Carriage of Neisseria meningitidis by Greek children: risk factors and strain characteristics.

Oropharyngeal swabs were cultured from 554 children aged 2-19 years attending nurseries, primary schools and secondary schools in the central Athens area. A questionnaire was completed to identify risk factors for carriage. Susceptibility to antimicrobial agents was determined by Etest. The genetic relatedness of the strains was examined by pulsed-field gel electrophoresis (PFGE), and isolate serogrouping was performed by slide agglutination. Twenty-two (4%) children were carriers of Neisseria meningitidis; seven isolates belonged to serogroup C, and five to serogroup B. One isolate was resistant to co-trimoxazole, and five showed intermediate resistance to penicillin. DNA analysis of 16 isolates revealed six distinct PFGE patterns. Clusters with indistinguishable PFGE patterns were noted in the same school. More than one serogroup was included in the same clonal group. On multivariate logistic regression analysis, only age > 12 years remained independently associated with the carrier state (odds ratio, 7.96; 95% CI, 2.24-28.33; p < 0.001). Overall, the N. meningitidis carriage rate among Greek schoolchildren increased with age, and the predominant serogroups in the Athens region were groups C and B. These findings may have important implications for future immunisation strategies with conjugate vaccines.