Performance of Gram Stain, Leukocyte Esterase, and Nitrite in Predicting the Presence of Urinary Tract Infections: A Diagnostic Accuracy Study
Introduction: While urine culture is the gold standard for the urinary tract infection (UTI) diagnosis, delays in results highlight the need for rapid tests. This study aimed to evaluate the accuracy of urine Gram staining, leukocyte esterase, and nitrite in predicting the presence of UTI. Method...
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| Format: | Article |
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Shahid Beheshti University of Medical Sciences
2025-04-01
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| Series: | Archives of Academic Emergency Medicine |
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| Online Access: | https://journals.sbmu.ac.ir/aaem/index.php/AAEM/article/view/2619 |
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| author | Carlos Solorzano Maria Camila Rubio Maricel Licht Ardila Camila Castillo Juan Camilo Valencia Silva Maria Alejandra Caro Edgar Fabian Manrique Hernandez Alexandra Hurtado-Ortiz Liliana Torcoroma García |
| author_facet | Carlos Solorzano Maria Camila Rubio Maricel Licht Ardila Camila Castillo Juan Camilo Valencia Silva Maria Alejandra Caro Edgar Fabian Manrique Hernandez Alexandra Hurtado-Ortiz Liliana Torcoroma García |
| author_sort | Carlos Solorzano |
| collection | DOAJ |
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Introduction: While urine culture is the gold standard for the urinary tract infection (UTI) diagnosis, delays in results highlight the need for rapid tests. This study aimed to evaluate the accuracy of urine Gram staining, leukocyte esterase, and nitrite in predicting the presence of UTI.
Methods: A cross-sectional diagnostic accuracy study was conducted on adult patients undergoing urine culture at a high-complexity hospital in northeastern Colombia. The results of Gram staining and urinalysis (nitrite and leukocyte esterase) were compared to urine culture as the gold standard test, and screening performance characteristics were calculated and reported for individual and combined tests.
Results: A total of 2,123 urine cultures were analyzed, with 49.8% testing positive. Escherichia coli was the most common pathogen (24.7%), and 76.17% of patients received antibiotics, primarily ceftriaxone (38.7%). Gram staining showed 56.9% (95% confidence interval (CI)=54.4 to 59.4) sensitivity and 76.8% (95% CI=72.6 to 80.5) specificity, leukocyte esterase had 67.9% (95% CI= 65.3 to 70.4) sensitivity and 84.5% (95% CI=81.4 to 87.2) specificity, and nitrite demonstrated the highest sensitivity (85.3%, 95% CI=82.0 to 88.2). The combination of Gram staining (+), leukocyte esterase (+), and nitrite (+) achieved 87.6% (95% CI=84.2 to 90.5) sensitivity and 94.6% (95% CI=93.1 to 95.9) negative predictive value (NPV), with the decision tree identifying this combination as having the highest diagnostic utility (positive likelihood ratio (PLR) = 23.77, 95% CI=18.34 to 30.80).
Conclusions: It seems that, integrating urine Gram staining with leucocyte esterase and nitrite improves UTI diagnosis in high-complexity emergency settings, reducing unnecessary urine cultures and antibiotic use while enhancing resource utilization and mitigating bacterial resistance.
