Purpose
Clinical, immunological and microbiological characteristics of recurrent invasive pneumo-
coccal disease (IPD) in children were evaluated, differentiating relapse from reinfection, in
order to identify specific risk factors for both conditions.
Methods
All patients <18 years-old with recurrent IPD admitted to a tertiary-care pediatric center
from January 2004 to December 2011 were evaluated. An episode of IPD was defined as
the presence of clinical findings of infection together with isolation and/or pneumococcal
DNA detection by Real-Time PCR in any sterile body fluid. Recurrent IPD was defined as
2 or more episodes in the same individual at least 1 month apart. Among recurrent IPD, we
differentiated relapse (same pneumococcal isolate) from reinfection.
Results
593 patients were diagnosed with IPD and 10 patients died. Among survivors, 23 episodes
of recurrent IPD were identified in 10 patients (1.7%). Meningitis was the most frequent form
of recurrent IPD (10 episodes/4 children) followed by recurrent empyema (8 episodes/4 chil-
dren). Three patients with recurrent empyema caused by the same pneumococcal clone
ST306 were considered relapses and showed high bacterial load in their first episode. In
contrast, all other episodes of recurrent IPD were considered reinfections. Overall, the rate
of relapse of IPD was 0.5% and the rate of reinfection 1.2%. Five out of 7 patients with rein-
fection had an underlying risk factor: cerebrospinal fluid leak (n = 3), chemotherapytreatment (n = 1) and a homozygous mutation in MyD88 gene (n = 1). No predisposing risk
factors were found in the remainder.
Conclusions
recurrent IPD in children is a rare condition associated with an identifiable risk factor in case
of reinfection in almost 80% of cases. In contrast, recurrent IPD with pleuropneumonia is
usually a relapse of infection