P18 Value of pneumococcal PCR in respiratory samples for exclusion of pneumococcal pneumonia

Abstract

Background

Streptococcus pneumoniae is the main aetiological agent in bacterial pneumonia, making it an essential component of respiratory multiplex PCR panels. Despite its relevance, PCR test results are difficult to interpret due to frequent non-pathogenic colonization on the mucosal surface of the upper airways.

Methods

A retrospective study was conducted for lytA-gene results as target for S. pneumoniae in hospitalized patients that were diagnosed with pneumonia and on which a respiratory multiplex PCR panel was performed. Patients were classified as probable, possible or unlikely of having a pneumococcal pneumonia.

Results

No difference in semi-quantitative Ct-values could be observed between the different groups. Sensitivity of 71.4% and specificity of 89.6% was found, corresponding with a negative predictive value and positive predictive value of 97.6% and 34.2%, respectively, when considering probable versus possible/unlikely.

Conclusions

We conclude that a negative qPCR for the lytA-gene is a good marker for the inability to culture S. pneumoniae in a respiratory sample and is possibly sufficient to exclude S. pneumoniae as a causative agent, due to which we can regard it as a relevant addition to a syndromic multiplex PCR panel.