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Volume 49, Number 3, June 2016

Time to positivity in blood cultures of adults with nontyphoidal Salmonella bacteremia 

Hui-Wen Lin, Hsin-Sui Hsu, Yu-Tsung Huang, Chia-Jui Yang, Meng-Shiuan Hsu, Chun-Hsing Liao


Corresponding author:

Corresponding author. Chun-Hsing Liao, Division of Infectious Diseases, Department of Internal Medicine, Far Eastern Memorial Hospital, Number 21, Section 2, Nan-Ya South Road, Pan-Chiao District, New Taipei City 220, Taiwan. 


Background and purpose: 

Nontyphoidal Salmonella (NTS) is an important bacterial etiology of diarrheal disease, and it causes invasive diseases in immunocompromised hosts. For bacteremia from some species, blood culture with a rapid time to positivity (TTP) is associated with greater mortality. This study investigated TTP of NTS bacteremia and its relationship to clinical parameters and prognosis. 



Adult patients with NTS bacteremia who were admitted to a tertiary care facility in northern Taiwan from January 2010 to December 2012 were enrolled. Demographics, clinical and microbiological characteristics, and treatment response were reviewed. The TTP for each patient was retrieved from the automated machine. 



Sixty-six adult patients (mean age, 66.1 years; range, 27–96 years) with NTS bacteremia were identified by the following serogroup distributions: serogroup B (23.4%), serogroup C1 (1.6%), serogroup C2 (6.3%), and serogroup D (68.8%). The in-hospital mortality, 14-day mortality, and 30-day mortality were 15.2%, 7.6%, and 12.1%, respectively. The TTP ranged 6.5–41.7 hours (median: 11.5 hours). Patients with rapid TTP (less than 10 hours), compared to patients without rapid TTP, were more likely to have liver cirrhosis (31.6% vs. 6.4%, p = 0.013), endovascular lesions (21.1% vs. 4.3%, p = 0.05), higher bacteremia score, intensive care unit admission (57.9% vs. 25.5%, p = 0.021), and septic shock (63.2% vs. 12.8%, p < 0.001). There were no significant differences in the in-hospital mortality and 14-day mortality between patients with TTP <10 hours and patients with TTP ≥10 hours.The TTP of blood cultures, interpreted with a cut-off point of <10 hours, in patients with NTS bacteremia may provide useful diagnostic and prognostic information. 


Key words:

bacteremia, nontyphoidal Salmonella, time to positivity