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
 · 
104 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: The study of the contacts of patients with tuberculosis has a long history. Where tuberculosis is endemic, regular recruitment of tuberculosis cases and their household contacts can be done for research and strategic intervention. This recruitment provides a platform whereby host, pathogen, and environmental factors related to tuberculosis can be investigated and new interventions can be assessed. We describe the types of study possible within a tuberculosis case-contact study platform and its essential components, including recruitment and follow-up of the patients with tuberculosis, their household contacts and community controls, assessments and sampling, and data management and processing. Sample handling and storage, local engagement, ethical challenges, and the strengths and weaknesses of study design are all important issues in case-contact research. A case-contact study platform is a powerful research tool to answer fundamental questions in tuberculosis and has relevance to the study of other major infectious diseases.
    The Lancet Infectious Diseases 10/2010; 10(10):723-32. · 19.97 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: BACKGROUND:: We aimed to determine whether serotype 1 (SP1) invasive pneumococcal disease (IPD) can be distinguished by demographic, clinical and laboratory characteristics from IPD caused by the other most common serotypes (MCS) in our region: 5, 14, 6A, 6B, 19A, 19F, 23F. METHODS:: Data for all IPD episodes in children <18 years old treated at the Soroka University Medical Center during 2000-2009 were retrospectively retrieved. Episodes caused by SP1-IPD were compared with those caused by MCS-IPD (both grouped and individual serotypes). Analyses were adjusted for age and ethnicity. RESULTS:: 94 SP1-IPD and 250 MCS-IPD episodes were documented. SP1-IPD cases were older (68.3 ± 52.6 months vs.30.4 ± 39.2 months; P< 0.001) and more likely to be found in Bedouin children than MCS-IPD (87.5% vs. 58.6%; P< 0.001). SP1 was less frequently isolated from patients with underlying disease than MCS (14.9% vs. 31.6 %; P< 0.001; RR 0.15 [95% CI: 0.07-0.32]). SP1 was more often associated with bacteremic pneumonia and primary peritonitis than MCS (70.2% vs. 38.4% and 7.4% vs. 0.8%, respectively; P< 0.001); the proportion of bacteremia without focus was higher in MCS-IPD (32.3% vs. 12.5 %; P< 0.001). There were no differences in hospitalization and mortality rates (70.2% vs. 68.0% [P = 0.22] and 4.3% vs. 5.6% [P = 0.26], respectively). CONCLUSIONS:: SP1 was found less frequently than MCS in children with underlying diseases, but was more frequent in older and Bedouin children with IPD. SP1was more frequently associated with bacteremic pneumonia and primary peritonitis than MCS grouped.
    The Pediatric Infectious Disease Journal 01/2013; · 3.57 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Pneumococcal vaccination has become obligatory due to the enormous burden of pneumococcal diseases. Quite recently, pneumococcal conjugate vaccines have been developed, and have been shown to be superior to the previous polyvalent polysaccharide vaccine of the organism. Pneumococcal conjugate vaccines (PCVs) are being introduced in many West African countries and it is important to understand the expected performance, relevance, and limitations of these vaccines in the subregion. The objective of the study presented here was to provide epidemiological insights into PCVs in West Africa based on the prevailing pneumococcal serotypes in the subregion. A systematic review was carried out on pneumococcal serotypes causing invasive and noninvasive diseases in West Africa. Studies included in the review were those that reported at least 20 serotyped pneumococcal isolates and which were conducted prior to the introduction of PCVs in the region in 2009. The proportion of pneumococcal disease associated with each serotype as well as the serotype coverage of various PCVs (PCV7, PCV10, and PCV13) were calculated. The data covered 718 serotyped pneumococcal isolates from six West African countries: Burkina Faso, Ghana, Nigeria, Mali, Senegal, and The Gambia. The 718 isolates covered more than 20 serotypes. Serotype 1 was the most prevalent serotype (32%), followed by serotype 5 (15%), serotype 6 (7%), serotype 2 (6%), serotype 3 (6%), and serotype 12 (5%). The estimated serotype coverage of PCVs among the West African countries was 2%-36% for PCV7, 39%-80% for PCV10, and 65%-87% for PCV13. A pneumococcal capsular vaccine for use in West Africa must contain serotypes 1 and 5, the most important serotypes responsible for pneumococcal disease in the region. Consequently, while PCV10 and PCV13 are generally suitable for use in West Africa, PCV7 is unsuitable.
    International Journal of General Medicine 01/2013; 6:757-64.

Full-text (2 Sources)

View
19 Downloads
Available from
May 20, 2014