Monitoring the genotype of meningococcal strains during an endemic period

Abstract

Obioctiie:To monitor the circulation of clones among the most frequent phenotypes of Neisseria meningitidis isolated from sporadic cases in Italy in recent years.Method.: N. meningitidis strains sent to the reference laboratory for meningococcal meningitis of the lstituto Superiore di Sanitir were typed for serogroup, serotype and serosubtype, and chromosomal DNAs were analyled by pulsed-field gel electrophoresis. k s u k Of 185 strains sent during the years 1995-97,75% belonged to serogroup B. Although many different serotypes and subtypes were present, the most common combinations were B14:P1.13, B:4:P1.13, B15P1.7 and C2bP1.2. PFGE analysis of patterns obtained by using Nhel and Bg/H enzymes showed a quite stable genomic structure, except in the phenotype B:4:P1.13.Conclusions: On the basis of serotype and serosubtype analysis of recently isolated meningococci, a great variety of phenotypes has been circulating during these endemic years. A clonal structure in strains belonging to the same phenotypes was found, suggesting that some favorable conditions have led to stability of these highly transmissible strains.

Serotype Distribution, Antibiotic Susceptibility, and Genetic Relatedness ofNeisseria meningitidisStrains Recently Isolated in Italy

“…The mean national incidence rate of meningococcal disease in the studied period was 0.4 cases per 100,000 persons, a figure slightly higher than the figures observed in previous years [18]; however, the rates differed regionally, ranging from a minimum of 0.06 cases per 100,000 persons in Sardinia in 1999 to a maximum of 3.22 cases of 100,000 persons in the northeastern provinces of Trento and Bolzano in the same year. Differences in incidence could also be observed among age groups (2.8 cases per 100,000 children aged р4 years, compared with 1.16 cases per 100,000 teenagers aged 15-19 years and 0.28 cases per 100,000 adults aged 45-64 years).…”