Usefulness of pneumococcal antigen detection in pleural effusion for the rapid diagnosis of infection by Streptococcus pneumoniae.

Pleural effusion is increasingly reported in children. Standard culture of blood or pleural fluid is frequently negative and molecular diagnosis by polymerase chain reaction is not available in all hospitals. The Binax NOW Streptococcus pneumoniae Antigen test (Binax, Portland, USA) is a rapid immunochromatographic test (ICT) for the detection of the C polysaccharide antigen. We evaluated the Binax NOW test on the pleural fluid of 73 children hospitalized with pleural effusion over a period of 4 years. In our sample, the sensitivity and specificity of ICT were high (88% and 71%, respectively), with a positive predictive value of 96%. Detection of the pneumococcal antigen in pleural fluid by ICT is easy and quick, and enables us to identify the pneumococcal origin of the effusion, thus, making the treatment of complicated pneumonia suitably and early.

A cross-reactive neisserial antigen encoded by the NMB0035 locus shows high sequence conservation but variable surface accessibility.

The meningococcal NMB0035 locus encodes a 47 kDa outer-membrane protein that is highly conserved antigenically, and is able to induce antibodies during infection and bactericidal responses in vitro. This study analysed the surface exposure of this protein using specific antibodies in flow cytometry assays and determined its nucleotide sequence in 33 Neisseria strains. Genomic analyses revealed no significant differences in the nucleotide or amino acid sequences, but flow cytometry showed that surface accessibility was highly variable among the strains. These results suggest that masking by and/or association with lipo-oligosaccharides or other membrane molecules can be crucial for antigen accessibility, which must be thoroughly analysed in new vaccine candidates.

Analysis of the genetic structure of nontypeable pneumococcal strains isolated from conjunctiva.

More than 50% of the nontypeable (NT) pneumococcal strains received in our laboratory for reference purposes are isolated in sporadic cases of conjunctivitis. To determine the genetic structure of the population of these NT conjunctival strains, we analyzed 75 pneumococci (40 NT and 35 typeable) isolated from conjunctivas and 30 (15 NT and 15 typeable) isolated from other sources. The NT and typeable conjunctival strains grouped in separate clusters, whereas NT and typeable pneumococci isolated from other sources were similarly distributed. NT conjunctival strains belonged to two well-differentiated clonal lineages. The first, represented by three newly described sequence types, featured fully antibiotic susceptible strains and appeared to be characteristic of conjunctival tissue; the second, represented by the previously described ST344, had a pattern of multiresistance to penicillin, tetracycline, and erythromycin and shared a genetic background with some NT strains isolated from other sources.

[Multilocus sequence typing: the molecular marker of the Internet era]. / Multilocus sequence typing: el marcador molecular de la era de Internet.

Global or longer term epidemiology track the spread of clonal lineages, associated with hipervirulence or resistance or multi-resistance to antimicrobial agents. Therefore, the application of a molecular typing system for this purpose should produce data easily shared by different and geographically distant laboratories, as well as distinguish those clonal lineages even with low levels of variability accumulated in the genome.A marker based on the DNA sequence will produce objective results easily organized in data bases accessible by Internet. The application of a similar strategy that was used in the analysis of isoenzymes, by sequencing variable fragments of selected housekeeping genes, will allow obtaining a general view of the distribution of the clonal lineages and tracking their spread.

Multilocus sequence typing: el marcador molecular de la era de Internet / Multilocus seqquence typing: the molecular marker of the Internet era

La epidemiología global o a largo plazo tiene como objetivo el trazado preciso de los procesos de dispersión de líneas clonales, asociadas a altos niveles de virulencia, a determinada resistencia o a multirresistencia frente a uno o varios agentes antimicrobianos, etc. Por lo tanto, un sistema de tipificación aplicado a este nivel, debe producir resultados que sean fácilmente intercambiables entre laboratorios alejados geográficamente entre sí, así como detectar las diferentes líneas clonales incluso en presencia de bajos niveles de variabilidad acumulada en el genoma.Un marcador basado en secuencia de ADN puede producir unos resultados objetivos (secuencias de letras) que son fácilmente almacenados en bases de datos accesibles mediante Internet. La aplicación de una estrategia similar a la ya utilizada en el análisis de isoenzimas, con la secuenciación de fragmentos variables de genes housekeeping seleccionados va a permitir obtener una visión global de la distribución de los principales complejos clonales en la población analizada, además de trazar su proceso de dispersión (AU)