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| format | Article |
| id | doaj-art-bd6feaa0b4dc4e429e6ddce289e60e4c |
| institution | OA Journals |
| issn | 2645-4904 |
| language | English |
| publishDate | 2025-04-01 |
| publisher | Shahid Beheshti University of Medical Sciences |
| record_format | Article |
| series | Archives of Academic Emergency Medicine |
| spelling | doaj-art-bd6feaa0b4dc4e429e6ddce289e60e4c2025-08-20T02:09:25ZengShahid Beheshti University of Medical SciencesArchives of Academic Emergency Medicine2645-49042025-04-0113110.22037/aaemj.v13i1.2619Performance of Gram Stain, Leukocyte Esterase, and Nitrite in Predicting the Presence of Urinary Tract Infections: A Diagnostic Accuracy StudyCarlos Solorzano0Maria Camila Rubio1Maricel Licht Ardila2Camila Castillo3Juan Camilo Valencia Silva4Maria Alejandra Caro5Edgar Fabian Manrique Hernandez6Alexandra Hurtado-Ortiz7Liliana Torcoroma GarcíaFundación Cardiovascular de ColombiaFundación Cardiovascular de ColombiaFundación Cardiovascular de ColombiaFundación Cardiovascular de ColombiaFundación Cardiovascular de ColombiaFundación Cardiovascular de ColombiaFundación Cardiovascular de ColombiaFundación cardiovascular Introduction: While urine culture is the gold standard for the urinary tract infection (UTI) diagnosis, delays in results highlight the need for rapid tests. This study aimed to evaluate the accuracy of urine Gram staining, leukocyte esterase, and nitrite in predicting the presence of UTI. Methods: A cross-sectional diagnostic accuracy study was conducted on adult patients undergoing urine culture at a high-complexity hospital in northeastern Colombia. The results of Gram staining and urinalysis (nitrite and leukocyte esterase) were compared to urine culture as the gold standard test, and screening performance characteristics were calculated and reported for individual and combined tests. Results: A total of 2,123 urine cultures were analyzed, with 49.8% testing positive. Escherichia coli was the most common pathogen (24.7%), and 76.17% of patients received antibiotics, primarily ceftriaxone (38.7%). Gram staining showed 56.9% (95% confidence interval (CI)=54.4 to 59.4) sensitivity and 76.8% (95% CI=72.6 to 80.5) specificity, leukocyte esterase had 67.9% (95% CI= 65.3 to 70.4) sensitivity and 84.5% (95% CI=81.4 to 87.2) specificity, and nitrite demonstrated the highest sensitivity (85.3%, 95% CI=82.0 to 88.2). The combination of Gram staining (+), leukocyte esterase (+), and nitrite (+) achieved 87.6% (95% CI=84.2 to 90.5) sensitivity and 94.6% (95% CI=93.1 to 95.9) negative predictive value (NPV), with the decision tree identifying this combination as having the highest diagnostic utility (positive likelihood ratio (PLR) = 23.77, 95% CI=18.34 to 30.80). Conclusions: It seems that, integrating urine Gram staining with leucocyte esterase and nitrite improves UTI diagnosis in high-complexity emergency settings, reducing unnecessary urine cultures and antibiotic use while enhancing resource utilization and mitigating bacterial resistance. https://journals.sbmu.ac.ir/aaem/index.php/AAEM/article/view/2619Urinary Tract InfectionUrine CultureGram StainingLeukocyte Esterase; Sensitivity and Specificity |
| spellingShingle | Carlos Solorzano Maria Camila Rubio Maricel Licht Ardila Camila Castillo Juan Camilo Valencia Silva Maria Alejandra Caro Edgar Fabian Manrique Hernandez Alexandra Hurtado-Ortiz Liliana Torcoroma García Performance of Gram Stain, Leukocyte Esterase, and Nitrite in Predicting the Presence of Urinary Tract Infections: A Diagnostic Accuracy Study Archives of Academic Emergency Medicine Urinary Tract Infection Urine Culture Gram Staining Leukocyte Esterase ; Sensitivity and Specificity |
| title | Performance of Gram Stain, Leukocyte Esterase, and Nitrite in Predicting the Presence of Urinary Tract Infections: A Diagnostic Accuracy Study |
| title_full | Performance of Gram Stain, Leukocyte Esterase, and Nitrite in Predicting the Presence of Urinary Tract Infections: A Diagnostic Accuracy Study |
| title_fullStr | Performance of Gram Stain, Leukocyte Esterase, and Nitrite in Predicting the Presence of Urinary Tract Infections: A Diagnostic Accuracy Study |
| title_full_unstemmed | Performance of Gram Stain, Leukocyte Esterase, and Nitrite in Predicting the Presence of Urinary Tract Infections: A Diagnostic Accuracy Study |
| title_short | Performance of Gram Stain, Leukocyte Esterase, and Nitrite in Predicting the Presence of Urinary Tract Infections: A Diagnostic Accuracy Study |
| title_sort | performance of gram stain leukocyte esterase and nitrite in predicting the presence of urinary tract infections a diagnostic accuracy study |
| topic | Urinary Tract Infection Urine Culture Gram Staining Leukocyte Esterase ; Sensitivity and Specificity |
| url | https://journals.sbmu.ac.ir/aaem/index.php/AAEM/article/view/2619 |
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