Introduction and Proliferation of Multidrug‐ResistantStreptococcus pneumoniaeSerotype 19A Clones That Cause Acute Otitis Media in an Unvaccinated Population

Abstract

The introduction and proliferation of multidrug-resistant Sp19A occurred before the introduction of PCV7. The increasing proportion of antibiotic-resistant Sp19A suggests that antibiotic use plays an important role in the community.

Antimicrobial resistance, penicillin-binding protein sequences, and pilus islet carriage in relation to clonal evolution of Streptococcus pneumoniae serotype 19A in Russia, 2002–2013

“…Besides vaccine use, clonal success of CC320 and other serotype 19A clones is attributed to antibiotic selective pressure [17]. Indeed, in the present study we observed that all CC320 isolates had an MDR phenotype with high β-lactam MICs, which is in agreement with previous studies [6,13,22]. However, in European Russia, CC320 has replaced another highly resistant clone, CC663.…”

“…We found only two CC320-related STs, the identifier ST320 and the new ST9656 that is emerging in Russia. Since our collection has been assembled before the introduction of PCV in the National immunization program in 2014, the genetic structure of serotype 19A pneumococci was evolving in a PCV-independent manner, as it has been reported from some other regions [12][13][14].…”

“…the proliferation of pre-existing minor non-PCV7 serotype pneumococcal populations under vaccine pressure [11]. However, in some territories, for instance, in Israel and South Korea, a rise of serotype 19A was observed in the pre-PCV7 period [12][13][14] suggesting that, in addition to serotype, other bacterial factors might be relevant for the expansion.…”

Current Trends in Streptococcus pneumoniae Infections and Their Treatment

“…The emergence of MDR S. pneumoniae has complicated the treatment of pneumococcal infections [10,11,25,26]. Over the past three decades, pneumococcal strains have emerged worldwide that are not susceptible to b-lactams (penicillin and ampicillin, third-generation cephalosporins such as ceftriaxone and cefotaxime), and other antimicrobial agents such as macrolides (including erythromycin, clarithromycin, and azithromycin), clindamycin, and trimethoprim-sulfamethoxazole (TMP-SMX) [10,11].…”

“…Prior to PCV7 introduction, penicillin-resistance in pneumococci was most commonly associated with serotypes 6A, 6B, 9V, 14, 19A, 19F, and 23F [24]. After PCV7 use, serotype 19A is the most frequent etiology of IPD, but has emerged in unvaccinated population causing acute otitis media (AOM) [25,26].…”