Use of nasopharyngeal Streptococcus Pneumoniae (Sp) load to define pneumococcal etiology of community acquired pneumonia (CAP)

Background: Pneumococcal CAP is frequently associated with chest X-ray findings suggesting alveolar involvement. Recently, it has been reported that determination of nasopharyngeal SP load could be useful for the identification of pneumococcal etiology in CAP. However, no data are available about the association between nasopharyngeal SP load and alveolar CAP as well as the relevance of viral coinfections in conditioning bacterial load. Methods: On nasopharyngeal secretions of 386 children aged <5 years with radiographically-confirmed CAP, the presence of 17 viruses and Sp was evaluated by means of Luminex xTAG Respiratory Virus Panel Fast assay and by specific Real-Time polymerase chain reaction (PCR) for LytA and Wgz (cpsA) Sp genes. Nasopharyngeal Sp load was calculated and analyzed according to chest X-ray characteristics. Conclusion: Higher nasopharyngeal Sp load is more common in children with alveolar CAP suggesting that determination of this variable can contribute to the definition of pneumococcal etiology of CAP. Viral coinfections do not influence bacterial load.