Characterization of invasive serogroup Y meningococci in Italy: prevalence of ST-23 Complex/Cluster A3

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Cecilia Fazio1, Arianna Neri, Stefania Starnino

  • 1Department of Infectious, Parasitic and Immune-mediated Diseases, Istituto Superiore di Sanità, Viale Regina Elena, 299-00161 Rome, Italy.

The New Microbiologica
|January 7, 2009
PubMed

Insights

Invasive meningococcal disease (IMD) caused by Neisseria meningitidis serogroup Y increased in Italy. The ST-23 complex/Cluster A3 clonal group dominated, with a shift to ST-3171 and emerging penicillin resistance.

Area of Science:

  • Microbiology
  • Epidemiology
  • Genetics

Background:

  • Neisseria meningitidis serogroup Y caused an increase in invasive meningococcal disease (IMD) in Italy between 1998 and 2006.
  • Understanding the genetic and phenotypic characteristics of these isolates is crucial for disease surveillance.

Purpose of the Study:

  • To investigate the phenotypic features and genetic relatedness of serogroup Y Neisseria meningitidis strains isolated from IMD cases in Italy from 1998 to 2006.
  • To characterize the dominant clonal complex and identify any emerging genetic or resistance patterns.

Main Methods:

  • Multilocus sequence typing (MLST) was used to determine the genetic relatedness of the isolates.
  • Phenotypic characterization included serotyping and antimicrobial susceptibility testing.
  • Pulsed-field gel electrophoresis (PFGE) was employed to assess strain similarity.

Main Results:

  • The ST-23 complex/Cluster A3 was the predominant clonal complex, accounting for 88.8% of strains.
  • Sequence type (ST) 23 was prevalent from 1998-2004, followed by ST-3171 (differing by one nucleotide in the pgm gene) in 2005-2006.
  • Over 80% of ST-23 complex/Cluster A3 strains exhibited the Y:14:NST phenotype, with 85% being indistinguishable by PFGE.
  • Decreased penicillin susceptibility was first observed in 2005 and noted in three of seven strains in 2006.

Conclusions:

  • A molecular profile of invasive serogroup Y Neisseria meningitidis in Italy was established.
  • The findings highlight the dominance of the ST-23 complex/Cluster A3 and the emergence of penicillin resistance.
  • This characterization will aid in monitoring the future spread of this serogroup.

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