1519. Identification of Neisseria meningitidis (Nn) Nasopharyngeal Carriage Among Non-Vaccinated Children and Isolations in Invasive Disease (ID) Cases in Argentina 2017.

Background Neisseria meningitides (Nm) cause different types of invasive infections.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.Aims To assess the rate of Nm carriage in healthy children and adolescents attending a public hospital in Buenos Aires city, to determine genogroup and clonal complex distribution,to describe genogroup distribution of Nm isolated from ID in Argentina, during the same period. Methods Between March and December 2017, a single-center, cross-sectional study was performed among 1,751 children 1–17 years old attending Ricardo Gutiérrez Children Hospital in Buenos Aires, Argentina. From oro-pharyngeal swabs, genogroup and clonal complex (CC) were identified. We analyzed Nm ID genogroups data reported to the Regional Surveillance Program (SIREVA II) in the same year. at the same period were relevated. Results 114Nm were isolated from the carriage study, with an overall carriage of 6.5%.Genogroups distribution: B 25(21.9%), W 9(7.8%), Y 7(6.1%), Z 6(5.2%), C 4(3.5%), non-groupable 9(7.8%) and non-capsulated (NC)54 (47.3%). 105 Clonal complex (CC) were determined: Genogroup B isolates belonged to ST-41/44, ST-35, ST-32 and ST-865. Genogroup W was associated to ST-11 and ST-35. SIREVA reported 76 strains of Nminvasive infections in 2017, 53.9% meningitis, 11.8% meningitis and sepsis, 22.4% sepsis, and 11.8% others. Genogroupsdistribution: B59.2% (45), W 23.6% (18), C 10.5% (8), Y 6.5% (5). Conclusion Genogroup B is the most frequent cause of ID followed by W in our country. In the pharyngeal carriage study we found that NmNC was prevalent and genogroup B was the most frequent among the encapsulated.Genogroup B CCs detected in our carriage study coincided with those found previously in ID in Argentina. Genogroup W carriage was low and hypervirulent CC ST-11 was detected. Although genogroup Z does not cause ID in our country it was found in carriage. Disclosures All authors: No reported disclosures. [ABSTRACT FROM AUTHOR]