Neisseria meningitidiscan cause life-threatening invasive infections. Although the incidence in Israel is not high (annual incidence less than 1/100,000), the public health impact is significant.
N. meningitidisis a notifiable disease and isolates are sent regularly to the National Center for Meningococci for confirmation and serogrouping. Since 2007, confirmed isolates have been genotyped at the Molecular Epidemiology Laboratory of the Ministry of Health.
All invasiveN. meningitidisisolates from 2007-2013 (273 strains) were analyzed by multi-locus sequence typing (MLST). A high diversity of 85 different Sequence Types (STs) including 36 new STs was identified. Group distribution was: 73.6% Group B, 11.7% Group Y, 7.7% Group C, 4% Group W135, 1.1% Group A and 1.8% non-groupable.
The 6 most prevalent STs were ST-32 (23.1%), ST-23 (9.9%), ST-207 (5.1%), ST-35 (4%), ST-162 (3.7 %) and ST-146 (3.7%). The remaining 79 STs had 1-5 representatives each, 55 STs had 1 representative. The isolates resolved into 20 different clonal complexes, main ones being ST-32 complex (29%), ST-41/44 complex (21%), ST-23 complex (12%), ST-11 complex (5.1%) and ST-162 complex (3.7%). For 8% of the STs a clonal complex was not assigned. The top six clonal complexes comprised 80% of all isolates. PFGE analysis was performed on isolates and controls in suspected outbreaks.
The distributions of STs and clonal complexes showed differences between the meningococcal population in Israel and those in Europe. Genotyping is essential for tracking virulent strains, planning preventive measures, establishing epidemiological investigations and undertaking interventions such as antibiotic prophylaxis and immunization.
