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

Abstract

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.MethodsCross-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.ResultsA 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.ConclusionOverall 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.