Evolution of pneumococcal serotypes in invasive diseases in Italy in the conjugate vaccine era
Annalisa Pantosti, National Health Institute, Rome
| When |
05 Dec, 2011
from
11:00 am to 12:00 pm |
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Seminar
Title: Evolution of pneumococcal serotypes in invasive diseases in Italy in the conjugate vaccine era
Speaker: Annalisa Pantosti
Affiliation: Head of the Unit of Respiratory and Sistemic Bacterial Diseases, Department of Infectious, Parasitic and Immune-mediated Diseases, Istituto Superiore di Sanità (National Health Institute), Rome
Abstract:
In Italy, pneumococcal conjugate vaccine (PCV7) was licensed in 2001 and slowly implemented in the Regional strategies for vaccination. Through a nation-wide surveillance we followed the changes in the serotypes circulating in invasive infections, and the antibiotic resistance patterns in relation to the introduction of the 7-valent conjugate vaccine. An increasing trend of serotypes not included in PCV-7 was observed, mainly due to an increase in antibiotic-resistant serotypes 19A and 24F and antibiotic-susceptible serotypes 1, 6C, and 7F.
The increase of serotype 19A in Italy was mainly due to expansion of the pre-existing CC199 and CC63 clones and the emergence of CC320. We searched for the pili islets PI-1 and PI-2 and found that their presence was clonally distributed: PI-1 was present in CC199 isolates and both islets in CC320 isolates. The presence of pili could have contributed to the success of serotype 19A isolates.
As for serotype 11A, we have found that strains that are phenotypically 11A, can have a genotypically different capsular locus, corresponding to that described for serotype 11D or for the new serotype 11E. The results of a study of Italian 11A isolates will be presented.
