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Volume 18, Issue 2 (2026)
Iran J War Public Health 2026, 18(2): 1001-1013 |
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Received: 2026/08/2 | Accepted: 2026/08/3 | Published: 2026/07/19
Received: 2026/08/2 | Accepted: 2026/08/3 | Published: 2026/07/19
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Amara Hameed Jasim, Amer Ali Hammadi, Stephen Barton. Comparative Diagnostic Methods: Culture Based and Molecular Approaches for the Identification of Bacterial Respiratory Pathogens. Iran J War Public Health 2026; 18 (2) :1001-1013
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Abstract (71 Views)
Background: RTIs are one of the major causes of morbidity and mortality in Iraq, but there are limited data available on comparing methods of diagnosis of bacterial pathogens. While conventional culture is time-consuming, it is not always able to detect fastidious organisms, whereas molecular methods can provide rapid and sensitive detection. The study showed the performance of culture, automated identification systems (VITEK® 2) and species specific PCR in the detection of bacterial pathogens in respiratory samples obtained from symptomatic Iraqi patients.
Methods: 180 patients (2–50 years) with symptoms of RTI were recruited for a cross sectional study. Sputum and nasopharyngeal swabs were cultured on blood and MacConkey agar. Colony morphology and Vitek® 2 were used for the identification of isolates. PCR targeting ply (Streptococcus pneumoniae), nuc (Staphylococcus aureus), CW753 (Klebsiella pneumoniae) and EsxA (Mycobacterium tuberculosis ( was done. Chi square tests were used to compare detection rates with a p value of < 0.05 deemed significant.
Results: 180 patients, 150 (83.3%) were confirmed with bacterial infection. By VITEK® 2, K. pneumoniae was most frequent (26.7%), followed by Streptococcus pneumoniae (20.0%) and Staphylococcus aureus (18.7%). PCR detected significantly more Streptococcus pneumoniae (41.3% vs. 20.0%, p < 0.001) and uniquely identified Mycobacterium tuberculosis in 20 cases (13.3%, p < 0.001). More Klebsiella pneumoniae (26.7% vs. 17.3%, p = 0.004) were detected by VITEK® 2, and commensal species (e.g., Streptococcus mitis, Kocuria kristinae., Kocuria varians) were detected that were not covered by PCR. There was a significant association between smoking and chronic diseases (hypertension and diabetes) and infection (p < 0.0001). Single pathogen infections were 57.2% while mixed bacterial viral infections were 18.3%.
Conclusion: PCR is more sensitive for the detection of S. pneumoniae, and can detect M. tuberculosis that would not have been detected by culture. Culture and Vitek® 2 are still important for the detection of Klebsiella pneumoniae, for identification of commensals and for antimicrobial susceptibility testing. Combining molecular and conventional methods is recommended to achieve the best management of bacterial RTIs in healthcare settings in Iraq.
Methods: 180 patients (2–50 years) with symptoms of RTI were recruited for a cross sectional study. Sputum and nasopharyngeal swabs were cultured on blood and MacConkey agar. Colony morphology and Vitek® 2 were used for the identification of isolates. PCR targeting ply (Streptococcus pneumoniae), nuc (Staphylococcus aureus), CW753 (Klebsiella pneumoniae) and EsxA (Mycobacterium tuberculosis ( was done. Chi square tests were used to compare detection rates with a p value of < 0.05 deemed significant.
Results: 180 patients, 150 (83.3%) were confirmed with bacterial infection. By VITEK® 2, K. pneumoniae was most frequent (26.7%), followed by Streptococcus pneumoniae (20.0%) and Staphylococcus aureus (18.7%). PCR detected significantly more Streptococcus pneumoniae (41.3% vs. 20.0%, p < 0.001) and uniquely identified Mycobacterium tuberculosis in 20 cases (13.3%, p < 0.001). More Klebsiella pneumoniae (26.7% vs. 17.3%, p = 0.004) were detected by VITEK® 2, and commensal species (e.g., Streptococcus mitis, Kocuria kristinae., Kocuria varians) were detected that were not covered by PCR. There was a significant association between smoking and chronic diseases (hypertension and diabetes) and infection (p < 0.0001). Single pathogen infections were 57.2% while mixed bacterial viral infections were 18.3%.
Conclusion: PCR is more sensitive for the detection of S. pneumoniae, and can detect M. tuberculosis that would not have been detected by culture. Culture and Vitek® 2 are still important for the detection of Klebsiella pneumoniae, for identification of commensals and for antimicrobial susceptibility testing. Combining molecular and conventional methods is recommended to achieve the best management of bacterial RTIs in healthcare settings in Iraq.
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