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Updated: Jan 3, 2026
Experimental Human Pneumococcal Carriage
Published on: February 15, 2013
Identifying pneumococci in parapneumonic pleural effusion: Is there a role for culture-independent methods?
Kauana Pizzutti1, Vinícius P Perez1, Caroline Barbiero2
1Basic Health Sciences, Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, Rio Grande do Sul, Brazil.
Objective:
To evaluate culture-independent procedures (immunochromatography and quantitative polymerase chain reaction [qPCR]) in the detection and susceptibility of Streptococcus pneumoniae directly from culture-negative pleural fluid (PF) in children.
Method:
Detection of S. pneumoniae in PF of children with parapneumonic effusion and/or empyema by using two culture-independent methods: an immunochromatographic membrane test (IMT) which identifies the pneumococcal C antigen, and a real-time PCR test to detect pneumococcal genes lytA and pbp2b, a marker of susceptibility of β-lactam agents, in PF samples.
Results:
We tested 36 PF specimens and recorded the previous use of antimicrobials. In the final analysis, 34 samples were included. IMT and qPCR presented positive results in 23 (67.6%) and 24 (70.6%) of the samples, respectively, showing a moderate agreement (k = 0.518) between the two methods. From the 36 children included, 34 (94.4%) had antibiotic data available by the time when PFs were collected. Thirty-four (100%) children had been given treatment before PF sampling, with 33 (97%) receiving β-lactam antibiotics administered empirically. Of the 24 lytA real-time positive samples, 21 (87.5%) were also positive for pbp2b, a marker of β-lactam susceptibility.
Conclusion:
The reduced sensitivity of culture for pneumococcal detection can be improved through the addition of IMT and qPCR analysis. The utility of qPCR combining detection of lytA and a marker of β-lactam susceptibility should be explored further.
Insights
Culture-independent methods, immunochromatography and quantitative PCR, improve detection of Streptococcus pneumoniae in pediatric pleural fluid. These techniques offer a valuable adjunct to traditional culture methods for diagnosing pneumonia.
Area of Science:
- Pediatric Infectious Diseases
- Microbiology
- Molecular Diagnostics
Background:
- Culture methods for detecting Streptococcus pneumoniae in pediatric pleural fluid can have reduced sensitivity.
- Parapneumonic effusion and empyema are serious conditions in children often caused by S. pneumoniae.
Purpose of the Study:
- To evaluate culture-independent procedures, including immunochromatography and quantitative PCR, for detecting Streptococcus pneumoniae directly from culture-negative pediatric pleural fluid.
- To assess the susceptibility of detected S. pneumoniae to beta-lactam agents.
Main Methods:
- Two culture-independent methods were employed: an immunochromatographic membrane test (IMT) for pneumococcal C antigen and real-time PCR for lytA and pbp2b genes.
- 34 pediatric pleural fluid samples were analyzed, with antibiotic treatment history recorded.
Main Results:
- IMT and qPCR detected S. pneumoniae in 67.6% and 70.6% of samples, respectively, showing moderate agreement.
- Of the S. pneumoniae detected by PCR, 87.5% also showed the pbp2b marker, indicating beta-lactam susceptibility, despite prior antibiotic treatment in 97% of cases.
Conclusions:
- Immunochromatography and qPCR enhance the detection of S. pneumoniae in pediatric pleural fluid compared to culture alone.
- Quantitative PCR, particularly when combined with a marker for beta-lactam susceptibility, warrants further investigation for clinical utility.
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