Paulo Camargos1, Ana Cristina Fonseca2, Sérgio Amantéa3, Elizabeth Oliveira1, Maria das Graças Benfica4, Chequer Chamone4. 1. Department of Pediatrics, Federal University of Minas Gerais, Medical School, Belo Horizonte, Brazil. 2. Child Health Division, Belo Horizonte Municipal Health Authority, Belo Horizonte, Brazil. 3. Department of Pediatrics, Federal University of Health Sciences of Porto Alegre, Porto Alegre, Brazil. 4. Epidemiology and Diseases Control Division, Public Health System Central Laboratory, Ezequiel Dias Foundation, Belo Horizonte, Brazil.
Abstract
INTRODUCTION: The etiological diagnosis of pleural effusion is a difficult task because the diagnostic tools can only establish a definitive etiological diagnosis in at most 76% of cases. OBJECTIVES: To verify the diagnostic accuracy of the latex agglutination test (LAT) for the etiological diagnosis of pleural effusions caused by Streptococcus pneumoniae and Haemophilus influenzae type b. METHODS: After thoracocentesis, paired fresh samples of pleural fluid from 418 children and adolescents were included in this investigation. They were tested blindly and simultaneously through counterimmunoelectrophoresis (CIE) and LAT for both bacteria. Sensitivity, specificity, predictive values and likelihood ratios (LR) were calculated taking CIE as a reference standard. RESULTS: The sensitivity and specificity of LAT was 100% (95% confidence interval, 94.4%-100%) and 83.3% (95% confidence interval, 79.0%-87.0%), respectively, whereas the positive (calculated from Bayes' theorem) and negative predictive values were, respectively, lower than 1% and 100% (95% confidence interval, 98.8%-100%). Positive and negative LR were 6.0 (95% confidence interval, 4.7-7.6) and zero, respectively. CONCLUSIONS: Our results suggest that LAT is a useful tool for the etiological diagnosis of pleural effusion. It is a reliable, rapid, simple to perform and shows an excellent yield in our studied population, helping to prescribe appropriate antibiotics for this clinical condition.
INTRODUCTION: The etiological diagnosis of pleural effusion is a difficult task because the diagnostic tools can only establish a definitive etiological diagnosis in at most 76% of cases. OBJECTIVES: To verify the diagnostic accuracy of the latex agglutination test (LAT) for the etiological diagnosis of pleural effusions caused by Streptococcus pneumoniae and Haemophilus influenzae type b. METHODS: After thoracocentesis, paired fresh samples of pleural fluid from 418 children and adolescents were included in this investigation. They were tested blindly and simultaneously through counterimmunoelectrophoresis (CIE) and LAT for both bacteria. Sensitivity, specificity, predictive values and likelihood ratios (LR) were calculated taking CIE as a reference standard. RESULTS: The sensitivity and specificity of LAT was 100% (95% confidence interval, 94.4%-100%) and 83.3% (95% confidence interval, 79.0%-87.0%), respectively, whereas the positive (calculated from Bayes' theorem) and negative predictive values were, respectively, lower than 1% and 100% (95% confidence interval, 98.8%-100%). Positive and negative LR were 6.0 (95% confidence interval, 4.7-7.6) and zero, respectively. CONCLUSIONS: Our results suggest that LAT is a useful tool for the etiological diagnosis of pleural effusion. It is a reliable, rapid, simple to perform and shows an excellent yield in our studied population, helping to prescribe appropriate antibiotics for this clinical condition.