Shahin Oftedah, Australia
NSW Pneumococcal Reference Laboratory Institute of Clinical Pathology and Medical Research, NSW Health PathologyAuthor Of 1 Presentation
GENOMICS ILLUMINATES RISK FACTORS FOR RECURRENT INVASIVE PNEUMOCOCCAL DISEASE (ID 720)
Abstract
Background
Recurrent invasive pneumococcal disease (rIPD) presents clinical management and diagnostic challenges as the infection may persist because of treatment failure or acquisition of a new strain of Streptococcus pneumoniae. This study aimed to characterise rIPD and differentiate cases of endogenous relapse over new exogenous infections.
Methods
A total of 50 rIPD episodes diagnosed >31 days apart (105 isolates) were investigated. All isolates were serotyped and subjected to whole genome sequencing.
Results
The same causal serotype was documented in 28 episodes. The majority of genomes associated with these relapses (25/28) had high homology (0-13 single nucleotide polymorphisms (SNPs)) between core genes, compared to rIPD caused by a different serovar (>1000 SNPs). The time between rIPD episodes was a predictor of relapse, with a significantly shorter time period between IPD infections (median time 11 months versus 1.5 years, P=0.0034). However, the acquisition of point mutations or mobile elements enabling resistance only occurred in three relapse cases.
Conclusions
Genomic comparisons of pneumococci associated with rIPD improved differentiation between relapse and reinfection, compared to traditional serotyping and streamlined follow-up investigations. High core genome and resistome homology were detected in relapse cases suggesting that the development of antibiotic resistance did not play a major role in rIPD.