Application of a Pneumococcal Serotype-specific Urinary Antigen Detection Test for Identification of Pediatric Pneumonia in Burkina Faso.

BACKGROUND: Serotype-specific diagnosis of pneumococcal community-acquired pneumonia in children under age 5 years would mark a major advancement for understanding pneumococcal epidemiology and supporting vaccine decision-making. METHODS: A Luminex technology-based multiplex urinary antigen detection (UAD) diagnostic assay was developed and subsequently validated in adults, but its applicability to children is unknown. This study aimed to set appropriate cutoffs for use of the UAD in a healthy pediatric population and apply these cutoffs in children with pneumonia in sub-Saharan Africa. The cutoffs were determined by assessing 379 urines obtained from healthy children under age 5 years from the Bobo-Dioulasso area for serotypes included in 13-valent pneumococcal conjugate vaccine (UAD-1) and the 11 other serotypes unique to 23-valent pneumococcal polysaccharide vaccine (UAD-2). RESULTS: Based on the assigned cutoff values, among 108 children who met the World Health Organization consolidation endpoint criteria, UAD-1 and UAD-2 were positive in 23.3% and 8.3%, respectively; among 364 children with clinically suspected pneumonia who did not meet the World Health Organization criteria, UAD-1 and UAD-2 were positive for 6.6% and 3.6%, respectively. Pneumococcal carriage prevalence was similar among pneumonia cases (30%) versus controls (35%) as was semiquantitative carriage density. CONCLUSIONS: UAD-1 and UAD-2 were able to distinguish community controls from children with pneumonia, particularly pneumonia with consolidation. Future studies are needed to confirm these results and more fully assess the contribution of pneumococcal carriage and concurrent viral infection.

Comparison of four commercial viral load techniques in an area of non-B HIV-1 subtypes circulation.

The aim of this study was to compare four HIV-1 viral quantitation platforms, Nuclisens EasyQ v2.0(®) (EQ), COBAS AmpliPreP/Cobas Taqman(®) HIV-1 test v 2.0 (CTM), GENERIC HIV CHARGE VIRALE(®) (GEN), with Abbott Real Time HIV-1(®) (m2000sp/rt) as reference technique. The study had first evaluated m2000sp/rt performances and then compared quantitation between techniques. Discordant samples were genotyped on gag and pol gene and sequences were analyzed using Sequence locator and SeqPublish to detect eventual mismatches. Performance analysis of m2000sp/rt showed good results with coefficients of variation values (CV) of 1.35%, 0.65%, and 0.54% for repeatability testing of low, intermediate and high concentrations, respectively. Reproducibility tests showed low CV values with 2.36% and 1.42% for low and high concentration levels, respectively and contamination test was very low value with 0.94%. Correlation and concordance between techniques ranged from r(2)=0.98 and bias=-0.00185 (for m2000sp/rt vs CTM) to r(2)=0.90 and bias=-0.135 (for EQ vs GEN). Discrepancies were observed on 37 samples mostly CRF02_AG but despite some mismatches, sequence analysis (26/37) did not show any remarkable differences between CRF02_AG queries and references. This study showed good correlation and good concordance between techniques. However, EQ yielded under-quantitation of CRF02_AG.