Epidemiologic characteristics, serotypes, and antimicrobial susceptibilities of invasive Streptococcus pneumoniae isolates in a nationwide surveillance study in Lebanon

Abstract

Invasive pneumococcal disease (IPD) associated with Streptococcus pneumonia is a major public health problem worldwide for all age groups, including in Lebanon. Prevention through vaccination remains the most valuable tool to decrease the burden of disease. Pneumococcal conjugate vaccine 7 (PCV7), marketed internationally including in the Middle East and North Africa region for the prevention of IPD, was introduced in Lebanon in 2006, followed by PCV10 and PCV13 in 2010. However, none of these is currently part of the Extended Program of Immunization schedule and published data on IPD incidence, pneumococcal serotypes and vaccine coverage in the region are lacking. The Lebanese Inter-Hospital Pneumococcal Surveillance Program is a surveillance system set up to determine the burden of IPD and the prevalent serotypes responsible. The aim of this prospective 6-year study carried out in 78 hospitals throughout Lebanon was to obtain such data to help health authorities make informed decisions on the implementation of pneumococcal vaccination at the national level. A total of 257 isolates of culture-confirmed Streptococcus pneumoniae were evaluated. Considering all age groups, vaccine coverage was 41.4%, 53.9%, and 67.2% for PCV7, PCV10, and PCV13 serotypes, respectively; for patients <2, 2-5, and >60 years of age, PCV7 coverage was 50%, 51%, and 35%, respectively; PCV10 coverage was 53%, 74%, 45%, respectively; and PCV13 coverage was 63%, 80%, and 68%, respectively. Overall, 17.4% of these isolates were penicillin-G non-susceptible using the latest established breakpoints and mortality occurred in 23.5% of the patients with non-susceptible isolates. In addition, 10.9% of isolates were multi-drug-resistant. The highest mortality rates were observed in the eldest (>60 years of age) and youngest (<2 years of age) patients. The most prevalent invasive serotypes identified were those found in currently available pneumococcal conjugate vaccines, emphasizing the importance of implementing the vaccine in the routine immunization schedule at the national level. Continuation of current surveillance practices will help assess the impact of vaccine implementation on IPD epidemiology, serotype distribution and antibiotic resistance patterns.