Strategy using a new antigenic test for rapid diagnosis of Streptococcus pneumoniae infection in respiratory samples from children consulting at hospital

Abstract

Background: Despite vaccination programs, Streptococcus pneumoniae remains among the main microorganisms involved in bacterial pneumonia, notably in terms of severity. The prognosis of pneumococcal infections is conditioned in part by the precocity of the diagnosis. The aim of this study was to evaluate the impact of a Rapid Diagnostic Test (RDT) targeting cell wall polysaccharide of Streptococcus pneumoniae and performed directly in respiratory samples, on the strategy of diagnosis of respiratory pneumococcal infections in children. Results: Upper-respiratory tract samples from 196 children consulting at hospital for respiratory infection were tested for detecting S. pneumoniae using a newly-designed RDT (PneumoResp, Biospeedia), a semi-quantitative culture and two PCR assays. If positive on fluidized undiluted specimen, the RDT was repeated on 1:100-diluted sample. The RDT was found highly specific when tested on non-S. pneumoniae strains. By comparison to culture and PCR assays, the RDT on undiluted secretions exhibited a sensitivity (Se) and negative predictive value (NPV) of more than 98%. By comparison to criteria of S. pneumoniae pneumonia combining typical symptoms, X-ray image, and culture ≥10 7 CFU/ml, the Se and NPV of RDT on diluted specimens were 100% in both cases. Conclusions: In case of negative result, the excellent NPV of RDT on undiluted secretions allows excluding S. pneumoniae pneumonia. In case of positive result, the excellent sensitivity of RDT on diluted secretions for the diagnosis of S. pneumoniae pneumonia allows proposing a suitable antimicrobial treatment at day 0.

Evaluation of Extraction Methods for Clinical Metagenomic Assay

“…The Gram-negative bacteria Escherichia coli was found in the sample with 23 f. The maximum frequency among all pathogens in the sample was for the Gram-positive bacteria Dolosigranulum pigrum with 85,751 f, followed by the Gram-positive bacteria Rothia mucilaginosa (14,625 f), Actinomyces graevenitzii (12,585 f), and Corynebacterium pseudodiphtheriticum (2429 f), which have been reported to form part of the oropharyngeal flora in opportunistic human pathogen infections [14][15][16]. Three Streptococcus species that are primary inhabitants of the human upper respiratory tract and are also considered to be respiratory pathogens were found in the sample: Streptococcus mitis (758 f), Streptococcus agalactiae (81 f), and Streptococcus pseudopneumoniae (37 f) [17][18][19]. Further tests were done by the hospital on different samples from the patient, and Gram-positive cocci sepsis in the blood and ESBL E. coli from the respiratory sample culture were detected.…”