Clinical features and complications of viridans streptococci bloodstream infection in pediatric hemato-oncology patients

Abstract

Background and purpose: Viridans streptococci (VS) are part of the normal flora of humans, but are fast emerging as pathogens causing bacteremia in neutropenic patients. The clinical features, outcomes, and antibiotic susceptibilities of VS bloodstream infections in children with hemato-oncological diseases are reported in this study.

Methods: A retrospective chart review of pediatric patients (< or =18 years) diagnosed with VS infections between January 1998 and December 2004 was conducted at the National Taiwan University Hospital.

Results: Among the 26 episodes noted in 25 pediatric patients, the incidence rate of VS bacteremia was found to be significantly higher in pediatric patients with acute myeloid leukemia compared with other hemato-oncological conditions. Most of the patients had profound neutropenia related to chemotherapy for a median of 5 days on the day of positive blood culture. Eight of the 25 patients had undergone stem cell transplantations. Streptococcus mitis was the most common bloodstream isolate and only 12 (44%) of the 27 isolated strains of VS were penicillin-susceptible. Empirical antibiotic treatments were not effective in half of the episodes, but did not affect overall mortality. Isolated bacteremia (63%) and pneumonia (22%) were the two leading clinical presentations. Complications were recognized more frequently in patients with pneumonia. Hypotension and mechanical ventilation each developed in 8 patients (31%). The overall mortality rate was 23%.

Conclusions: Penicillin non-susceptible VS infection has emerged as a threat in children with hemato-oncological diseases, especially those with acute myeloid leukemia. S. mitis is the most common spp. of VS causing bacteremia in children and is associated with serious complications. The development of pneumonia resulted in clinical complications and higher mortality. Empirical antibiotic treatments with activity against the infecting strains did not reduce the overall mortality rate in this study.