Dominance of Multidrug-Resistant Denmark¹⁴-32 (ST230) Clone AmongStreptococcus pneumoniaeSerotype 19A Isolates Causing Pneumococcal Disease in Bulgaria from 1992 to 2013

Abstract

A pneumococcal conjugate vaccine (PCV10) was introduced in Bulgarian national immunization program since April 2010. Clonal composition based on pulsed-field gel electrophoresis and multilocus sequence typing genotyping of 52 serotype 19A Streptococcus pneumoniae isolates was analyzed. These were invasive and respiratory isolates collected between 1992 and 2013 from both children (78.8% <5 years) and adults with pneumococcal infections. Multidrug resistance was found in 82.7% of all 19A isolates. The most prevalent genotype (63.5%) among serotype 19A pneumococcal strains was the multidrug-resistant clonal complex CC230, which is a capsular switched variant of the Denmark(14)-32 (ST230) global clone. The most frequent sequence type (ST) was ST230 (48.1%) and together with four other closely related STs (15.4%), belonging to ST1611, ST276, ST7466, and ST2013, which were single- and double-locus variants; they were included in the main CC230. The disappearance of highly drug-resistant ST663 clone and emergence of new clones as CC320 and CC199 was also observed among the rest 19A isolates. A comparison of clonal composition between invasive and noninvasive isolates did not show a great genetic diversity among both kinds of isolates. Continuous surveillance of serotype 19A population following the introduction of PCV10 is essential to evaluate the impact of the vaccine on the epidemiology of this serotype.

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

“…These lineages related to major international clones that have different distributions over the world. CC156 has a minor representation among serotype 19A pneumococci, and this has not changed significantly under PCV pressure [6, 7, 13, 18, 21]. The same was true for the PMEN clone Colombia 23F -26, to which our ST663 clonal group was attributed by the eBURST analysis [6, 18].…”

Serotypes and Clonal Diversity of Streptococcus pneumoniae Causing Invasive Disease in the Era of PCV13 in Catalonia, Spain

“…Also interesting, serotype 24F was the second most common serotype in children less than 2 years old during the study period when analyzing the results by age groups. The major clone detected in serotype 24F was ST230, a multidrug resistant clone related with the increase of serotype 19A in Bulgaria, Portugal and in our geographical area [ 29 , 31 , 32 ]. A previous study conducted in our area also observed an increase in the rate of serotype 24 several years after PCV7 introduction associated with the clonal expansion of this genotype [ 33 ].…”

Emerging non-PCV13 serotypes of noninvasive Streptococcus pneumoniae with macrolide resistance genes in northern Japan

“…Serotype 19A has been recognized as a multidrug-resistant type in the United States [22] , [23] , [24] and Europe during the PCV7 era [25] , [26] . Also in Japan, as demonstrated in the present study, serotype 19A emerged as a dominant serotype after PCV7 introduction, showing the highest rate of isolates with both erm (B) and mef (A/E) among all the serotypes.…”