Serotyping of invasive disease isolates in children under five year old by sequential multiplex PCR in Paraguay

Abstract

Through the implementation of a sequential multiplex PCR with CDC protocol for Latin America, strains of Streptococcus pneumoniae isolated from invasive disease in children under five in Paraguay during the period 2011 to 2013 were serotyped. 58.6% of serotypes were identified in the first PCR reaction, 19.1% in the second, 8.3% in the third, 3.8% in the fourth, 0.6% in the fifth, 3.8% in the sixth, 1.3 % In the seventh and eighth reaction. Total isolates (N = 157) were confirmed by Quellung. Serotype 14 was found with higher prevalence in 33.1% of invasive disease, followed by serotype 3 and 6A with 8.3%; serotype 19F with 7%, with 5.7% serotype 6B and 4.5% with serotype 7F. Since the introduction of pneumococcal conjugate vaccine (PCV10) in Paraguay occurred in 2012, a decrease of isolates of vaccine serotypes is evident as serotypes 1,5, 9V,14, 18C, 19F and 23F. Likewise, an increase in serotypes 3 and 9A could be observed, as well as the appearance of other serotypes not previously seen such as serotypes 9N, 23B, 24F and 38. This may indicate a post vaccine change in the frequency of serotypes.