Background. It has been previously shown that study of susceptibility of nasopharyngeal isolates in healthy carriers can predict resistance in clinical isolates. The purpose of this multicenter study was to determine the carriage rate of Streptococcus pneumoniae in healthy children attending day-care centers in Moscow, Smolensk and Yartsevo, Russia, and in vitro activity of penicillin G, amoxicillin/clavulanate, cefaclor, erythromycin, roxithromycin, clarithromycin and trimethoprim-sulfamethoxazole (TMP-SMX) against representative isolates.
Methods. Included in this study were 305 pneumococcal isolates from 733 children attending 9 day-care centers in Moscow, Smolensk and Yartsevo. All children enrolled in this study were <7 years of age. MICs of selected antimicrobials were determined by Etest. Serotyping of selected pneumococcal isolates was done with pool and type antisera.
Results. The carriage rate of S. pneumoniae in the 3 centers varied from 44.9% to 66.0% (mean, 55.9%). Susceptibility testing was performed with 305 (74.4%) of 410 isolates. Only 23 (7.5%) of 305 pneumococcal isolates were penicillin-intermediate (range, 2.8 to 12.8%) with no penicillin-resistant strains. All tested pneumococci were susceptible to amoxicillin/clavulanate. Macrolides possessed comparable activity against S. pneumoniae, at 4.6% resistant strains for both erythromycin (range, 1.1 to 17.1%) and clarithromycin (range, 1.7 to 17.1%). The highest level of resistance was observed with TMP-SMX, 53.4% (range, 43.8 to 70.9%). Of 23 strains 20 (87.0%) with intermediate resistance to penicillin were serotyped. The most prevalent serotype was 14 (5 isolates), followed by serogroups 19 (4) and 23 (4).
Conclusions. Resistance to penicillin, other beta-lactams and macrolides does not seem to be a problem for Russia now. The high level of resistance to TMP-SMX considerably restricts its usage for the treatment of pneumococcal infections.