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Updated: Feb 9, 2026

Monitoring Neutrophil Elastase and Cathepsin G Activity in Human Sputum Samples
Published on: May 21, 2021
Sputum sample collected over a period of 5 h: A reliable procedure for early bactericidal activity studies
Cristina Paula do Nascimento1, David Jamil Hadad1, Luiz Guilherme Schmidt Castellani1
1Núcleo de Doenças Infecciosas, Universidade Federal do Espírito Santo, Vitória, ES, Brazil, Av. Marechal Campos, Santos Dumont, Vitória, ES, CEP 29040-091.
Abstract:
Our study was designed to test the hypothesis that an early morning sputum may be sufficient for calculation of early bactericidal activity (EBA). Patients underwent sputum collection randomly (spot, 5 h and 12 h) in consecutive days. The median CFU count in the spot samples group was 5.67 log10 CFU/mL compared to 6.17 log10 CFU/mL in 5 h and 6.23 log10 CFU/mL in 12 h samples. Inter-patient comparison showed low coefficient of variation for both 12 h (11%) and 5 h samples (10%). Intrapatient samples analysis demonstrated that the median bacillary load variation (0.037 log10 CFU/mL and 0.022 log10 CFU/mL for 5 and 12 h samples respectively) was comparable to the other EBA studies and did not vary significantly from one day of collection to another. We concluded that 5 h pooled sputum when collected appropriately in the morning can be sufficient for calculation of EBA.
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