Unexpected falsely high vancomycin concentrations in a patient with endocarditis during routine therapeutic drug monitoring
Introduction: Vancomycin is a glycopeptide antibiotic indicated for the treatment of infections caused by methicillin-resistant Staphylococcus aureus. Appropriate vancomycin therapeutic drug monitoring is an essential exercise to improve the achievement of the target therapeutic levels. Case descrip...
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| Language: | English |
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SMC MEDIA SRL
2025-06-01
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| Series: | European Journal of Case Reports in Internal Medicine |
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| Online Access: | https://www.ejcrim.com/index.php/EJCRIM/article/view/5464 |
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| author | Laura Galán-Caballero María del Rosario Salas-Butrón Daniel Lozano-Martín Iván Alejandro Díaz-Rengifo Isabel Ortega-Madueño Lucia Diaz-Garcia Ana Isabel Terleira-Fernández |
| author_facet | Laura Galán-Caballero María del Rosario Salas-Butrón Daniel Lozano-Martín Iván Alejandro Díaz-Rengifo Isabel Ortega-Madueño Lucia Diaz-Garcia Ana Isabel Terleira-Fernández |
| author_sort | Laura Galán-Caballero |
| collection | DOAJ |
| description | Introduction: Vancomycin is a glycopeptide antibiotic indicated for the treatment of infections caused by methicillin-resistant Staphylococcus aureus. Appropriate vancomycin therapeutic drug monitoring is an essential exercise to improve the achievement of the target therapeutic levels.
Case description: An 87-year-old female was admitted with diagnosis of endocarditis. She was started on antibiotic therapy with intravenous vancomycin. The first vancomycin level registered in our hospital was 36.4 µg/ml. Because this value exceeded the critical threshold (15–20 µg/ml) the prescription was interrupted. New vancomycin concentration tests were indicated for the next days with 65.8 µg/ml, 73 µg/ml, 55.1 µg/ml, 77.9 µg/ml and 100 µg/ml results. Two samples were reanalysed in Hospital Universitario La Paz and were undetectable. Our Clinical Analysis Department found an analytical interference; however, the responsible molecule could not be identified, so the clinical team changed antibiotic treatment to daptomycin, and the infectious condition of the patient improved.
Conclusions: It is recommended that clinicians have a high index of suspicion to investigate cases where drug concentrations do not correlate with clinical expectations. Healthcare professionals need to understand that occasional interference still occurs due to the binding of proteins. |
| format | Article |
| id | doaj-art-4ddb2a51e82b4f44aaaabdab547c6f21 |
| institution | Kabale University |
| issn | 2284-2594 |
| language | English |
| publishDate | 2025-06-01 |
| publisher | SMC MEDIA SRL |
| record_format | Article |
| series | European Journal of Case Reports in Internal Medicine |
| spelling | doaj-art-4ddb2a51e82b4f44aaaabdab547c6f212025-08-20T03:30:40ZengSMC MEDIA SRLEuropean Journal of Case Reports in Internal Medicine2284-25942025-06-0110.12890/2025_0054644999Unexpected falsely high vancomycin concentrations in a patient with endocarditis during routine therapeutic drug monitoringLaura Galán-Caballero0María del Rosario Salas-Butrón1https://orcid.org/0009-0001-6040-6403Daniel Lozano-Martín2Iván Alejandro Díaz-Rengifo3Isabel Ortega-Madueño4Lucia Diaz-Garcia5Ana Isabel Terleira-Fernández6Department of Clinical Pharmacology, Hospital Clínico San Carlos; IdISSC, Madrid, SpainDepartment of Clinical Pharmacology, Hospital Clínico San Carlos; IdISSC, Madrid, Spain; Department of Pharmacology and Toxicology, Universidad Complutense; IdISSC, Madrid, SpainDepartment of Clinical Pharmacology, Central de la Defensa “Gómez Ulla” Hospital, Madrid, SpainDepartment of Clinical Pharmacology, Hospital Clínico San Carlos; IdISSC, Madrid, SpainDepartment of Clinical Analysis, Hospital Clínico San Carlos, Instituto de Medicina del Laboratorio, Madrid, SpainDepartment of Clinical Pharmacology, IdiPAZ, La Paz University Hospital, School of Medicine, Autonomous University of Madrid, Madrid, SpainDepartment of Clinical Pharmacology, Hospital Clínico San Carlos; IdISSC, Madrid, Spain; Department of Pharmacology and Toxicology, Universidad Complutense; IdISSC, Madrid, SpainIntroduction: Vancomycin is a glycopeptide antibiotic indicated for the treatment of infections caused by methicillin-resistant Staphylococcus aureus. Appropriate vancomycin therapeutic drug monitoring is an essential exercise to improve the achievement of the target therapeutic levels. Case description: An 87-year-old female was admitted with diagnosis of endocarditis. She was started on antibiotic therapy with intravenous vancomycin. The first vancomycin level registered in our hospital was 36.4 µg/ml. Because this value exceeded the critical threshold (15–20 µg/ml) the prescription was interrupted. New vancomycin concentration tests were indicated for the next days with 65.8 µg/ml, 73 µg/ml, 55.1 µg/ml, 77.9 µg/ml and 100 µg/ml results. Two samples were reanalysed in Hospital Universitario La Paz and were undetectable. Our Clinical Analysis Department found an analytical interference; however, the responsible molecule could not be identified, so the clinical team changed antibiotic treatment to daptomycin, and the infectious condition of the patient improved. Conclusions: It is recommended that clinicians have a high index of suspicion to investigate cases where drug concentrations do not correlate with clinical expectations. Healthcare professionals need to understand that occasional interference still occurs due to the binding of proteins.https://www.ejcrim.com/index.php/EJCRIM/article/view/5464vancomycininterferenceimmunoassaytherapeutic drug monitoring |
| spellingShingle | Laura Galán-Caballero María del Rosario Salas-Butrón Daniel Lozano-Martín Iván Alejandro Díaz-Rengifo Isabel Ortega-Madueño Lucia Diaz-Garcia Ana Isabel Terleira-Fernández Unexpected falsely high vancomycin concentrations in a patient with endocarditis during routine therapeutic drug monitoring European Journal of Case Reports in Internal Medicine vancomycin interference immunoassay therapeutic drug monitoring |
| title | Unexpected falsely high vancomycin concentrations in a patient with endocarditis during routine therapeutic drug monitoring |
| title_full | Unexpected falsely high vancomycin concentrations in a patient with endocarditis during routine therapeutic drug monitoring |
| title_fullStr | Unexpected falsely high vancomycin concentrations in a patient with endocarditis during routine therapeutic drug monitoring |
| title_full_unstemmed | Unexpected falsely high vancomycin concentrations in a patient with endocarditis during routine therapeutic drug monitoring |
| title_short | Unexpected falsely high vancomycin concentrations in a patient with endocarditis during routine therapeutic drug monitoring |
| title_sort | unexpected falsely high vancomycin concentrations in a patient with endocarditis during routine therapeutic drug monitoring |
| topic | vancomycin interference immunoassay therapeutic drug monitoring |
| url | https://www.ejcrim.com/index.php/EJCRIM/article/view/5464 |
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