Estimation of the invasive disease potential of Streptococcus pneumoniae in children by the use of direct capsular typing in clinical specimens

Abstract

Traditionally, invasiveness indexes have been based on culture methods. We aimed to establish a new classification of the invasive disease potential of pneumococcal serotypes causing invasive pediatric disease in the era of conjugate vaccines in Catalonia, Spain, by adding capsular typing of Streptococcus pneumoniae in direct sample. Two samples of children attended at the University Hospital Sant Joan de Déu (Barcelona, Spain) between 2007 and 2011 were compared: a first sample of 358 children with invasive pneumococcal disease and a second sample of 402 pneumococcal nasopharyngeal carriers selected from 714 healthy children admitted for minor surgical procedures. The most common invasive serotypes were 1 (20.1 %, n = 72), 19A (13.9 %, n = 50), 3 (12.3 %, n = 44), and 7FA (7.5 %, n = 27), whereas the most common serotypes in carriage were 19A (8.7 %, n = 38), 10FC33C (7.8 %, n = 34), 6C (6.9 %, n = 30), and 19FBC (5.5 %, n = 24). We detected a rate of cocolonization of 26.4 % (n = 89) among the 336 samples serotyped in the carriers population. Serotypes 1, 3, and 7FA were significantly associated with high invasiveness. Serotypes 6C, 10FC33C, 23A, 35B, 19FBC, 21, 11AD, 15BC, 23B, 34, and 6A were significantly associated with low invasiveness. Our results proved that the use of molecular techniques in direct sample for both the detection and the capsular identification of Streptococcus pneumoniae is very useful to obtain a more accurate calculation of the invasiveness of the different pneumococcal serotypes.

Invasive Pneumococcal Disease and Influenza Activity in a Pediatric Population: Impact of PCV13 Vaccination in Epidemic and Nonepidemic Influenza Periods

“…The serotypes found were classified into two groups according to their invasiveness, namely, highly invasive serotypes (HIS; serotypes 1, 3, 4, 5, 7F, 8, 9N, 9V, 12F, 14, 18C, 19A, and 22F) and the remaining serotypes (non-HIS), as described by various authors (30)(31)(32)(33)(34).…”

Nasopharyngeal Microbiota in Children With Invasive Pneumococcal Disease: Identification of Bacteria With Potential Disease-Promoting and Protective Effects

“…All pneumococcal isolates were identified by standard microbiological methods, including the optochin sensitivity test and an antigenic test targeting the capsular polysaccharide (Slidex pneumo-kit, bioMérieux, Marcy-l'Etolie, France). DNA detection of pneumococcal LytA gene was performed by a duplex real-time PCR as previously reported (Selva et al, 2014; del Amo et al, 2015). This duplex real-time PCR also included as target the Rnase P human single-copy gene to detect and measure the number of human cells (Brotons et al, 2017), using primers and probes recommended by CDC (Meningitis, 2011).…”

Effectiveness of the 13-valent pneumococcal conjugate vaccine in preventing invasive pneumococcal disease in children aged 7-59 months. A matched case-control study

“…pneumoniae or DNA detection of the Lyt A gene and an additional capsular gene of S . pneumoniae by real-time polymerase chain reaction (PCR) in any normally-sterile site according to a previously reported method [ 14 ]. Strains isolated by culture were serotyped using the Quellung reaction or dot blot by the National Centre for Microbiology, Majadahonda, Madrid.…”