Article

Seasonality and outbreak of a predominant Streptococcus pneumoniae serotype 1 clone from The Gambia: expansion of ST217 hypervirulent clonal complex in West Africa.

Bacterial Diseases Programme, Medical Research Council Laboratories, Banjul, The Gambia.
BMC Microbiology (Impact Factor: 2.98). 11/2008; 8:198. DOI: 10.1186/1471-2180-8-198
Source: PubMed

ABSTRACT Streptococcus pneumoniae serotype 1 causes > 20% of invasive disease, among all age groups combined, in The Gambia. In contrast, it is rarely detected in carriage studies. This study compares the molecular epidemiology of S. pneumoniae serotype 1 causing invasive disease in The Gambia between 1996 and 2005 to those carried in the nasopharynx between 2004 and 2006.
A total of 127 invasive and 36 nasopharyngeal carriage serotype 1 isolates were recovered from individuals of all age groups and were analyzed by serotyping, antibiotic susceptibility testing and MLST. MLST analysis revealed 23 different sequence types (STs), 18 of which were novel. The most prevalent clone among the 163 isolates was ST618 (70.5%), followed by ST3575 (7.4%), ST2084 (2.5%) and ST612 (2.5%). A single ST (ST618), previously shown to belong to the ST217 hypervirulent clonal complex, was frequent among carriage (61.1%) and invasive (72.7%) serotype 1 isolates. ST618 causing both paediatric and adult disease peaked annually in the hot dry season and caused outbreak in 1997 and 2002.
For over a decade, isolates of ST618 have been the dominant lineage among serotype 1 carriage and disease isolates circulating in the Gambia. This lineage shows similar epidemiological features to those of the meningococcus in the African meningitis belt being able to cause outbreaks of disease.

0 Bookmarks
 · 
115 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: Objectif Le but de ce travail était de déterminer les caractéristiques épidémiologiques des infections invasives méningées et pulmonaires dues à Streptococcus pneumoniae au Burkina Faso. Matériel et méthodes S. pneumoniae a été recherché par des techniques de bactériologie classique et par PCR en temps réel (rt-PCR) dans 7917 échantillons de liquides céphalorachidiens (LCR) et de liquides pleuraux (LP) collectés au CHU Yalgado de Ouagadougou de 2007 à 2011. Résultats S. pneumoniae a été identifié dans 476 (6 %) des échantillons analysés dont 455 (5,7 %) dans les LCR et 21 (0,3 %) dans les LP. Soixante-sept pour cent des infections invasives confirmées sont survenus chez les patients de 15 ans et moins. Aucune différence significative n’était associée au sexe des patients. Les cas surviennent entre janvier et août principalement, avec un premier pic entre janvier et mai (saison sèche) plus important que le second observé entre juin et août (début d’hivernage). L’introduction de la rt-PCR a montré une sous-notification des cas confirmés d’infections invasives pneumococciques par les techniques bactériologiques classiques (détection de l’antigène capsulaire soluble par des particules de latex sensibilisées et culture). Conclusion Les infections invasives pneumococciques surviennent dans toutes les tranches d’âge, avec une fréquence plus élevée chez les 15 ans et moins, sans distinction de sexe et avec des pics en saison sèche. Les perspectives vaccinales devraient prendre en compte toutes les tranches d’âges des populations du pays.
    Médecine et Maladies Infectieuses 03/2014; · 0.75 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Streptococcus pneumoniae is the world's leading cause of pneumonia, bacteremia, meningitis and otitis media. A major pneumococcal virulence factor is the cholesterol-dependent cytolysin, which has the defining property of forming pores in cholesterol-containing membranes. In recent times a clinically significant and internationally successful serotype 1 ST306 clone has been found to express a non-cytolytic variant of Ply (Ply306). However, while the pneumococcus is a naturally transformable organism, strains of the ST306 clonal group have to date been virtually impossible to transform, severely restricting efforts to understand the role of non-cytolytic Ply in the success of this clone. In this study isogenic Ply mutants were constructed in the D39 background and for the first time in the ST306 background (A0229467) to enable direct comparisons between Ply variants for their impact on the immune response in a macrophage-like cell line. Strains that expressed cytolytic Ply were found to induce a significant increase in IL-1β release from macrophage-like cells compared to the non-cytolytic and Ply-deficient strains in a background-independent manner, confirming the requirement for pore formation in the Ply-dependent activation of the NLRP3 inflammasome. However, cytolytic activity in the D39 background was found to induce increased expression of the genes encoding GM-CSF (CSF2), p19 subunit of IL-23 (IL23A) and IFNβ (IFNB1) compared to non-cytolytic and Ply-deficient D39 mutants, but had no effect in the A0229467 background. The impact of Ply on the immune response to the pneumococcus is highly dependent on the strain background, thus emphasising the importance of the interaction between specific virulence factors and other components of the genetic background of this organism.
    PLoS ONE 01/2014; 9(8):e103625. · 3.53 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A significant human pathogenic bacterium, Streptococcus pneumoniae was recognized as a major cause of pneumonia, and is the subject of many humoral immunity studies. Diagnosis is generally made based on clinical suspicion along with a positive culture from a sample from virtually any place in the body. But the testing time is too long. This study is to establish a rapid diagnostic method to identification of Streptococcus pneumoniae.
    Journal of thoracic disease. 09/2014; 6(9):1193-1199.

Full-text (2 Sources)

Download
21 Downloads
Available from
May 20, 2014