European Journal of Clinical Microbiology & Infectious Diseases

, Volume 28, Issue 1, pp 99–103

Population structure of invasive Streptococcus pneumoniae isolates in Italy prior to the implementation of the 7-valent conjugate vaccine (1999–2003)

  • G. Gherardi
  • F. D’Ambrosio
  • M. Monaco
  • R. Camilli
  • L. De Florio
  • F. D’Ancona
  • G. Dicuonzo
  • A. Pantosti
Brief Report

DOI: 10.1007/s10096-008-0581-8

Cite this article as:
Gherardi, G., D’Ambrosio, F., Monaco, M. et al. Eur J Clin Microbiol Infect Dis (2009) 28: 99. doi:10.1007/s10096-008-0581-8

Abstract

A total of 773 pneumococcal isolates were collected from a nationwide surveillance of invasive pneumococcal diseases during 1999–2003 prior to the implementation of the 7-valent conjugate vaccine (PCV7) in Italy. The isolates included vaccine serotypes (VS, 393 isolates), vaccine-related serotypes (VRS, 93), and nonvaccine serotypes (NVS, 279). The ten most prevalent serotypes were: 14 (16.4%), 3 (8.4%), 23F (8%), 19F (7.4%), 4 (5.9%), 7F (5.8%), 9V (5.3%), 6B (4.9%), 19A (4.7%), and 1 (3.7%). VRS or NVS isolates showed a lower rate of penicillin or drug resistance than VS. Representative isolates of the major VS, VRS, and NVS were genotyped by pulsed field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). The isolates examined were found to belong to 18 international clones and to eight newly described clones. VS isolates sharing clonal groups with VRS or NVS were also detected. Evidence of a past history of capsular switching events was observed in five clones.

Abbreviations

PCV7

7-valent pneumococcal conjugate vaccine

VS

Vaccine serotypes

VRS

Vaccine-related serotypes

NVS

Nonvaccine serotypes

IPD

Invasive pneumococcal diseases

PFGE

Pulsed field gel electrophoresis

PNSSP

Penicillin-nonsusceptible Streptococcus pneumoniae

DR-PSSP

Drug-resistant penicillin-susceptible Streptococcus pneumoniae

DSSP

Drug-susceptible Streptococcus pneumoniae

MLST

Multilocus sequence typing

ST

Sequence type

PMEN

Pneumococcal Molecular Epidemiology Network

Copyright information

© Springer-Verlag 2008

Authors and Affiliations

  • G. Gherardi
    • 2
  • F. D’Ambrosio
    • 1
  • M. Monaco
    • 1
  • R. Camilli
    • 1
  • L. De Florio
    • 2
  • F. D’Ancona
    • 3
  • G. Dicuonzo
    • 2
  • A. Pantosti
    • 1
  1. 1.Dipartimento di Malattie Infettive, Parassitarie ed ImmunomediateIstituto Superiore di SanitàRomeItaly
  2. 2.Dipartimento di Scienze BiomedicheUniversità Campus Bio-MedicoRomeItaly
  3. 3.Centro Nazionale di Epidemiologia, Sorveglianza e Promozione della SaluteIstituto Superiore di SanitàRomeItaly