With the introduction of clinical practice of the 7-valent pneumococcal conjugate vaccine (PCV7 [Prevnar]), there has been a tendency to change the sensitivity spectrum of pneumococci that cause acute otitis media in children.

The aim of the study by M.C. McEllistrem et al. (USA), was a study on the effect of the vaccine on penicillin sensitivity of strains of Streptococcus pneumoniae isolated from children with acute otitis media (ACS). During the period from January 1, 1999 to December 31, 2002, 505 strains were collected, of which 158 were subjected to molecular subtyping.

The study found a tendency to increase the incidence of ACC caused by non-PCV7 serogroups (including serotype 3) during the study period (from 12% in 1999 to 32% in 2002; p less than 0.01), as well as with an increase in the number of doses taken of the vaccine (18% with less than 1 dose vs 35% with 2-4 doses; p less than 0.01 ). At the same time, the incidence of ACC caused by serotypes of the vaccine-related pathogen (including serotype 19A) increased in direct proportion to the number of doses of vaccine received (10% with less than 1 dose vs 19% with 2 4 doses; p = 0.05), but did not change over time, and the frequency of cases caused by the 19F serotype remained unchanged. All strains isolated from serotype 3 were genetically linked, while 88% of isolates belonging to serotypes 19F or 23F were linked to 1 of 3 international clones.

Insensitivity to penicillin among the PCV7 serotypes (variation from 65 to 75%) and non-PCV7 serogroups (variation from 11 to 27%) did not change significantly during the study period. Although there was no change in the sensitivity spectrum of the strains obtained in patients with spontaneous emptying of the middle ear cavity, the frequency of isolation of penicillin-insensitive pneumococci during myringotomy and / or tympanopuncture increased from 73% in 1999 to 53% in 2002 (p = 0.03).

Thus, with the introduction of the vaccine into clinical practice, there has been a significant change in the spectrum of strains causing acute otitis media in children, as well as in the sensitivity of these pneumococci to penicillin. According to some researchers, active use of the vaccine may lead to a decrease in the frequency of isolation of penicillin-insensitive pneumococcal strains with acute otitis media, however, more studies are needed to reliably determine future trends.