Dried blood spots for Streptococcus pneumoniae and Haemophilus influenzae detection and serotyping among children < 5 years old in rural Mozambique

Abstract

Background: Dried blood spots (DBS) have been proposed as potentially tool for detecting invasive bacterial diseases. Methods: We evaluated the use of DBS for S. pneumoniae and H. influenzae detection among children in Mozambique. Blood for DBS and nasopharyngeal (NP) swabs were collected from children with pneumonia and healthy aged < 5 years. Bacterial detection and serotyping were performed by quantitative PCR (qPCR) (NP and DBS; lytA gene for pneumococcus and hpd for H. influenzae) and culture (NP). Combined detection rates were compared between children with pneumonia and healthy. Results: Of 325 children enrolled, 205 had pneumonia and 120 were healthy. Pneumococci were detected in DBS from 20.5 and 64.2% of children with pneumonia and healthy, respectively; NP specimens were positive for pneumococcus in 80.0 and 80.8%, respectively. H. influenzae was detected in DBS from 22.9% of children with pneumonia and 59.2% of healthy; 81.4 and 81.5% of NP specimens were positive for H. influenzae, respectively. Conclusion: DBS detected pneumococcal and H. influenzae DNA in children with pneumonia and healthy. Healthy children were often DBS positive for both bacteria, suggesting that qPCR of DBS specimens does not differentiate disease from colonization and is therefore not a useful diagnostic tool for children.