Evaluation of semi-quantitative compared to quantitative cultures of tracheal aspirates for the yield of culturable respiratory pathogens – a cross-sectional study

Autor: Ghazala Jabeen, Salima Rattani, Qaiser Kash, Joveria Farooqi, Saeeda Chandio, Kauser Jabeen, Aijaz Khan
Jazyk: angličtina
Rok vydání: 2020
Předmět:
Male
Respiratory pathogens
Cross-sectional study
Semi-quantitative culture
Tertiary Care Centers
0302 clinical medicine
Cohen's kappa
Pakistan
030212 general & internal medicine
Child
False Negative Reactions
Respiratory Tract Infections
Respiratory tract infections
Middle Aged
Trachea
Child
Preschool
Female
Quantitative culture
Bronchoalveolar Lavage Fluid
Semi quantitative
Research Article
Tracheal aspirate
Adult
Pulmonary and Respiratory Medicine
medicine.medical_specialty
Adolescent
Concordance
Suction
Gram-Positive Bacteria
Sensitivity and Specificity
Young Adult
03 medical and health sciences
Internal medicine
Gram-Negative Bacteria
medicine
Humans
False Positive Reactions
Bronchitis
Aged
lcsh:RC705-779
business.industry
Infant
Newborn
Infant
Pneumonia
lcsh:Diseases of the respiratory system
Endotracheal suction aspirate
Lower respiratory tract infections
Cross-Sectional Studies
030228 respiratory system
business
Kappa
Zdroj: BMC Pulmonary Medicine, Vol 20, Iss 1, Pp 1-7 (2020)
BMC Pulmonary Medicine
ISSN: 1471-2466
DOI: 10.1186/s12890-020-01311-7
Popis: Background Diagnosis of lower respiratory tract infections (LRTI) depends on the presence of clinical, radiological and microbiological findings. Endotracheal suction aspirate (ETSA) is the commonest respiratory sample sent for culture from intubated patients. Very few studies have compared quantitative and semi-quantitative processing of ETSA cultures for LRTI diagnosis. We determined the diagnostic accuracy of quantitative and semi-quantitative ETSA culture for LRTI diagnosis, agreement between the quantitative and semi quantitative culture techniques and the yield of respiratory pathogens with both methods. Methods This was a cross-sectional study conducted at the Aga Khan University clinical laboratory, Karachi, Pakistan. One hundred and seventy-eight ETSA samples sent for routine bacteriological cultures were processed quantitatively as part of regular specimen processing method and semi-quantitatively. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and diagnostic accuracy was calculated for both methods using clinical diagnosis of pneumonia as reference standard. Agreement between the quantitative and semi quantitative methods was assessed via the kappa statistic test. Pathogen yield between the two methods was compared using Pearson’s chi-square test. Results The quantitative and semi-quantitative methods yielded pathogens in 81 (45.5%) and 85 (47.8%) cases respectively. There was complete concordance of both techniques in 155 (87.1%) ETSA samples. No growth was observed in 45 (25.3%) ETSA specimens with quantitative culture and 37 (20.8%) cases by semi-quantitative culture. The diagnostic accuracy of both techniques were comparable; 64.6% for quantitative and 64.0% for semi-quantitative culture. The kappa agreement was found to be 0.84 (95% CI, 0.77–0.91) representing almost perfect agreement between the two methods. Although semi-quantitative cultures yielded more pathogens (47.8%) as compared to quantitative ETSA cultures (45.5%), the difference was only 2.3%. However, this difference achieved statistical (chi-square p-value Conclusion In conclusion, there is a strong agreement between the performances of both methods of processing ETSA cultures in terms of accuracy of LRTI diagnosis. Semi-quantitative cultures of ETSA yielded more pathogens as compared to quantitative cultures. Although both techniques were comparable, we recommend processing of ETSA using semi-quantitative technique due to its ease and reduced processing time.
Databáze: OpenAIRE
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