Acute otitis media-causing bacteria before and after the application of the 13-valent pneumococcal conjugate vaccine

Organisms most frequently responsible for acute otitis media (AOM) (Streptococcus pneumoniae and Haemophilus influenzae) are the same in developing countries as in developed ones. In countries that administered the pneumococcal conjugate vaccine, pneumococci decreased as a cause of AOM, but over time began to re-emerge, especially due to strains belonging to serotypes not included in the vaccine. The objective of this work was to document the change generated in the bacteriology of the OMA from the incorporation of the 13-valent pneumococcal conjugate vaccine in 2012 in the official Argentinean calendar. Two prospective, descriptive, cross-sectional studies were carried out prior to the incorporation of the vaccine into the national calendar (May 2009-August 2010), where the population studied was not covered for S. pneumoniae and a subsequent one, where most of the patients were immunized (January 2016-December 2016). We obtained 433 samples from 324 patients in the first period and 461 from 246 patients in the second. A total of 326 bacteria were isolated in the first period and 388 in the second. The microorganisms respectively isolated in both periods were S.pneumoniae (39.5-21.1%), H.influenzae (37.4-44.6%), Moraxella catarrhalis (6.1-7.5%), Staphylococcus aureus (8.6-9.8%), Streptococcus pyogenes (3.0-5.9%), Turicella otitidis (1.8-2.1%), Pseudomonas aeruginosa (0.9-4.1%) and others (2.4-4.9%). Pneumococci belonging to vaccine serotypes suffered a significant decrease, especially 6A, 9V, 14, 18C, 19A, while nonvaccine serotypes increased significantly, particularly 15B, 11A, 7C, 16F, and 22F (AU)