Although the incidence of polymicrobial bloodstream infection (PBSI) has increased, only a few studies have so far focused on children. Therefore, in an effort to prevent more serious situations in pediatric patients, we analyzed the clinical features, organisms, and laboratory results of PBSI.

We performed a retrospective review of the case records of 97 patients with polymicrobial bloodstream infection in the Severance hospital, from 2001 to 2008. Using t-test and chi-square test, we analyzed the underlying medical conditions, clinical characteristics, organisms, and laboratory results of those patients.

Annual incidence of polymicrobial bloodstream infection increased from 1.4% in 2001 to 10.9% in 2008 in pediatric patients. Immunocompromised hemato-oncological malignancy was found in 31 (31.9%) patients, and was the most common underlying medical condition; cardiovascular disease was found in 15 patients (15.4%), neurologic disease in 10 patients (10.3%), and so on. Gram positive organisms were recovered in 143 cases and gram negative organisms were recovered in 101 cases of PBSI. Staphylococcus epidermidis was the most common organism. Factors affecting mortality included underlying medical disease, immune status, nosocomial infection, and central catheter-related infection, for which the rate of mortality showed a greater increase (P<0.05).

Due to the close connection between PBSI and fatal conditions or high mortality, it requires more aggressive management. Compared with previous studies, we discovered that immunocompromised hemato-oncological malignancy was the most common underlying medical condition and that frequency of gram-positive bacteria and fungus isolated has increased.