Pneumococcal urinary antigen positivity in healthy colonized children: is it age dependent?

BACKGROUND: Pneumococcal urinary antigen test is a valuable tool for diagnosing pneumococcal pneumonia and meningitis in adults. Its use in children is generally not accepted because of nonspecificity at this age. It is frequently positive in asymptomatic nasopharyngeal carriers. The aim of our study was to assess the age limit from which the test is no longer positive in asymptomatic healthy carriers. METHODS: A total of 197 children aged 36-83 months attending 9 day care centers in Prague were enrolled during February and March 2010. Nasopharyngeal swab specimens were collected from each participant and selectively cultivated. The presence of pneumococcal antigen in urine was detected by BinaxNOW® S. pneumoniae kit. RESULTS: Streptococcus pneumoniae was cultivated in 53.3 % of healthy children with the highest colonization rate (59.3 %) in children aged 48-59 months. The most frequently colonizing serotypes were: 19F, 23F, 3, 19A, 6B and 4. The presence of pneumococcal antigen in urine decreased with age from 39.0 % in 36-47 months to 17.9 % in 72-83 months old (p = 0.031). The antigen positivity was serotype-dependent and more frequent in nonvaccinated children. CONCLUSION: We demonstrated age-dependent linear decrease of pneumococcal antigen excretion into urine in healthy children. The positivity rate of the test in children aged 72-83 months was similar to that referred in healthy adults, irrespective of colonization. To confirm this age limit for use of this test in diagnostics of pneumococcal diseases, further study in school-age children is justified.

Circular dichroism and guanine quadruplexes.

Circular dichroism (CD) is remarkably sensitive to the conformational states of nucleic acids; therefore, CD spectroscopy has been used to study most features of DNA and RNA structures. Quadruplexes are among the significant noncanonical nucleic acids architectures that have received special attentions recently. This article presents examples on the contribution of CD spectroscopy to our knowledge of quadruplex structures and their polymorphism. The examples were selected to demonstrate the potential of this simple method in the quadruplex field. As CD spectroscopy detects only the global feature of a macromolecule, it should preferably be used in combination with other techniques. On the other hand, CD spectroscopy, often as a pioneering approach, can reveal the formation of particular structural arrangements, to search for the conditions stabilizing the structures, to follow the transitions between various structural states, to explore kinetics of their appearance, to determine thermodynamic parameters and also detect formation of higher order structures. This article aims to show that CD spectroscopy is an important complementary technique to NMR spectroscopy and X-ray diffraction in quadruplex studies.

Impact of the 10-valent pneumococcal non-typeable Haemophilus influenzae Protein D conjugate vaccine (PHiD-CV) on bacterial nasopharyngeal carriage.

Pneumococcal conjugate vaccines (PCV) may reduce nasopharyngeal carriage (NPC) of Streptococcus pneumoniae vaccine strains (VT), but serotype replacement with non-vaccine strains (NVT) has been reported. Bacterial NPC after PHiD-CV vaccination was assessed in the second year of life. Open descriptive study of NPC reported for 414 subjects vaccinated at 3-5 and 12-15 months of age with PHiD-CV with or without prophylactic paracetamol (PP) compared to 336 age-matched PCV-naïve controls. Carriage was assessed prior to and 1, 3, 7 and 12 months after PHiD-CV booster or MenACWY-TT control vaccination at 12-15 months of age. At each visit, carriage of VT was reduced by 22-35% in PHiD-CV recipients. Vaccine efficacy across all visits was 21.7% [95% CI 2.6; 37.0] (26.8% carriage in the PHiD-CV group versus 34.2% in controls). Carriage rates of NVT tended to be higher in PHiD-CV recipients. Pre-booster, these findings were more pronounced when PP had not been administered. No substantial effect of PHiD-CV vaccination was observed on NPC of other bacterial pathogens including non-typeable Haemophilus influenzae. Primary and booster vaccination with PHiD-CV reduced NPC of VT in the second year of life and tended to slightly increase that of NVT in line with previous experience with the 7-valent PCV.

Serotype-specific invasive disease potential of Streptococcus pneumoniae in Czech children.

To estimate the invasive disease potential of Streptococcus pneumoniae serotypes, invasive isolates (n=138) were compared with nasopharyngeal isolates (n=153) from children under 6 years of age in the Czech Republic. Odds ratios (ORs) based on a comparison of the distribution of S. pneumoniae serotypes amongst invasive and carriage isolates were calculated for individual serotypes and 172 strains were characterized using multilocus sequence typing. The ORs of serotypes 9V and 14 were significantly greater than 1, suggesting an association with invasive disease, while serotypes 6A and 23F were significantly associated with carriage (ORs less than 1). A single predominant clone with high invasive disease potential was found in each of the 9V, 7F, 14 and 1 serotypes while carriage-associated serotypes were highly heterogeneous.

Clonal distribution of invasive pneumococci, Czech Republic, 1996-2003.

We conducted surveillance on invasive pneumococci isolated from adults in the Czech Republic during 1996-2003. The 7 most prevalent serotypes were characterized. Coverage with the 7-valent pneumococcal conjugate vaccine was low. Our observations confirm that detection methods may have modified the expected effect of this vaccine.

Virulence properties of type VII Streptococcus agalactiae (group B streptococci) and immunochemical analysis of capsular type polysaccharide.

Strains of a new polysaccharide type of group B streptococci (GBS), type VII, have been isolated from human carriers and invasive infections. Some of these strains bear the protein antigen c or R, as do other GBS serotypes. The capsular type polysaccharide is sialylated and this residue is involved in the immunodeterminant structure. All type VII strains examined were virulent in CD-1 mice; the LD50 after intraperitoneal (i.p.) challenge was 4.57 (SD 0.12) x10(7) cfu for the reference strain and 5.49 (SD 1.5) x10(7) cfu for clinical isolates. A particular feature of this serotype was the ability to induce septic arthritis not only when injected intravenously (i.v.), but also when injected i.p. Rabbit antiserum against the capsular type VII polysaccharide exhibited opsonic activity in a phagocytosis assay and protective activity against infection.