18th March, 2016
Infections of S. pneumoniae represent an important public health problem in both industrialized nations as well as those that are less-developed. It is responsible for high mortality and lethality, as it is one of the main causative agents for a large variety of clinical conditions, from benign infections, like otitis media and acute sinusitis, to more severe infections, such as septicaemia, meningitis and pneumonia.
Among the interesting structures of this bacteria is a capsule outside the cell wall, made of complex polysaccharides. This capsule protects the bacterium from phagocytosis and is essential to its virulence. In fact, the non-encapsulated forms of the bacteria are, normally, not virulent.
The antigenic composition of the capsule is variable between the various strains and allows S. pneumoniae to be grouped into over 100 different capsular serotypes and approximately 45 serogroups. Serotypes that present cross-immunogenicity are considered to belong to the same serogroups.
The serotyping of S. pneumoniae is important from a clinical and an epidemiological point of view, to determine the distribution of serotypes causing severe diseases and to estimate the efficiency of vaccines.
The identification of each serotype is made using an antigen-antibody reaction with specific antisera, which results in swelling of the capsule, a phenomenon known as “Quellung”, a German term that means swelling. This method remains as the gold standard, but it is a complex, long and laborious method that requires trained staff, and its use is therefore restricted to qualified laboratories.
The new S. PneumoStrip kit is the only test that allows the easy, quick and single identification of 42 different serotypes of S. pneumoniae in DNA samples, extracted from bacterial culture. Among the known serotypes are the 23 included in the most common vaccines available.
The 42 detected serotypes are: 1, 2, 3, 4, 5, 6A, 6B, 6C, 6D, 7F/7A, 8, 9N/9L, 9A/9V, 10A, 10B, 10F/C, 11A/D, 11B, 11C, 11F, 12F, 14, 15B/15C, 17F, 18A, 18B/18C, 18F, 19A, 19F, 20, 22F/22A, 23F, 33F/33A..
1. Easy and single interpretation: the presence of a serotype is determined just by the appearance of a defined line after a single assay.
2. Reliability of detection in multiple infections: as every serotype has a different band, it is possible to differentiate them easily.
3. Quick: the result can be obtained in less that 4 hours.
4. Easy handling: there is no need to highly specialized staff, as it can be done by a technician with basic Molecular Biology skills.
5. Adaptability: the test can be performed manually or using Automation Instruments.
6. All needed reagents are included and they are ready to use.
7. Amplification and hybridization internal controls included.