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Development of DNA Microarray for Parallel Detection of Community-Acquired Pneumonia Bacterial Pathogens
N A Sakharnov1, E N Filatova2, M I Popkova3
1PhD, Senior Researcher, Laboratory of Molecular Biology and Biotechnology; Academician I.N. Blokhina Nizhny Novgorod Scientific Research Institute of Epidemiology and Microbiology of Rospotrebnadzor (Russian Federal Consumer Rights Protection and Human Health Control Service), 71 Malaya Yamskaya St., Nizhny Novgorod, 603950, Russia.
Insights
A new DNA microarray was developed for rapid detection of common bacterial pneumonia pathogens. This tool enhances laboratory diagnostics by providing efficient and specific identification of Streptococcus pneumoniae and Haemophilus influenzae.
Area of Science:
- Molecular diagnostics
- Microbiology
- Bioinformatics
Background:
- Community-acquired pneumonia (CAP) is a significant global health concern.
- Accurate and rapid identification of bacterial pathogens is crucial for effective treatment.
- Existing diagnostic methods can be time-consuming or lack comprehensive pathogen coverage.
Purpose of the Study:
- To develop and validate an experimental DNA microarray for the parallel detection of key bacterial CAP pathogens.
- To optimize hybridization parameters for efficient and specific pathogen identification.
- To establish threshold values for reliable detection of Streptococcus pneumoniae and Haemophilus influenzae.
Main Methods:
- Design and synthesis of a DNA microarray targeting five CAP pathogens: S. pneumoniae, H. influenzae, M. pneumoniae, C. pneumoniae, and L. pneumophila.
- Optimization of DNA hybridization parameters (fragment size, DNA amount, temperature) using pooled DNA samples.
- Validation of the microarray using clinical samples and ROC analysis to determine signal thresholds.
Main Results:
- A microarray with 142 DNA probes was successfully designed and synthesized.
- Optimal hybridization conditions were identified: 2 μg DNA, 300 nt fragment size, and 47°C.
- Threshold values for S. pneumoniae (4.5 Z) and H. influenzae (4.9 Z) detection were established, demonstrating high efficiency and specificity.
Conclusions:
- The developed DNA microarray enables parallel detection of bacterial CAP pathogens.
- Optimized hybridization parameters and established signal thresholds ensure efficient and specific identification.
- This microarray holds potential for improving laboratory diagnostics of CAP.
Abstract:
The aim of the study was to develop an experimental version of a DNA microarray for parallel detection of community-acquired pneumonia bacterial pathogens.
Materials And Methods:
We studied the samples of the pharyngeal mucosa smears taken from children aged 1-15 years with X-ray confirmed pneumonia. The selection of DNA probes for specific detection of community-acquired pneumonia pathogens (S. pneumoniae, H. influenzae, M. pneumoniae, C. pneumonia, and L. pneumophila) and development of the microarray design were carried out using the disprose program. The nucleotide sequences of pathogens were obtained from NCBI Nucleotide database. In the research we used CustomArray microarrays (USA). For a pooled sample containing S. pneumoniae and H. influenzae DNA, we performed a sequential selection of the best combinations of hybridization parameters: DNA fragment size, DNA amount, hybridization temperature. The selection criteria were: the percentage of effective probes with a standardized hybridization signal (SHS) ≥3 Z, and the excess of SHS levels of effective specific probes compared to SHS of effective nonspecific probes. We selected the probes to detect of S. pneumoniae and H. influenzae characterized by an effective hybridization signal under optimal conditions. The developed microarray was tested under the selected conditions on clinical samples containing S. pneumoniae or H. influenzae DNA. Using ROC analysis there were established threshold values for the signals of specific probes at optimal sensitivity points and the test specificity, the excess of which was interpreted as the evidence of pathogen presence in a sample.
Results:
A microarray design included 142 DNA probes to detect S. pneumoniae, H. influenzae, M. pneumoniae, C. pneumoniae, and L. pneumophila, the probes being synthesized onto slides. Using the example of clinical samples containing S. pneumoniae and/or H. influenza DNA, we selected optimal parameters for DNA hybridization on microarrays, which enabled to identify bacterial pathogens of community-acquired pneumonia with sufficient efficiency, specificity and reproducibility: the amount of hybridized DNA was 2 μg, the DNA fragment size: 300 nt, hybridization temperature: 47°C. There was selected a list of probes for specific detection of S. pneumoniae and H. influenzae characterized by an effective hybridization signal under the identified conditions. We determined the threshold values of standardized probe signals for specific detection of S. pneumoniae (4.5 Z) and H. influenzae (4.9 Z) in clinical samples.
Conclusion:
A DNA microarray was developed and synthesized for parallel indication of bacterial pathogens of community-acquired pneumonia. There were selected the optimal parameters for DNA hybridization on a microarray to identify bacterial pathogens - S. pneumoniae and H. influenzae, and determined the threshold values of significant probe signals for their specific detection. The interpretation of the microarray hybridization results corresponds to those obtained by PCR. The microarray can be used to improve laboratory diagnostics of community-acquired pneumonia pathogens.
