Epidemiological analysis of pneumococcal serotype 19A in healthy children following PCV7 vaccination

Abstract

After the introduction of conjugate vaccines, a strong rearrangement of pneumococcal serotypes was observed globally. Probably most concerning was the emergence of serotype 19A, which has not only high invasive disease potential, but also high antibiotic resistance. In the current study we focused on the increased prevalence of serotype 19A after the PCV vaccination rate became widely used in Hungary. A total of 2262 children aged 3-6 years were screened for pneumococcus carriage using nasal swabs. Children were divided into two groups according to the vaccination rates, low level (group 1) vs. high level (group 2). While the carriage rate did not change over time (average 32·9%), the serotype distribution differed greatly in the two groups. The prevalence of serotype 19A increased>eightfold. Almost all 19A isolates had high-level macrolide resistance and elevated penicillin minimum inhibitory concentrations. Genotyping methods revealed that these new 19A isolates are different from the previously frequent Hungary19A-6 PMEN clone. Both the carriage rate and the overall penicillin and macrolide resistance remained stable over time, but while several serotypes were represented in group 1, serotype 19A alone was clearly dominant in group 2.

Molecular characterization of Streptococcus pneumoniae, particularly serotype19A/ST320, which emerged in Krasnoyarsk, Russia

“…The first small‐scale PCV7 trial in Krasnoyarsk resulted in serotype replacement with global, MDR ST320/serotype19A (Fig. S3), which is consistent with previous findings . Nasopharyngeal colonization precedes any type of pneumococcal disease, including AOM.…”

“…PCV7 serotypes in HC, such as 23F and 19F, were controlled by administration of PCV7; the number of serotypes/serogroups changed from eight (23F, 19F, 15AF, 23A, 14, 6, 35AC/42 and 18) to five (19A, 15BC, 6, 35AC/42 and 11AD) (Fig. ), but with prominent emergence of the non‐PCV7 serotype 19A, confirming PCV7‐related serotype replacement over the two‐year period . There were no non‐encapsulated strains.…”

Co-carriage of Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis among three different age categories of children in Hungary

“…Most importantly, a clear decrease in PCV13 serotypes could be observed in parallel to the increasing PCV vaccination rates. It fell from an initial 57.3% in the pre-PCV7 era to 32.5% in the post-PCV7-pre-PCV13 era (40), and further to 6.2% in the post-PCV13 era (current report).…”

“…Here, we also found a negative association between S. pneumoniae carriage and exposure to passive smoking (Table 3). Interestingly, we have found earlier that a much higher percentage of the serotype 19A carriers were exposed to passive smoking, although this was not statistically significant [40].…”

“…We could follow pneumococcal carriage along with the changing vaccination situation over the last few years [40]. Although there has been a huge serotype rearrangement in these years, Co-carriage of four respiratory pathogens the carriage rate of children from DCCs remained nearly the same: 34.1% in the pre-PCV7 era and 32.5% in the post-PCV7-pre-PCV13 period.…”