. TTP and clinical parameters were determined and analyzed.

 



 

Results:

In 139 cases of P. aeruginosa bacteremia, TTP ≤ 13 hours was associated with higher Pitt bacteremia scores (5.3 ± 4.2 vs. 2.3 ± 2.8, p < 0.001), severe sepsis (66.1% vs. 35.0%, p < 0.001), higher 30-day mortality rate (54.2% vs. 15.0%, p < 0.001), longer hospitalization in the survivors (25.6 ± 48.5 days vs. 16.3 ± 15.3 days, p = 0.16), and more admission to intensive care unit (27.2% vs. 16.3%, p = 0.14). Risk factors for 30-day mortality in the univariate analysis included corticosteroid exposure, primary bacteremia, concurrent pneumonia, a high Pitt bacteremia score, severe sepsis, and TTP ≤ 13 hours. In the multivariate analysis, primary bacteremia, a pulmonary origin of bacteremia, severe sepsis, and TTP ≤ 13 hours were independent risk factors for 30-day mortality.

 



 

Conclusion:

In cases of monomicrobial P. aeruginosa bacteremia, a short TTP (≤ 13 hours) provides prognostic information, in addition to clinical parameters. 



 

Key words:

bacteremia, Pseudomonas aeruginosa, time-to-positivity