Surveillance of invasive Neisseria meningitidis with a serogroup Y update, Sweden 2010 to 2012

Area of Science:

• Microbiology
• Epidemiology
• Molecular typing

Background:

• An increasing trend of invasive meningococcal disease (IMD) caused by Neisseria meningitidis serogroup Y has been observed in Sweden since 2005 and across Europe.
• Serogroup Y strains have become a significant cause of IMD in Sweden.

Purpose of the Study:

• To describe the epidemiology of invasive N. meningitidis isolates in Sweden from 2010 to 2012, with a specific focus on serogroup Y.
• To evaluate optimal molecular typing schemes for IMD surveillance and outbreak investigations.

Main Methods:

• Epidemiological data and genetic characterization of 208 invasive N. meningitidis isolates from Sweden (2010-2012).
• Analysis included serogroup determination, multilocus sequence typing (MLST), and characterization of specific genes (porB, fHbp, penA, FetA).
• Evaluation of highly variable multilocus variable-number tandem repeat analysis (HV-MLVA) for outbreak investigations.

Main Results:

• Serogroup Y predominated, with its proportion increasing annually from 2010 to 2012 (38.6% to 48.9%).
• Invasive isolates of serogroup Y showed genetic clonal expansion, with specific sequence types and allele profiles (e.g., ST-23).
• FHbp (fumarate and ஹெச் (h) binding protein) typing is suggested as a replacement for FetA typing, and HV-MLVA proved effective for rapid small outbreak investigations.

Conclusions:

• Serogroup Y remains a dominant cause of IMD in Sweden, exhibiting clonal expansion.
• FHbp typing is a viable alternative to FetA typing for meningococcal surveillance.
• HV-MLVA is a rapid and effective tool for initial investigations of small meningococcal outbreaks.