Viridans streptococcal bacteraemia in paediatric immunocompromised patients with malignant disease
Amongst the paediatric haematology/oncology patients attending the Royal Hospital for Sick Children, Glasgow, episodes of viridans streptococcal bacteraemia increased from 12% of al microbiologically documented bacteraemias (i.e. 10/81) in 1993 to 22% (18/83) in 1994. During the first year of this project (which started in December 1994), ITU support was required following the development of viridans streptococcal bacteraemia on 6 occasions, and of these, there were two fatalities. The overall aim of this study was to improve the management of this infection and to explore preventative strategies. Three different approaches were adopted: (1) an extensive epidemiological analysis was undertaken - to include all episodes of viridans streptococcal bacteraemia from December 1994 to December 2000. (2) Phenotypic, followed by genotypic analyses of isolates of viridans streptococci from mouth swabs and blood cultures were carried out to determine whether the mouth was in fact the source of organisms responsible for this infection. (3) Extensive antibiotic susceptibility studies were performed on all isolates of viridans streptococci from blood culture. In total, 69 episodes of viridans streptococcal bacteraemia occurred in 54 children. The infection was more often associated with patients with haematological malignancy (particularly AML), than those with solid tumours, and in the majority (84%) of episodes, the patients suffered from chemotherapy-induced mucositis or other forms of oral compromise. Forty-eight episodes of infection (70% of total) responded well to antimicrobial therapy with no evidence of additional clinical complications. However, in 21 cases (30% of total), pulmonary complications developed, with 8 of these requiring mechanical ventilation and supplemental oxygen. Five of these 8 cases also developed septic shock. S. oralis was the species most commonly isolated from blood culture (63% of total isolates of viridans streptococci) and S. mitis represented 25% of total isolates. Polymicrobial bloodstream infection occurred in 23% of episodes.