Diagnosis of pneumococcal pneumonia using quantitative PCR targeting lytA and piaB in adult patients with community-acquired pneumonia
In brief
qPCR finds only 4% more pneumococcal pneumonia cases than standard tests in adults with CAP
In a prospective study of 251 adults with community-acquired pneumonia, conventional methods identified Streptococcus pneumoniae in 21% of patients, while quantitative PCR of lytA and piaB raised overall detection to 26% but added just 4% of cases not found by standard tests. Overlap in bacterial load between sick and healthy subjects limited the test's diagnostic value, so routine qPCR use is not recommended, though sputum PCR may aid future surveillance.
- Journal
- European journal of clinical microbiology & infectious diseases : official publication of the European Society of Clinical Microbiology (Q1)
- Published
- 3 September 2026
- Study design
- Prospective / inception cohort
- Evidence level
- Level 2, Moderate (CEBM 2b)
- Authors
- Nienke Paternotte, Willem R Miellet, Tessa Nieuwenhuijsen, Rob Mariman, Wil A van der Reijden, Wouter Rozemeijer, et al.
- PMID
- 42690274
- DOI
- 10.1007/s10096-026-05655-6
Why clinicians should know about it
- Picked for Microbiology (medical) (paper of the day, 4 September 2026): qPCR for pneumococcal pneumonia detection
Abstract
PURPOSE: Accurate diagnosis of pneumococcal pneumonia remains challenging due to suboptimal sensitivity of conventional microbiological methods. Molecular techniques may improve Streptococcus pneumoniae detection, but their clinical utility remains uncertain. METHODS: In this prospective observational study, we compared conventional diagnostics with qPCR-based detection of lytA and piaB genes in nasopharyngeal, oropharyngeal, saliva, and sputum samples collected from adults with community-acquired pneumonia (CAP) and three control groups without acute respiratory symptoms. Stringent sample-specific cut-offs (lowCq), defined by the lowest cycle threshold (Cq) values observed among controls, were applied to reduce classification of background carriage as pneumococcal CAP. RESULTS: S. pneumoniae was detected by conventional methods in 53 (21.1%) of 251 CAP patients. Overall pneumococcal detection by qPCR was higher in CAP patients than in 564 individuals without CAP (35.9% vs. 10.3%, p < 0.001), but pneumococcal density showed substantial overlap between CAP patients and controls and across aetiological groups within the CAP cohort. Using the lowCq criteria, 63 (25.1%) CAP patients met the study definition of pneumococcal CAP (PCAP), including ten (4.0%) identified by qPCR alone. Detection rates and pneumococcal density were highest in sputum and lower in patients pretreated with antibiotics. CONCLUSIONS: qPCR targeting lytA and piaB increased pneumococcal detection in CAP patients, but substantial overlap in pneumococcal density limited its added diagnostic value for PCAP. Using stringent lowCq criteria, qPCR identified only a small number of additional PCAP cases beyond conventional diagnostics. Our findings do not support routine use of qPCR as a stand-alone diagnostic test for PCAP. Nevertheless, sputum-based molecular detection may contribute to future surveillance studies when combined with serotype-specific analyses.
Abstract as published, via PubMed.
For healthcare professionals. The summary is generated by AI from the published abstract, and the evidence level is assigned automatically from the study design on the Oxford CEBM hierarchy. Neither is medical advice. Read the full paper before changing practice.