2315. Neisseria meningitidis Oro-Pharyngeal Carriage, Serogroups and Clonal Complex in Children and Adolescents in Argentina

BACKGROUND: Neisseria meningitidis (Nm) pharyngeal carriage is a necessary condition for invasive meningococcal disease. In 2017, Argentina introduced a tetravalent meningococcal conjugated vaccine (MenACYW) to the National Immunization Program for children. We present the first carriage study in children in the prevaccine era. Aims: 1) to assess the rate of Nm carriage in healthy children and adolescents attending a public hospital in Buenos Aires city; 2) to determine serogroup and clonal complex distribution; 3)to determine carriage risk factors by age. METHODS: Cross-sectional study including children 1–17 years, stratified in two age groups (1–9 years and 10–17 years) assisted at Ricardo Gutiérrez Children Hospital between March-December 2017. Oro-pharyngeal swabs were plated and meningococci identified by conventional microbiology methods. Serogroup was determined by PCR. Clonal complex was determined by MLST. RESULTS: A total of 1751 children were included. Group aged 1–9 years: 38 Nm were isolated from 943 samples collected: overall carriage 4.0%. Serogroups distribution: B 26.3%, Y 2.6%, W 5.3%, Z 5.3%, non-groupable 7.9% and non-capsulated 52.6%. Clonal complex was determined for 25 isolates. Attendance at social venues was the only independent predictor of Nm carriage (adjusted OR: 2.02, CI 95% = 1.01–4.03; P = 0.04). Group aged 10–17 years: 76 Nm were isolated from 808 samples: overall carriage 9.4%. Serogroups distribution: B 19.7%, C 5.3%, W 7.9%, Y 9.2%, Z 5.3%, non-groupable 7.9% and non-capsulated 44.7%. Clonal complex was determined for 58 isolates. Independent predictor of Nm carriage: attendance at night clubs (adjusted OR: 3.38, CI95% = 1.28–8.93; P = 0.013); passive smoking at home (adjusted OR: 0.55, CI 95% = 0.32–0.93; P = 0.025). Preliminary data show a total of 10 different clonal complexes present among all serogroups in the 1–9 years group aged and 13 in 10–17 years. CONCLUSION: Overall carriage was higher in the 10–17 years population. The non-encapsulated Nm was prevalent in both groups and serogroup B was the most frequent among the encapsulated. The results demonstrated a high diversity of N. meningitis in pharyngeal carriage. DISCLOSURES: All authors: No reported disclosures.