Infection by Streptococcus pneumoniae in children with or without radiologically confirmed pneumonia

Dafne C. Andrade, Igor C. Borges, Ana Luísa Vilas-Boas, Maria S.H. Fontoura, César A. Araújo-Neto, Sandra C. Andrade, Rosa V. Brim, Andreas Meinke, Aldina Barral, Olli Ruuskanen, Helena Käyhty, Cristiana M. Nascimento-Carvalho

Community-acquired pneumonia (CAP) is an important cause of morbidity in childhood, but the detection of its causative agent remains a diagnostic challenge. The authors aimed to evaluate the role of the chest radiograph to identify cases of CAP caused by typical bacteria. The frequency of infection by Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis was compared in non-hospitalized children with clinical diagnosis of CAP aged 2-59 months with or without radiological confirmation (n=249 and 366, respectively). Infection by S. pneumoniae was diagnosed by the detection of a serological response against at least one of eight pneumococcal proteins (defined as an increase ≥2-fold in the IgG levels against Ply, CbpA, PspA1 and PspA2, PhtD, StkP-C, and PcsB-N, or an increase ≥1.5-fold against PcpA). Infection by H. influenzae and M. catarrhalis was defined as an increase ≥2-fold on the levels of microbe-specific IgG. Children with radiologically confirmed pneumonia had higher rates of infection by S. pneumoniae. The presence of pneumococcal infection increased the odds of having radiologically confirmed pneumonia by 2.8 times (95% CI: 1.8-4.3). The negative predictive value of the normal chest radiograph for infection by S. pneumoniae was 86.3% (95% CI: 82.4-89.7%). There was no difference on the rates of infection by H. influenzae and M. catarrhalis between children with CAP with and without radiological confirmation. Among children with clinical diagnosis of CAP submitted to chest radiograph, those with radiologically confirmed pneumonia present a higher rate of infection by S. pneumoniae when compared with those with a normal chest radiograph.