domingo, 20 de marzo de 2016

Phylogenetic Analysis of Invasive Serotype 1 Pneumococcus in South Africa, 1989-2013. - PubMed - NCBI

Phylogenetic Analysis of Invasive Serotype 1 Pneumococcus in South Africa, 1989-2013. - PubMed - NCBI





 2016 Mar 9. pii: JCM.00055-16. [Epub ahead of print]

Phylogenetic Analysis of Invasive Serotype 1 Pneumococcus in South Africa, 1989-2013.

Abstract

BACKGROUND:

Serotype 1 is an important cause of invasive pneumococcal disease in South Africa and has declined following introduction of the 13-valent pneumococcal conjugate vaccine in 2011.

METHODS:

We genetically characterized 912 invasive serotype 1 isolates from 1989-2013. Simpson's diversity index and recombination ratios were calculated. Factors associated with sequence types (ST) were assessed.

RESULTS:

Clonal complex 217 represented 96% (872/912) of sampled isolates. Post PCV13, ST diversity increased in children <5 years (0.39 to 0.63, p=0.002) and individuals >14 years (0.35 to 0.54, p<0.001): ST-217 declined proportionately in children <5 years [153/203 (75%) vs. 21/37 (57%), p=0.027], and individuals >14 years [242/305 (79%) vs. 96/148 (65%), p=0.001], whereas ST-9067 increased [4/684 (0.6%) vs. 24/228 (11%), p<0.001]. Three sub-clades were identified within ST-217: ST-217C1 (353/382, 92%), ST-217C2 (15/382, 4%) and ST-217C3 (14/382, 4%). ST-217C2, ST-217C3 and single-locus variant (SLV) ST-8314 (20/912, 2%) were associated with non-susceptibility to chloramphenicol, tetracycline and co-trimoxazole. ST-8314 (20/912, 2%) was also associated with increased non-susceptibility to penicillin (p<0.001). ST-217C3 and newly reported ST-9067 had higher recombination ratios compared to ST-217C1 (4.344 vs. 0.091, p<0.001 and 0.086 vs. 0.013, p<0.001, respectively).

CONCLUSIONS:

Increases in genetic diversity were noted post PCV13, and lineages associated with antimicrobial non-susceptibility were identified.
Copyright © 2016 du Plessis# et al.

PMID:
 
26962082
 
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